inr0225-03_guidelines for network management planning of siae radio equipments - al series_2005

NETWORK ENGINEERING DEPARTMENT

GUIDELINES FOR NETWORK MANAGEMENT PLANNING OF SIAE RADIO EQUIPMENTS - AL SERIES

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Property of Siae Microelettronica all right reserved

Document Code INR.0225

Ver. 03

GUIDELINES FOR NETWORK

MANAGEMENT PLANNING OF

SIAE RADIO EQUIPMENTS

- AL SERIES -



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1 Introduction

The aim of this document is to guide the NMS planner in the design of the DCN for the supervision of a SIAEs AL radio network. First it will be described the AL equipment and the dedicated supervision ports that it can provide. For each port it will be provided the description of the relevant configuration parameters and, when applicable, the default settings that can be used. In the next paragraphs it will be then provided some guidelines about the IP addressing of the equipments, the usage of the serial connections available and the required bandwidth for the supervision channels. Finally it will be provided four case studies where it will be provided some examples of DCN configuration.

2 General description of the AL equipment

In this paragraph it will be provided a general description of the AL equipment for the supervision point of view. The AL equipment supports the SNMP protocol for its remote management. The communication with the remote management centre can be realised by means of several communication channels. Each AL equipment can establish the following management connections: - Connection to a LAN by means of the supervision Ethernet port provided on the Indoor

Unit (IDU). This port can be chosen as 10baseT or 10base2, depending on planning considerations or customer requirements and allows the equipment to be connected to a Local Area Network.

- PPP (Point-to-Point Protocol) connection on the radio port. This connection is realised by means of a dedicated service channel embedded on the radio stream. This channel allows each AL radio equipment to communicate with the AL on the other side of a radio link, without affecting the tributary traffic.

- PPP connection over the serial port LCT. This port is an USB port that allows the direct connection of a PC with the SCT management software for on-site configuration of the equipment.

- PPP connection over the serial port RS2321. Following are listed some usage examples of such connection:

o Remote control of the equipment by means of a MODEM and a link over the telephone switched network.

o Daisy chain connection of IDUs. o Transmission of the management traffic over the service channels of other

suppliers radio links. - PPP connection over a 2Mbs tributary. This connection allows carrying the supervision

traffic over a TS (Time Slot) of a 2Mbs tributary connection of the IDU. This option can be useful in order to reach remote and isolated SIAEs links, exploiting a TS of the tributary traffic.

1 The RS232 port is not available for the AL-Compact configuration ( unit).



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Figure 1

In Figure 1 is shown the AL equipment with its supervision ports and the relevant connections. The processor of the AL equipment works like a Level 3 router on the supervisions IP packets. It needs an IP address for each supervision port and uses a routing table to route traffic between their ports. This means that different sub-networks must be used in order to address AL equipments. From the figure it can be also noted that the ports RS232 and 2Mbs are seen under the same connection by the internal router. This means that the PPP connection can be done alternatively over the RS232 port or over the 2Mbs ports. The connection cannot be associated to both RS232 and 2Mbs ports at the same time. In the next paragraph more details will be provided about the configuration of the AL supervision ports.

2.1 Configuration parameters of the AL supervision ports

The supervision ports of the AL equipment can be configured by means of the SCT software. The configuration window is accessible by means of the menu EquipmentCommunication SetupPort Configuration. This window provides several cards for the configuration of the supervision ports. These cards will be described in the following,

AL

10 Base T/10Base 2RS232/2 Mbs

Tributary

To/from a 10BaseT/10Base 2 LAN

PPP connectionover RS-232 port or

2Mbit/s Tributary

PPP connection overthe embedded 64 Kbit/s

supervision service channel

USBEthernet

PPPConnection to SCT

over USB port



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2.1.1 IP Ethernet

Figure 2

This card allows the configuration of the Ethernet supervision port. The required parameters are the IP Address to be assigned to the port (IP Address) and the relevant sub-network mask (IP NetMask).

2.1.1 PPP Radio

Figure 3



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This card allows establishing a PPP connection over the radio link, by means of an embedded 64kbit/s supervision service channel. The required parameters are the IP Address to be assigned to the port (IP PPP Address) and the relevant sub-network mask (IP PPP NetMask). The field PPP Mode must be always set to Client.

2.1.2 LCT PPP

Figure 4

This port allows establishing a PPP connection over the USB port named LCT on the IDU. This port is used to locally configure the AL by means of the SCT software (e.g., by means of a laptop computer). The required parameters are the IP Address to be assigned to the port (IP PPP Address) and the relevant mask (IP PPP NetMask). In the field PPP Baud Rate can be set the transmission rate of the port. When the SCT terminal is locally connected by means of the LCT port, it automatically receives an IP Address equal to the LCT PPP address plus 1. For example, if LCT PPP is 10.0.1.3, the connected PC will get the address 10.0.1.4. This address must be taken into account, in order to avoid addresses duplication.



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2.1.3 PPP RS232/2Mbps

Figure 5

This card allows the configuration of the PPP connection that can be established, alternatively, over the RS232 port or over one 2Mbs tributary interface. For both the choices there are three common parameters that must be configured: - IP PPP Address: it is IP address of the equipment serial port, for the connection with

other network elements. - IP PPP NetMask: It is the mask for the network address. - PPP Mode: it is the functioning mode of the PPP protocol and can be set to either

Client, Server or Automatic. When this parameter is set to Automatic, the system automatically sets the IP PPP Address of the equipment under examination plus 1 to the element (equipment, PC, etc.) placed at the other line end. If the Automatic setting is not desired, the port can be always set to Client.

- Remote Access Type: It allows detecting the interface type to be used for the port under examination. Two options can be selected:

o RS232: in this case the PPP connection will be established over the RS232 serial interface.

o 2Mbs: in this case the PPP connection will be established over one or more 16Kbit channels of a time slot relevant to one of the 2Mb/s tributaries available for the equipment.

Depending on the Remote Access Type selected, additional configurations are required:

o If Remote Access Type is set to RS232, the PPP communication will be taken over the RS232 port. In this case the designer is required to define the transmission rate of the port, making a choice in the PPP Baud Rate selector (see Figure 5).

o If Remote Access Type is set to 2Mbs, the PPP communication will be taken over a Time Slot of a 2Mbs tributary connection. The capacity assigned to the



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PPP connection can be from a minimum of 16Kbit/s to the maximum capacity of the Time Slot (4x16kbit/s = 64kbit/s). The designer is required to set the parameters relevant to this connection, filling the following field shown in the EOC frame:

2Mbit Selector box: it is pointed out the number of the used tributary. The wording No 2Mb Used points out that the system does not use any tributary.

Slot Selector box: it is pointed out the number of the used time slot. 16 kbit Map box: Through this box the designer can select the 16Kbit/s

sub-channels of the TS to be used for the communication. The equipment located at the other end of the PPP connection must be configured in the same way. Up to four sub-channels can be selected, raising the maximum rate of the Time Slot (64kbit/s).

Figure 6

2.2 Proxy ARP feature

As explained in Paragraph 2, the AL equipment manage the supervision traffic as a Layer 3 router and uses a routing table to route traffic between their ports. This means that it is necessary to sub-net in order to address our equipments and a different sub-network should be used for each connection. For example, looking at Figure 1, four different sub-networks should be used to address the four connections that can be established by the equipment. However, this would waste a lot of IP addresses. In fact, each PPP connection uses 2 IP addresses (one for the AL port involved in the connection and another one to address the port at the other side of the connection). The minimum sub-network size that can be deployed is a four IPs LAN, in which two IPs are available to address network elements, while the other two IPs are reserved because used as sub-network address and broadcast address. This means that to address the AL equipment, a total of 6 IP addresses would be wasted (2 IP for each PPP connection). In order to avoid this, the AL



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equipment has been provided with the Proxy ARP feature (RFC 1027). Proxy ARP is the technique in which one host, usually a router, answers ARP requests intended for another machine. By faking its identity, the router accepts responsibility for routing packets to the real destination. To better clarify the Proxy ARP features we can consider the example of Figure 7.

Figure 7

Let us suppose that Host A (10.0.1.100/24), directly connected to the LAN cloud, needs to send packets to Host B (10.0.1.3/24), connected to the LCT port of the AL equipment. To reach Host B, Host A needs the MAC address (Layer 2 address) of Host B. Both these computers belong to the sub-network 10.0.1.0/24. So, Host A believes that Host B is directly connected to the LAN cloud and sends it an ARP request in order to know its MAC address. This ARP request is encapsulated in an Ethernet frame with Host As MAC Address as the source address and a broadcast as the destination address. Since ARP request is a broadcast, it reaches all the nodes in the LAN cloud, including the ALs LAN port, but does not reach Host B. The broadcast will not reach Host B, because routers, by default, do not forward broadcasts. Since ALs router knows that the target address (10.0.1.3) is on its LCT PPP connection, it will reply with its own MAC address to Host A. The Proxy ARP reply packet is encapsulated in an Ethernet frame with routers MAC address as the source address and Host As MAC address as the destination address. The ARP replies are always unicast to the original requester. On receiving this ARP reply, Host A updates its ARP table associating the IP address 10.0.1.3 to the ALs LAN port MAC address. From now on Host A will forward all the packets that it wants to reach 10.0.1.3 (Host B) to this MAC address. ALs router will receive these packets and it will forward them to Host B, since it knows how to reach Host B.

RADIO

LAN LCT

10.0.1.3/24

10. 0. 1. 6/24

RS23210. 0. 1 .1/24 10. 0. 1. 4/24

10.0.1.5/24

LAN 10.0.1.0/24

Host A

Host B Host C

10. 0. 1. 2/24



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The main advantages of Proxy ARP are the following two: - No IP addresses are wasted to address the ALs PPP connections, because no

dedicated sub-network is requested for them. - It simplifies the routing tables of the ALs equipments. In fact, the routing table of each

equipment should be able to address all the sub-networks deployed in the management network. Using a single sub-network for each equipment instead of four will save a lot of routing tables rows.

It is worth to note that Proxy ARP will act only between the ALs ports belonging to the same sub-network. In the example of Figure 8 the radio ports IP Address belongs to sub-network 10.0.2.0/24, while the other ports (LAN, LCT and RS232) belong to sub-network 10.0.1.0/24. In this case the Proxy ARP will work only between the ports LAN, LCT and RS232.

Figure 8

2.3 Example: Radio link addressing

Based on the considerations made previously, in this section it is shown an example of radio links addressing.

Figure 9

Figure 9 shows the general principle for the equipments addressing. As already stated, the AL works like a Layer 3 router on the management traffic. So, passing from AL-1 to AL-2 it

RADIO

LAN LCT

10.0.1.3/24

10. 0. 2. 7/24

RS23210. 0. 1 .1/24 10. 0. 1. 4/24

10.0.1.5/24

LAN 10.0.1.0/24 Host B Host C

10. 0. 1. 2/24

LAN A AL - 110B aseT LAN BAL - 2 10BaseT



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is required to pass through two different sub-networks (LAN A and LAN B). In this example, we can suppose LAN A with sub-network address 10.0.1.0/24 and LAN B with sub-network address 10.0.2.0/24.

Figure 10

One possible addressing scheme is shown in Figure 10. As can be seen, all the IP addresses of AL-1 belong to LAN A. Proxy ARP will be active between all the ports of this equipment. All the AL-2 addresses belong to LAN B, apart from the radio address, which again belongs to LAN A. In this case, Proxy ARP will be active between LAN, RS232 and LCT ports, but will not be active on the radio port. So, we have deployed 5 IPs belonging to LAN A and 3 IPs of LAN B. However, we have to consider two additional IP addresses for each station, to take into account the IPs assigned to a network element if connected to the LCT port or to the RS232 port. Looking at Figure 11, if a PC running the SCT software is connected to the LCT port it will be automatically configured to the address 10.0.1.3/24. In addition, if a network element is connected to the RS232 port, it will use an IP address of the network 10.0.1.0/24, for example 10.0.1.5/24. This two addresses, 10.0.1.3/24 and 10.0.1.5/24 cannot be used by other network elements in LAN A, in order to avoid address duplication. So, we are busying a total number of 7 IP addresses of LAN A. For the same reason, a total number of 5 LAN Bs IP addresses are busied for AL-2 addressing. The designer must be careful to take into account all the IP addresses busied by the equipment. An aid to this job can come from Table 1, where are reported the IP addresses deployed for AL-1 of Figure 10. Filling such a table for each equipment can be useful to take into account all the IP addresses required by the management network.

LANLCT

10. 0. 1. 7/24

RS23210. 0. 2. 1/2410. 0. 2 .4/24 10. 0. 2. 2/24

RADIO

LAN LCT

10. 0. 1. 6/24

RS23210. 0. 1. 4/2410. 0. 1 .1/24 10. 0. 1. 2/24

Station A Station B

AL-1 AL-2RADIO

LAN A 10.0.1.0/24

LAN B 10.0.2.0/24



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PORT IP ADDRESS MASK LAN 10.0.1.1 255.255.255.0

RADIO 10.0.1.6 255.255.255.0 LCT 10.0.1.2 255.255.255.0

RS232/2Mbs 10.0.1.4 255.255.255.0 RADIO remote 10.0.1.7 255.255.255.0

PC on LCT 10.0.1.3 255.255.255.0 Element on RS232/2Mbs 10.0.1.5 255.255.255.0

Table 1: IP addresses table for AL-1 equipment of Figure 10.

This addressing scheme can be used as a basic brick for the whole management network. For example, let us consider the addition of a second radio links in daisy chain to AL-1 AL-2, as shown in Figure 11.

Figure 11

As can be seen, 7 new LAN Bs IP addresses are used for AL-3 equipment: 4 directly assigned to the AL-3s ports, 1 assigned to the AL-4s port and two (10.0.2.8/24 and 10.0.2.10/24) for the remote elements that can be connected to LCT and RS232 ports. In conclusion, a total number of 12 LAN Bs IP addresses are busied for the management network. AL-4 is addressed in the same way of AL-2. Therefore, the management network uses 5 IP addresses of LAN C. In the same way, other radio links can be added to the management network.

2.4 IP Unnumbered feature

As shown in the previous paragraphs, the Proxy ARP feature usage allows to simplify the IP addressing of the AL equipments, avoiding the definition of specific sub-networks to address the serial connections. However, a lot of IPs could be required to address the radio equipments. For example, 7 IPs from LAN A must be used in the example of Figure 11. IP Unnumbered is a feature available on SIAE equipments that allows saving IP addresses on the serial connections. The IP unnumbered feature allows enabling IP processing on a serial interface without assigning it an explicit IP address. For routing purposes this interface is seen by the other equipments with the same IP address of the LAN port.

RADIO

LAN LCT

10. 0. 2. 11/24

RS23210. 0. 2. 9/2410. 0. 2 .6/24 10. 0. 2. 7/24

LANLCT

10. 0. 1. 7/24

RS23210. 0. 2. 1/2410. 0. 2 .4/24 10. 0. 2. 2/24

RADIO

LAN LCT

10. 0. 1. 6/24

RS23210. 0. 1. 4/2410. 0. 1 .1/24 10. 0. 1. 2/24

RADIO

LANLCT

10. 0. 2. 12/24

10. 0. 3. 1/2410. 0. 3 .4/24 10. 0. 3. 2/24

Station ALAN A: 10. 0. 1. 0/24

Station BLAN B: 10. 0. 2. 0/24

Station CLAN C: 10. 0. 3. 0/24

AL-1 AL-2RADIO

AL-3

RS232

AL-4



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Figure 12

Figure 12 shows an example of IP addressing using the IP Unnumbered feature. As can be seen, all the LCT ports are set to Unnumbered, while on the radio ports the Unnumbered feature is used for AL-1 and AL-3. The radio ports of AL-2 and AL-4 have been configured with a dedicated IP, because these two ports do not belong to the same sub-network of their relevant LAN ports. As a final results it can be seen, for example, that for LAN A just 3 IP addresses are used (instead of 7 as in the example of Figure 11). Note that in Figure 12 a dummy address has been assigned to the RS232 port. However, if the designer wants to give the possibility to use also this port to connect the equipment with the SCT program, it will be possible to configure also it as Unnumbered. In this case, however, it is important to note that it will not be possible to have 2 laptops connected at the same time to both the LCT and RS232 ports, otherwise an IP duplication conflict will occur. To set a serial port to Unnumbered is enough to click on the IP Unnumbered button present on the relevant configuration window (see Figure 3, Figure 4 and Figure 5). A port set to Unnumbered can be easily recognised, because its IP address is set to 0.0.0.0.

2.5 Routing Table

As a Layer 3 router, the AL equipment uses a Routing Table to route the management traffic through its ports (LAN, RADIO, LCT and RS232). The routing table can be configured by means of the SCT software. The configuration window is accessible by means of the menu EquipmentCommunication SetupRouting Table (Figure 13). This window shows the equipment Routing Table. This table has the following 5 columns: - Destination: is the destination network addressed by each row. - Net Mask: Network Mask of the destination network. - Hop: a packet will be sent to the Hop address if its destination IP address belong to the

sub-network defined by the couple Destination / Net Mask. Generally, Hop is the address of another router (e.g., the address of an AL equipment).

- Interface: defines the ALs port through which the packet is sent to the Hop address. - Protocol: specifies how the routing row has been inserted. Four different wording can

appear in this column:

RADIO

LAN LCT RS23210. 0. 2 .3/24

LANLCTRS23210. 0. 2 .1/24

RADIO

LAN LCT RS23210. 0. 1 .1/24 Unnumbered

RADIO

LANLCT10. 0. 3. 1/24




AL-1 AL-2RADIO

AL-3

RS232

AL-4Unnumbered

1.0.0.1/8 Unnumbered

10.0.1.3/24

Unnumbered

Unnumbered

Unnumbered

10.0.2.5/25

10.0.2.2/2410.0.1.2/24 10.0.3.2/2410.0.2.4/24

1.0.0.1/8 1.0.0.1/8 1.0.0.1/8

RADIO

LAN LCT RS23210. 0. 2 .3/24

LANLCTRS23210. 0. 2 .1/24

RADIO

LAN LCT RS23210. 0. 1 .1/24 Unnumbered

RADIO

LANLCT10. 0. 3. 1/24




AL-1 AL-2RADIO

AL-3

RS232

AL-4Unnumbered

1.0.0.1/8 Unnumbered

10.0.1.3/24

Unnumbered

Unnumbered

Unnumbered

10.0.2.5/25

10.0.2.2/2410.0.1.2/24 10.0.3.2/2410.0.2.4/24

1.0.0.1/8 1.0.0.1/8 1.0.0.1/8



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o LOCAL: points out that the element has been automatically inserted by the ALs controller. The element identifies the network and/or the interface directly connected with the equipment.

o NETMGMT: points out that the element has been manually inserted by the user (static element).

o OSPF: points out that the element has been automatically inserted by the OSPF protocol (dynamic element).

o OTHER, point out all the other situations that are not comprised into one of the previous cases.

In addition, this window allows the user to define a default gateway.

Figure 13

For the correct functioning of the router, the Routing Table must be populated of some LOCAL rows which aims is to address the sub-networks or the PPP connections directly connected to the ALs interfaces. As an example, in Table 2 are reported the LOCAL rows for the AL of Figure 7.



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Destination Net Mask Hop Interface Protocol 127.0.0.1 0.0.0.0 127.0.0.1 LOCAL 224.0.0.0 255.0.0.0 10.0.1.1 LAN LOCAL 10.0.1.0 255.255.255.0 10.0.1.1 LAN LOCAL 10.0.1.3 0.0.0.0 10.0.1.2 LCT LOCAL 10.0.1.5 0.0.0.0 10.0.1.4 RS232 LOCAL 10.0.1.7 0.0.0.0 10.0.1.6 RADIO LOCAL

Default Gateway

Table 2: LOCAL routing table rows for the AL equipment of Figure 7.

The first two rows (127.0.0.1 ., 224.0.0.0 ) are relevant to the loop-back address and multicast traffic, required for the correct functioning of the TCP/IP protocol. The third row addresses the Ethernet network connected to the LAN interface, while the other rows address the three PPP connections established by the ALs controller (through LCT, RS232 and RADIO ports). These rows are very important, because without them the equipment cannot correctly route the traffic. For example, if the third row would not be present, no packets could be forwarded through the LAN port. In the same way, if the last row would not be present, no packets could be forwarded through the RADIO port. The ALs router generates the LOCAL rows automatically in order to address the sub-networks directly connected to its interfaces. To route packets towards remote sub-networks, other routing rows must be added. The addition of these rows can be automatic through the OSPF protocol (dynamic route) or manual (static route).

2.6 Example: Routing Tables for a radio link

In this section an example of static Routing Table designing will be provided for the two radio links of Figure 11. Let us suppose that the Network Management Centre is located in Station A. So, a computer running the SCT or NMS5UX/LX software is connected, through Station As LAN, to the Ethernet port of AL-1. In order to reach the AL supervision network, the Default Gateway of this computer can be set to 10.0.1.1 (IP address of AL-1s LAN port). The AL-1 equipment is directly connected only to LAN A (10.0.1.0/24). In order to allow it to forward packets to Station B and Station C, its Routing Table must be updated with the static rows shown in Table 2 (where for simplicity the LOCAL rows have been omitted).

Destination Net Mask Hop Interface Protocol 10.0.2.0 255.255.255.0 10.0.1.7 RADIO NETMGMT 10.0.3.0 255.255.255.0 10.0.1.7 RADIO NETMGMT

Default Gateway

Table 3: static Routing Table for AL-1 equipment of Figure 11.

As can be seen, any packet belonging to sub-networks 10.0.2.0/24 or 10.0.3.0/24 are forwarded to 10.0.1.7 (RADIO address of AL-2) through the RADIO port of AL-1. However, it can be noted that this routing table is not optimized. In fact these two rows can be



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summarized in a single row using a Net Mask 255.255.254.0 instead of 255.255.255.0. The optimized routing table is shown in Table 4.

Destination Net Mask Hop Interface Protocol 10.0.2.0 255.255.254.0 10.0.1.7 RADIO NETMGMT

Default Gateway

Table 4: static Routing Table for AL-1 equipment of Figure 11 after summarization.

Summarization is a very important goal for the network management design. In fact, it reduces the routing table complexity. Short routing tables are simpler to design, update and configure respect to routing tables with a lot of rows. In this simple example, there is no need to define any Default Gateway on AL-1 because the management network remains confined to LAN A in Station A. About the other AL equipments, the following rule is suggested for the designing of their Routing Tables: - Use static routes to address sub-networks that are found going from the equipment

towards the border of the network respect to the main site with the management system.

- Use the default gateway to go back from the equipment towards the management centre.

Applying this rule to the equipments AL-2, AL-3 and AL-4, the resulting Routing Tables are shown in Table 5, Table 6 and Table 7.

Destination Net Mask Hop Interface Protocol 10.0.3.0 255.255.255.0 10.0.2.6 LAN NETMGMT

Default Gateway 10.0.1.6 RADIO



Default Gateway 10.0.2.1 LAN


Destination Net Mask Hop Interface Protocol





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As an example of Routing Table of a network where the IP Unnumbered feature is used, in the following the static Routing Tables for the network of Figure 12 are provided.


Default Gateway


Destination Net Mask Hop Interface Protocol 10.0.3.0 255.255.255.0 10.0.2.3 LAN NETMGMT











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3 Guidelines for the IP addresses design

In this chapter some guidelines will be provided for the IP addressing design of the management network. During this activity, the designer must answer four main questions:

1. What is the addresses range that can be deployed in the management network? 2. How many IP addresses are required for each network station (i.e., for each sub-

network)? 3. What is the network address to be assigned to each sub-network? 4. Are future network upgrading known?

Following, each one of these items is analyzed and some guidelines are provided to give an optimal answer to these questions. In addition, in the last section are discussed some techniques that can be used in order to reduce the number of IP addresses deployed.

3.1 IP Addresses range for the Management Network

The first problem the designer must face is the IP addresses range to be used for the equipments management. Basically, two scenarios can occur: 1. The customer requires that a specific address range will be used.

Typically, this occurs when the management network must be connected to a customers LAN already existent. In this case the customer must provide to the designer two parameters: the address range and the default gateway for the management network. The address range can be specified by means of an IP address and a mask. An example can be the following range:

10.175.54.0 mask 255.255.254.0 (or 10.175.54.0/23)

This range includes all the IP addresses from 10.175.54.0 to 10.175.55.255. The designer will subdivide this range into sub-networks in order to properly address all the equipments. The default gateway is required to proper interface the management LAN to the existing customers LAN. These two LANs are typically interfaced by means of a customers router, and the default gateway is the IP address of the routers interface connected to the management LAN (see the example of Figure 14).



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Figure 14

2. The customer has no requirements about the address range. This scenario typically occurs when the management network will remain isolated, not connected to any other LAN. In this case the address range choice is left to the designer. However, even if any address could be used, the designer is recommended to deploy only private IP addresses. RFC 1918 defines the following three private address ranges:

10.0.0.0 10.255.255.255 172.16.0.0 172.31.255.255

192.168.0.0 192.168.255.255

Addresses in these ranges are defined as not routable on the Internet and are used exclusively in a private network. Internet routers immediately discard private addresses. A management network in which only private addresses are deployed can be connected to the Internet (for example to allow the customer to remotely access the equipments through the web). In this case a translation of the private addresses to public addresses is required. This translation process is referred to as Network Address Translation (NAT) and is usually performed by a router or a firewall. If the management network is deploying public addresses, the translation process will fail, because neither a router nor a firewall will be able to distinguish between the Internet and the private network.

In scenario 1, sometimes, the available range could be very narrow respect to the number of radio equipments to address. In this case the designer could not have enough addresses for the equipments and the usage of the IP Unnumbered feature is strongly suggested. In addition, in next Section 3.5 some guidelines to save IP addresses will be provided. If such techniques will not be enough, an additional address range must be agreed with the customer. This problem usually does not occur in scenario 2, where the designer has the availability of a lot of addresses.

LAN

RADIONETWORK

ALEquipment

ExistingCustomer

LAN MANAGEMENTLAN

AL's Default Gatewayis equal to the IP Addressof the router's interface

Customer Router



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3.2 Sub-network designing

In the previous section 2.3 it has been described how the IP addresses must be assigned to the radio equipments. From the examples shown there (Figure 9, Figure 10 and Figure 11), it can be seen that basically a sub-network must be assigned to each network site. The second step in the IP Addresses design is to decide how many IP addresses must be assigned to each sub-network. This decision depends from the number of equipments presently deployed and from consideration about the future expansion of the network. The minimum size of each network depends from the number of IPs required to address the equipments deployed. For example, considering Figure 11, 7 IPs are required for Station A, 12 IPs for Station B and 5 IPs for Station C. In the example of Figure 12, 3 IPs are required for Station A, 5 IPs for Station B and 2 IPs for Station C. The sub-network size can be chosen with the aid of Table 12, in which are listed the sub-networks that can be defined with a dimension up to 4096 IPs.

Sub-Network Dimension Mask

Number of Hosts IPs

4 255.255.255.252 2 8 255.255.255.248 6

16 255.255.255.240 14 32 255.255.255.224 30 64 255.255.255.192 62 128 255.255.255.128 126 256 255.255.255.0 254 512 255.255.254.0 510

1024 255.255.252.0 1022 2048 255.255.248.0 2046 4096 255.255.240.0 4094

Table 12

The first column indicates the number of IPs belonging to each sub-network. Two of these IPs, however, are reserved as Network Address and Broadcast Address. So, the real number of IPs that can be assigned to the network elements (Hosts IPs) is equal to the total number of IPs minus 2. This number is shown in the third column. Looking now at Figure 11, we can see that the minimum sub-networks to be deployed are: Station A: 16 IPs sub-network, mask = 255.255.255.240 Station B: 16 IPs sub-network, mask = 255.255.255.240 Station C: 8 IPs sub-network, mask = 255.255.255.248 Let us now suppose to implement these sub-networks to the radio links of Figure 11. An example is shown in Table 13, where for each sub-network is indicated the Network Address, Minimum Host Address, Maximum Host Address and the Broadcast Address.

Station Name

Network Address

Sub-Network Mask

Min. Host Address

Max. Host Address

Broadcast Address

Station A 10.0.1.0 255.255.255.240 10.0.1.1 10.0.1.14 10.0.1.15 Station B 10.0.1.16 255.255.255.240 10.0.1.17 10.0.1.30 10.0.1.31 Station C 10.0.1.32 255.255.255.248 10.0.1.33 10.0.1.38 10.0.1.39

Table 13

The new network layout is shown in Figure 15.



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Figure 15

Let us now suppose the network is upgraded, by means of the addition of a new radio link connecting Station B to a new Station D. Due to this upgrading, a new equipment is deployed in Station B and 7 new IPs are required for its addressing from Station B sub-network. However, only 10.0.1.29 and 10.0.1.30 still remain available. So, Station B sub-network must be changed in a larger one (e.g., a 32 IPs sub-network) and the equipments IP addresses of this station must be changed. In addition, also the routing tables of all the equipments must be properly modified to take into account the new addressing scheme. In conclusion, equipment readdressing can be very expensive, especially in large networks. In order to reduce the probability of readdressing, any future-upgrading forecast must be considered and taken as much as possible into account during the sub-network sizing. For example, in Figure 11 all the stations have been addressed with a 256 IPs sub-network (mask 255.255.255.0). In this case it has been supposed that the customer has stated no requirements about the IP to be used and the private range 10.0.0.0/8 has been chosen. 256 IPs will give to each sub-network a lot of available IPs for future expansions. In addition, the range 10.0.0.0/8 can be subdivided in 65536 sub-networks of 256 IPs, which give the possibility to address practically any real network.

3.3 Sub-Network addressing

After having decided the addresses range and the number of IPs for each station, the next step is to give a network address to each sub-network. The main goal of sub-network addressing is to reduce the complexity of the equipments routing tables. In fact, as stated in Section 2.6, summarization is a very important objective for the network management design. In the following an example will be presented to show how network addressing can impact the routing table complexity.

RADIO

LAN LCT

10. 0. 1. 27/28

RS23210. 0. 1. 25/2810. 0. 1 .22/28 10. 0. 1. 23/28

LANLCT

10. 0. 1. 7/28

RS23210. 0. 1. 17/2810. 0. 1 .20/28 10. 0. 1. 18/28

RADIO

LAN LCT

10. 0. 1. 6/28

RS23210. 0. 1. 4/2810. 0. 1 .1/28 10. 0. 1. 2/28

RADIO

LANLCT

10. 0. 1. 28/28

10. 0. 1. 33/2910. 0. 1 .36/29 10. 0. 1. 34/29


Station BLAN B: 10. 0. 1. 16/28

Station CLAN C: 10. 0. 1. 32/29

AL-1 AL-2RADIO

AL-3

RS232

AL-4



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Figure 16

In Figure 16 is shown a networks graph, where for simplicity only the networks stations are shown. Each connection between two stations represents a radio link. For example, Station A is connected to other four stations. So, in station A there are four radio equipments each one connected to one remote station, as shown in Figure 17.

RADIO

LAN LCT

10. 0. 1. 6/24

RS23210. 0. 1. 4/2410. 0. 1 .1/24 10. 0. 1. 2/24

AL-1RADIO

LANLCT

10. 0. 1. 27/24

10. 0. 1. 22/2410. 0. 1 .25/24 10. 0. 1. 23/24RS232

AL-4

RADIO

LAN LCT

10. 0. 1. 13/24

RS23210. 0. 1. 11/2410. 0. 1 .8/24 10. 0. 1. 9/24

AL-2RADIO

LANLCT

10. 0. 1. 20/24

10. 0. 1. 15/2410. 0. 1 .18/24 10. 0. 1. 16/24RS232

AL-3

To Station BRemote RADIO:

10.0.1.7/24

To Station CRemote RADIO:

10.0.1.14/24

To Station MRemote RADIO:

10.0.1.28/24

To Station KRemote RADIO:

10.0.1.21/24




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Figure 17

The network of Figure 16 has been addressed in a no-optimized way, starting from the top and assigning IP network addresses to the links found turning clockwise the graph. On the base of such addressing, the routing tables of the four equipments of Figure 17 will be as shown in tables from Table 14 to Table 17.



Table 14: static Routing Table for AL-1 equipment, deployed in Figure 16s network.

Station A10. 0. 1. 0/24

Station B10. 0. 2. 0/24

Station C10. 0. 3. 0/24

Station D10. 0. 4. 0/24

Station E10. 0. 5. 0/24

Station F10. 0. 6. 0/24

Station G10. 0. 7. 0/24

Station H10. 0. 8. 0/24

Station I10. 0. 9. 0/24

Station J10. 0. 10. 0/24

Station K10. 0. 11. 0/24

Station L10. 0. 12. 0/24

Station M10. 0. 13. 0/24

Station N10. 0. 14. 0/24

Station O10. 0. 15. 0/24

Station P10. 0. 16. 0/24



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Destination Net Mask Hop Interface Protocol 10.0.2.0 255.255.255.0 10.0.1.1 LAN NETMGMT 10.0.3.0 255.255.255.0 10.0.1.14 RADIO NETMGMT 10.0.4.0 255.255.252.0 10.0.1.14 RADIO NETMGMT 10.0.8.0 255.255.248.0 10.0.1.14 RADIO NETMGMT

10.0.10.0 255.255.255.0 10.0.1.14 RADIO NETMGMT 10.0.11.0 255.255.255.0 10.0.1.15 LAN NETMGMT 10.0.12.0 255.255.255.0 10.0.1.15 LAN NETMGMT 10.0.13.0 255.255.255.0 10.0.1.22 LAN NETMGMT 10.0.14.0 255.255.254.0 10.0.1.22 LAN NETMGMT 10.0.16.0 255.255.255.0 10.0.1.22 LAN NETMGMT






Destination Net Mask Hop Interface Protocol 10.0.13.0 255.255.255.0 10.0.1.28 RADIO NETMGMT 10.0.14.0 255.255.254.0 10.0.1.28 RADIO NETMGMT 10.0.16.0 255.255.255.0 10.0.1.28 RADIO NETMGMT



As can be seen from these tables, several Routing Table lines are required to address the whole network. AL-2 has the larger routing table because it acts as default gateway for the other Station As equipments. If we connect the SCT to AL-2 (through LCT port) we will be able to connect the whole network, because AL-2s Routing Table has all the information required to reach any networks station. Even if we connect the SCT to AL-1 we will be able to connect the whole network. In fact, AL-1 is provided with the Routing Tables information required to reach the sub-network of Station B. The other sub-networks are instead reached through the default gateway AL-2. Figure 16 shows an example of how a no-optimized IP addressing can impact the Routing Tables complexity. In fact, 10 routing rows are required on AL-2 to address a network of 15 radio links. In very larger network this could take to routing tables of several tenth of rows, which could be very difficult to manage. In Figure 18 is shown the same network of Figure 17 with an optimized IP addressing. The sub-networks deployed are the same of Figure 17, but they are assigned in order to allow addressing the whole network with the minimum number of routing rows.



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Figure 18

For example, all the sub-networks of stations from C to J can be summarized with a single address: 10.0.8.0/21. The new Routing Tables of equipments AL-1, AL-2, AL-3 and AL-4 of Figure 17 will be as shown in tables from Table 18 to Table 21.




Destination Net Mask Hop Interface Protocol 10.0.16.0 255.255.255.0 10.0.1.1 LAN NETMGMT 10.0.8.0 255.255.248.0 10.0.1.14 RADIO NETMGMT 10.0.2.0 255.255.254.0 10.0.1.15 LAN NETMGMT 10.0.4.0 255.255.252.0 10.0.1.22 LAN NETMGMT

Default Gateway


Station A10. 0. 1. 0/24

Station B10. 0. 16. 0/24

Station C10. 0. 8. 0/24

Station D10. 0. 9. 0/24

Station E10. 0. 10. 0/24

Station F10. 0. 11. 0/24

Station G10. 0. 12. 0/24

Station H10. 0. 14. 0/24

Station I10. 0. 15. 0/24

Station J10. 0. 13. 0/24

Station K10. 0. 2. 0/24

Station L10. 0. 3. 0/24

Station M10. 0. 4. 0/24

Station N10. 0. 5. 0/24

Station O10. 0. 6. 0/24

Station P10. 0. 7. 0/24



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As can be seen, optimizing the IP addressing allows a remarkable reduction of the Routing Tables complexity. The example of Figure 18 offers the opportunity to discuss two different design solutions that can be adopted in the main site of a network. AL-2 Routing Tables rows (Table 19) address all the sub-networks. Any other Station As Routing Table addresses only the sub-networks reachable by means of its radio port. For example, AL-1 only addresses the sub-network 10.0.16.0/24. If we connect the SCT to the LCT port of AL-1, we will be able to see the sub-networks different from 10.0.16.0/24 by means of AL-2, which is the Default Gateway. This design solution reduces the updating work in case of future network upgrading. In fact, let us suppose that a new radio link will be added to the network, from Station B to Station Q (Figure 19).



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Figure 19

To address this new network, an updating is required to the routing tables of AL-1 and AL-2, changing the Net Mask of the Destination 10.0.16.0 from 255.255.255.0 to 255.255.254.0 (see Table 22 and Table 23).





Default Gateway


Station A10. 0. 1. 0/24

Station B10. 0. 16. 0/24 Station C

10. 0. 8. 0/24

Station D10. 0. 9. 0/24

Station E10. 0. 10. 0/24

Station F10. 0. 11. 0/24

Station G10. 0. 12. 0/24

Station H10. 0. 14. 0/24

Station I10. 0. 15. 0/24

Station J10. 0. 13. 0/24

Station K10. 0. 2. 0/24

Station L10. 0. 3. 0/24

Station M10. 0. 4. 0/24

Station N10. 0. 5. 0/24

Station O10. 0. 6. 0/24

Station P10. 0. 7. 0/24

Station Q10. 0. 17. 0/24

New Radio Link



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No updating is required on AL-3 and AL-4. In conclusion, the usage of an equipment as Default Gateway in the main site has two main advantages: - Limits the Routing Tables complexity of the main sites equipments, apart from that

which is acting as Default gateway. - Simplify the Routing Table upgrading in case of network expansion. The main drawback, however, is that if the Default Gateway fails we lose the possibility to connect the whole network. For example, if AL-2 fails and we connect the SCT to AL-1s LCT port, we will be able to connect only the sub-networks 10.0.16.0/23. To connect sub-network 10.0.5.0/24, for example, we need to connect the SCT to the LCT port of AL-4. To avoid this problem, an alternative design solution can be adopted for the Routing Tables of the main sites equipments. This alternative solution does not use any equipment as default Gateway. Each Routing Table will be filled with the information relevant to the whole network. Choosing this design solution, the Routing Tables of AL-1, AL-2 AL-3 and AL-4 deployed in the network of Figure 19 will become as shown in tables from Table 24 to Table 27.

Destination Net Mask Hop Interface Protocol 10.0.16.0 255.255.254.0 10.0.1.7 RADIO NETMGMT 10.0.8.0 255.255.248.0 10.0.1.8 LAN NETMGMT 10.0.2.0 255.255.254.0 10.0.1.15 LAN NETMGMT 10.0.4.0 255.255.252.0 10.0.1.22 LAN NETMGMT

Default Gateway



Default Gateway


Destination Net Mask Hop Interface Protocol 10.0.16.0 255.255.255.0 10.0.1.1 LAN NETMGMT 10.0.8.0 255.255.248.0 10.0.1.8 LAN NETMGMT 10.0.2.0 255.255.254.0 10.0.1.21 RADIO NETMGMT 10.0.4.0 255.255.252.0 10.0.1.22 LAN NETMGMT

Default Gateway


Destination Net Mask Hop Interface Protocol 10.0.16.0 255.255.254.0 10.0.1.1 LAN NETMGMT 10.0.8.0 255.255.248.0 10.0.1.8 LAN NETMGMT 10.0.2.0 255.255.254.0 10.0.1.15 LAN NETMGMT 10.0.4.0 255.255.252.0 10.0.1.28 RADIO NETMGMT

Default Gateway




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As can be seen, even if an equipment fails, we can connect the whole network (apart from the branch reachable only by means of the failed equipments radio) attaching the SCT to the LCT port of any main sites equipment. However, the main drawback is that in case of network expansion, all the main sites equipment must be updated with the routing rows relevant to the new sub-network deployed. In general, this second design solution (no Default Gateway) is deployed when the network is not very large (few tenth of radio links) and with little perspective of future expansions. In large networks or network with good perspective of expansion is generally preferred to use the first solution (usage of an equipment as Default Gateway) because provides more flexibility.

3.4 Future upgrading of the Management Network

Usually the lifecycle of a radio network consists of an initial deployment followed from several upgrading. Changes in the network can be due to different factors as network expansions for the addition of new stations, doubling of radio links to increase capacity, modification in the network layout due to propagation problems (e.g. loss of visibility between two sites due to a new building raised after the equipment installation), etc. These changes can require a lot of work to update the management network. To reduce this workload the designer must perform a careful IP addressing during the networks initial development, taking into account any information available about future networks upgrading. Two main factors must be taken into account in this IP addressing design: 1. Size of the Sub-networks.

In Section 3.2 we have already discussed how is important to provide each sub-network with a sufficient number of IP addresses, taking into account future equipments that could be added in the relevant station. The designer must take into account any information relevant to future links that can be added to the network. Looking for example at Figure 15, if the designer knows that a new links will be added in Station B to connect a new Station D, he must take it into account. As a consequence, Station B sub-network must be sized with an enough number of IP address for the present equipments (AL-2 and AL-3) plus the future equipment. So, the sub-network must have available 12 IPs for the present equipments plus 7 IPs for the future equipment. So, a total number of 19 IPs must be available in Station B sub-network, which means that at least a sub-network with mask 255.255.255.224 must be deployed. In this example we have supposed that the designer knows what and where new future links will be added to the network. However, often this is not the case. A lot of factor can influence the network growth, and not all of them can be predicted. So, the designer should try to take precautions against this. Any feedback from the customer can be useful in this sense. Anyway, these two general principles should be taken into account:

o If the customer has not requirements about the address range to be used, choose for the sub-network a number of IP address quite greater than those required to address the equipments deployed during the initial deployment. For example, as already stated in Section 3.2, the choice of sub-networks with mask 255.255.255.0 in the private IP range 10.0.0.0 will provide up to 65536 sub-networks of 256 IPs. In this case in each sub-network can be hosted at least



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254/7=36 equipments, which is sufficient for practically all the real networks. Even the number of sub-networks, 65536, is a very high number sufficient to address all the stations of any real network.

o If the customer has requirements about the address range to be used, make a station classification giving a priority index to each site. This classification must assign maximum priority to the main nodal sites, while minimum priority must be given to terminal nodes with only one equipment. Once this classification has been done, the available address range must be subdivided between the stations giving more IPs to high priority sites and less to stations with low priority. In fact, new radio links are often added to the network starting from main nodal sites. About low priority sites, the sub-networks should be provided with a number of IPs enough to add at least one new equipment. This could be a very hard work when the available address range is very limited. The guidelines to save IP addresses that will be provided in the next Section 3.5 will be very useful to solve this problem.

2. Routing Table Updating Another issue related to the future growth of a network, from the management point of view, is the Routing Table updating required to address new sub-networks. On large networks this task could be very time consuming. Even in this case, the collection of information from the customer about the future growth of the network can help the designer to make easier the network upgrading. To better understand how this can be done, an example is provided in Figure 20.

Figure 20

In this simple network three links will be deployed during the initial phase. The customer foresees to add about 4 6 new links starting form Station C. Figure 21 shows a possible IP addressing for this network. Sub-networks 10.0.1.0/24, 10.0.2.0/24 and 10.0.3.0/24 have been assigned for the initial deployments equipments.

Station A(Main site)

Station BStation C New Links

foreseen to connect4 6 new stations



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Figure 21

In addition, the IP range 10.0.8.0/21 is reserved for the network expansion foreseen from Station C. Starting from this plan, the Routing Tables of the equipments deployed in stations A, B and C (see Figure 22) are shown in tables from Table 28 to Table 31.

Figure 22


Default Gateway


Destination Net Mask Hop Interface Protocol 10.0.3.0 255.255.255.0 10.0.2.6 LAN NETMGMT 10.0.8.0 255.255.248.0 10.0.2.6 LAN NETMGMT






RADIO

LAN LCT

10. 0. 2. 11/24

RS23210. 0. 2. 9/2410. 0. 2 .6/24 10. 0. 2. 7/24

LANLCT

10. 0. 1. 7/24

RS23210. 0. 2. 1/2410. 0. 2 .4/24 10. 0. 2. 2/24

RADIO

LAN LCT

10. 0. 1. 6/24

RS23210. 0. 1. 4/2410. 0. 1 .1/24 10. 0. 1. 2/24

RADIO

LANLCT

10. 0. 2. 12/24

10. 0. 3. 1/2410. 0. 3 .4/24 10. 0. 3. 2/24




AL-1 AL-2RADIO

AL-3

RS232

AL-4

Station A10. 0. 1. 0/24

Station B10. 0. 2. 0/24

Station C10. 0. 3. 0/24

Future Upgrading10. 0. 8. 0/21



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As can be seen, a row has been already inserted to address the new links (highlighted with yellow color). When new links will be added to Station C no updating must be done to the Routing Tables of AL-1, AL-2 and AL-3, unless more than 8 links will be added. Such a strategy could reduce a lot of workload especially in large networks.

3.5 Guidelines to save IP addresses

As already shown in Section 2.4, the IP Unnumbered feature can be used to save IP addresses. The guidelines provided into this section are mainly dedicated to the old version of AL equipments that do not support this feature. In Section 2.3 it has been shown that (without using the IP Unnumbered feature) for each AL equipment 7 IP addresses must be taken into account. Such addresses, listed in Table 1, are split in the following way: 1 for the LAN port, 2 for the PPP radio connection, 2 for the PPP connection over the LCT port and 2 for the PPP connection over RS-232 or 2Mbs. Taking into account that one of the two IPs used for the radio PPP connection corresponds to the remote radio IP address, we can say that for each AL equipment 6 IPs must be reserved. In the previous sections, all the examples have been done considering PPP connections over LCT and RS-232/2Mbs addressed with IPs belonging to the same sub-network of the LAN port. The LCT port is generally used to locally connect the equipment with a lap-top running the SCT. Giving it an IP address belonging to the same LAN ports sub-network allow connecting the whole network from each equipment. This feature can be very useful to make tests during the installation of the radio links or during their maintenance. About the RS-232/2Mbs port, even if not used to make a permanent PPP connection it could be useful to give it an IP address belonging to LAN ports sub-network, using it as an alternative to the LCT port. In fact, this allows the equipment to be locally connected by means of a lap-top either through an RS-232 or USB cable and could be useful to avoid useless waste of time. As already commented in Section 3.1, in several cases the management network must use a limited address range defined by the customer. In such cases, the full addressing of the equipment can be impossible and two alternative addressing methodologies can be used. The first alternative is to not address the RS-232/2Mbs port when it is not used to connect other equipments (Figure 23). In this case a dummy address 1.0.0.1 can be assigned at the RS-232/2Mbs port of each equipment.



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Figure 23

In this case it is still possible to see the whole network from a laptop running the SCT connected to the LCT port of each equipment. As can be seen two IP addresses are saved in this way for each equipment. In fact a total number of 8 IPs are reserved for each radio link (4 IP addresses per equipment): 5 IPs belong to Station As sub-network (LAN A) and 3 IPs belong to Station Bs sub-network (LAN B). The second alternative is to not address both LCT and RS-232/2Mbs ports (Figure 24). In this case three dummy addresses must be assigned for each equipment: 1.0.0.1 (LCT port), 1.0.0.2 (remote PC connected to the LCT port) and 1.0.0.3 (RS-232/2Mbs port).

Figure 24

LANLCT

10. 8. 15. 5/28

RS23210. 8. 15. 17/2810. 0. 0 .1/8 10. 8. 15. 18/28

RADIO

LAN LCT

10. 8. 15. 4/28

RS23210. 8. 15 .1/28 10. 8. 15. 2/28

Station A Station B

AL-1 AL-2RADIO

LAN A LAN B

10. 0. 0. 1/8

LANLCT

10. 8. 15. 3/29

RS23210. 8. 15. 9/2910. 0. 0 .3/8 1. 0. 0. 1/8

RADIO

LAN LCT

10. 8. 15. 2/29

RS23210. 8. 15 .1/29 10. 0. 0. 1/8

Station A Station B

AL-1 AL-2RADIO

LAN A LAN B

10. 0. 0. 3/8



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In this case four IP addresses are saved for each equipment. In fact, a total number of 4 IPs are reserved for each radio link (2 IP addresses per equipment): 3 IPs belong to Station As sub-network (LAN A) and 1 IP belong to Station Bs sub-network (LAN B). However, with this second alternative we lose the possibility to connect the whole network from a laptop running the SCT connected to the LCT port of each equipment. In addition, we also lose the possibility to connect the remote equipment. In fact, when we connect a laptop to the LCT port of AL-2 in Figure 24, the PPP connection automatically assigns the address 1.0.0.2 to the laptop. If now we try to connect the AL-1 equipment, the laptop sends IP packets to AL-1 (either by means of its RADIO address or its LAN address). However, when AL-1 tries to reply to the laptop by sending packets to 1.0.0.2, it is not able to route properly the packet back to AL-2. To solve this problem, two different classes of dummy addresses can be used for each radio link. Figure 25 shows an example.

Figure 25

So doing, if AL-2 uses AL-1s RADIO address as Default Gateway, it will be enough to add the Routing Tables row shown in Table 32 to make it possible to connect the remote equipments.


.

.

Other Routing Table rows .

.

Table 32: AL-1s Routing Table row required for the connection of its remote equipment.

In fact, when AL-2 must reply to a packet sent by a laptop connected to AL-1s LCT port, it sends a packet to 1.0.0.2. AL-2 routes this packet to AL-1 by means of its Default Gateway

LANLCT

10. 8. 15. 3/29

RS23210. 8. 15. 9/292. 0. 0 .3/8 2. 0. 0. 1/8

RADIO

LAN LCT

10. 8. 15. 2/29

RS23210. 8. 15 .1/29 1. 0. 0. 1/8

Station A Station B

AL-1 AL-2RADIO

LAN A LAN B

1. 0. 0. 3/8



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and so can reach the laptop. When instead AL-1 must replay to a packet sent by a laptop connected to AL-2s LCT port, it sends a packet to 2.0.0.2. AL-1 routes this packet to AL-2 by means of the row added in Table 32. Repeating this scheme for each radio link, we can maintain on each radio equipment the possibility to manage the remote equipment without use IPs of the customer range to address the LCT ports.

4 Guidelines for the usage of the PPP connections

As already described in Paragraph 2, the AL equipment can establish three PPP connections over the RADIO, LCT and RS232/2Mbs ports. The first two are reserved for very specific usage: PPP connection over LCT port can be used only to connect a PC/laptop for local management purpose, while PPP connection over the RADIO port is used to connect two radio equipments through the radio link between them. The third PPP connection can be instead used to connect other network elements over either an RS232 connection or a 64kbit/s Time Slot of a tributary E1. This connection is mainly exploited when there is the needing to carry ALs management traffic over a radio network of another supplier. To better understand this thing, an example is shown in Figure 26.

Figure 26

In this example it has been supposed to have a remote ALs network to be managed from the main site. In between there is an existing radio network provided by another supplier. In the remote site, the AL equipment is connected to the other suppliers equipment through several E1 tributary connections. In the main site, however, both AL and the other suppliers equipments are connected to a local switch. A first solution for the management of remote sites ALs is to carry the ALs supervision traffic over the management channels of the other suppliers equipment, if this latter is done through IP packets. However, the customer often requires keeping separated each management networks.

AL

ALRadio Links

Main Site

2 Mbit/s Tributary

Connections

AL

Remote ALRadio Links

2 Mbit/s TributaryConnections

Local Switch

Other SupplierNetwork

Remote Site

Other supplierradio equipment



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Two solutions can be proposed to solve this problem exploiting the ALs PPP connections: - First solution, through the RS-232 port.

Figure 27

If the other suppliers equipment provides an RS-232 service channel, it can be used to carry ALs supervision traffic between main and remote sites. As shown in Figure 27, this service channel can be connected to the ALs RS-232 port both in main and remote sites. If the transport over RS232 service channel is fully transparent, the final result is like if the two AL equipments would be directly connected by means of an RS232 cable. From the point of view of the IP addressing, the IP assigned to the RS232 port of the remote sites AL must belong to the Main Sites sub-network. For example we could have:

Main Site sub-network: 10.0.1.0/24 RS-232 IP address of Main sites AL: 10.0.1.4/24 RS-232 IP address of Remote sites AL: 10.0.1.5/24

The Remote sites AL must be configured with the address 10.0.0.4 as Default Gateway. In addition, the main sites AL Routing Table must be properly configured in order to address all the sub-networks defined for the Remote AL radio links addressing. For example, if all these sub-networks can be summarized with the sub-network 10.1.0.0/20, in the Routing Table of the main sites AL must be inserted the row indicated in Table 33.

Destination Net Mask Hop Interface Protocol 10.1.0.0 255.255.240.0 10.0.1.5 RS232/2Mb NETMGMT

.

.

Other Routing Table rows .

.

Table 33: Routing Table row required for into main sites AL of Figure 27.

AL

ALRadio Links

Main Site

2 Mbit/s Tributary

Connections

AL



Local Switch


Remote Site

RS232

Other SupplierRadio Equipment

RS232



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- Second solution, through the 2Mbs port.

Figure 28

Another solution that can be adopted is to use a free 64kbit/s Time Slot (TS) of an E1 tributary connection. In Figure 28 it is shown an example of such solution. In the figure, the main sites AL uses TS30 (Time Slot number 30) of the 2Mbs connection number 1 for the PPP connection. This time slot is cross-connected to TS14 of a second E1 when passing through the Local Switch. This E1 is then carried from the Other Supplier Network until the Remote Sites AL, where it is received over the tributary 2Mbs number 2. Supposing to use the same IP addressing of the previous example (connection through RS-232), the PPP connection must be configured as follow:

o Main Sites AL: IP PPP Address = 10.0.1.4 IP PPP NetMask = 255.255.255.0 PPP Mode = Client Remote Access Type = 2Mbs 2Mbit Selector = 1 Slot Selector = 30 16kbit Map = All selected

o Remote Sites AL: IP PPP Address = 10.0.1.5 IP PPP NetMask = 255.255.255.0 PPP Mode = Client Remote Access Type = 2Mbs 2Mbit Selector = 2 Slot Selector = 14 16kbit Map = All selected

Even in this case, the Remote Sites AL must be configured with the address 10.0.0.4 as Default Gateway and the Main Sites AL Routing Table must be configured with the same row shown in Table 33.

Both the solutions described in this paragraph require some support from the customer. In fact, in the first solution the customer must guarantee the availability of the RS232 service channel for the transport of ALs management traffic. In addition, the customer must also provide support about any required configuration of the non-AL equipments and their connections in order to implement the RS232 connection between Main and Remote Sites.

AL

ALRadio Links

Main Site

AL



Local Switch


Remote Site

2 Mbit/s Tributary

Connections

NetworkManagement

over TS30

NetworkManagement

over TS14

NetworkManagement

over TS14

12



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About the second solution, the customer must guarantee that the Time Slots used for the management are free of tributary traffic. In addition, the customer must provide support about the proper configuration of the Local Switch. Finally, it is important to note that the PPP connection over the 2Mbs can also be used to overcome problem due to congestion over the supervision channel. More details about this application will be provided in the next Paragraph.

5 Capacity design of the supervision channels

One of the main problems to be considered during the management network design is the required capacity for the supervision channel. The problem is only relevant to the embedded supervision radio channel, that for the AL equipment has a capacity of 64kbit/s. In fact, on the Ethernet port we have an higher capacity of 10Mbit/s. Looking at the example of Figure 29 we can see that on the embedded channel of the radio link between AL-1 and AL-2 is carried the supervision traffic of the whole network.

Figure 29

As can be seen from the figure, the supervision traffic on said radio link grows if the number of radio equipment deployed in the daisy chain grows. It is important to note that in normal working conditions, the management traffic is very low and due to the periodic polling of the management system (SCT or NMS) towards the network elements. However, if one or more radio links have alarms due to failures or propagation, a lot of SNMP traps are sent from the alarmed equipments to the management centre. If the supervision channel has not been dimensioned properly, it can result congested from this traffic. In order to avoid this, SIAE suggests reserving a capacity of 2.4kbit/s for each radio equipment. In the example of Figure 29, the supervision channel of the radio link AL-1 AL-2 carries the management traffic of 5 equipments. So, the total capacity to be reserved for these equipments is 5x2.4=12kbit/s. The radio channel capacity is 64kbit/s and so it is enough to carry such traffic. In general it can be seen that the 64kbit/s channel is enough to carry the management traffic of about 64/2.427 radio equipments (which means 14 radio links). If the number of radio equipments is greater than 27, additional capacity must be provided

Main Site

AL - 1

SCT

AL - 3AL - 2 AL - 5AL - 4 AL - 6

Intermediate SitesSupervision traffic

of AL-2 AL-6 equipments



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for the supervision network exploiting some unused time slots of the payload traffic2. Two different solutions can be adopted for this problem: - PPP 2Mbs connection between two AL equipments

This solution uses a PPP connection over a 2Mbs between two AL equipments to provide additional capacity to the radio supervision channel. An example of such solution is represented in Figure 30.

Figure 30

In this example we have a network with more than 13 radio links. The supervision radio channel is enough for the management of the equipments up to AL-26. For the remaining equipments, the management traffic is carried over a Tributary Time Slot between AL-27 and AL-n. Supposing that the sub-networks from AL-26 on can be addressed with the address 10.0.16.0/20, the following configurations must be included:

o AL-n: Its routing table must contain the following row: Destination: 10.0.16.0 Mask: 255.255.240.0 Hop: 10.0.1.5 Interface: RS232/2Mbs

The Default Gateway must be set to 10.0.1.8, which is the LAN port of AL-1. o AL-1: Its routing table must contain the following row:

Destination: 10.0.16.0 Mask: 255.255.240.0 Hop: 10.0.1.1 Interface: LAN

Other routing table rows must route the sub-networks deployed for AL-2AL-25 management, using the AL-2s RADIO address as Hop.

o AL-27: Its Default Gateway must be set to 10.0.1.4, which is the PPP 2Mbs port of AL-n. Other routing table rows must route the sub-networks deployed for the next radio links, using the RADIO address of the remote equipment connected to AL-27as Hop.

2 When available, the 2Mbit/s wayside channel can be used for this scope. In this way, no payload Time

Slots are wasted for the supervision of the network.

Main Site

AL - 1 AL - 2

10. 0. 1. 0/24

AL - n

10. 0. 1. 1LAN Address


Network Managementover a Tributary TS

PPP 2 Mbs port.IP Address = 10. 0. 1. 4

12 Radio Links

AL - 25 AL - 26 AL - 27



Up to 13Radio Links

Legend:Ethernet connectionE1 connection

SCT

10.0.16.0 mask 255.255.240.0



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The advantage of this solution is that it is entirely done with AL equipments, without any external router device. However two main disadvantages limit the use of this solution: 1. It is not adapted to manage very large networks. In fact, each AL equipment can

establish only one PPP connection. So, multiple connections over tributary timeslots require an equivalent number of AL equipments in the main site to terminate each PPP connection.

2. This solution cannot be applied if in the main site we have only one AL equipment. For example, if AL-n would not be present in Figure 30, we will not be able to terminate the PPP connection in the main site.

In the following, solutions using an external router will be shown that solve these problems.

- PPP connection using the PROXY equipment PROXY equipment is a router that can map Ethernet traffic over a TDM channel, exploiting up to 4x64kbit/s Time Slots. The PROXY equipment is provided with a 10baseT Ethernet port and two E1 ports. Figure 31 shows the general working principle of the PROXY equipment, also named IP-BOX.

Figure 31

The Ethernet traffic is extracted or inserted into one of the two E1 ports by means of the Drop/Insert functionality, as shown in Figure 7. As can be seen, the Ethernet traffic from the 10baseT port is inserted into a Time Slot of the E1 port number 2. On the contrary, the traffic received from the same Time Slot on port 2 is Dropped and transmitted on the 10baseT port. The other tributary Time Slots of the E1 flux pass

IP - BOX

Ethernet

Rx Tx Rx Tx

Dropped TS

Inserted TS

E1ports

E1port selected

for Drop/Insert

Tributary Time slotwith traffic

Free Tributary Time slot

TributaryTime slot used to carry Ethernet traffic

Port 1 Port 2



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unchanged into the PROXY. The routing of the packets between E1 and Ethernet ports is regulated by means of a Routing Table. IP addresses must be assigned also the PROXY ports. This addressing is required for its management and to make it able to route IP packets properly between its ports. Let us considering again the example of Figure 30, in which now we suppose that only AL-1 is present in the main site. In this case, a PROXY can be used in the main site to terminate the PPP connection over the 2Mbs, as shown in Figure 32.

Figure 32

In this case for the equipments AL-1 and AL-27 it still remain valid the considerations made for the example of Figure 31. So, the same configurations must be included. About the PROXY equipment, the following row must be included in its Routing Table:

Destination: 10.0.16.0 Mask: 255.255.240.0 Hop: 10.0.1.5 Interface: RS232/2Mbs

The Default Gateway must be set to 10.0.1.8, which is the LAN port of AL-1. Figure 33 shows an example in which the PROXY is used to carry the management traffic over a multiple number of Time Slots.

Main Site

AL - 1 AL - 2

10. 0. 1. 0/24

PRO

XY





12 Radio Links

AL - 25 AL - 26 AL - 27



Up to 13Radio Links

Legend:Ethernet connectionE1 connection

SCT

10.0.16.0 mask 255.255.240.0



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Figure 33

In the figure is shown a nodal centre in which are converging 3 daisy chains of radio links. The nodal centre is then connected to the Main Site through the radio link AL-1AL-2. Over this radio link must be carried the management traffic of 8+5+8=21 links, which means 42 radio equipments. So, the embedded supervision channel cannot

inr0225-03_guidelines for network management planning of siae radio equipments - al series_2005

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