quality of service · white paper . page 2 of 24 contents ... qm option [no]voice [no]dot1p [no]tos...

Quality of Service (architecture, implementation

and configuration examples)

TECHNOLOGY WHITE PAPER

of 24

Contents

INTRODUCTION ............................................................................................................................... 3

GENERAL INFORMATION ................................................................................................................. 4

QOS FEATURES OFFERED BY INFINET WIRELESS DEVICES .................................................................. 4

FEATURE SUMMARY .................................................................................................................................... 4

IMPLEMENTING QOS IN MINT NETWORKS ....................................................................................... 8

TRANSPARENT PACKET PRIORITIZATION ........................................................................................................... 8 Manual QoS configuration ................................................................................................................ 9 Dynamic Bandwidth Allocation ......................................................................................................... 9

QOS MONITORING ................................................................................................................................... 10 MINT AS PART OF A MULTI-SERVICE NETWORK ............................................................................................... 12

Public safety surveillance system segment ..................................................................................... 13 Residential area segment ................................................................................................................ 14 TDM PtP segment ........................................................................................................................... 17

QOS LAB TEST RESULTS .................................................................................................................. 18

TESTING WIRELESS LINK QUALITY ................................................................................................................ 20 WIRELESS LINK TESTING AND TCP WINDOW SIZE CONSIDERATIONS .................................................................... 23

CONCLUSION ................................................................................................................................. 24

of 24

Introduction Without implementing Quality of Service(QoS) in a wireless network, every application has an equal share of the available link bandwidth. Critical and non-critical applications, Web traffic, streaming video or audio, worm or bot-net traffic – all compete for the available bandwidth, and if there is a bigger flow, it gets a bigger share. Wired links can be upgraded or aggregated to a higher speed, but adding additional bandwidth to wireless networks is a difficult task. Introduction of another wireless link may face interference, absence of line of sight, government regulations, etc. So optimizing the link often is the only choice. QoS gives service providers the tools needed for traffic optimization and congestion management. Adding the ability to suppress non priority traffic and offer different traffic plans to customers, according to their requirements and abilities, is a way to meet customer expectations and force SLA in the network. QoS is a tool for optimizing wireless network bandwidth and prioritizing mission‐critical applications to ensure they are accessible in times of network congestion. Adding QoS operator is able to offer services comparable to ones offered by wire but with increased flexibility, offered by wireless infrastructure. This document will give some insights on InfiNet Wireless devices and the available QoS features in MINT networks (on MINT architecture see http://www.InfiNetwireless.com/products/technology-white-papers/mint-mesh-interconnection-networking-technology/?searchterm=MINT).

http://www.infinetwireless.com/products/technology-white-papers/mint-mesh-interconnection-networking-technology/?searchterm=MINT

http://www.infinetwireless.com/products/technology-white-papers/mint-mesh-interconnection-networking-technology/?searchterm=MINT

of 24

General information

Quality of Service(QoS) is a common name for the technologies that ensure the quality of data transmission over communication networks. Introduction of QoS in a network leads to the ability to satisfy various measurable application requirements, such as delay, jitter, bandwidth and packet loss. Having this, operators are able to offer their customers network services with predictable characteristics and Service Level Agreements(SLA). Implementing QoS in a wireless environment is always a difficult task. As wireless networks have different error characteristics comparing to wired networks, this has to be taken into account. Wireless medium presents many challenges that must be addressed prior moving to QoS configuration: interference, obstructions in the transmission path, weather conditions, geography and these are the most obvious. This is why the QoS mechanisms provided in a wireless network environment have to be robust and capable of providing reasonable QoS resolution, without sacrificing performance.

QoS features offered by InfiNet Wireless devices

Feature summary

• Up to 200 service classes and service channels • Up to 17 priority levels for granular traffic prioritization • End-to-end traffic prioritization through MINT network (wired/wireless) • Automatic VoIP (RTP) streams prioritization • Automatic traffic prioritization based on DSCP, IP ToS or 802.1p QoS tags • Smart and flexible traffic classification using any attributes including IP ToS/DSCP/802.1p tags,

VLAN/IP/MAC address, protocol and port fields, etc. • Service channels and classes hierarchy for building granular QoS policies • Policy-based IP ToS/DSCP/802.1p QoS field set/change/strip • All QoS features are available in both routing and in switching mode • TDMA (polling) operation mode support for minimal jitter • Traffic shaping (absolute/relative/mixed) with maximum latency limiting (from 20 to 200 ms)

on service class/channel basis • Strict priority queueing and Weighted fair queuing support

With more than 15 years of of intense research and product development InfiNet Wireless can offer its customers a wireless broadband solution, that can satisfy most of their requirements to Quality of Service in a wireless environment. The core element of any InfiNet Wireless device is WANFLeX Operating System. All Quality of Service parameters are managed by the QM manager module of WANFLeX. On the figure below you can see the data flow from ingress to egress on an InfiNet Wireless device.

of 24

Figure 1. WANFLeX packet flow

Every data bit entering or leaving any interface of InfiNet Wireless device goes through QM module. There it can be classified, marked, redirected, scheduled and shaped. Classification and marking in WANFLeX OS is done using simple rules and the so called logical channels (or simply channels). Every rule applies to a certain logical channel in the system. Every channel is characterized by several parameters like data rate, priority, DSCP, 802.1q and 802.1p tags etc. Rules direct certain types of traffic to specified logical channels, and channels modify traffic properties. Up to 200 channels can be created on a single device to facilitate granular classification of any traffic type.

Figure 2. WANFLeX packet flow

qm add ch1 all from 0/0 to 0/0 qm addout ch1 all from 0/0 to 0/0

QM

manager

Switching

core

Routing

core

Ipfw

Ipfw QM

manager

IpStat

Wireless

medium

Ingress Egress

IpStat

Wired

medium

Ipfw Ingress

qm add rule qm add rule qm add rule

qm channel qm channel qm channel

qm class qm class qm class

Switching

core

Routing

core

QM manager

IpStat Wired

Medium

of 24

Channels can be grouped into service classes, allowing bandwidth sharing between several channels (see Figure 2). Classes can be organized into a hierarchy to allow bandwidth sharing between service classes. An example hierarchy of service classes and channels is presented below(see Figure 3).

Figure 3. Service class hierarchy

Priority is one of the parameters that define how different types of data traversing every InfiNet Device in MINT network are treated. Each channel can be assigned a priority (0 ..16) (see table 1). Once assigned, a priority will be automatically recognized by every node inside MINT network. Each priority value corresponds to a device queue. Once in a queue, every packet is scheduled according to the queuing algorithm set on the device. QM manager supports Strict Priority Queuing and Weighted Fair Queuing scheduling algorithms. Strict Priority Queuing means that packets from queue with lower priority are not processed until the queue with higher priority is not empty. Weighted Fair Queuing uses weights for every queue of an interface and allows different queues to have different service shares depending on that weight. Every channel is also characterized by the latency parameter. This parameter determines the maximum time for the packets to stay in the channel. If a packet is waiting in a queue of the channel more than the time specified in the latency parameter then it is discarded. This can be used to give some traffic flows larger latency value thus increasing the queue size. Latency can be set to any value between 5 and 200 ms.

Class

2

Interface

Chan

2

Class

1

Class

3

Chan

1

Chan

4

Chan

3

of 24

Table 1. MINT priorities and WANFLeX queues

Queue name Priority/Queue number

QM_PRIO_NETCRIT 0

QM_PRIO_VOICE 1

QM_PRIO_RT1 2

QM_PRIO_VIDEO 3

QM_PRIO_RT2 4

QM_PRIO_QOS1 5

QM_PRIO_QOS2 6

QM_PRIO_QOS3 7

QM_PRIO_QOS4 8

QM_PRIO_BUSINESS1 9

QM_PRIO_BUSINESS2 10







Transparent packet prioritization is another WANFLeX feature worth mentioning. QM manager is able to transparently map 802.1p/TOS/DSCP priority to MINT priority for ease of deployment. No complicated configuration needed. This is done by just enabling qm option dot1p or qm option tos on the device. See priority mappings in Table 2.

Table 2. MINT priority to 802.1p/TOS priority/DSCP map

MINT priority 802.1p/TOS priority/DSCP

QM_PRIO_BUSINESS8 00/00/00 (CS0, 000000)

no priority 01/01/08 (CS1, 001xxx)

no priority 02/02/16 (CS2, 010xxx)

QM_PRIO_BUSINESS1 03/03/24 (CS3, 011xxx)

QM_PRIO_QOS3 04/04/32 (CS4, 100xxx)

QM_PRIO_VIDEO 05/05/40 (CS5, 101xxx)

QM_PRIO_VOICE 06/06/48 (CS6, 110xxx)

QM_PRIO_NETCRIT 07/07/56 (CS7, 111xxx)

of 24

It should be mentioned that prioritization in MINT networks is conducted by priority, given by the option pri=N. DSCP and TOS bits transparently traverse MINT network while 802.1p priority is transparently transmitted only in switch MINT mode. By default all traffic passing through an InfiNet Wireless device is marked with pri=16 (i.e. the lowest priority in the system).

Implementing QoS in MINT networks

Transparent packet prioritization

As it was mentioned before, the easiest way to implement QoS in a MINT network is by using transparent packet prioritization. Setting voice, tos or dot1p parameters in QM manager instantly sets QoS mapping on the node's interfaces. This can be done through the Web-interface (Basic Settings -> QoS Options):

Or using CLI, by setting the QM manager qm option parameters: qm option [no]voice [no]dot1p [no]tos [no]icmp [no]tcpack [no]strict

If we need voice traffic prioritized we should issue qm option voice command, to disable we should issue qm option novoice. Voice traffic is prioritized automatically when two conditions are met – this traffic is transported using RTP protocol and TOS bits are set and are not zero. The same can be done to enable or disable dot1p or TOS automatic prioritization using options qm option dot1p or qm option tos. Using qm option icmp and qm option tcpack options ICMP or TCPACK packets can be

of 24

prioritized. The last strict/nostrict option sets default qm manager queue behavior to Strict Priority or Weighted Fair Queuing. When MINT priority is set it is automatically recognized and prioritized accordingly on every node in the wireless network.

Manual QoS configuration

Another way is to create a logical channel with a set of rules for specific traffic type or types: qm ch1 pri=10 #Create channel 1 which will #set priority to 10 for all #data passing through it. qm add eth0 ch1 all from 0/0 to 0/0 #Direct all data coming into #eth0 port to channel 1.

In this case all packets from eth0 interface will be put into channel 1 with priority 10. Rules can select traffic by interface, port, IP or MAC address, protocol etc. Below there is another example: qm ch1 Max=64 #Create channel 1 with #maximum bit rate of 64 kpbs #for all data passing through #it. qm add eth0 ch1 all from 0/0 to 0/0 #Direct all data coming into #eth0 port to channel 1.

Word-by-word: channel 1 has maximum data rate limit of 64 kbps. This data rate is applied to the incoming traffic on eth0 interface, for all types of packet (tcp, udp, arp and so on) from all (0/0) sources to all (0/0) destinations.

Dynamic Bandwidth Allocation

If we would like to dynamically allocate bandwidth between different channels on the same interface we would need to create service classes. A service class combines several channels into a logical group for bandwidth sharing (see fig. 4). For example: We have a service class with 600kbps bandwidth allocated to it: qm class1 Max=600

And 3 channels in this class for different types of traffic (we will omit the channel rules as they are of no significance here). Each getting 200 kbps as their transfer rate, and the ability to use up to 600 kbps of their parent class: qm ch1 pri=10 Max=200 ceil=600 class1

of 24

qm ch2 pri=10 Max=200 ceil=600 class1 qm ch3 pri=10 Max=200 ceil=600 class1

If there is free bandwidth in class1, then each of the channels can compete for it. The allocated bandwidth is divided between them equally, regardless of the rate given in Max command. See diagram below:

Figure 4. Service class with service channels attached If we would like to make one of the channels preferable, then we must set ceilprio property while defining the channel. Note, that default ceilprio value is 1, so we can lower priority for a given channel. Allowed ceilprio values are from 0 to 10. qm ch1 pri=10 Max=200 ceil=600 class1 qm ch2 pri=10 Max=200 ceil=600 ceilprio=2 class1 qm ch3 pri=10 Max=200 ceil=600 ceilprio=2 class1

Now channel 1 is the priority channel and it will get all the excess bandwidth it needs. Only then spare excess bandwidth will be equally divided between channel 2 and channel 3. If there are more channels with a higher ceilprio value – then they are getting excess bandwidth first, just like in the initial example and then all the others, etc. If we use nested classes, like on Figure 3, we can share bandwidth between classes. Bandwidth allocation between nested classes is done the same way as with channels sharing the same class.

QoS Monitoring

QoS monitoring of InfiNet Wireless devices can be done using CLI or SNMP. When using CLI, several commands give some insight on QM manager performance:

config show qm – shows current qm manager configuration Example command output #console> config show qm #QoS manager qm option novoice nodot1p notos noicmp notcpack nostrict qm class1 max=100000

Class

1

Chan

1

Chan

2 Chan

3

of 24

qm class99 max=100 qm class100 max=100 qm class200 max=100 qm ch1 pri=0 max=3000 ceil=100000 ceilprio=2 class1 qm ch2 pri=3 max=10000 ceil=100000 class1 qm ch3 pri=9 max=50000 ceil=100000 ceilprio=2 class1 qm add 1 eth0 ch1 vlan=3 all from any to any qm add 2 eth0 ch2 vlan=30 all from any to any qm add 3 eth0 ch3 vlan=300 all from any to any

qm stat and qm stat full – show channel statistics Example command output #console> qm stat qm ch1 pri=0 max=3000 ceil=100000 ceilprio=2 class1 cur=0 pps=0 packets=0 (0) bytes=0 (0) curQL=0 maxQL=0 qm ch2 pri=3 max=10000 ceil=100000 class1 cur=0 pps=0 packets=0 (0) bytes=0 (0) curQL=0 maxQL=0 qm ch3 pri=9 max=50000 ceil=100000 ceilprio=2 class1 cur=0 pps=0 packets=0 (0) bytes=0 (0) curQL=0 maxQL=0 #console> qm stat full qm ch1 pri=0 max=3000 ceil=100000 ceilprio=2 class1 cur=0 pps=0 packets=0 (0) bytes=0 (0) curQL=0 maxQL=0 qm ch2 pri=3 max=10000 ceil=100000 class1 cur=0 pps=0 packets=0 (0) bytes=0 (0) curQL=0 maxQL=0 qm ch3 pri=9 max=50000 ceil=100000 ceilprio=2 class1 cur=0 pps=0 packets=0 (0) bytes=0 (0) curQL=0 maxQL=0 0 qm add 1 eth0 ch1 vlan=3 all from any to any 0 qm add 2 eth0 ch2 vlan=30 all from any to any 0 qm add 3 eth0 ch3 vlan=300 all from any to any

When using SNMP - detailed channel can be obtained(channel and class parameters, current data rates per channel, drop statistics per channel).

of 24

MINT as part of a multi-service network

MINT can be seamlessly integrated into an existing service provider multi-service network. The ability to transport extended Ethernet frames (MTU up to 1580 for QinQ and MPLS), transparent traffic prioritization and integrated QoS features give service providers additional flexibility in customer service delivery. Below we offer an example of a ISP network with MPLS backbone for POP interconnection. There are three wireless segments present: 1. Public safety surveillance system segment. 2. Residential area segment. 3. TDM PtP segment.

Figure 5. MINT network segments

Every segment uses latest InfiNet MIMO devices and can operate in speeds up to 300Mbps. Below we offer a short description and sample configurations for every segment. Sample configurations accommodate only the lines differing from default unit configurations.

of 24

Public safety surveillance system segment

InfiNet Wireless offers a flexible approach to building wireless CCTV networks. MINT architecture offers the ability to create a virtual switching entity spread over any number of wireless nodes. This virtual switch is capable of QoS and IGMP Snooping mechanisms, thus enabling the use of multicast priority data flows in a wireless environment. Below, there are two sample configurations for master and slave nodes for the presented in figure 5 PtMP scenario. Slave nodes are used for connecting remote IP-cameras. Master node is connected to service provider MPLS backbone and is used to transport a 802.1q VLAN with multicast video to the data center. Master configuration:

#QoS manager qm ch2 pri=3 #Create logical channel for #multicast video. qm add 5 eth0 ch2 vlan=30 all from any to any #Rule for adding video VLAN #30 to channel 2 with #priority 3. #MINT configuration mint rf5.0 poll start #Enabling polling to #minimize jitter. mint rf5.0 -type master #Set unit type to master. #MAC Switch config switch group 30 add eth0 rf5.0 #Creating switch group for #VLAN 30. switch group 30 vlan 30 switch group 30 igmp-snooping on #Enable IGMP-snooping switch group 30 start

Slave configuration:

#QoS manager qm ch2 pri=3 #Create logical channel for #multicast video. qm add 5 eth0 ch2 vlan=30 all from any to any #Rule for adding video VLAN #30 to channel 2 with #priority 3. #MINT configuration mint rf5.0 poll start #Enabling polling to #minimize jitter. mint rf5.0 -type slave # Set unit type to slave. #MAC Switch config switch group 30 add eth0:0 rf5.0:30 #Creating switch group for #our VLAN, but as camera will #most likely send untagged #traffic, we will do tagging #and untagging on the InfiNet #device. switch group 30 igmp-snooping on #Enable IGMP-snooping. switch group 30 start

of 24

This wireless segment can be used for transporting other types of traffic as well. For concurrent data flows, see Residential area segment configurations below.

Residential area segment

Nowadays residential subscribers are seeking triple play services from their service providers. Internet access, VoIP and multicast video can be delivered trough wireless infrastructure built with InfiNet Wireless devices. 802.1q VLAN, QoS and IGMP snooping support give service providers valuable tools to satisfy their customer needs. In this scenario we need to transport three different data streams using three VLANs: voice in VLAN 3, Video in VLAN 30 and Internet traffic in VLAN 300. Video is transported using multicast. All types of traffic are marked with IP TOS values and are automatically prioritized in MINT network.

Transparent prioritization

Master configuration:

#QoS manager qm option tos #Enable TOS transparent #prioritization. #MINT configuration mint rf5.0 poll start #Enabling polling to #minimize jitter. mint rf5.0 -type master #Set unit type to master. #MAC Switch config switch group 3 add eth0 rf5.0 #Creating switching groups #for VLANs. switch group 3 vlan 3 switch group 3 start switch group 30 add eth0 rf5.0 switch group 30 vlan 30 switch group 30 igmp-snooping on #Enable IGMP snooping in #multicast video switching #group. switch group 30 start switch group 300 add eth0 rf5.0 switch group 300 vlan 300 switch group 300 start


#QoS manager qm option tos #Enable transparent #prioritization. #MINT configuration mint rf5.0 -type slave #Set unit type to slave. #MAC Switch config switch group 3 add eth0 rf5.0 #Creating switch groups for

of 24

#VLANs. switch group 3 vlan 3 switch group 3 start switch group 30 add eth0 rf5.0 switch group 30 vlan 30 switch group 30 igmp-snooping on #Enable IGMP snooping in #multicast video switch #group. switch group 30 start switch group 300 add eth0 rf5.0 switch group 300 vlan 300 switch group 300 start

This configuration implies that on the client side packets are market with TOS bits according to their traffic type and there is a way to sort client traffic into different VLANs. Otherwise QM manager and switching group rules should be applied to distinguish different types of traffic. QM manager and switching group rules description can be found in WANFLeX OS documentation. If there is no TOS or 802.1p marking, then MINT prioritization marking can be done on InfiNet devices:

Manual QoS

Master configuration:

#QoS manager qm class1 max=20000 #Create class 1 with 20mbps #bit rate. qm ch1 pri=1 max=1000 ceil=10000 class1 #Channel 1 with 1Mbps CIR, #priority 1, and up to 10Mbps # borrowed from class 1 unused #bandwidth. qm ch2 pri=3 max=4000 ceil=10000 class1 #Channel 2 with 4Mbps CIR, #priority 3, and up to 10Mbps #borrowed from class 1 unused #bandwidth. qm ch3 pri=9 max=5000 ceil=10000 ceilprio=2 class1 #channel 3 with 5Mbps CIR, #priority 9 and up to 10Mbps # borrowed from class 1 unused #bandwidth. ceilprio=2 makes #sure that unused bandwidth #is borrowed only after #channels 1 and 2 get their #share. qm add 1 eth0 ch1 vlan=3 all from any to any #VLAN 3 traffic is assigned #to channel 1 qm add 2 eth0 ch2 vlan=30 all from any to any #VLAN 30 traffic is assigned #to channel 2 qm add 3 eth0 ch3 vlan=300 all from any to any #VLAN 300 traffic is assigned #to channel 3

of 24

#MINT configuration mint rf5.0 poll start #Enabling polling to minimize #jitter. mint rf5.0 -type master #Set unit type to master. #MAC Switch config switch group 3 add eth0 rf5.0 #Creating switching groups #for VLANs. switch group 3 vlan 3 switch group 3 start switch group 30 add eth0 rf5.0 switch group 30 vlan 30 switch group 30 igmp-snooping on #Enable IGMP snooping in #multicast video switching #group. switch group 30 start switch group 300 add eth0 rf5.0 switch group 300 vlan 300 switch group 300 start


#QoS manager qm class1 max=20000 #Create class 1 with 20mbps #bit rate. qm ch1 pri=1 max=1000 ceil=10000 class1 #Channel 1 with 1Mbps CIR, #priority 1, and up to 10Mbps #borrowed from class 1 unused #bandwidth. qm ch2 pri=3 max=4000 ceil=10000 class1 #Channel 2 with 4Mbps CIR, #priority 3, and up to 10Mbps #borrowed from class 1 unused #bandwidth. qm ch3 pri=9 max=5000 ceil=10000 ceilprio=2 class1 #channel 3 with 5Mbps CIR, #priority 9 and up to 10Mbps #borrowed from class 1 unused #bandwidth. ceilprio=2 makes #sure that unused bandwidth #is borrowed only after #channels 1 and 2 get their #share. qm add 1 eth0 ch1 vlan=3 all from any to any #VLAN 3 traffic is assigned #to channel 1. qm add 2 eth0 ch2 vlan=30 all from any to any #VLAN 30 traffic is assigned #to channel 2. qm add 3 eth0 ch3 vlan=300 all from any to any #VLAN 300 traffic is assigned #to channel 3. #MINT configuration mint rf5.0 -type slave #Set unit type to slave.

of 24

#MAC Switch config switch group 3 add eth0 rf5.0 #Creating switch groups for #VLANs. switch group 3 vlan 3 switch group 3 start switch group 30 add eth0 rf5.0 switch group 30 vlan 30 switch group 30 igmp-snooping on #Enable IGMP snooping in #multicast video switch #group. switch group 30 start switch group 300 add eth0 rf5.0 switch group 300 vlan 300 switch group 300 start

TDM PtP segment

InfiNet Wireless devices offer the ability to transport up to 4 TDM (E1 or T1) streams using PtP topology. TDM streams can be transported over single or multi-hop wireless links. Here we offer a single-hop example, as transit nodes in a multi-hop scenario don't feature any specific settings. Master configuration:

#MINT configuration mint rf5.0 poll start #Enabling polling to minimize #jitter. mint rf5.0 -type master #Set unit type to master. #CES-over-Wlan parameters ces mode e1 loopback #Set TDM flow mode. ces maxjitter 20 #Set maximum expected jitter #for this link. ces frames 16 #Set number of TDM frames to #be sent in one CES-over-Wlan #frame. ces bwlimit 30000 auto ces ports 0 ces start


#MINT configuration mint rf5.0 -type slave #Set unit type to master #CES-over-Wlan parameters ces mode e1 recovery #Set CES module to receive #TDM stream and recover #synchronization from the #stream. ces start #Start CES module process.

of 24

QoS Lab Test Results In this section we would like to present some test results using Residential area configurations, mentioned above. Figure 6 shows the setup used in this test. Figure 7 shows data flow graphs on the transmitting and the receiving end during four test stages.

Figure 6. QoS lab test setup Test scenario: Three data flows traverse a wireless segment built with InfiNet Wireless devices(VLANs 3, 30, 300). They are serviced by three logical channels (1,2 and 3) combined in a class (class 1). Wireless link capacity is 20Mbps. The same capacity is set in class 1. Test stage descriptions are presented below: Stage 1. All three flows use bandwidth specified in max command - 1000, 4000 and 5000 kbps respectively. On figure 7 there is an additional upper line, representing the sum of all flows exiting or entering traffic generator port. Stage 2. VLAN 300 flow uses additional 5 Mbps borrowed from class 1. As a consequence, traffic sum went from 10 to 15 Mbps. No shaping occurs here as we did not exceed 20 Mbps threshold of class 1. Stage 3. VLAN 3 uses additional 5 Mbps borrowed from class 1. As a consequence, traffic sum went from 15 to 20 Mbps. No shaping occurs here as we did not exceed 20 Mbps threshold of class 1. Stage 4. Additional 5 Mbps added to flow in VLAN 30. Shaping mechanisms started as 25 Mbps are transmitted, when only 20 Mbps are permitted on the link. As channels 1 and 2 have higher ceilprio value, they are the first to borrow excess bandwidth. As a result – VLAN3 and VLAN30 flows both get additional 5Mbps of bandwidth, depleting class 1. VLAN 300 gets only the bandwidth specified in max command – 5 Mbps.

of 24

Figure 7. QoS lab test results

of 24

Testing Wireless Link Quality

There several ways to test wireless links built with InfiNet Wireless devices. The easiest is by using the web interface. After you login, choose the link you wish to test and press left mouse button:

A window will pop out, giving you the option to start alignment tool or start performance tests:

of 24

On the performance test page you have the options to run unidirectional or bidirectional tests.

There is also a MINT check box, which chooses the method the tests are performed. When MINT check box is checked the tests are conducted in current network conditions using automatic power and bit rate control, showing you the best performance with lowest number of errors and retries:

of 24

When the check box is not checked the tests are performed consequently, using current power level and all the available bit rates without using automatic bit rate or power control:

Same tests can be done using CLI. Below there is a sample output for unidirectional and bidirectional tests: Unidirectional: #console> ltest rf5.0 000E8E1F63F9 -tu Unidirectional throughput test to 000E8E1F63F9 via rf5.0 with no priority packet size 1536, bitrate 130000, reply bitrate 130000 Please wait..... ============================================================================= Direction | Kbit/s | Pkt/s | Retries | Errors | min/avg/max/stddev (usec) ============================================================================= Transmit | 99496 | 8291 | 8.52% | 0.00% | 1/120/11516/627

Bidirectional: #console> ltest rf5.0 000E8E1F63F9 -tb Bidirectional throughput test to 000E8E1F63F9 via rf5.0 with no priority packet size 1536, bitrate 130000, reply bitrate 104000 Please wait..... ============================================================================= Direction | Kbit/s | Pkt/s | Retries | Errors | min/avg/max/stddev (usec) ============================================================================= Transmit | 34519 | 2876 | 31.20% | 0.00% | 2/347/38018/1973 Receive | 34121 | 2843 | 29.99% | 0.00% | 3/351/45110/1867 ----------------------------------------------------------------------------- Total | 68640 | 5719 |

of 24

When testing wireless links using external tools TCP window size should be taken into account. See explanation in the section below.

Wireless Link Testing and TCP window size considerations

One can face limited throughput on a wireless link, when using suboptimal or default TCP window size values in some operating systems. MINT networks are characterized by high bandwidth (up to 300Mbps) and higher then LAN latency (around 2-5ms on every wireless node). Calculating the available throughput for a MINT wireless link with 20ms latency gives us: • 20-22Mbps per TCP flow using 64K window size • 3-4 Mbps per TCP flow using 8K window size (WinNT) • 6-7 Mbps per TCP flow using 17K window size (Win2000-win2003-WinXP) If we enable TCP Window Scaling and Compound TCP on Microsoft operating systems we can get up to the full available bandwidth using one TCP stream. But It should be taken into account that real-world network scenarios mostly deal with multiple TCP streams, so TCP Window tuning is done only when you need to transport few high bandwidth streams through InfiNet Wireless devices. One of the scenarios when high bandwidth streams are used is MINT bandwidth testing. We recommend using iperf/jperf software, so no TCP parameters are changed on the devices. For iperf see example below: Server command line parameters: iperf -s -w 256k -l 256k

Client command line parameters: iperf -c <IP> -w 256k -l 256k -P 4 -d where -c <IP> - IP address on the client PC used in the test -w 256k - TCP Window Size -l 256k - buffer size -P 4 - number of simultaneous flows -d - bidirectional test flag

This will make iperf use 256 kilobyte TCP window size and start 4 TCP streams to test your wireless link. Using these parameters makes certain that test streams use all the available bandwidth of the link.

of 24

Conclusion Implementing Quality of Service in wireless networks has always been a challenge. InfiNet Wireless innovative MINT architecture enables QoS for layer-2 and layer-3 applications in a broadband wireless environment, giving service providers the necessary tools for offering innovative services to their customers lowering complexity and Total Cost of Ownership for broadband wireless networks.

quality of service · white paper . page 2 of 24 contents ... qm option [no]voice [no]dot1p [no]tos...

Documents