NETWORKINGFUNDAMENTALS

K.GAYATHRI

IPv4 Addressing●The IPv4 addresses are unique and universal.●An IPv4 address is 32 bits long.●The address space of IPv4 is 232 (4,294,967,296)

2 Types of IPv4 Notations.Binary notationDotted-decimal notation

SUBNETTING AND VLSMSubnetting●Divide a large address block into smaller sub-groups.●Use of flexible net mask.

VLSM-Variable Length Subnet Mask●Technique that allows network administrators to divide an IP address space into subnets of different sizes, unlike simple same-size Subnetting. ●Subnetting a subnet.

ROUTING PROTOCOLS●Routing ProtocolProtocols used by routers to make path determination choices

and to share those choices with other routers●Autonomous system (AS) Uses Interior Gateway Protocols as routing protocols

A group of routers under the control of a single administration●Interior Gateway Protocols (IGPs) Routing protocols used within an AS

●Exterior Gateway Protocols (EGPs) Routing protocols used to route information between multiple

autonomous systems

ROUTING PROTOCOLS(continued)

Examples of IGPs●Routing Information Protocol (RIP)●Enhanced Interior Gateway Routing Protocol (EIGRP)●Open Shortest Path First (OSPF)

Example of EGP●Border Gateway Protocol (BGP)

ROUTING INFORMATION PROTOCOL(RIP)●Routing Information Protocol (RIP)●The easiest Interior Gateway Protocol to configure is RIPv1●A distance-vector routing protocol that broadcasts entire routing tables to neighbors every 30 seconds●RIP has a maximum hop count of 15●As a result, RIP does not work in large internetworks●Enabling RIP Routing, the following commands are used,

Router(config)#router rip

Router(config-router)#network 192.168.1.0●To troubleshoot RIP Routing,

Router#show ip rip

ENHANCED INTERIOR GATEWAY PROTOCOL(EIGRP)●EIGRP is a Cisco-proprietary Hybrid routing protocol, incorporating features of both Distance-Vector and Link-State routing protocols. ●It sends routing updates only when network topology changes instead of its entire routing table at regular intervals.●Its convergence is very fast●It supports classless inter-domain routing (CIDR) and variable-length subnet masks

(VLSM)●EIGRP Major Drawback

It is Cisco proprietary - it does not inter-operate with other vendors' devices. This, of course, is the big one. If you are working in a mixed environment, EIGRP doesn't make as much sense

EIGRP(Continued)●EIGRP uses Diffusing Update Algorithm (DUAL)to determine the best path among all “feasible” paths. DUAL also helps ensure a loop-free routing environment.●EIGRP will form neighbor relationships with adjacent routers in the same Autonomous System (AS)●EIGRP traffic is either sent as unicasts, or as multicasts on address 224.0.0.10, depending on the EIGRP packet type.●Reliable Transport Protocol (RTP) is used to ensure delivery of most EIGRP packets.●EIGRP packets are Hello,Update,Query,Reply and Ack

EIGRP(Continued)EIGRP, much like OSPF, builds three separate tables,●Neighbor table– list of all neighboring routers. neighbors must belong to the same Autonomous System●Topology table– list of all routes in the Autonomous System ●Routing table– contains the best route for each known network●Enabling EIGRP Routing, the following commands are used,

Router(config)#router eigrp 100

Router(config-router)#network 10.10.1.0●To troubleshoot EIGRP Routing,following commands are used,

Router#show ip route eigrp

Router#show ip eigrp neighbor

Router#show ip eigrp traffic

OPEN SHORTEST PATH FIRST(OSPF) PROTOCOL●OSPF is a standardized Link-State routing protocol,designed to scale efficiently to support larger networks●Special routers (autonomous system boundary routers) or backbone routers responsible to dissipate information about other AS into the current system.●It minimizes routing table entries by dividing AS into areas●Fast convergence Protocol●Low bandwidth requirements●Supports different types of areas●Route summarization and authentication●Cisco's implementation is fully compliant with the specification OSPF v2.

OSPF(Continued)OSPF Packet Types,

● Hello packets● Database Description (DBD)● Link-State Request (LSR)● Link-State Update (LSU)● Link-State Acknowledgement (LSA)

Different Types of LSAs,●Router LSA●Network LSA●Network Summary LSA●ASBR Summary LSA●AS-External LSA

OSPF(Continued)●Enabling OSPF Routing, the following commands are used,

Router(config)#router ospf 1(process id)

Router(config-router)#network 192.168.1.1 0.255.255.255 area 1●To troubleshoot OSPF Routing,following commands are used,

Router# show ip route

Router# show ip ospf

Router# show ip ospf interface

Router# show ip ospf neighbor

Router# show ip ospf database

BORDERED GATEWAY PROTOCOL(BGP)

●Routing Protocol used to exchange routing information between Autonomous System●Exterior gateway protocol and path vector protocol●A Path vector protocol defines a route as a pairing between a destination and the attributes of the path to that destination●Types of BGP Messages are Open,update, Keep-alive and Notification

Two types of BGP

External BGP Peering (eBGP)

Internal BGP Peering (iBGP)

BGP(Continued)Internal BGP (iBGP)●BGP peer within the same AS●Not required to be directly connected●iBGP speakers need to be fully meshed●They originate connected networks●They do not pass on prefixes learned from other iBGP speaker

External BGP Peering (eBGP)●Between BGP speakers in different AS●Should be directly connected●Do not run an IGP between eBGP peers

BGP Configuration Example

SWITCHING IN VLAN'S●Switches also have enabled the creation of Virtual LANs (VLANs). ●VLANs provide greater opportunities to manage the flow of traffic on the LAN and reduce broadcast traffic between segments.●VLANs are groups of computers in an intelligent switched network.●Allow us to split switches into separate (virtual) switches●Only members of a VLAN can see that VLAN’s traffic

VLAN'S Types,●Port-based VLANs ●MAC address based ●Protocol based VLANs●Application based VLANs

VIRTUAL TRUNKING PROTOCOL(VTP)●VTP reduces the complexity of managing and monitoring VLAN networks●VTP maintains VLAN configuration consistency across a common network administration domain●VTP allows VLANs to be trunked over mixed media●VTP provides for accurate tracking and monitoring of VLANs●VTP provides “Plug-and-Play” configuration when adding new VLANs

VTP switches operate in one of three modes:●Server – default mode. Sends VLAN information to other switches.●Client – receives VLAN information and forwards it to other switches.●Transparent – forward VTP traffic but do not originate or use it. They can have their own VLANs, not shared with other switches.

VTP(Continued)

Command to set the VTP mode:

Switch(vlan)#vtp {client | server | transparent}

VTP Pruning-VTP pruning increases network available bandwidth by restricting flooded traffic to those trunk links that the traffic must use to reach the destination devices

VLAN1

VLAN2

VLAN3

VLAN4

●STP is a link management protocol that provides path redundancy while preventing undesirable loops in the network

Spanning Tree Algorithm

The switches use this algorithm to decide which ports should be shut down.●Choose one switch to be “root bridge”●Choose a “root port” on each other switch●Choose a “designated port” on each segment.●Close down all other ports.

SPANNING TREE PROTOCOL(STP)

STP TYPES1.CSTP-Comman STP

2.RSTP(Rapid STP)-RSTP(Rapid Spanning Tree Protocol-802.1w Standard): it is the enhanced protocol of STP,the main caracteristic of this one is Faster than STP (it converge in less than 6 seconds).

3.MST(Multiple STP)-allows multiple spanning tree domains to be configured in a network and on a switch.It is based on RSTP, and is backwards-compatible with RSTP and STP.

4.PVST(Per VLAN STP)- Maintains a spanning-tree instance for each VLAN configured in the network.

5.PVST+ -Per-VLAN Spanning Tree Plus is a Cisco

proprietary spanning tree protocol based on STP.

VIRTUAL PRIVATE NETWORK(VPN)

●Creates a secure tunnel over a public network●Uses the Internet as the public backbone to access a

secure private network●Remote employees can access their office network

VPN Protocols●PPTP (Point-to-Point tunneling Protocol)●L2F (Layer 2 Forwarding Protocol)●L2TP (Layer 2 Tunneling Protocol)●IPSec (Internet Protocol Security)

IPsec(IP security)●Provides Layer 3 security (RFC 2401)●Transparent to applications (no need for integrated IPSec support)●A set of protocols and algorithms used to secure IP data at the network layer

Combines different components:●Security associations (SA)●Authentication headers (AH)●Encapsulating security payload (ESP)●Internet Key Exchange (IKE)

Ipsec Modes

Tunnel Mode●Entire IP packet is encrypted and becomes the data component of a new (and larger) IP packet.●Frequently used in an IPsec site-to-site VPN

Transport Mode●Ipsec header is inserted into the IP packet●No new packet is created●Works well in networks where increasing a packet’s size could cause an issue●Frequently used for remote-access VPNs

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