Advanced Routing Protocols

CCNA Guide to Cisco Networking Chapter 9 : Advanced Routing Protocols

Objectives • Describe classful and classless routing protocols • Describe and configure RIPv2 • Describe and configure EIGRP • Describe and configure OSPF • Control routing traffic

Classful And Classless Routing Protocols • How the routing protocols handles subnets masks information • Classful routing protocols – RIPv1 – IGRP – Major network boundaries (Class A, B, or C) – Don not carry subnet mask information – Cannot use or work with • Discontiguous subnets • VLSM

Classful And Classless Routing Protocols (continued)






Classful And Classless Routing Protocols (continued) • Classless routing protocols – RIPv2 – EIGRP – OSPF – BGP – Not restricted to Major network boundaries – Carry subnet mask information – Work with • Discontiguous subnets • VLSM





Routing Information Protocol Version 2 • Metric – Hops – Max 15 hops

• 16th hop unreachable • Carry subnet mask information • Updates are multicast 224.0.0.9 • Ability to authenticate routing peers

Routing Information Protocol Version 2 (continued)





Routing Information Protocol Version 2 (continued) • RIPv2 authentication steps – Define a key chain – Define keys in the key chain – Enable authentication on the interface by specifying the key chain to be used – Enable either clear text or MD5 authentication – Manage the keys (optional key lifetimes)




Enhanced Interior Gateway Routing Protocol • Cisco proprietary protocol – Hybrid protocol – Features both distance-vector and link-state protocols

• Classless – Not restricted to Major network boundaries – Carry subnet mask information – Work with • Discontiguous subnets • VLSM

• Route IP, IPX, and AppleTalk – Protocol Dependent Modules (PDMs)

Enhanced Interior Gateway Routing Protocol (continued) • Routing updates are – Non-periodic – Partial – Bounded

• Authentication of peers • Backwards compatible with IGRP • Automatically share or redistribute between IGRP and EIGRP

Enhanced Interior Gateway Routing Protocol (continued) • EIGRP components – Protocol Dependent Modules – Neighbor discovery and maintenance – Reliable Reliable Transport T ransport Protocol – Diffusing Update Algorithm (DUAL)

• Hello packets – Multicast packets to 224.0.0.10 • Every 5 seconds on T1 or greater links

– Unicast packets • Every 60 seconds on less than T1 speeds

Enhanced Interior Gateway Routing Protocol (continued) • Hello packets (continued) – – – –

Hold-down timer is 3 times Hello interval Peer routers do not need to have same settings Timers are configurable on a per-interface basis Hello packets use the Reliable Transport Protocol (RTP)

• EIGRP uses 5 packets types – – – – –

Hellos Acknowledgements Updates Queries Replies

Enhanced Interior Gateway Routing Protocol (continued)

Enhanced Interior Gateway Routing Protocol (continued) • Diffusing Update Algorithm (DUAL) key terms – – – – – –

Successor Feasible distance (FD) Reported distance (RD) Feasible successor Feasible condition Adjacency

• EIGRP tables – Neighbor table – Topology table – Routing table







EIGRP Configuration

EIGRP Configuration (continued)

EIGRP Configuration (continued) • EIGRP peer routing authentication steps – Define a key chain – Define keys in the key chain – Enable authentication on the interface by specifying the key chain to be used – Manage the keys (optional key lifetimes)

EIGRP Configuration (continued)

Open Shortest Path First • OSPF – Open standard – Link-state routing protocol – Classless routing and VLSM – Authentication of routing peers – Share a common view of the entire enti re network – Sends out link-state advertisements (LSA) • LSAs are not periodic • Sent only when a change occurs

Open Shortest Path First (continued) • Suited for large networks • High CPU and memory demands • OSPF creates the following – Adjacency database – Topology database – Touting table

Open Shortest Path First (continued)

Open Shortest Path First (continued) • OSPF Concepts – Link – Link-state – Area – Cost – Adjacencies database – Topological database – Designated router • Router election with router ID

– Backup designated router




OSPF Operation • OPSP operation – First: Form adjacencies with neighbors – Second: Election of DR and BDR – Third: Flood LSAs – Fourth: Select best routes

• Dijkstra’s Shortest Path Algorithm – Loop-free – Best cost path – CPU and Memory demands

OSPF Operation (continued)

Single-Area OSFP Configuration

Single-Area OSFP Configuration (continued)

Controlling Route Traffic • “passive-interface” command • RIP will receive updates not send – RouterD(config)# RouterD(config)# router rip – RouterD(config-router) RouterD(config-router)# # passive-interface s0

• EIGRP and OSPF will not send or receive updates

Controlling Route Traffic (continued)

Summary • Large, complex internetworks using variable length subnet masks require routing protocols that can handle the task • Several advanced routing protocols are in common use on networks today • These protocols are classless and carry subnet mask information in their routing table updates

Summary (continued) • RIPv2 is a classless routing protocol built as an extension to RIPv1 • It supports modern networks’ use of VLSM and authentication • In addition, it provides backward compatibility with RIPv1 when configured correctly • Still, RIPv2 suffers from all the pitfalls of distance-vector routing protocols

Summary (continued) • EIGRP is a Cisco proprietary protocol pr otocol designed to incorporate some of the features of link-state routing protocols • It is, however, still a distance-vector routing protocol • EIGRP does support classless routing • Its use of neighbor, topological, and routing tables allows for quick convergence in the event of a link failure • In fact, for each destination network, EIGRP keeps a successor or best route, and if possible a feasible successor or backup route

Summary (continued) • The open standards protocol OSPF is the linkl inkstate protocol of choice in many networks; it supports VLSM, classless routing, and fast convergence • In OSPF, each router uses the Shortest Path First Algorithm to determine the best loop-free path to each network • Each router also uses an adjacency table, topological table, and routing table to pick the best route to a destination

Advanced Routing Protocols

Recommend Documents