CCNA part 6 igrp,ospf,eigrp
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- An autonomous system (AS) is a group of networks under single administrative control, each with a unique ID number. Interior gateway protocols (IGPs) like RIP, IGRP, EIGRP, OSPF route within an AS, while exterior gateway protocols like BGP route between ASes. - IGRP is a distance vector protocol that uses a composite metric and broadcasts updates. EIGRP is an advanced hybrid protocol that uses multicast updates and three tables to store routing information. OSPF is a link-state protocol that forms adjacencies and uses areas and least-cost routing. - Configuring these protocols involves enabling IP routing, specifying the routing protocol and associated networks, and verifying
CCNA part 6 igrp,ospf,eigrp
- 2. Autonomous System(AS):- • An autonomous system (AS) is a group of networks under a single administrative control, which could be your company, a division within your company, or a group of companies. • Each AS is assigned a unique number in order to differentiate it from other autonomous systems. • Range of AS no:- total AS nos.= 1 - 65535 public AS nos = 1 – 64512 private AS no = 64513 – 65535.
- 3. Routing protocol classification:- IGP • Interior Gateway Protocol. • Routing protocols used within an AS. • All routers will be routing within the same AS boundary. • IGPs include RIP, IGRP, EIGRP, OSPF, and IS-IS. EGP • Exterior Gateway Protocol • Routing protocols used between different AS. • Routers in different AS need as EGP. • E.g. BGP is used to route traffic across the Internet backbone between different autonomous systems.
- 4. IGRP:- • Interior Gateway Routing Protocol. • It is a Cisco-proprietary routing protocol for IP. • It is a distance vector protocol. • IGRP uses a composite metric (24-bit), which includes bandwidth,delay, reliability, load, and MTU(Maximum Transmission Unit). • It is a classful routing protocol. • Updates are broadcasted via 255.255.255.255. • Administrative distance is 100. • Used for large organization. • Maximum hop count is 255 and 100 is by default.
- 5. Timers of IGRP:- • Update timer= 90 seconds. • Invalid timer= 270 seconds. • Holddown timer= 280 seconds. • Flush timer= 630 seconds.
- 6. IGRP Configuration:- BANGLORE#config t BANGLORE(config)#no ip routing BANGLORE(config)#ip routing BANGLORE(config)#router igrp 100 (A S) BANGLORE(config-router)#network 192.168.1.0 BANGLORE(config-router)#network 10.0.0.0 BANGLORE(config-router)#^Z BANGLORE#show ip route
- 7. EIGRP:- • Enhanced Interior Gateway Routing Protocol. • It is a Cisco-proprietary protocol, and is based on IGRP. • It is a hybrid protocol. • It is a classless routing protocol. • EIGRP uses a composite metric (32-bit), which includes bandwidth,delay, reliability, load, and MTU(Maximum Transmission Unit). • Administrative distance is 90. • Maximum hop counts is 255 , and 100 by default. • It support IP, IPX Apple Talk. • Updates are through multicast (224.0.0.10).
- 8. Characteristics of EIGRP:- • Fast convergence • Loop-free topology • Multicast and incremental updates • Routes for multiple routed protocols • Hello packets are send every 5 seconds. • EIGRP uses Diffusing update algorithm (DUAL) for selecting and maintaining the best path to each remote network. • It supports for multiple ASes on a single router.
- 9. EIGRP maintain three tables to store route information:- • Neighbor ship Table:- This table records information about routers with whom neighbor ship have been formed. • Topology Table:- This tables stores the routes that are advertisements about every route in the internetwork received from each neighbor. • Root Table:- This tables stores the route that are currently used to make routing decisions. There would be separate copies of each tables for each protocols that is actively being supported by EIGRP, where its IP,IPX,or Apple Talk.
- 10. Configuration of EIGRP:- BANGLORE#config t BANGLORE(config)#no ip routing BANGLORE(config)#ip routing BANGLORE(config)#router eigrp 200 BANGLORE(config-router)#network 192.168.1.0 BANGLORE(config-router)#network 10.0.0.0 BANGLORE(config-router)#^Z BANGLORE#show ip route
- 11. OSPF:- • Open Shortest Path First. • It is a open standard routing protocol. • It is a link state protocol. • It is successor of RIP. • It is classless routing protocol. • Update are through multicast (224.0.0.5), minimize routing traffic. • Administrative Distance is 110. • OSPF uses metric as cost & cost=(10^8)/bandwidth in bps.
- 12. Characteristics of OSPF • Fast convergence. • Hello packets are sent every 10 seconds. • Consists of Areas and autonomous systems. • Allow scalability. • It support VLSM/CIDR. • It has unlimited hop counts. • Allows multi vendor deployment.
- 13. OSPF Areas:- • An OSPF area is grouping of contiguous networks and routers. • All routers in the same area share a common area ID. • Router can be member of more than one area at a time. • Area 0 is called as backbone/Transient area. • 1 – 65535 is a general areas.
- 14. OSPF Three Tables:- • Neighbor table:- Neighbor table contains information about the directly connected ospf neighbors forming adjacency. • Database table:- Database table contain information about all entries view of the topology with respect to each router. • Routing information table:- Routing information table contain information about the best path calcuted by the shortest path first (SPF) algorithm in the database table.
- 15. Disadvantages of OSPF:- • It requires more memory to hold the adjacency (list of OSPF neighbors), topology (a link state database containing all of the routers and their routes), and routing tables. • It requires extra CPU processing to run the SPF algorithm . • For large networks, it requires careful design to break up the network into an appropriate hierarchical design by separating routers into different areas. • It is complex to configure and more difficult to troubleshoot.
- 16. OSPF Configuration: BANGLORE#config t BANGLORE(config)#no ip routing BANGLORE(config)#ip routing BANGLORE(config)#router ospf 200 (process id) BANGLORE(config-router)#network 192.168.1.0 0.0.0.255(wild card mask) area 0 BANGLORE(config-router)#network 10.0.0.0 0.255.255.255 area 0 BANGLORE(config-router)#^Z BANGLORE#show ip route
- 17. Administrative distances • Connected 0 • Static route 1 • RIP 120 • IGRP 100 • EIGRP 90 • OSPF 110 • External EIGRP 170 • Unknown 255