Post on 03-Jan-2016
Chapter 9 Objectives
• Enhanced IGRP– EIGRP tables– Configuring EIGRP– Verifying EIGRP
• Open Shortest Path First– Configuring OSPF– Verifying OSPF– Configuring OSPF with wildcards
2
What Is Enhanced IGRP (EIGRP)?
• Supports IP and IPv6 (and other routed protocols) via protocol dependent modules
• Considered classless• Support for VLSM/CIDR• Support for summaries and discontiguous
networks• Efficient neighbor discovery• Communication via Reliable Transport Protocol
(RTP)• Best path selection via Diffusing Update
Algorithm (DUAL)
EIGRP for IP
• Route updates sent only when a change occurs – multicast on 224.0.0.10
• Hello messages sent to neighbors every 5 seconds (60 seconds in most WANs)
Enhanced IGRP
EIGRP EIGRP
hello
EIGRP Terminology
Neighbor Table—IPNext Hop Interface Router
Topology Table—IPDestination 1 SuccessorDestination 1 Feasible Successor
Routing Table—IPDestination 1 Successor
Note: A feasible successor is a backup route and stored in the Topology table
EIGRP Tables
• The neighbor table and topology table are held in RAM and are maintained through the use of hello and update packets.
Enhanced IGRP
EIGRP EIGRP
hello
To see all feasible successor routes known to a router, use the show ip eigrp topology command
Successor routes
• Successor route is used by EIGRP to forward traffic to a destination
• A successor routes may be backed up by a feasible successor route
• Successor routes are stored in both the topology table and the routing table
Routing Table—IPDestination 1 Successor
Topology Table—IPDestination 1 SuccessorDestination 1 Feasible Successor
Choosing Routes
• EIGRP uses a composite metric to pick the best path: bandwidth and delay of the line
• EIGRP can load balance across six unequal cost paths to a remote network (4 by default)
IPX
19.2
T1
T1 T1
IPX
AppleTalk
IP
AppleTalk
IPA B
DC
Configuring EIGRP for IP
172.16.10.010.110.1.0192.168.0.0
TokenRing
AS=10
Router(config)#router eigrp 10
Router(config-router)#network 10.0.0.0Router(config-router)#network 172.16.0.0
192.168.0.0
A C
B
Enable EIGRP
Assign networks
Route Path
Assuming all default parameters, which route will RIP (v1 and v2) take, and which route will EIGRP take?
T1 T1
100BaseT
100BaseT
10BaseT
56K
Verifying EIGRP Operationshow ip route
Shows the entire routing table
show ip route eigrp
Shows only EIGRP entries in the routing table
show ip eigrp neighbors
Shows all EIGRP neighbors
show ip eigrp topology Shows entries in the EIGRP topology table
show ip protocols
Shows routing protocols configuration
debug eigrp packet
Shows Hello packets sent/received
debug ip eigrp events Shows EIGRP changes and updates
Show IP Route
D is for “Dual”
[90/2172] is the administrative distance and cost of the route. The cost of the route is a composite metric comprised from the bandwidth and delay of the line
P1R1#sh ip route[output cut]Gateway of last resort is not setD 192.168.30.0/24 [90/2172] via 192.168.20.2,00:04:36, Serial0/0C 192.168.10.0/24 is directly connected, FastEthernet0/0D 192.168.40.0/24 [90/2681] via 192.168.20.2,00:04:36, Serial0/0C 192.168.20.0/24 is directly connected, Serial0/0D 192.168.50.0/24 [90/2707] via 192.168.20.2,00:04:35, Serial0/0P1R1#
•Open standard•Shortest path first (SPF) algorithm•Link-state routing protocol (vs. distance vector)•Can be used to route between AS’s
Introducing OSPF
OSPF Hierarchical Routing
• Consists of areas and autonomous systems• Minimizes routing update traffic• Supports VLSM• Unlimited hop count
Link State Vs. Distance Vector
Link State:• Provides common view of entire topology• Calculates shortest path• Utilizes event-triggered updates• Can be used to route between AS’s
Distance Vector:•Exchanges routing tables with neighbors•Utilizes frequent periodic updates
Types of OSPF Routers
InternalRouters
Area 1 Area 2
ASBR andBackbone Router
Backbone/InternalRouters
ABR and BackboneRouter
Backbone Area 0
ABR and BackboneRouter
InternalRouters
•External AS
OSFP Neighbors• OSPF uses hello packets to create
adjacencies and maintain connectivity with neighbor routers
• OSPF uses the multicast address 224.0.0.5
Hello?224.0.0.5
•Hello packets provides dynamic neighbor discovery•Hello Packets maintains neighbor relationships•Hello packets and LSA’s from other routers help build and maintain the topological database
Router(config-router)#network address mask area area-id
Assigns networks to a specific OSPF area
Router(config)#router ospf process-id
Defines OSPF as the IP routing protocolNote: The process ID is locally significant and is needed to identify a unique instance of an OSPF database
Configuring Single Area OSPF
OSPF Example
hostname R3
router ospf 10
network 10.1.2.3 0.0.0.0 area 0
network 10.1.3.1 0.0.0.0 area 0
hostname R2
router ospf 20network 10.0.0.0 0.255.255.255 area 0
hostname R1
router ospf 30network 10.1.0.0 0.0.255.255 area 0network 10.5.5.1 0.0.0.0 area 0
R3
R2R1
10.1.2.0
10.1.1.0
10.5.5.0
Area 010.1.3.0
Configuring Wildcards
If you want to advertise a partial octet (subnet), you need to use wildcards.– 0.0.0.0 means all octets match exactly– 0.0.0.255 means that the first three
match exactly, but the last octet can be any value
After that, you must remember your block sizes….
Wildcard
The wildcard address is always one less than the block size….– 192.168.10.8/30 = 0.0.0.3– 192.168.10.48/28 = 0.0.0.15– 192.168.10.96/27 = 0.0.0.31– 192.168.10.128/26 = 0.0.0.63
Router#show ip ospf interface
Verifying the OSPF Configuration
Displays area-ID and adjacency information
Router#show ip protocols
Verifies that OSPF is configured
Router#show ip route
Displays all the routes learned by the router
Router#show ip ospf neighbor
Displays OSPF-neighbor information on a per-interface basis
Electing the DR and BDR
• OSPF sends Hellos which elect DRs and BDRs
• Router form adjacencies with DRs and BDRs in a multi-access environment
Multicast Hellos are sent and compared
Router with Highest Priority is Elected as DR
Router with 2nd Highest Priority is Elected as BDR
Router ID (RID)
Each router in OSPF needs to be uniquely identified to properly arrange them in the Neighbor tables.
Configuring Loopback Interfaces
Router ID (RID): – Number by which the router is known to OSPF– Default: The highest IP address on an active interface at the
moment of OSPF process startup– Can be overridden by a loopback interface: Highest IP address
of any active loopback interface – also called a logical interface
Interface PrioritiesWhat is the default OSPF interface priority?
Router# show ip ospf interface ethernet0/0Ethernet0 is up, line protocol is upInternet Address 192.168.1.137/29, Area 4Process ID 19, Router ID 192.168.1.137, Network Type
BROADCAST,Cost: 10 Transmit Delay is 1 sec, State DR, Priority 1Designated Router (ID) 192.168.1.137, Interface address
192.168.1.137No backup designated router on this networkTimer intervals configured, Hello 10, Dead 40, Wait 40,
Retransmit 5Hello due in 00:00:06Index 2/2, flood queue length 0Next 0x0(0)/0x0(0)Last flood scan length is 0, maximum is 0Last flood scan time is 0 msec, maximum is 0 msecNeighbor Count is 0, Adjacent neighbor count is 0Suppress hello for 0 neighbor(s)
Specifying a DR
What options can you configure that will ensure that R2 will be the DR of the LAN segment?
Summary Routes EIGRP
Core(config)#router eigrp 10
Core(config-router)#network 192.168.10.0
Core(config-router)#network 10.0.0.0
Core(config-router)#no auto-summary
Core(config-router)#interface ethernet 0
Core(config-if)#ip summary-address eigrp 10 192.168.10.64 255.255.255.224
Summary Routes OSPF
Core#config t
Core(config)#router ospf 1
Core(config-router)#network 192.168.10.64 0.0.0.3 area 1
Core(config-router)#network 192.168.10.68 0.0.0.3 area 1
Core(config-router)#network 10.10.10.0 0.0.0.255 area 0
Core(config-router)#area 1 range 192.168.10.64 255.255.255.224