Implementing an EIGRP-Based Solution Implementing and Verifying Basic EIGRP for the Enterprise LAN Architecture Implementing an EIGRP-Based Solution

EIGRP Deployment R1# R2# interface FastEthernet0/0 ip address 172.16.1.1 255.255.255.0 ! interface Serial0/0/1 bandwidth 512 ip address 192.168.1.101 255.255.255.224 router eigrp 110 network 172.16.1.0 0.0.0.255 network 192.168.1.0 interface FastEthernet0/0 ip address 172.17.2.2 255.255.255.0 ! interface Serial0/0/1 bandwidth 512 ip address 192.168.1.102 255.255.255.224 router eigrp 110 network 172.17.2.0 0.0.0.255 network 192.168.1.0

Verifying EIGRP Neighbors R1#show ip eigrp neighbors IP-EIGRP neighbors for process 110 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.102 Se0/0/1 10 00:07:22 10 2280 0 5 R2#show ip eigrp neighbors IP-EIGRP neighbors for process 110 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.101 Se0/0/1 10 00:17:02 10 1380 0 5

Verifying EIGRP Neighbors (Cont.) R1#show ip eigrp neighbors IP-EIGRP neighbors for process 110 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.102 Se0/0/1 10 00:07:22 10 2280 0 5 1 2 3 4 5 6 7 8 9 1. Neighbor index 2. Neighbor IP address 3. Interface on which the neighbor is reachable 4. Remaining hold time 5. Neighbor uptime 6. Smooth round-trip time 7. Retransmission timeout 8. Number of packets to send to neighbor 9. Last sequence received

Verifying EIGRP Neighbors (Cont.) Total retransmission count Current retry count R1#show ip eigrp neighbors detail IP-EIGRP neighbors for process 110 H Address Interface Hold Uptime SRTT RTO Q Seq (sec) (ms) Cnt Num 0 192.168.1.102 Se0/0/1 14 00:17:55 0 4500 3 274 Last startup serial 569 Version 12.4/1.0, Retrans: 2, Retries: 2, Waiting for Init Ack UPDATE seq 307 ser 29-569 Sent 8924 Init Sequenced UPDATE seq 310 ser 570-573 Sequenced UPDATE seq 312 ser 574-578 Sequenced Neighbor version of Cisco IOS Current pending packets

Verifying EIGRP Routes Network EIGRP route type Next hop Route age AD / Metric R1#show ip route eigrp D 172.17.0.0/16 [90/40514560] via 192.168.1.102, 00:07:01, Serial0/0/1 172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks D 172.16.0.0/16 is a summary, 00:05:13, Null0 192.168.1.0/24 is variably subnetted, 2 subnets, 2 masks D 192.168.1.0/24 is a summary, 00:05:13, Null0

Verifying EIGRP Operation R1#show ip protocols Routing Protocol is "eigrp 110" Outgoing update filter list for all interfaces is not set Incoming update filter list for all interfaces is not set Default networks flagged in outgoing updates Default networks accepted from incoming updates EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0 EIGRP maximum hopcount 100 EIGRP maximum metric variance 1 Redistributing: eigrp 110 EIGRP NSF-aware route hold timer is 240s <output omitted> Maximum path: 4 Routing for Networks: 172.16.1.0/24 192.168.1.0 Routing Information Sources: Gateway Distance Last Update (this router) 90 00:09:38 192.168.1.102 90 00:09:40 Distance: internal 90 external 170 K values Load-balancing setting Networks being announced EIGRP local AD

Verifying EIGRP Operation (Cont.) R1#show ip eigrp interfaces IP-EIGRP interfaces for process 110 Xmit Queue Mean Pacing Time Multicast Pending Interface Peers Un/Reliable SRTT Un/Reliable Flow Timer Routes Fa0/0 0 0/0 0 0/10 0 0 Se0/0/1 1 0/0 10 10/380 424 0 Peer count R1#show ip eigrp topology IP-EIGRP Topology Table for AS(110)/ID(192.168.1.101) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply, r - reply Status, s - sia Status P 192.168.1.96/27, 1 successors, FD is 40512000 via Connected, Serial0/0/1 P 192.168.1.0/24, 1 successors, FD is 40512000 via Summary (40512000/0), Null0 P 172.16.0.0/16, 1 successors, FD is 28160 via Summary (28160/0), Null0 P 172.16.1.0/24, 1 successors, FD is 28160 via Connected, FastEthernet0/0 P 172.17.0.0/16, 1 successors, FD is 40514560 via 192.168.1.102 (40514560/28160), Serial0/0/1 Route status Feasible distance Advertised distance Outgoing interface Next hop

Verifying EIGRP Operation (Cont.) R1#show ip eigrp traffic IP-EIGRP Traffic Statistics for AS 110 Hellos sent/received: 429/192 Updates sent/received: 4/4 Queries sent/received: 1/0 Replies sent/received: 0/1 Acks sent/received: 4/3 Input queue high water mark 1, 0 drops SIA-Queries sent/received: 0/0 SIA-Replies sent/received: 0/0 Hello Process ID: 113 PDM Process ID: 73 EIGRP packet counters

Using Passive Interfaces EIGRP announces the directly connected network of an interface EIGRP does not try to form neighbor relationships over the interface where only the host is connected Reduces traffic overhead No peer here No peer here R1# R2# router eigrp 110 passive-interface FastEthernet0/0 network 172.16.1.0 0.0.0.255 network 192.168.1.0 router eigrp 110 passive-interface FastEthernet0/0 network 172.17.2.0 0.0.0.255 network 192.168.1.0

Using Passive Interfaces (Cont.) No need to talk to host by EIGRP Disables EIGRP on all interfaces by default Enables EIGRP only on selected interfaces R1(config)# router eigrp 110 passive-interface default no passive-interface Serial0/0/1 network 172.16.1.0 0.0.0.255 network 192.168.1.0

Verify Operation with Passive Interfaces R1#sh ip protocols Routing Protocol is "eigrp 110" <output omitted> Automatic network summarization is in effect Automatic address summarization: 172.16.0.0/16 for Serial0/0/1 Summarizing with metric 28160 Maximum path: 4 Routing for Networks: 172.16.1.0/24 192.168.1.0 Passive Interface(s): FastEthernet0/0

Using the ip default network Command with EIGRP Default routes decrease the size of the routing table Multiple candidates: 0.0.0.0 is statically set or advertised by the routing protocol Any EIGRP major network route is flagged as a candidate default with the ip default-network command EIGRP solution: Flags network as a default route candidate Multiple default candidates supported Announced with the Exterior flag

Using the ip default network Command with EIGRP (Cont.) Flagging an external network as a default route candidate R2# router eigrp 110 network 10.0.0.0 ip default-network 172.31.0.0 ip route 172.31.0.0 255.255.0.0 172.31.1.1

Verifying Default Network Information R2#show ip route 0.0.0.0 via Serial0/0/0 <output omitted> S* 0.0.0.0/0 [1/0] via 172.31.1.1 C 172.31.1.0/24 is directly connected, Serial0/0/0 C 10.64.0.0/24 is directly connected, FastEthernet0/0 Flagged candidate Flagged candidate R1#show ip route <output omitted> Gateway of last resort is 10.64.0.2 to network 0.0.0.0 10.0.0.0/8 is variably subnetted, 7 subnets, 2 masks C 10.64.0.0/24 is directly connected, FastEthernet0/0 D* 172.31.0.0/16 [90/10514560] via 10.64.0.2, 00:07:01, FastEthernet0/0

Route Summarization Improves network scalability Smaller routing tables Fewer updates Should follow IP addressing

EIGRP Automatic Route Summarization Performed on major network boundaries Subnetworks are summarized to a single classful (major) network. Automatic summarization occurs by default. Could result in routing issues—disable auto summarization

EIGRP Manual Route Summarization Configurable on a per-interface basis in any router within a network. Summarization results in a route pointing to null0. Loop prevention mechanism When the last specific route of the summary goes away, the summary is deleted. The minimum metric of the specific routes = metric of the summary route.

Configuring Route Summarization Creating a summary route for 172.16.0.0/16 router eigrp 110 network 10.0.0.0 network 172.16.0.0 no auto-summary R1(config)# interface Serial0/0/0 ip address 192.168.4.2 255.255.255.0 ip summary-address eigrp 110 172.16.0.0 255.255.0.0 ! router eigrp 110 network 10.0.0.0 network 192.168.4.0 no auto-summary R3(config)# router eigrp 110 network 10.0.0.0 network 172.16.0.0 no auto-summary R2(config)#

Verifying Route Summarization R3#show ip route <output omitted> Gateway of last resort is not set 172.16.0.0/16 is variably subnetted, 3 subnets, 2 masks D 172.16.0.0/16 is a summary, 00:00:04, Null0 D 172.16.1.0/24 [90/156160] via 10.1.1.2, 00:00:04, FastEthernet0/0 D 172.16.2.0/24 [90/20640000] via 10.2.2.2, 00:00:04, Serial0/0/1 C 192.168.4.0/24 is directly connected, Serial0/0/0 10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks C 10.2.2.0/24 is directly connected, Serial0/0/1

Summary EIGRP operation can be verified by examining the EIGRP neighbor relationship information and IP routing table for the presence of EIGRP routes. The neighbor command can be used to form the EIGRP neighbor relationship with only specific neighbors using unicast packets. EIGRP is, by default, enabled on all interfaces included with the network command. To prevent unnecessary traffic, interfaces without neighbors should be made passive.

Summary (Cont.) Create and advertise a default route in an EIGRP autonomous system with the ip default-network network-number command. EIGRP performs automatic network-boundary summarization, but administrators can disable automatic summarization and perform manual route summarization on an interface-by-interface basis. Summarizing routes results in smaller routing tables. For manual route summarization, the summary route is advertised only if a more specific entry of the summary route is present in the routing table.