Friday, January 9, 2015

EIGRP - Troubleshooting LAB 1

Objective:
  • When Gig2 is shutdown on R1, metric for the route to reach Loopback1 should not change on R2.  
Here is a simple topology and let's get started.


Relevant configs are posted below so you can lab it up. 

R1
 hostname R1   
 interface Loopback1                                                           
  ip address 10.0.0.1 255.255.255.0                                                   
 !                                                                    
 interface GigabitEthernet1        
  description connected to r2                                               
  ip address 1.1.1.1 255.255.255.0 
  ip summary-address eigrp 100 10.0.0.0 255.255.254.0
 !                                                                    
 interface GigabitEthernet2                                                       
  ip address 10.0.1.1 255.255.255.0
 !                                                                    
 !                                                                    
 router eigrp 100                                                            
  network 1.1.1.0 0.0.0.255                                                       
  redistribute connected                                                         
 !                    

R2
 hostname R2  
 interface GigabitEthernet1  
  ip address 1.1.1.2 255.255.255.0  
 !  
 router eigrp 100  
  network 1.1.1.0 0.0.0.255  

Take note of the metric (3072) for the route in R2 to reach R1's Loopback1 and Gig2.

 R2#sh ip route   
 
 Gateway of last resort is not set  
    1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks  
 C    1.1.1.0/24 is directly connected, GigabitEthernet1  
 L    1.1.1.2/32 is directly connected, GigabitEthernet1  
    10.0.0.0/23 is subnetted, 1 subnets  
 D    10.0.0.0 [90/3072] via 1.1.1.1, 00:03:59, GigabitEthernet1  
 

Now shutdown Gig2 on R1 and notice the metric (130816) for the route in R2 to reach 10.0.0.0/23 has changed.
 R1#conf t                                                                
 Enter configuration commands, one per line. End with CNTL/Z.                        
 R1(config)#int gig2                                                           
 R1(config-if)#                                                             
 R1(config-if)#shutdown  
 !!!!!  
 !!!!!  
 R2#sh ip route   
 Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP  
     D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area   
     N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2  
     E1 - OSPF external type 1, E2 - OSPF external type 2  
     i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2  
     ia - IS-IS inter area, * - candidate default, U - per-user static route  
     o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP  
     a - application route  
     + - replicated route, % - next hop override  
 Gateway of last resort is not set  
    1.0.0.0/8 is variably subnetted, 2 subnets, 2 masks  
 C    1.1.1.0/24 is directly connected, GigabitEthernet1  
 L    1.1.1.2/32 is directly connected, GigabitEthernet1  
    10.0.0.0/23 is subnetted, 1 subnets  
 D    10.0.0.0 [90/130816] via 1.1.1.1, 00:00:05, GigabitEthernet1  

Post comments on possible solutions as to how you can avoid the metric change on R2 when R1's Loopback1 is shutdown.

Many more articles to come so ....

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