IS-IS Lab 17 Troubleshoot Multi-Area Continue

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Download Lab: VIRL | EVE-NG | GNS3


Image requirements:

Cisco IOSv (vios-adventerprisek9-m.vmdk.SPA.156-2.T)


Introduction: 
In the last lab, while troubleshooting the connectivity issues between L1 routers, it appears that there are additional issues in the IS-IS topology even though IP communications remain intact, it is vital to the company that everything has to be configured as designed.


Nodes Access: 
Enable:       cisco 
Username:  cisco 
Password:   cisco 



Topology:






Reported Issues:

L1 only routers (A2, B2, D2, E2) in their IS-IS databases, missing IP information about L1/L2 border routers' loopback0 interfaces. These routers should not use a default route to access subnets in their own local areas. 

Note: a solution that you are going to implement, should not affect how L1/L2 border routers share their link-state information with the core L2 area. 

Example of the problem: 

A2#show  isis database detail A1.00-00IS-IS Level-1 LSP A1.00-00
LSPID                 LSP Seq Num  LSP Checksum  LSP Holdtime/Rcvd      ATT/P/OL
A1.00-00              0x00000003   0xBFB3                 983/1199      1/0/0
  Area Address: 49.a000
  NLPID:        0xCC
  Hostname: A1
  Metric: 10         IS A1.01
  IP Address:   10.0.0.25
  Metric: 10         IP 10.0.0.24 255.255.255.252


As the output shows, router A1 only includes in its L1 updates prefix of the link between nodes A1 and A2.


Validation: 

The output from command "show isis database detail" on the L1 only routers (A2, B2, D2, E2) will contain prefixes of L1/L2 routers' loopback0 interfaces. 



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