IS-IS Lab 17 Troubleshoot Multi-Area Continue

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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 


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:
  Metric: 10         IP

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


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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