You want to look at each router's link-state database to make sure that all the IS-IS routers know about each other.
show isis database command to view the contents of the link-state database:
show isis databaseIS-IS level 1 link-state database: LSP ID Sequence Checksum Lifetime Attributes RouterG.00-00 0x65 0xfa35 851 L1 L2 Attached RouterA.00-00 0x5e 0xf289 661 L1 L2 RouterA.02-00 0x59 0xeda9 632 L1 L2 3 LSPs IS-IS level 2 link-state database: LSP ID Sequence Checksum Lifetime Attributes RouterH.00-00 0x61 0xa315 923 L1 L2 RouterG.00-00 0x61 0x125e 741 L1 L2 RouterG.02-00 0x5e 0x79f0 741 L1 L2 3 LSPs
IS-IS routers exchange LSPs that describe each individual router's view of the network topology and they store the LSPs in a link-state database. The SPF algorithm then runs on the link-state database to create the IS-IS routing table. Use the
show isis database command to look at the contents of the link-state database. In this recipe, RouterG is a Level 1–Level 2 router, so you see two
link-state databases, one for each level.
The first part of the output shows that the Level 1 link-state database has three LSPs. The entry for RouterG includes the attach bit (
Attached), which indicates that it is connected to another IS-IS area. From the configuration, you know that this router is connected to area 30.
If you check on the other Level 2 router, its Level 2 database is identical to that of ...