Configuring the Optional Checksum
Context
When a network is running, Intermediate System to Intermediate System (IS-IS) routers may be attacked or IS-IS packets may be modified. As a result, important network information may be intercepted, causing serious loss to the network. The optional checksum encapsulates optional checksum TLVs into the Complete Sequence Numbers Protocol Data Units (CSNPs), Partial Sequence Number Protocol Data Units (PSNPs), and Hello packets sent by IS-IS routers. When the peer device receives the encapsulated packets, it checks whether TLVs carried in the packets are correct. If TLVs are not correct, the peer device discards the packets for network security.
Procedure
- Run system-view
The system view is displayed.
- Run isis
An IS-IS process is created and the IS-IS view is displayed.
- Run optional-checksum enable
IS-IS optional checksum is enabled.
If MD5 authentication or Keychain authentication with valid MD5 authentication is configured on an IS-IS interface or area, IS-IS routers send Hello packets and SNP packets carrying no checksum TLVs and verify the checksum of the received packets.