AIS AI2524 Log Adjacency State Changes, Change IS-IS LSP MTU Size, Log-adjacency-changes

Chapter 9: AI2524 OSI/CLNP Configuration Steps

Log Adjacency State Changes

You can configure IS-IS to generate a log message when an IS-IS ad jacency changes state (up or down). This may be useful when monitor- ing large networks. Messages are logged using the system error message facility. Messages are in this form:

%CLNS-5-ADJCHANGE: ISIS: Adjacency to 0000.0000.0034 (Serial0) Up, new adjacency

%CLNS-5-ADJCHANGE: ISIS: Adjacency to 0000.0000.0034 (Serial0) Down, hold time expired

In router configuration mode, generate log messages when an IS-IS adjacency changes state:

log-adjacency-changes

Change IS-IS LSP MTU Size

Under normal conditions, the default maximum transmission unit (MTU) size should be sufficient. However, if the MTU of a link is low- ered to less than 1500 bytes, the LSP MTU must be lowered accord- ingly on each router in the network. If this is not done, routing will become unpredictable.

The MTU size must be less than or equal to the smallest MTU of any link in the network. The default size is 1497 bytes.

Caution: The CLNS MTU of a link (which is the applicable value for IS-IS, even if it is being used to route IP) may differ from the IP MTU. To be certain about a link MTU as it pertains to IS-IS, use the show clns interface command to display the value.

In router configuration mode, change the MTU size of IS-IS link state packets:

lsp-mtu size

Warning: This rule applies for all routers in a network. If any link in the network has a reduced MTU, all routers must b changed, not just the routers directly connected to th link.

August 1997	Page 9-29
2524UM