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Chapter 9: AI2524 OSI/CLNP Configuration Steps
August 1997 Page 9-29
2524UM
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.