Chapter 9: AI2524 OSI/CLNP Configuration Steps
August 1997 Page 9-29
2524UM
Log Adjacency State Changes
You can configure IS-IS to ge nerate 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 th is form:
%CLNS-5-ADJCHANGE: ISIS: Adjacency to 0000.0000.0034 (Ser ial0) Up , ne w ad jace ncy
%CLNS-5-ADJCHANGE: ISIS: Adjacency to 0000.0000.0034 (Ser ial0) Do wn, 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 th e 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 siz e 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.