142
Each router needs to refresh its LSPs at a configurable interval and send them to other routers
to prevent valid routes from aging out. A smaller refresh interval speeds up network
convergence but consumes more bandwidth.
When the network topology changes, for example, a neighbor is down or up, or the interface
metric, system ID, or area ID is changed, the router generates an LSP after a configurable
interval. If such a change occurs frequently, excessive LSPs are generated, consuming a large
amount of router resources and bandwidth. To solve the problem, you can adjust the LSP
generation interval.
When network changes are not frequent, the minimum-interval is adopted. If network changes
become frequent, the LSP generation interval is incremented by incremental-interval × 2
n-2
(n is
the number of calculation times) each time a generation occurs until the maximum-interval is
reached.
To specify the LSP refresh interval and generation interval:
Step Command Remarks
1. Enter system view.
system-view
N/A
2. Enter IS-IS view.
isis
[ process-id ] [
vpn-instance
vpn-instance-name ]
N/A
3. Specify the LSP refresh
interval.
timer lsp-refresh
seconds
By default, the LSP refresh
interval is 900 seconds.
4. Specify the LSP
generation interval.
timer lsp-generation
maximum-interval
[ minimum-interval [ incremental-interval ] ]
[
level-1
|
level-2
]
By default:
• The maximum interval
is 5 seconds.
• The minimum interval is
50 milliseconds.
• The incremental interval
is 200 milliseconds.
3. Specify LSP sending intervals.
If a change occurs in the LSDB, IS-IS advertises the changed LSP to neighbors. You can
specify the minimum interval for sending these LSPs to control the amount of LSPs on the
network.
On a P2P link, IS-IS requires an advertised LSP be acknowledged. If no acknowledgment is
received within a configurable interval, IS-IS will retransmit the LSP.
To configure LSP sending intervals:
Step Command Remarks
1. Enter system view.
system-view
N/A
2. Enter interface view.
interface
interface-type
interface-number
N/A
3. Specify the minimum interval
for sending LSPs and the
maximum LSP number that
can be sent at a time.
isis timer lsp
time [
count
count ]
By default, the minimum interval is 33
milliseconds, and the maximum LSP
number that can be sent at a time is
5.
4. Specify the LSP
retransmission interval on a
P2P link.
isis timer retransmit
seconds
By default, the LSP retransmission
interval on a P2P link is 5 seconds.
Specifying LSP lengths
IS-IS messages cannot be fragmented at the IP layer because they are directly encapsulated in
frames. IS-IS routers in an area must send LSPs smaller than the smallest interface MTU in the area.
To Next Page
Loading...
Need help?
General