3Com 8807 Configuration Manual page 357

Configuring IS-IS GR
n
Resetting All the IS-IS
Data Structure
interfaces. On a switch, this command can disable/enable the specified VLAN
interface to send IS-IS packets.
The network is interrupted temporarily when an IS-IS router is restarted because
the neighbor relationship of this router with other neighbors is removed and LSP
packets are flooded. The GR feature of IS-IS can solve this problem. This feature
enables the restarted router to notify its neighbors of its restart state and permits
the neighbors to establish new adjacency relation without disconnection. The GR
feature of IS-IS has the following benefits:
This GR feature is applied on the restarted routers and initially started routers,
■
and enables the restarted routers to send connection requests to neighbors
again instead of ending the adjacency relation.
This GR feature reduces the influence on the network caused by waiting for
■
database synchronization before generating LSP packets to the utmost extent.
This feature sets overload flag bits in LSP packets until database
■
synchronization for the routers started first, so that route loops do not occur in
the network.
Table 342 Configure IS-IS GR
Operation
Enter system view
Enable the IS-IS routing
process and enter IS-IS view
Enable IS-IS GR capability
Configure the restart interval
Configure SA suppression
when a router is restarted
The restart interval specifies the interval of restarting routers. The restart
■
interval is set as holdtime in Hello PDU of IS-IS. In this way, the neighbors of a
router will not break adjacency relations with it when it is restarted.
The restarted router suppresses SA bits in Hello PDU to request its neighbors to
■
suppress advertising the adjacency relation in the set time range. SA bits are
deleted when the database of this router is synchronized. You can use the
graceful-restart suppress-sa command to disable this function if you do not
want to enable this router to set SA bits in Hello PDU. With the help of this
feature, the black hole effect caused by sending/receiving LSP packets can be
avoided during the GR process.
When it is necessary to refresh some LSPs immediately, perform the following
configuration in user view.
Configuring Integrated IS-IS
Command
system-view
isis [ process id ]
graceful-restart
graceful-restart interval
timer
graceful-restart
suppress-sa
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Description
-
Required
The IS-IS routing process can
not be enabled by default
Required
IS-IS GR capability is disabled
by default
Optional
The restart interval is 300
seconds by default
Required
By default, the SA bit is not
suppressed