Configuring Is-Is Gr - 3Com Switch 4800G 24-Port Configuration Manual

352 C 29: IS-IS C
HAPTER
Enabling SNMP Trap

Configuring IS-IS GR

ONFIGURATION
To do...
Enter system view
Enter interface view
Enable the interface to send
small hello packets that have
no padding field
Follow these steps to enable IS-IS trap:
To do...
Enter system view
Enter IS-IS view
Enable SNMP Trap
An ISIS restart may cause the termination of the adjacencies between a restarting
router and its neighbors, resulting in a transient network disconnection.
IS-IS Graceful Restart can help to solve this problem by notifying its neighbors its
restarting state to allow them to reestablish the adjacency without removing it.
The IS-IS Graceful Restart provides the following features:
When restarting ISIS, a Graceful Restart capable device will resend connection
■
requests to its neighbors instead of terminating their neighboring relationships.
Graceful Restart minimizes network disruption caused by LSDB synchronization
■
before LSP packets generation.
When a router starts for the first time, it sets the overload bit in LSP packets
■
before LSDB synchronization is complete, which ensures no routing loop is
created.
The Graceful Restart interval on a router is used as the holdtime in the IS-IS Hello
PDUs so that its neighbors can maintain the adjacencies within the interval after
the router restarts.
By setting the SA (Suppress-Advertisement) bit in the hello PDUs sent by the GR
Restarter, its neighbors will not advertise adjacencies within the specified period
until the completion of LSDB synchronization between the GR Restarter and its
neighbors. This feature helps to effectively avoid blackhole routes due to the
sending or receiving of LSPs across the restart.
n
A device can act as both the GR Restarter and GR Helper at the same time.
Follow these steps to configure GR on the GR Restarter and GR Helper
respectively:
To do...
Enter system view
Use the command...
system-view
interface interface-type
interface-number
isis small-hello
Use the command...
system-view
isis [ process-id ]
is-snmp-traps enable
Use the command...
system-view
Remarks
--
--
Required
Standard hello packets are
sent by default.
Remarks
--
--
Required
Enabled by default
Remarks
-