Dell BigIron RX Series, Configuration Manual

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734 BigIron RX Series Configuration Guide
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Displaying OSPF information
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Displaying OSPF virtual link information
Use the show ip ospf virtual link command to display OSPF virtual link information. The output
below represents the virtual links configured in
Figure 109 .
Syntax: show ip ospf virtual link [ <num> ]
The <num> parameter displays the table beginning at the specified entry number.
OSPF graceful restart
With OSPF graceful restart enabled, a restarting router sends special LSAs, called grace-lsas, to its
neighbors. These LSAs are sent to neighbors either before a planned OSPF restart or immediately
after an unplanned restart. A grace LSA contains a grace period value that the requesting routers
asks its neighbor routers to use for the existing routes, to and through the router after a restart. The
restarting router comes up, it continues to use its existing OSPF routes to forward packets. In the
background, it re-establishes OSPF adjacencies with its neighboring router, relearns all OPSF LSAs,
recalculates its OSPF routes, and replaces them with new routes as necessary. Once the restarting
router relearns all OSPF routes, it flushes the grace LSAs from the network, informing the helper
routers of the completion of the restart process. If the restarting router does not re-establish
adjacencies with the helper router within the restart time, the helper router stops the helping
function and flushes the stale OSPF routes.
Configuring OSPF graceful restart
To configure OSPF Graceful Restart on a router, the restarting router and its directly connected
OSPF peers must be configured with Graceful Restart.
BigIron RX(config)#router ospf
BigIron RX(config-ospf-router)#area 0
BigIron RX(config-ospf-router)#graceful-restart
graceful-restart
Enabling and disabling OSPF helper
When OSPF is enabled, the helper mode is enabled by default. OSPF routers that do not have
graceful restart enabled will act as if the graceful restart helper is enabled. To prevent the graceful
restart from performing its function, disable it by entering the following command.
BigIron RX(config-ospf-router)#graceful-restart helper-disable
Syntax: [no] graceful-restart helper disable
Use the no form of the command to re-enable the graceful restart helper.
BigIron RX#show ip ospf virtual link
Indx Transit Area Router ID Transit(sec) Retrans(sec) Hello(sec)
1 1 131.1.1.10 1 5 10
Dead(sec) events state Authentication-Key
40 1 ptr2ptr None
MD5 Authentication-Key: None
MD5 Authentication-Key-Id: None
MD5 Authentication-Key-Activation-Wait-Time: 300