Dell PowerConnect B-FCXs, Configuration Manual

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1026 PowerConnect B-Series FCX Configuration Guide
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BGP null0 routing
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Configuring the BGP4 graceful restart stale routes timer
Use the following command to specify the maximum amount of time a helper device will wait for an
end-of-RIB message from a peer before deleting routes from that peer.
PowerConnect (config-bgp)# graceful-restart stale-routes-time 120
Syntax: [no] graceful-restart stale-routes-time < seconds >
The < seconds > variable is the maximum time before a helper device cleans up stale routes.
Possible values are from 1 through 3600 seconds. The default value is 360 seconds.
Configuring the BGP4 graceful restart purge timer
Use the following command to specify the maximum amount of time a device will maintain stale
routes in its routing table before purging them.
PowerConnect (config-bgp)# graceful-restart purge-time 900
Syntax: [no] graceful-restart purge-time < seconds >
The <seconds> variable sets the maximum time before a restarting device cleans up stale routes.
Possible values are from 1 through 3600 seconds. The default value is 600 seconds.
BGP null0 routing
The null0 routes were previously treated as invalid routes for BGP next hop resolution. BGP now
uses the null0 route to resolve its next hop. Thus, null0 route in the routing table (for example,
static route) is considered as a valid route by BGP. If the next hop for BGP resolves into a null0
route, the BGP route is also installed as a null0 route in the routing table.
The null0 routing feature allows network administrators to block certain network prefixes, by using
null0 routes and route-maps. The combined use of null0 routes and route maps blocks traffic from
a particular network prefix, telling a remote router to drop all traffic for this network prefix by
redistributing a null0 route into BGP.