Dell BigIron RX Series, Configuration Manual

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BigIron RX Series Configuration Guide 819
53-1002253-01
Filtering
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Syntax: show ip bgp neighbors <ip-addr> received-routes [detail]
The detail parameter displays detailed information for the routes. The example above shows
summary information.
NOTE
The syntax for displaying received routes is shown. For complete command syntax, refer to
“Displaying BGP4 neighbor information” on page 829.
Dynamically requesting a route refresh from a BGP4 neighbor
You can easily apply changes to filters that control BGP4 routes received from or advertised to a
neighbor, without resetting the BGP4 session between the device and the neighbor. For example, if
you add, change, or remove a BGP4 IP prefix list that denies specific routes received from a
neighbor, you can apply the filter change by requesting a route refresh from the neighbor. If the
neighbor also supports dynamic route refreshes, the neighbor resends its Adj-RIB-Out, its table of
BGP4 routes. Using the route refresh feature, you do not need to reset the session with the
neighbor.
The route refresh feature is based on the following specifications:
•
RFC 2842. This RFC specifies the Capability Advertisement, which a BGP4 router uses to
dynamically negotiate a capability with a neighbor.
•
RFC 2858 for Multi-protocol Extension.
•
RFC 2918, which describes the dynamic route refresh capability
The dynamic route refresh capability is enabled by default and cannot be disabled. When the
device sends a BGP4 OPEN message to a neighbor, the device includes a Capability Advertisement
to inform the neighbor that the device supports dynamic route refresh.
NOTE
The option for dynamically refreshing routes received from a neighbor requires the neighbor to
support dynamic route refresh. If the neighbor does not support this feature, the option does not
take effect and the software displays an error message. The option for dynamically re-advertising
routes to a neighbor does not require the neighbor to support dynamic route refresh.
Dynamically refreshing routes
The following sections describe how to dynamically refresh BGP4 routes to place new or changed
filters into effect.
BigIron RX# show ip bgp neighbor 192.168.4.106 routes
There are 97345 received routes from neighbor 192.168.4.106
Searching for matching routes, use ^C to quit...
Status A:AGGREGATE B:BEST b:NOT-INSTALLED-BEST C:CONFED_EBGP D:DAMPED
E:EBGP H:HISTORY I:IBGP L:LOCAL M:MULTIPATH S:SUPPRESSED F:FILTERED
Prefix Next Hop Metric LocPrf Weight Status
1 3.0.0.0/8 192.168.4.106 100 0 BE
AS_PATH: 65001 4355 701 80
2 4.0.0.0/8 192.168.4.106 100 0 BE
AS_PATH: 65001 4355 1
3 4.60.212.0/22 192.168.4.106 100 0 BE
AS_PATH: 65001 4355 701 1 189
4 6.0.0.0/8 192.168.4.106 100 0 BE