Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 52)

24 Multi-Service IronWare Routing Configuration Guide
53-1003033-02
BGP router reflector
Syntax: show ip bgp route
In the previous output, BGP4 receives 333,422 routes and the rib-route-limit command is
configured to 300,000 routes. The always-propagate command has not been enabled. However,
because the rib-route-limit command is configured to allow for 300,000 routes in the RTM, BGP4
installs only 300,000 routes of the 333,422 routes received in the RTM. When the
always-propagate command is enabled, a preferred BGP4 route not installed in the RTM is now
considered as the best BGP4 route to be advertised to other peers. The route is identified by the
letter “b” (for NOT-INSTALLED-BEST) in the Status field. However, when the always-propagate
command is not enabled, the status field displays only the default letter “E”, as displayed for BGP4
route 10.12.0.0/24. The letter “B” or “b” is missing from the Status field.
NOTE
The description of the status “b: NOT-INSTALLED-BEST” has changed. The status description for “b:
NOT-INSTALLED-BEST” is now: The routes received from the neighbor are the best BGP4 routes to
their destinations, but were nonetheless not installed in the IP route table due to the rib-route-limit
option (or RTM route table size limit), and the always-propagate option to allow the propagating of
those best BGP routes.
NOTE
Traffic loss on a BGP4 route occurs when a device is advertising preferred BGP4 routes not installed
in the RTM as part of the forwarding path.
Because the BGP4 route 10.12.0.0/24 is not considered as the best BGP4 route, the route is not
advertised to other BGP4 neighbors.
Syntax: show ip bgp route ip-address/prefix
After enabling the always-propagate command, the BGP4 route is now considered the best BGP4
route, even though the route is not installed in the RTM. Because the rib-route-limit command was
configured to allow for only 300,000 routes in the RTM some preferred BGP4 routes are not
installed in the RTM, and are not advertised to other BGP4 neighbors. By enabling the
Brocade(config-bgp)# show ip bgp route
Total number of BGP Routes: 333422
Status A:AGGREGATE B:BEST b:NOT-INSTALLED-BEST C:CONFED_EBGP D:DAMPED
E:EBGP H:HISTORY I:IBGP L:LOCAL M:MULTIPATH m:NOT-INSTALLED-MULTIPATH
S:SUPPRESSED F:FILTERED s:STALE
Prefix Next Hop MED LocPrf Weight Status
…5 10.12.0.0/24 10.100.100.4 100 0 E
AS_PATH: 48 1994 65148 21948 6461 1239 4837 4808 17431 18245…
Brocade(config-bgp)# show ip bgp route 10.12.0.0/24
Number of BGP Routes matching display condition : 1
Status A:AGGREGATE B:BEST b:NOT-INSTALLED-BEST C:CONFED_EBGP D:DAMPED
E:EBGP H:HISTORY I:IBGP L:LOCAL M:MULTIPATH m:NOT-INSTALLED-MULTIPATH
S:SUPPRESSED F:FILTERED s:STALE
Prefix Next Hop MED LocPrf Weight Status
1 10.12.0.0/24 10.100.100.4 100 0 E
AS_PATH: 48 1994 65148 21948 6461 1239 4837 4808 17431 18245
Last update to IP routing table: 0h16m2s
No path is selected as BEST route