Dell PowerConnect B-RX Configuration Manual page 846

26
Enabling next-hop recursion
BigIron RX# show ip bgp route
Total number of BGP Routes: 5
Status A:AGGREGATE B:BEST b:NOT-INSTALLED-BEST C:CONFED_EBGP D:DAMPED
1
2
3
4
5
In this example, the BigIron RX cannot reach 240.0.0.0/24, because the next-hop IP address for
the route is an IBGP route instead of an IGP route, and thus is considered unreachable by the
device. Here is the IP route table entry for the BGP route's next-hop gateway (102.0.0.1/24).
BigIron RX# show ip route 102.0.0.1
Total number of IP routes: 37
The route to the next-hop gateway is a BGP route, not an IGP route, and thus cannot be used to
reach 240.0.0.0/24. In this case, the device tries to use the default route, if present, to reach the
subnet that contains the BGP route's next-hop gateway.
BigIron RX# show ip route 240.0.0.0/24
Total number of IP routes: 37
Example when recursive route lookups are enabled
When recursive next-hop lookups are enabled, the device recursively looks up the next-hop
gateways along the route until the device finds an IGP route to the BGP route's destination. Here is
an example.
774
H:HISTORY I:IBGP L:LOCAL M:MULTIPATH S:SUPPRESSED
Prefix Next Hop
0.0.0.0/0 10.1.0.2
AS_PATH: 65001 4355 701 80
102.0.0.0/24 10.0.0.1
AS_PATH: 65001 4355 1
104.0.0.0/24 10.1.0.2
AS_PATH: 65001 4355 701 1 189
240.0.0.0/24 102.0.0.1
AS_PATH: 65001 4355 3356 7170 1455
250.0.0.0/24 209.157.24.1
AS_PATH: 65001 4355 701
Network Address Gateway
102.0.0.0 10.0.0.1
Network Address Gateway
0.0.0.0 10.0.0.202
Metric LocPrf
0 100
1 100
0 100
1 100
1 100
Port Cost Type
1/1 1 B
Port Cost Type
1/1 1 S
BigIron RX Series Configuration Guide
Weight Status
0 BI
0 BI
0 BI
0 I
0 I
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