Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 535)

IPv6 route table. Otherwise, the device performs another lookup on the next-hop IPv6 address of the
next-hop for the next-hop gateway, and so on, until one of the lookups results in an IGP route.
You must configure a static route or use an IGP to learn the route to the EBGP multihop peer.
Enabling recursive next-hop lookups
The recursive next-hop lookups feature is disabled by default.
To enable recursive next-hop lookups, enter the following command at the BGP4+ address family
configuration level of the CLI.
Brocade(config-bgp-ipv6u)# next-hop-recursion
Syntax: [no] next-hop-recursion
Example when recursive route lookups are disabled
The output here shows the results of an unsuccessful next-hop lookup for a BGP4+ route. In this case,
next-hop recursive lookups are disabled. This example is for the BGP4+ route to network 2001:db8::/64.
device# show ipv6 bgp route
Total number of BGP Routes: 4
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 2001:ab::1/128 2116:21:16::2 1 100 0 BI
AS_PATH:
2 2001:db8::/64 2001:ab::1 100 0 I
AS_PATH: 65000 65001
3 2007:7002:17::/64 2071:34::1 0 100 0 BE
AS_PATH: 60750
4 2007:7002:17::/64 2071:33::1 0 100 0 I
AS_PATH: 60750
In this example, the device cannot reach 2001:db8::/64, because the next-hop IPv6 address for the
route is an IBGP route instead of an IGP route, and is considered unreachable by the device. The IPv6
route table entry for the BGP4+ route’s next-hop gateway (2001:ab::1) is shown here.
device# show ipv6 route 2001:ab::1
Type Codes - B:BGP C:Connected I:ISIS L:Local O:OSPF R:RIP S:Static
BGP Codes - i:iBGP e:eBGP
OSPF Codes - i:Inter Area 1:External Type 1 2:External Type 2
Type IPv6 Prefix Next Hop Router Interface Dis/Metric Uptime
Bi 2001:ab::1/128 fe80::768e:f8ff:fef9:7d80
ve 40 200/1 29m27s
Since the route to the next-hop gateway is a BGP4+ route, and not an IGP route, it cannot be used to
reach 2001:db8::/64. In this case, the device tries to use the default route, if present, to reach the
subnet that contains the BGP4+ route next-hop gateway.
Example when recursive route lookups are enabled
When recursive next-hop lookups are enabled, the device continues to look up the next-hop gateways
along the route until the device finds an IGP route to the BGP4+ route destination.
device# show ipv6 bgp route
Total number of BGP Routes: 4
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 2001:ab::1/128 2116:21:16::2 1 100 0 BI
Enabling recursive next-hop lookups
FastIron Ethernet Switch Layer 3 Routing Configuration Guide 535
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