Brocade Network OS Administrator’s Guide v4.1.1 - Manual (Page 631)

NOTE
A dampening value for half-life can also be adjusted through a route map, by means of the set
dampening option for the route-map command.
Default route origination
While redistributing routes from OSPF, BGP does not advertise default route 0.0.0.0/0 even if it exists.
You can enable default route origination by using the default-information-originate command under
IPv4 address-family mode:
switch(config-bgp-ipv4u)# default-information-originate
In order to advertise a default route without OSPF redistribution, use the network command.
Multipath load sharing
Unlike IGP, BGP does not perform multipath load sharing by default. Therefore, the maximum number
of paths across which BGP can balance the traffic is set to 1 by default. You can change this value by
using the maximum-paths command in IPv4 address-family mode:
switch(config-bgp-ipv4u)# maximum-paths 4
You can specify the maximum path value explicitly for IBGP or EBGP:
switch(config-bgp-ipv4u)# maximum-paths ebgp 2
In case the maximum-path value must be picked up from the ip load-sharing configuration on the
router, use the following:
sw0(config-bgp-ipv4u)# maximum-paths use-load-sharing
You can enable multipathing for both IBGP or EBGP. By default, the AS numbers of the two paths
should match for them to be considered for multipathing. However, you can remove this restriction by
specifying a multi-as option, as illustrated in the following running-config excerpt:
router bgp
local-as 6500
address-family ipv4 unicast
multipath ebgp
multipath ibgp
multipath multi-as
Configuring the default route as a valid next-hop
BGP does not use the default route installed in the device to resolve the BGP next-hop. You can
change this in IPv4 address-family mode to enable BGP to use default route for next-hop resolution:
sw0(config-bgp-ipv4u)# next-hop-enable-default
Next-hop recursion
Next-hop recursion is disabled by default in BGP, but you can enable it. When next-hop recursion is
disabled, only one route lookup is performed to obtain the next-hop IP address. If the lookup result does
not succeed or the result points to another BGP path, then route destination is considered unreachable.
Enable it as follows:
sw0(config-bgp-ipv4u)# next-hop-recursion
Default route origination
Network OS Administrator’s Guide 631
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