Brocade Communications Systems Layer 3 Routing Configuration ICX 6650 - Manual (Page 328)

310 Brocade ICX 6650 Layer 3 Routing Configuration Guide
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Optional BGP4 configuration tasks
Advertising the default route
By default, the Layer 3 switch does not originate and advertise a default route using BGP4. A BGP4
default route is the IP address 0.0.0.0 and the route prefix 0 or network mask 0.0.0.0. For example,
0.0.0.0/0 is a default route. You can enable the router to advertise a default BGP4 route using
either of the following methods.
NOTE
The Brocade Layer 3 switch checks for the existence of an IGP route for 0.0.0.0/0 in the IP route
table before creating a local BGP route for 0.0.0.0/0.
To enable the router to originate and advertise a default BGP4 route, enter the following command.
Brocade(config-bgp-router)#default-information-originate
Syntax: [no] default-information-originate
Changing the default MED (Metric) used for
route redistribution
The Brocade Layer 3 switch can redistribute directly connected routes, static IP routes, RIP routes,
and OSPF routes into BGP4. The MED (metric) is a global parameter that specifies the cost that will
be applied to all routes by default when they are redistributed into BGP4. When routes are selected,
lower metric values are preferred over higher metric values. The default BGP4 MED value is 0 and
can be assigned a value from 0 through 4294967295.
NOTE
RIP and OSPF also have default metric parameters. The parameters are set independently for each
protocol and have different ranges.
To change the default metric to 40, enter the following command.
Brocade(config-bgp-router)#default-metric 40
Syntax: default-metric num
The num indicates the metric and can be a value from 0 through 4294967295.
Enabling next-hop recursion
For each BGP4 route a Layer 3 switch learns, the Layer 3 switch performs a route lookup to obtain
the IP address of the route next hop. A BGP4 route becomes eligible for installation into the IP route
table only if the following conditions are true:
• The lookup succeeds in obtaining a valid next-hop IP address for the route.
• The path to the next-hop IP address is an Interior Gateway Protocol (IGP) path or a static route
path.
By default, the software performs only one lookup for a BGP route next-hop IP address. If the
next-hop lookup does not result in a valid next-hop IP address or the path to the next-hop IP
address is a BGP path, the software considers the BGP route destination to be unreachable. The
route is not eligible to be installed in the IP route table.