Brocade FastIron Ethernet Switch Layer 3 Routing Configuration Guide - Manual (Page 423)

NOTE
MED comparison is not performed for internal routes originated within the local AS or confederation
unless the compare-med-empty-aspath command is configured.
To configure the device to always compare MEDs, enter the following command.
device(config-bgp-router)# always-compare-med
Syntax: [no] always-compare-med
The following BGP4 command directs BGP4 to take the MED value into consideration even if the route
has an empty as-path path attribute.
device(config)# router bgp
device(config-bgp-router)# compare-med-empty-aspath
Syntax: [no] compare-med-empty-aspath
Treating missing MEDs as the worst MEDs
By default, the device favors a lower MED over a higher MED during MED comparison. Since the
device assigns the value 0 to a route path MED if the MED value is missing, the default MED
comparison results in the device favoring the route paths that are missing their MEDs.
To change this behavior so that the device favors a route that has a MED over a route that is missing its
MED, enter the following command at the BGP4 configuration level of the CLI.
device(config-bgp-router)#med-missing-as-worst
Syntax: [no] med-missing-as-worst
NOTE
This command affects route selection only when route paths are selected based on MED comparison. It
is still possible for a route path that is missing its MED to be selected based on other criteria. For
example, a route path with no MED can be selected if its weight is larger than the weights of the other
route paths.
Configuring route reflection parameters
Normally, all the BGP4 devices within an AS are fully meshed. Since each device has an IBGP session
with each of the other BGP4 devices in the AS, each IBGP device has a route for each IBGP neighbor.
For large autonomous systems containing many IBGP devices, the IBGP route information in each fully-
meshed IBGP device may introduce too much administrative overhead.
To avoid this overhead, you can organize your IGP devices into clusters:
• A cluster is a group of IGP devices organized into route reflectors and route reflector clients. You
configure the cluster by assigning a cluster ID on the route reflector and identifying the IGP neighbors
that are members of that cluster. All configuration for route reflection takes place on the route
reflectors. Clients are unaware that they are members of a route reflection cluster. All members of the
Treating missing MEDs as the worst MEDs
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