Dell BigIron RX Series, Configuration Manual

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770 BigIron RX Series Configuration Guide
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Treating missing MEDs as the worst MEDs
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Syntax: [no] maximum-paths <number>
The <num> parameter specifies the maximum number of paths across which the BigIron RX can
balance traffic to a given BGP4 destination. You can change the maximum number of paths to a
value from 2 – 8. The default is 1.
Treating missing MEDs as the worst MEDs
By default, the BigIron RX favors a lower MED over a higher MED during MED comparison. Since the
device assigns the value 0 to a route path’s 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.
BigIron RX(config-bgp)# 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.
Customizing BGP4 load sharing
By default, when BGP4 load sharing is enabled, both IBGP and EBGP paths are eligible for load
sharing, while paths from different neighboring ASs are not eligible. You can change load sharing
to apply only to IBGP or EBGP paths, or to support load sharing among paths from different
neighboring ASs.
To enable load sharing of IBGP paths only, enter the following command at the BGP configuration
level of the CLI.
BigIron RX(config-bgp)# multipath ibgp
To enable load sharing of EBGP paths only, enter the following command at the BGP configuration
level of the CLI.
BigIron RX(config-bgp)# multipath ebgp
To enable load sharing of paths from different neighboring ASs, enter the following command at
the BGP configuration level of the CLI.
BigIron RX(config-bgp)# multipath multi-as
Syntax: [no] multipath ebgp | ibgp | multi-as
The ebgp | ibgp | multi-as parameter specifies the change you are making to load sharing:
•
ebgp – Load sharing applies only to EBGP paths. Load sharing is disabled for IBGP paths.
•
ibgp – Load sharing applies only to IBGP paths. Load sharing is disabled for EBGP paths.
•
multi-as – Load sharing is enabled for paths from different ASs.