Dell Brocade DCX, Configuration Manual

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BigIron RX Series Configuration Guide 769
53-1001810-01
Customizing BGP4 load sharing
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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.
By default, load sharing applies to EBGP and IBGP paths, and does not apply to paths from
different neighboring ASs.
Configuring BGP4 neighbors
The BGP4 protocol does not contain a peer discovery process. Therefore, for each of the router’s
BGP4 neighbors (peers), you must indicate the neighbor’s IP address and the AS each neighbor is
in. Neighbors that are in different ASs communicate using EBGP. Neighbors within the same AS
communicate using IBGP.
NOTE
If the BigIron RX has multiple neighbors with similar attributes, you can simplify configuration by
configuring a peer group, then adding individual neighbors to it. The configuration steps are similar,
except you specify a peer group name instead of a neighbor IP address when configuring the
neighbor parameters, then add individual neighbors to the peer group. Refer to
“Configuring a BGP4
peer group” on page 776.
NOTE
The BigIron RX attempts to establish a BGP4 session with a neighbor as soon as you enter a
command specifying the neighbor’s IP address. If you want to completely configure the neighbor
parameters before the BigIron RX establishes a session with the neighbor, you can administratively
shut down the neighbor. Refer to
“Administratively shutting down a session with a BGP4 neighbor”
on page 779.