Brocade Multi-Service IronWare Routing Configuration Guide (Supporting R05.6.00) - Manual (Page 49)

Multi-Service IronWare Routing Configuration Guide 21
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Disabling or re-enabling comparison of the AS-Path length
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.
Brocade(config)# router bgp
Brocade(config-bgp-router)# compare-med-empty-aspath
Syntax: [no] compare-med-empty-aspath
Disabling or re-enabling comparison of
the AS-Path length
AS-Path comparison is Step 5 in the algorithm that BGP4 uses to select the next path for a route.
Comparison of the AS-Path length is enabled by default. To disable it, enter the following command
at the BGP4 configuration level of the CLI.
Brocade(config-bgp)# as-path-ignore
Syntax: [no] as-path-ignore
This command disables comparison of the AS-Path lengths of otherwise equal paths. When you
disable AS-Path length comparison, the BGP4 algorithm shown in
“How BGP4 selects a path for a
route (BGP best path selection algorithm)” on page 5 skips from Step 4 to Step 6.
Redistributing IBGP routes
By default, in default VRF instance, the device does not allow redistribute IBGP routes from BGP4
into RIP, OSPF, or IS-IS. This behavior helps eliminate routing loops. In non-default VRF instances,
by default, the device does allow redistribution IBGP routes from BGP4 into RIP, OSPF.
To enable the device to redistribute BGP4 routes into OSPF, RIP, or IS-IS, enter the following
command.
Brocade(config-bgp)# bgp-redistribute-internal
Syntax: [no] bgp-redistribute-internal
To disable redistribution of IBGP routes into RIP, IS-IS, and OSPF, enter the following command.
Brocade(config-bgp)# no bgp-redistribute-internal
BGP router reflector
A BGP router selects a preferred BGP4 route for a specific prefix learned from multiple peers by
using the BGP best path selection algorithm, and installs the BGP4 route in the Routing Table
Manager (RTM). The BGP router marks the preferred BGP4 route as the best route, and advertises
the route to other BGP4 neighbors. Generally, the RTM route table size is larger than the number of
unique BGP4 routes in the BGP4 route table. All preferred BGP4 routes are installed in RTM and
are marked as the best BGP4 routes.