Reference Guide

By default, the bestpath as-path multipath-relax command is disabled. This prevents BGP from load-balancing a
learned route across two or more EBGP peers. To enable load-balancing across different EBGP peers, enter the bestpath
as-path multipath-relax command.
If you configure the bgp bestpath as-path ignore command and the bestpath as-path multipath-relax
command at the same time, an error message displays—only enable one command at a time.
More path support
More path (Add-Path) reduces convergence times by advertising multiple paths to its peers for the same address prefix without
replacing existing paths with new ones. By default, a BGP speaker advertises only the best path to its peers for a given address
prefix.
If the best path becomes unavailable, the BGP speaker withdraws its path from its local router information base (RIB) and
recalculates a new best path. This situation requires both IGP and BGP convergence and is a lengthy process. BGP add-path
also helps switch over to the next new best path when the current best path is unavailable.
The Add-Path capability to advertise more paths is supported only on IBGP peers—it is not supported on EBGP peers and BGP
peer groups.
Ignore router ID calculations
Avoid unnecessary BGP best path transitions between external paths under certain conditions. The bestpath router-
id ignore command reduces network disruption caused by routing and forwarding plane changes and allows for faster
convergence.
Advertise cost
As the default process for redistributed routes, OS10 supports IGP cost as MED. Both auto-summarization and synchronization
are disabled by default.
BGPv4 and BGPv6 support
● Deterministic MED, default
● A path with a missing MED is treated as worst path and assigned an 0xffffffff MED value
● Delayed configuration at system boot — OS10 reads the entire configuration file BEFORE sending messages to start BGP
peer sessions
4-Byte AS numbers
OS10 supports 4-byte AS number configurations by default. The 4-byte support is advertised as a new BGP capability -
4-BYTE-AS, in the OPEN message. A BGP speaker that advertises 4-Byte-AS capability to a peer, and receives the same from
that peer must encode AS numbers as 4-octet entities in all messages.
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Layer 3