bgpPeerConfAltLocalAs

DC-BGP-MIB · .1.2.826.42.1.1578918.5.65.1.3.1.1.1.96

Object

column r/w BgpAutonomousSystemNumber
An alternative local AS number that can be used to
establish a session with this peer.  This is used when
merging two ASs into a single AS.
              
A value of zero means 'not configured'.
              
If an alternative local AS number is configured then the
peering session can be established using the alternative
local AS instead of the primary local AS number specified
by bgpRmEntLocalAs.
              
Setting an alternative local AS number allows the primary
local AS number to be changed without reconfiguring the
peer at the same time.  Later the peer can be reconfigured
to establish the session using the new remote AS number
and the alternative local AS number can be reset to zero.
              
An alternative local AS number should only be used as an
intermediate step on one side of a BGP session.  Do not
configure an alternative local AS number on both sides of
a BGP session - configure the correct remote AS numbers
instead.
              
If this is an IBGP peer then bgpPeerRemoteAs must have the
same value as bgpRmEntLocalAs.  In this case the IBGP
session can be established using either
bgpRmEntLocalAs/bgpPeerRemoteAs or bgpPeerConfAltLocalAs.
              
If this is an EBGP peer then bgpPeerRemoteAs must specify
the remote peer's AS number, and bgpRmEntLocalAs,
bgpPeerConfAltLocalAs and bgpPeerRemoteAs must all be
different.  In this case the EBGP session can be
established using bgpRmEntLocalAs or bgpPeerConfAltLocalAs
as the local AS number, but the remote AS number must
match bgpPeerRemoteAs.
              
The bgpPeerConfAltLocalAsMode field controls detailed
operation of the alternative local AS number, including
whether the peering session can be established using
bgpRmEntLocalAs or only using bgpPeerConfAltLocalAs.
              
Use of alternative local AS numbers is not supported if
the router is a member of a confederation.
              
The constraints explained above mean that this field is
only used if the following conditions are all met:
-  bgpRmEntConfederationId = 0
-  bgpPeerConfAltLocalAs != 0
-  bgpPeerConfAltLocalAs != bgpRmEntLocalAs
-  bgpPeerConfAltLocalAs != bgpPeerRemoteAs.
              
This field can be changed at any time.  However, if the
field is changed while the peer is admin_status UP, the
change will only take effect after the peer has been
cycled admin_status DOWN and then UP, thus forcing the
peer session to be restarted.  In this case, until the
peer is set admin_status DOWN, the peer will be marked as
out of date (as reported by the config_state field in the
AMB_BGP_PEER_STATUS row for the peer).

Context

MIB
DC-BGP-MIB
OID
.1.2.826.42.1.1578918.5.65.1.3.1.1.1.96
Type
column
Access
readwrite
Status
current
Parent
bgpPeerEntry
Table
bgpPeerTable
Siblings
130

Syntax

BgpAutonomousSystemNumber
Source
BgpAutonomousSystemNumber
Base type
Unsigned32

Values & Constraints

No enumerated values or constraints recorded.

Related Objects

Sibling Objects