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Configuring a BGP Peer Configuring BGP
page 4-26 OmniSwitch 6800/6850/9000 Advanced Routing Configuration Guide December 2007
Configuring a BGP Peer
BGP supports two types of peers, or neighbors: internal and external. Internal sessions are run between
BGP speakers in the same autonomous system (AS). External sessions are run between BGP peers in
different autonomous systems. Internal neighbors may be located anywhere within the same autonomous
system while external neighbors are adjacent to each other and share a subnet. Internal neighbors usually
share a subnet.
BGP speakers can be organized into groups that share similar parameters, such as metrics, timers, and
route preferences. It is also possible to configure individual speakers with unique parameters.
An OmniSwitch is assigned an AS number. That same router may contain peers with different AS
numbers. The router may also contain information on peer routers residing in different physical routers.
However, the OmniSwitch will not dynamically learn about peers in other routers; you must explicitly
configure peers operating in other routers.
Note. In this document, the BGP terms “peer” and “neighbor” are used interchangeably to mean any BGP
entity known to the local router.
Peer Command Defaults
The following table lists the default values for many of the peer commands:
Parameter Description Command
Default Value/
Comments
Configures the time interval for
updates between external BGP
peers.
ip bgp neighbor advertisement-interval 30
Enables or disables BGP peer
automatic restart.
ip bgp neighbor auto-restart enabled
Configures this peer as a client to
the local route reflector.
ip bgp neighbor route-reflector-client disabled
The interval, in seconds,
between
BGP retries to set up a
connection via the transport
protocol with another peer.
ip bgp neighbor conn-retry-interval 120
Enables or disables BGP peer
default origination.
ip bgp neighbor default-originate disabled
Configures the tolerated hold
time interval, in seconds, for this
peer’s session.
ip bgp neighbor timers 90
Configures the timer interval
between KEEPALIVE messages
sent to this peer.
ip bgp neighbor timers 30
Configures the maximum number
of prefixes, or paths, the local
router can receive from this peer
in UPDATE messages.
ip bgp neighbor maximum-prefix 5000