Configuring BGP

This section provides details for BGP configuration on S- and 7100-Series products.

Default BGP Parameters lists BGP default values.

Default BGP Parameters

Parameter	Description	Default Value
advertisement interval	The minimum interval in seconds between sending EBGP routing updates.	30 seconds
AS origination interval	The interval in seconds between successive update messages for route prefixes that originate in the local AS.	15 seconds
AS path limit	The upper limit on the AS path length when configuring a route.	1
connection retry interval	The amount of time between attempts to reestablish a connection to configured peers that are no longer available.	120 seconds
cutoff	The route suppression threshold used by flap dampening to determine when a flapping route should be suppressed.	125
distance (External to AS)	The priority given to external BGP routes relative to other protocols for the local router.	20
distance (Internal to AS)	The priority given to internal BGP routes relative to other protocols for the local router.	200
graceful restart	A BGP extension that provides for the continued processing and forwarding of packets by the data-forwarding plane even if the control plane fails.	disabled
half-life reachable	The time in seconds after which a reachable route‘s penalty value decays to half of its current value.	300 seconds
half-life unreachable	The time in seconds after which an unreachable route‘s penalty value decays to half of its current value.	900 seconds
hold-time (flap dampening)	The maximum amount of time a route can be suppressed.	900 seconds
hold-time (peering session negotiation)	The number of seconds to use when negotiating a peering session within a group.	90 seconds
idle hold interval	The interval in seconds between returning to the idle state and reinitiating a TCP connection for the peer.	15 seconds
keepalive timer	The interval between keepalive messages	30 seconds or one-third of the hold-time setting
local preference	The preference for this route over other possible routes on the local router.	100
maximum EBGP ECMP routes	The maximum number of external BGP ECMP routes on the local router.	1
maximum IBGP ECMP routes	The maximum number of internal BGP ECMP routes on the local router.	1
maximum ORF entries	The maximum number of outbound route filtering entries that will be accepted from the peer.	100000
maximum prefixes	The peak number of prefixes that BGP will accept for installation into the routing information base.	0 – unlimited
MED	The Multi-Exit Discriminator value when configuring a route.	0
memory limit reachable	The maximum time in seconds any memory of a previous instability is retained for a reachable route, given the route state is both unchanged and reachable.	700 seconds
memory limit unreachable	The maximum time in seconds any memory of a previous instability is retained for an unreachable route, given the route state is both unchanged and unreachable.	1800 seconds
open delay	The interval in seconds between the establishment of a TCP connection and the sending of an OPEN message to open a BGP session.	0 – no delay
origin	The value of the origin process attribute when configuring a route	0 – IGP
peer type	The type of peer or peer group	IBGP
peering type	Determines whether updates for prefixes containing the NOPEER community will be accepted by or sent to this neighbor.	unspecified
restart defer period	The time in seconds that route selection is deferred after a graceful restart.	120 seconds
restart time	The time in seconds to wait for a graceful restart capable peer to come back after a graceful restart.	120 seconds
restart timeout	The estimated time in seconds that is advertised to peers in the OPEN message for the session to be reestablished after a graceful restart.	120
reuse penalty	The route penalty value below which a suppressed route is reused.	50
route withdrawal interval	The interval between the advertisement and subsequent withdrawal of a route.	30 seconds
stale path time	The maximum time in seconds following a restart before removing stale routes from the peer.	120
time-to-live (TTL)	Specifies the number of hops for this neighbors TTL.	64