Advanced BGP Configuration

Advanced Options

Default Local Preference

Configure default Local Preference value (0-4294967295, higher=more preferred)

Table Map

Uses the specified route map to control how routes received from BGP peers are passed to the dynamic routing manager process, and thus, into routing tables.

Advanced Timers

Coalesce Timer

Configures the Subgroup coalesce timer, in milliseconds (1-4294967295).

Route Map Delay

Time to wait (in seconds) before processing route map changes. A value of 0 disables the timer and stops route updates from happening when route maps change.

Dampening

BGP route flap dampening (RFC 2439) prevents unstable routers from adversely affecting routing behavior.

Time Penalty Half Life

The time duration during which the stability value will be reduced by half if the route is unreachable.

When to Reuse a Route

Stability threshold that must be crossed for a route to be reused.

Start Suppressing Route

Stability threshold that, when crossed, a route will be suppressed.

Max Time to Suppress

Maximum time to suppress a route considered stable.

Advanced Routing Behavior

Disable Fast External Failover

Do not immediately reset session if a link to a directly connected external peer goes down.

Network Import Check

Checks if a BGP network route exists in IGP before creating BGP table entries.

Note

This should be disabled if this router wants to advertise manually summarized routes that do not exist in the routing table, such as collecting all local routes into a larger network in which they can be contained (e.g. 10.14.0.0/16).

Reject AS_SET/AS_CONFED_SET Routes

Reject incoming and outgoing routes with AS_SET or AS_CONFED_SET type.

Route Reflecting

Route Reflector Outbound

Allows attributes modified by route maps to be reflected.

Cluster ID

Route reflector cluster ID.

Disable Client-to-Client

Disables reflection of routes from one client to another client.

Aggregate Behavior

Configures route aggregation using a list of prefixes. More specific routes contained within the specified prefixes will be aggregated into the larger prefix, minimizing the set of networks advertised to peers.

Aggregate Address

The prefix to aggregate.

Generate AS Set

When present, routes for the specified prefix will include an AS set. An AS set is a collection of AS numbers for which routes have been aggregated. This allows peers to detect routing loops, duplicate routes, and so on.

Summary Only

When present, aggregated routes for this prefix will not be announced, so peers only see the aggregate prefix and not the component networks.

Multi-Exit Discriminator

Deterministic MED

Determine route selection locally, even when MED values are present. Picks the best MED path from neighbor advertisements.

Always Compare MED

Instructs the BGP daemon to always consult MED values in routes, no matter which AS the routes were received through.

Max MED

Administratively applied max MED (Indefinite)

Sends a MED value of 4294967294 at all times.

Definite admin max MED

Sends this value at all times instead of the default 4294967294.

Time Period for Max MED on startup

Sends a MED value of 4294967294 at startup for this number of seconds.

Max MED used during startup

Sends this value at startup instead of the default 4294967294.

Confederation

AS Confederation

Configures an AS number for the entire group of iBGP routers participating in confederation.

Confederation Peers

Configures the sub-AS number for the subset of peers inside a group of iBGP routers participating in confederation.

Distance

Administrative Distance

Manually configures the administrative distance for a given prefix

Define

The administrative distance for this prefix, from 1-255.

IP Source Prefix

The IP prefix to which this distance will be applied.

Access List

An access list which can be used to apply the distance to only a subset of the configured prefix.

BGP Distance

Configures distance values which control how BGP will treat routes based on the length of their AS path.

AS External Routes

The distance at which routes are considered external, from 1-255.

AS Internal Routes

The distance at which routes are considered internal, from 1-255.

Local Routes

The distance at which routes are considered local, from 1-255.

Best Path Selection

Controls how the BGP daemon determines the best path to a destination.

Compare Path with Confederation

Considers the length of confederation path sets and sequences.

Ignore AS Path

Ignores AS path lengths when computing the route to a destination.

Multipath Relax

Allow Load Sharing

Consider paths of equal length when choosing between multiple paths to a destination, rather than looking for an exact match. This allows load sharing across different AS paths, so long as they are of equal length.

Generate an AS_SET

Adds AS set information for aggregate routes.

Compare Router ID

Uses the router ID of peers (or originator ID, if present) to break ties when computing paths to a destination based on other information. A lower router ID will win in a tie.

MED Confederation

Compare MED among confederation paths

Compare confederation path MEDs

Treat missing MED as least preferred path

If a route is missing MED information, it will be considered least preferred.

eBGP

eBGP Nexthop Connected

Disable checking if nexthop is an eBGP session.

Enforce First AS

Enforce the first AS for eBGP routes

Disable eBGP Require Policy

Disable the requirement to apply incoming and outgoing filter to eBGP sessions.

Networking Behavior

Subgroup Packet Queue

Maximum size of the subgroup packet queue.

Write Quanta

Controls the size of peer update transmissions.