Advanced BGP Configuration¶
- 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.
- Coalesce Timer
Configures the Subgroup coalesce timer, in milliseconds (
- Route Map Delay
Time to wait (in seconds) before processing route map changes. A value of
0disables the timer and stops route updates from happening when route maps change.
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.
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.
- Reject AS_SET/AS_CONFED_SET Routes
Reject incoming and outgoing routes with AS_SET or AS_CONFED_SET type.
- 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.
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.
- 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
4294967294at all times.
- Definite admin max MED
Sends this value at all times instead of the default
- Time Period for Max MED on startup
Sends a MED value of
4294967294at startup for this number of seconds.
- Max MED used during startup
Sends this value at startup instead of the default
- 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.
- Administrative Distance
Manually configures the administrative distance for a given prefix
The administrative distance for this prefix, from
- 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
- AS Internal Routes
The distance at which routes are considered internal, from
- Local Routes
The distance at which routes are considered local, from
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 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.
- Subgroup Packet Queue
Maximum size of the subgroup packet queue.
- Write Quanta
Controls the size of peer update transmissions.