Method and an apparatus for route selection in routing protocols

A non-transitory machine-accessible storage medium that provides instructions that, if executed by a processor, will cause the processor to perform operations for Border Gateway Protocol (BGP) route selection in a router in a BGP network, the operations comprising:

• receiving a first route entry and a second route entry, wherein the first route entry is received from a BGP peer router and is stored in a BGP table maintained by a BGP module within the router, wherein the second route entry is received from a routing protocol different than BGP;
• downloading the first route entry from the BGP module to a route information base (RIB);
• and downloading the second route entry from the routing protocol different than BGP to the RIB;
• assigning a first administrative distance to the first route entry and assigning a second administrative distance to the second route entry;
• redistributing the second route entry including the second administrative distance from the RIB of the router to the BGP table;
• selecting, at the BGP module, one of the first and the second route entries to download to the RIB based on their respective administrative distances, wherein selecting the one of the first and second route entries based on their respective administrative distances includes:
• comparing the administrative distances of the first and second route entries, and
• selecting the route entry with a more preferred administrative distances based on a predetermined criterion out of the first and the second route entries;
• and
• the BGP module downloading the selected entry to the RIB.

An apparatus comprising:

• a first storage device to store a Border Gateway Protocol (BGP) table having a plurality of route entries, wherein at least one of the plurality of route entries is learned from a BGP peer and at least another one of the plurality of route entries is locally redistributed and is of a different routing protocol than BGP, and wherein each of the plurality of route entries is associated with an administrative distance;
• a second storage device to store a route information base (RIB);
• and
• a processor coupled via a bus to the first storage device and the second storage device, the processor to compare the administrative distances of the plurality of route entries and to select a route entry out of the plurality of route entries that has a most preferred administrative distance to download to the RIB, the processor further to download the selected entry to the RIB.

A system comprising:

• an interior Border Gateway Protocol (iBGP) network;
• a first router coupled to the BGP network;
• a second router coupled to the first router via the BGP network, wherein iBGP sessions are maintained between the first and the second routers;
• and
• a customer device coupled to the first router via a first path and the second router via a second path, wherein the first path is a primary path and the second path is a backup path, and wherein the second router comprises:
• a first storage device to store a Border Gateway Protocol (BGP) table having a route entry of the first path and a second route entry of the second path, wherein the first path is learned from the first router through BGP and the second path is learned from local redistribution, and wherein each of the first and the second route entries is associated with an administrative distance;
• a second storage device to store a route information base (RIB);
• and
• a processor coupled via a bus to the first storage device and the second storage device, the processor to compare the administrative distances of the first and the second route entries and to select a route entry out of the first and second route entries that has a most preferred administrative distance to download to the RIB, the processor further to download the selected entry to the RIB.

A method comprising:

• maintaining in a router a primary path from a Border Gateway Protocol (BGP) peer router over a secondary path from another routing protocol, the maintaining including,
• locally assigning an administrative distance to a plurality of routing protocols, wherein the plurality of routing protocols includes BGP and a plurality of other routing protocols, and wherein the administrative distance assigned to BGP is such that BGP will be selected over the plurality of other routing protocols,
• downloading routes from at least two of the plurality of other routing protocols to a route information base (RIB) of the forwarding and routing engine, wherein each such route has associated with it the administrative distance locally assigned to the one of the plurality of other routing protocols that downloaded that route;
• redistributing, from the RIB of the forwarding and routing engine to the BGP module in the router, routes from the plurality of other protocols including the administrative distances associated with those routes;
• and
• selecting, by the BGP module, routes for downloading to the RIB of the forwarding and routing engine based at least on a most preferred administrative distance associated with those routes.

A non-transitory machine-accessible storage medium that provides instructions that, if executed by a processor, will cause the processor to perform operations comprising:

• maintaining in a router a primary path from a Border Gateway Protocol (BGP) peer router over a secondary path from another routing protocol, the maintaining including,
• locally assigning an administrative distance to a plurality of routing protocols, wherein the plurality of routing protocols includes BGP and a plurality of other routing protocols, and wherein the administrative distance assigned to BGP is such that BGP will be selected over the others of the plurality of routing protocols,
• downloading routes from at least two of the plurality of other routing protocols to a route information base (RIB) of the forwarding and routing engine, wherein each such route has associated with it the administrative distance locally assigned to the one of the plurality of other routing protocols that downloaded that route;
• redistributing, from the RIB of the forwarding and routing engine to the BGP module in the router routes from the plurality of other protocols including the administrative distances associated with those routes;
• and
• selecting, by the BGP module, routes for downloading to the RIB of the forwarding and routing engine based at least on a most preferred administrative distance associated with those routes.