Differences between version 5 and previous revision of BGP.
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| Newer page: | version 5 | Last edited on Wednesday, August 18, 2004 2:30:41 pm | by LindsayDruett | Revert |
| Older page: | version 4 | Last edited on Wednesday, August 18, 2004 12:05:01 pm | by LindsayDruett | Revert |
@@ -22,7 +22,31 @@
|Route reflector client|A client is a router that has a TCP session with its iBGP peer that is acting as a route reflector. It forwards routes to the route reflector, which propagates these on to other routers. The client does not have peer connections with other clients.
|Route reflector cluster|A cluster is a group consisting of a route reflector and clients. There can be more than one route reflector in a cluster.
|Synchronization rule|This rule states that a router cannot forward a route to an eBGP peer unless the route is in its local IP routing table. This requires that the IGP and BGP routing tables are synchronized. This is to prevent BGP from advertising routes that the autonomous system cannot cirect to the destination.%%%If BGP is fully meshed, it does not have to rely on the IGP routing tables and you can disable synchronization.%%%Use the ''Router(config-router)#__no synchronization__'' command to turn off synchronization.
|Transit autonomous system|An autonomous system that is used to carry BGP traffic across to another autonomous system. None of the traffic is destined for any router within the transit autonomous system; it is simply being routed through it.
+
+----
+!!BGP Attributes
+
+|__Category__|__Description__
+|__Well-known:__
+|Mandatory|These attributes are required and are therefore recognized by all BGP implementations.
+|Discretionary|It is not required that these attributes be present in the update messages, but if they are present, all routers running BGP will recognize and act on the information contained.
+|__Optional:__
+|Transitive|The router might not recognize these attributes, but if this is the case, it marks the update as partial and sends the update, complete with attributes, to the next router. The attributes traverse the router unchanged, if they are not recognised.
+|Nontransitive|Nontransitive attributes are dropped if they fall onto a router that does not understand or recognize the attribute.
+%%%
+|__Attribute Name__|__Category__|__Code__|__Preference__
+|Origin|Well-known, mandatory|1|Lowest origin code.%%% %%%IGP < EGP < Incomplete
+|AS_Path|Well-known, mandatory|2|Shortest path
+|Next Hop|Well-know, mandatory|3|Shortest part or IGP metric
+|Multiple Exit Discriminator|Optional, nontransitive|4|Lowest value
+|Local preference|Well-known, discretionary|5|Highest value
+|Atomic aggregate|Well-known, discretionary|6|Information not used in path selection
+|Aggregator|Optional, transitive|7|Information not used in path selection
+|Community|Optional, transitive|8|Information not used in path slection
+|Originator ID|Optional, nontransitive|9|Information not used in path selection
+|Cluster ID|Optional, nontransitive|10|Information not used in path selection
+|Weight|Cisco-defined| |Highest value
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CategoryProtocols
