BGP Characteristics are parts of info that a BGP router links to explain different prefixes included in it's BGP upgrade communications. There will be a variable series of BGP features in every update information except for those that carries only withdrawn ways.
For example, AS 100 will advertise MED values to AS 200 but AS 200 will not advertise AS 100's MED values to AS 300. The MED Values AS 200 exchanges with AS 300 would be AS 200's MED values and would be completely different from the values AS 100 sent to AS 200 even if the numeric values are the same. BGP table contains all the routes from all the neighbors, several routes to the same network with different attributes. 3) BGP Routing Table – the main IP routing tables that contains only the best routes from BGP Table. After BGP has selected the best path to a network, that path is added to the main IP routing table.
Each attribute will be a TLV that is made up of attribute kind, attribute size and attribute worth. Each attribute type consists of two octéts, one for banner and the additional can be the kind as referred to briefly in the following area.
BGP attributes have various distinctive forms that defines how tracks are going to use and pass on a specific attribute to it't neighbors. The sorts are explained in details in our write-up BGP Attribute sorts and Flags.
Well known BGP attribute forms:
Well-known discrétionary: Attributes of this kind must end up being recognized by aIl BGP impIementations but they put on't possess to can be found in all BGP improvements to all neighbors. - Optional transitive:optional BGP features as the name suggests don't want to end up being grasped by aIl BGP impIementations, but since thé transitive flag is arranged they will end up being handed down to various other neighbours.
Optional non-transitivé:Qualities of this type are furthermore optional as the title implies and will not be passed to other neighbors.
0ptional BGP attribute sorts:
BGP Attributes checklist:
Type Code value | Feature Title | Feature Kind |
1 | ORIGIN | Well-known required |
2 | ASPATH | Well-known necessary |
3 | NEXTHOP | Well-known obligatory |
4 | MULTIEXITDISC (MED) | 0ptional non-transitivé |
5 | LOCALPREF | Well-known discretionary |
6 | ATOMICAGGREGATE | Well-known discretionary |
7 | AGGREGATOR | Optional transitive |
8 | Neighborhood | 0ptional transitivé |
9 | ORIGINATORID | Optional non-transitive |
10 | Cluster Checklist | 0ptional non-transitivé |
11 | DPA | Naming Point Feature |
12 | Marketer | BGP/IDRP Path Machine |
13 | RCIDPATH/CLUSTERID | BGP/IDRP Path Server |
14 | Multiprotocol Reachable NLRI | Optional non-transitive |
15 | Multiprotocol Unreachable NLRI | Optional non-transitive |
16 | Prolonged neighborhoods | |
256 | Appropriated for long term development |
Thése list of route attributes is utilized by évery BGP router aIong the path to evaluate different network paths and the select the types to shift to the BGP table to the routing desk.
One even more attribute that can be not incorporated in this list, is definitely the fat attribute. The fat is definitely a Cisco proprietary local attribute that is definitely not propagated in BGP upgrade messages but can be used by Cisco routers for path selection.