BGP Attributes

Features of BGP
BGP supports a wide range of path attributes, BGP chooses a path to a network based on its path attributes.

There are four categories of features are the following:
Known mandatory
Estimated known
Transitive optional
Optional non-transitive

The mandatory attribute known by all BGP routers, present in all BGP updates, must be recognized and transferred to other BGP routers. As the track and origin the next jump.

All BGP routers must recognize the known discretion and pass them on to other BGP routers, but they do not need to be present in an update. Local preference

An BGP router may recognize or not recognize an optional transitive, but it is passed to other BGP routers.
If it is not recognized, it is marked as partial. Assembly, community.

Optional Non-Transitive If BGP does not recognize the attribute, you can ignore the update and not announce the path to its counterpart. Highlight Multiple Output (MED), Author ID

AS_Path attribute: This path attribute lists the independent system numbers in the path from end to end. BGP uses AS_Path as its main loop prevention tool.

The AS_Path attribute is a known mandatory attribute. List your AS and from which the updates come. A shorter list of AS_PATH is more desirable.

Next_hop is a known mandatory attribute. The following jump means that the IP address reaches the next independent system because BGP is AS by the AS routing protocol.

Attribute of origin

The origin of all ASS in the intranet is how the network was presented in the BGP.

(I) represents PGI
E Represents EBGP
(?) Represent incomplete

Feature weight is a feature of Cisco. That is, how to get out of AS, track with higher weight is more desirable. Weight is a partial feature, where weight 0 learns by default the 32,769 track for locally injected methods. Your local router is not advertised for any BGP counterpart.

Local preference feature

Local preferences determine how data traffic should leave an independent system. The route with the highest preference value is the most popular by default is 100, the range of preference from 0 to 232 is well known, an estimate attribute is only announced to adjacent iBGP within a standalone system.

The version of the BGP table is 5, the local router ID is
Status codes: suppressed, padded, h record, * valid,> better, i - internal,
RIB malfunction, S Stale, m m, backup paths b, f RT-Filter,
The best external roads, additional path, compressed by RIB,
Symbols of origin: i - IGP, e - EGP,? - incomplete
Validation codes RPKI: valid V, invalid, N does not exist

Weight way for the next jump network

r> i 0 100 0 i
r> i 0 100 0 i
*> 0 32768 i
r> i 0 100 0 i
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