What is BGP attribute & How many types of attributes are
used by BGP???

Answer Posted / shahin

Lets start from first... I m gonna explain each attributes
one by one -

Well Known:
Well known attributes are must be recognized by
each compliant of BGP implementations. Well known attributes
are propagated to other neighbors also.

Optional:
Optional attributes are recognized by some
implementation of BGP & expected that not recognized by
everyone. Optional attributes are propagated to their
neighbors based on the meanings.


Mandatory:
Mandatory is BGP well known attributes. Mandatory
attributes are must be present in all update message passed
between BGP peers. It is present in route description.

Discretionary:
Discretionary is BGP well known attributes.
Discretionary attributes are may be present on update message.

AS Path:
AS path is BGP well known mandatory attributes. AS
path defines the list of Autonomous System that a route has
passed through. AS path attributes are used in path
selection process & lowest path attributes will be preferred
over highest one.

Next-Hop:
Next hop is BGP well known mandatory attributes. In
BGP, next hop is the IP address which is used to reach the
advertising BGP router.

For EBGP, next hop is the ip address of the connection
between the peers.

For IBGP, EBGP next hop address is carried into local
autonomous system.

Origin:
Origin is BGP well known mandatory attributes.
Origion attributes define how BGP router learned about the
particular route. Origin attribute have three possible
values i.e. internal (i), External (e) & Incomplete (?).

Internal(i):
BGP learned about the route from Interior
routing protocol.

External(e):
BGP learned about the router from External BGP.

Incomplete(?):
The origin of the route is unknown or learned by
some other way. The origin of incomplete occurs when routes
are redistributed into BGP.



NB:
1. Due to lack of time, rest of attributes I'll discuss on
next post.
2. Its little bit difficult to draw diagram here & explain
each & every attributes.
3. If anyone need more about this, mail me on
mr.shahin07@gmail.com

Thanks & enjoys the weekend party tonight.... hehehe

Is This Answer Correct ?    62 Yes 8 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

How do you configure a cisco router for routing ipx?

580


What is ccna?

673


What is 10base2 ethernet lans?

659


Define network congestion?

651


Explain how many collision domains are in switch?

675






Can you explain PPP link process step by step?

1761


Why we use filter option?

673


On which base switches take decisions?

673


Explain why is udp lease favored when compared to tcp?

680


Suppose a Switch interface went in error-dis mode what you will do for Troubleshooting List all Possibilities

1962


What is the size of an ip address?

678


When does network congestion occurs?

628


What is the name of distance vector algorithm?

648


If line up, but protocol down which layer should be troubleshot?

707


What does the show protocol display?

882