"show ip bgp <prefix>" output question

[kfarrington]

R1>sh ip bgp 0.0.0.0 0.0.0.0

BGP routing table entry for 0.0.0.0/0, version 159313

Paths: (3 available, best #1, table Default-IP-Routing-Table)

Multipath: eBGP

Advertised to peer-groups:

External Internal

Local

155.195.1.1 from 0.0.0.0 (155.195.1.2)

Origin IGP, metric 31232, localpref 100, weight 32768, valid, sourced, local, best

Guys,

have the above, now the next hop I assume is 155.195.1.1 as I see this by doing a show ip bgp

Is there a document explaining what the output of this command is showing, ie is this a correct assumption

next hop for the route is 155.195.1.1 but from 0.0.0.0 (155.195.1.2) this router

a little confused. sorry :)

[Harold Ritter]

the first address represents the BGP next hop, the second one the BGP peer address and the third one the BGP peer RID.

0.0.0.0 in the output you provided means that the prefix is locally originated.

Let me know if I answered your question,

[kfarrington]

it does thx mate.

but what also, what are the

"valid, sourced, local"

I assume the local - it is either, intenal, external or local and that is all the options you will see for that option.

With that in mind, if a local BGP prefix is generated, say from an aggregate (or another way) that does not exist in the routing table, what is the AD of a local. I know an aggreegate creates a null0 and the AD is 200 (iBGP). Is it safe to say that a local (not internal) generated prefix would always have an internal AD of 200?

Also

Valid, sourced, what other options could there be for these? If any?

Many thx mate. I am really having a bad hair day :(

[Harold Ritter · Accepted solution]

The paths should always be valid if you see them in the output of "show ip bgp".

Sourced means the prefix is locally originated.

You are correct about the local. It is either local, internal or external.

A route created using from the aggregate command would also have an AD of 200.

Let me know if I answered your question,

[kfarrington]

thx buddy

[kfarrington]

Sorry, one last point.

in the URL for the distance BGP command it states:

Administrative distance for BGP local routes. Local routes are those networks listed with a network router configuration command,

But as you say, aggregates also have the same AD (which is effectivley a network command)

Is it safe to say that redistributed IGP routes into BGP also have an AD of 200?

Kind regards,

Ken

[Harold Ritter]

On the router where the redistribution is done, the BGP route redistributed from an IGP is not installed in the RIB, since the IGP route is. We can therefore not talk about an AD for the BGP route.

Hope this helps,

[kfarrington]

I understand. :)

of course!

[ปลาวาฬทราย RMUTT CPE IX]

  (65001 64955 65003) 65089, (Received from a RR-client)
    172.16.254.226 (metric 20645) from 172.16.224.236 (172.16.224.236)
      Origin IGP, metric 0, localpref 100, valid, confed-internal
      Extended Community: RT:1100:1001
      mpls labels in/out nolabel/362

  (65008 64955 65003) 65089
    172.16.254.226 (metric 20645) from 10.131.123.71 (10.131.123.71)
      Origin IGP, metric 0, localpref 100, valid, confed-external
      Extended Community: RT:1100:1001
      mpls labels in/out nolabel/362

	Both paths have reachable next hops <- reachable because it's on the show ip bgp?
	Both paths have a WEIGHT of 0 <- where the 0 came from? metric 0?
	Both paths have a LOCAL_PREF of 100
	Both paths are learned <- how to know?
	Both paths have AS_PATH length 1 <- where the 1 came from?
	Both paths are of origin IGP
	The paths have different neighbor AS's so ignoring MED <- how it different? 65001 & 65008?
	Both paths are internal
	  (no distinction is made between confed-internal and confed-external)
	Both paths have an IGP metric to the NEXT_HOP of 20645
Path 2 is better than path 1 because it has a lower Router-ID. <- 10.131.123.71?

Thank you very much.