RE: BGP LABEL LSP

BGP LSPs work the same as any other LSP, whether LDP or RSVP (MPLS TE)
derived. If the route is installed in the routing table as a BGP route, and
there is a corresponding BGP label, and the interface is MPLS enabled, then
traffic to the destination will be label switched. The general rule of thumb
is that if the route is learned from IGP, the label must come from LDP. If
the route is learned from BGP, the label must come from BGP. MPLS TE is an
exception. "show ip route w.x.y.z" will tell you how the route is learned and
hence how the label should be bound. If the cef table doesn't show the label
stack then something is broken.

Like I said it's hard to infer what the problem is in your case without
further information, but it's possible this issue could be that you're
learning the route via IGP and your label is via BGP, which is not valid, or
vice versa that your route is via BGP and your label is via LDP.

Post more information if you can, otherwise any other answers beyond this
would just be a guess which would probably not be helpful to you.

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com<mailto:bmcgahan_at_INE.com>

Internetwork Expert, Inc.
http://www.INE.com

From: Routing Freak [mailto:routingfreak_at_gmail.com]
Sent: Friday, December 14, 2012 9:57 PM
To: Brian McGahan
Cc: Darlington Ngaiso; Marko Milivojevic; Cisco certification; Brian Dennis
Subject: Re: BGP LABEL LSP

Brian

As i told, i dont have the access to the routers now. it is a production
router where u can get only for a day.
I just want to know how BGP LSP works and i havent found any single document
in cisco doc.

It is not Inter AS L3VPN or CSC. Intra AS VPN over InterAS

 iBGP connection over eBGP is the order of the day.

If someone find , pls reply me.THanks

On Thu, Dec 13, 2012 at 10:00 PM, Brian McGahan
<bmcgahan_at_ine.com<mailto:bmcgahan_at_ine.com>> wrote:
No offense but you can't expect anyone to help troubleshoot your issue unless
you post the output relevant to the issue. The configuration alone is not
enough to infer what the current state of your topology is. If you still want
help with the problem post the outputs that I mentioned on each of the
routers.

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com<mailto:bmcgahan_at_INE.com>

Internetwork Expert, Inc.
http://www.INE.com

From: Routing Freak
[mailto:routingfreak_at_gmail.com<mailto:routingfreak_at_gmail.com>]
Sent: Thursday, December 13, 2012 8:58 AM
To: Darlington Ngaiso
Cc: Brian McGahan; Marko Milivojevic; Cisco certification; Brian Dennis
Subject: Re: BGP LABEL LSP

Joe

I know about PHP, but i m not sure whether BGP LSP will have PHP enabled or
not by default as there is no MPLS enabled anywhere.

Brian

sh ip route shows me the route

sh ip bgp labels shows me the labels for the prefixes with the > best path
enabled on it.

sh mpls forwarding has also the labels associated with it.

But it is not properly programmed in CEF , i dont see it in CEF table.

On Thu, Dec 13, 2012 at 1:44 PM, Darlington Ngaiso
<ngaissod_at_gmail.com<mailto:ngaissod_at_gmail.com>> wrote:
Hi

Did you manage to send the output of the commands below.

Are you trying to Simulate CsC or this is a scenario at work.

regards

On Tue, Dec 11, 2012 at 11:08 PM, Brian McGahan
<bmcgahan_at_ine.com<mailto:bmcgahan_at_ine.com>> wrote:
Post the following:

show ip route
show mpls forwarding
show ip bgp labels
show ip cef w.x.y.z

Where w.x.y.z is the destination in question.

Brian McGahan, CCIE #8593 (R&S/SP/Security)
bmcgahan_at_INE.com<mailto:bmcgahan_at_INE.com>

Internetwork Expert, Inc.
http://www.INE.com

On Dec 11, 2012, at 11:20 AM, "Routing Freak"
<routingfreak_at_gmail.com<mailto:routingfreak_at_gmail.com>> wrote:
Hi

The following are the configs

R5

router bgp 100

neighbor 1.1.1.1 remote-as 100
neighbor 1.1.1.1 update-source loopback0
network 55.55.55.55 mask 255.255.255.255

R1

router bgp 100

neig 5.5.5.5 remote-as 100
neighbor 5.5.5.5 route-reflector client
nei 5.5.5.5 update source loopback0
neighbor 12.12.12.2 remote-as 200
neighbor 12.12.12.2 send label
neighbor 12.12.12.2 send community both
neighbor 3.3.3.3 remote-as 100
neig 3.3.3.3 update-source loopback0
neig 3.3.3.3 route-reflector client
neig 3.3.3.3 send label
neigh 3.3.3.3 send community both

int fa 0/1
description Connected to AS200
ip add 12.12.12.1 255.255.255.0
mpls bgp forwarding
no sh

R2

router bgp 200

neig 12.12.12.1 remote as 100
neigh 12.12.12.1 send label
nei 12.12.12.1 send community both
nei 23.23.23.3 remote-as 100
neig 23.23.23.3 send label
neigh 23.23.23.3 send community both

int fa 0/1
description Connected to R1
ip add 12.12.12.1 255.255.255.0
mpls bgp forwarding

int fa 0/2
description Connexted to R3
ip add 23.23.23.2 255.255.255.0
mpls bgp forwarding

R3

router bgp 100
nei 23.23.23.2 remote-as 200
nei 23.23.23.2 send label
nei 23.23.23.2 send community both

nei 1.1.1.1 remote-as 100
nei 1.1.1.1 update sour loopback0
nei 1.1.1.1 send comm both
nei 1.1.1.1 send label

THere is also one more doubt

What is the differecne between Send Label to a iBGP neighbor and eBGP
neighbor

On Tue, Dec 11, 2012 at 8:32 PM, Darlington Ngaiso
<ngaissod_at_gmail.com<mailto:ngaissod_at_gmail.com>> wrote:
Hi

Can you please send the config on the routers in question.

regards
On Tue, Dec 11, 2012 at 5:26 PM, Routing Freak
<routingfreak_at_gmail.com<mailto:routingfreak_at_gmail.com>> wrote:
Hi Marko

I can see that the route is not using BGP LSP. I am seeing that it is
taking only the IP Path and not the LSP path.

I want the traffic to go into LSP and not take the Ip routing path.

I am not seeing that BGP LSP is formed from R3 to R1.

On Tue, Dec 11, 2012 at 9:52 AM, Marko Milivojevic
<markom_at_ipexpert.com<mailto:markom_at_ipexpert.com>>wrote:

> What happened when you labbed it up?
>
> --
> Marko Milivojevic - CCIE #18427 (SP R&S)
> Senior CCIE Instructor - IPexpert
>
> :: This message was sent from a mobile device. I apologize for errors and
> brevity. ::
>
> On Dec 10, 2012, at 18:00, Routing Freak
<routingfreak_at_gmail.com<mailto:routingfreak_at_gmail.com>> wrote:
>
> Anybody get this ? ANy thoughts on this ?
>
>
>
>
> On Mon, Dec 10, 2012 at 10:41 PM, Routing Freak
<routingfreak_at_gmail.com<mailto:routingfreak_at_gmail.com>>wrote:
>
>> Hi
>>
>> I have a topology like this
>>
>> ____________ibgp______________
>>
>> R5------------------R1-------------------R2-----------------------R3
>> ibgp ebgp ebgp
>>
>>
>> R1 and R3 are running iBGP in AS 100 and R1 and R2 are running eBGP with
>> R2 in AS 200 and respectively R2 and R3 are eBGP neighbors.
>>
>> There is no physical connection between R1 and R3 . There is an iBGP peer
>> between R1 and R3 via R2 which is a eBGP peer with both R1 and R3
>>
>> Now R1 is a RR and R5 and R3 are clients
>>
>> MPLS is enabled between R1 and R2 and R2 and R3. But there is no LDP or
>> RSVP enabled on those interfaces.I have just enabled the forwarding place
>> saying that this interface can receive labelled packets.
>>
>> R3 is learning R5's routes via R1's iBGP connection with a next hop as R5.
>>
>> R5's loopback is advertised as ebGP route to R2 from R1 and it is passed
>> to R3 from R2 as eBGP route.
>>
>> Now when R1 is sending as Ipv4 Unicast routes with Labels on it. ( with
>> Send label option ) to R2.
>>
>> R2 is also having the send label in the eBGP peering with R3 .
>>
>> So now for R3 to reach R5s loopback there it should use a label sent from
>> eBGP neighbor R2.
>>
>> So now here is the problem part. I dont have a label for the prefixes (
>> ie R5 advertised prefixes ) and i only have the next hop which is R5
>> loopback label ( ie advertised by R2 to R3 ) .
>>
>> So when R3 is sending traffic to R5's prefixes, will it use the BGP label
>> to R2 and R2 will use the BGP label to reach R1 and then R1 will strip the
>> label and do a normal routing lookup to send traffic to R5
>>
>> Will BGP label forms an LSP ?. When a next hop in a BGP table is again
>> learned by BGP, will it use the BGP label to send the traffic ?
>>
>> Without the prefix label , will only the next hop BGP label will work to
>> form LSP ?
>>
>>
>>
>>
>>
>

--
Regards
Routing Freak CCIE#35889 (SPv3)
Blogs and organic groups at http://www.ccie.net