Re: BGP LABEL LSP

Hey Brian

THanks for the write up .. Hmm i tried to get the outputs but
unfortunately, i dont have the access to the routers. it went oit of my way
and went on to the first level escalation, so i cannot get the ouptuts,
sorry for that.

But anyways thanks for the write-up. Really good one. :)

On Sat, Dec 15, 2012 at 2:47 PM, Brian McGahan <bmcgahan_at_ine.com> wrote:

> 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 doesnt
> show the label stack then something is broken.****
>
> ** **
>
> Like I said its hard to infer what the problem is in your case without
> further information, but its possible this issue could be that youre
> 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****
>
> ** **
>
> 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> wrote:*
> ***
>
> No offense but you cant 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****
>
> ****
>
> Internetwork Expert, Inc.****
>
> http://www.INE.com****
>
> ****
>
> *From:* Routing Freak [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>
> 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> 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****
>
> ****
>
> Internetwork Expert, Inc.****
>
> http://www.INE.com****
>
>
> On Dec 11, 2012, at 11:20 AM, "Routing Freak" <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>
> 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>
> 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
> >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> wrote:
> >
> > Anybody get this ? ANy thoughts on this ?
> >
> >
> >
> >
> > On Mon, Dec 10, 2012 at 10:41 PM, Routing Freak <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)****
>
>
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> ****
>
> ****
>
>
>
> ****
>
> ****
>
> --
> Regards****
>
> Routing Freak CCIE#35889 (SPv3)****
>
> ****
>
> ****
>
>
>
> ****
>
> ****
>
> --
> Regards****
>
> Routing Freak CCIE#35889 (SPv3)****
>
> ****
>
>
>
> ****
>
> ** **
>
> --
> Regards****
>
> Routing Freak CCIE#35889 (SPv3)****
>
> ** **
>

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