set mpls-label @ Full Lab 4

@ Full lab 4,

I am not very clear that BGP needs rout-map with 'set mpls-label' at R3 (Border Router) of AS200.  But, this kind of configuration doesn't need to R5 and XR1 of AS1000.  It is working well but I don't understand, why R3 just need while R5 and XR1 don't need.  Please clarify me.

Comments

  • Hi

    If I remember R3 is setting communities towards R5 and XR1, is that right?  When you are doing IPv4 + label and you use a prefix list to alter values the label is stripped from the prefix, so you need to re-add a label in there or your LSP will fail.

    The reason you don't need it between R5 and XR1 I think is becasue they are iBGP VPNv4 peers and I don't think it's possible to remove labels by any means, even intended from VPNv4 because that would totally break the point of that address family.

    I remember when I first hit that part of the lab, nightmare, I just stared at the screen for about two hours confused :)

  • Thanks Iamjeffvader,

    I didn't mean between R5 and XR1 but I mean R5 to R3 & XR1 to R3.  But, after your explanation, I understand that, we need to set mpls-label if there is existing route-map which is not set label explicitly.  As R5 and XR1 don't have outbound route-policy, we don't need route-map with 'set mpls-label'.  'nei xxxx send-lebel' at R5 and 'address-family labeled-unicast' at XR1 is enough to carry label.

    By the way, what is the equivalent XR command of 'set mpls-label' IOS-command?  I could not find.  I like to know if R3 is XR.

    Thank you so much for your clarification.

  • There doesn't seem to be a set mpls label command in RPL, only set label for bgp which doesn't help here.  I think XR might not need to as you are saying allocate all under vpnv4 address family. Ill lab it up quickly and revert 

  • So when I set a community on XR1 and advertise R2 to R3 adding this community the prefix is labelled.

    R3#sho bgp ipv4 uni 10.0.0.2/32
    BGP routing table entry for 10.0.0.2/32, version 9
    Paths: (1 available, best #1, table default)
      Advertised to update-groups:
         2        
      1000
        10.0.193.19 from 10.0.193.19 (10.0.0.19)
          Origin IGP, metric 20, localpref 100, valid, external, best
          Community: 2000:80
          mpls labels in/out 22/16000

    R3#sho mpls for 10.0.0.2  
    Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop   
    Label      Label      or Tunnel Id     Switched      interface             
    22         16000      10.0.0.2/32      0             Fa0/0.193  10.0.193.19

    When you remove allocate all from under the AF then all prefixes are removed

    R3#sho bgp ipv4 uni summ | i 193
    10.0.193.19     4         1000    4231    4670       14    0    0 2d22h           0
    RP/0/0/CPU0:XR1(config-bgp-af)#do sho bgp ipv4 lab neig 10.0.193.3 adv
    Sat Sep 21 08:17:43.740 UTC
    RP/0/0/CPU0:XR1(config-bgp-af)#

    And put it back in it goes back to normal

    RP/0/0/CPU0:XR1(config-bgp-af)#all all
    RP/0/0/CPU0:XR1(config-bgp-af)#commit
    Sat Sep 21 08:18:03.263 UTC
    RP/0/0/CPU0:XR1(config-bgp-af)#do clear bgp ipv4 lab * soft          
    Sat Sep 21 08:18:05.897 UTC
    RP/0/0/CPU0:XR1(config-bgp-af)#do sho bgp ipv4 lab neig 10.0.193.3 adv
    Sat Sep 21 08:18:08.021 UTC
    Network            Next Hop        From            AS Path
    10.0.0.2/32        10.0.193.19     Local           i
    10.0.0.19/32       10.0.193.19     Local           i

    Processed 2 prefixes, 2 paths

  • By the way, what is the equivalent XR command of 'set mpls-label' IOS-command? I could not find. I like to know if R3 is XR.

    Two things for the send-label in XR:

    1)  under the address-family ipv4 unicast portion of the BGP configuration:  allocate-label all

    2)  activate the address-family ipv4 labeled-unicast

    These combined are the equivalent of the IOS send-label command.

    -HTH

    Warjack

     

  • Hi Iamjeffvader,

    Thanks for you effort.  I also can see label of all routers of AS1000 from R3R1,R4.  But, I wonder I may need some command equivalent to 'set mpls-lable', if I have a route-map like R3 at XR1. I don't have XR router but I booked remote lab tonight.  I will test and find out.  And, I will update to you.  Thanks,

  • Thanks Wrjack,

    But, my intention is to know equivalent XR command of

    IOS:

    route-map xxx

    set mpls-lab

    Not for bgp command "nei x.x.x.x send-label"

  • Oh sorry!  Gotcha

    Sent from my iPad

    On Sep 21, 2013, at 10:27 PM, khine <[email protected]> wrote:

    Thanks Wrjack,

    But, my intention is to know equivalent XR command of

    IOS:

    route-map xxx

    set mpls-lab

    Not for bgp command "nei x.x.x.x send-label"




    INE - The Industry Leader in CCIE Preparation

    http://www.INE.com



    Subscription information may be found at:

    http://www.ieoc.com/forums/ForumSubscriptions.aspx
  • Hi khine

    there isn't anything that I could see in the command reference to indicate you can. My output above suggests it's not required as setting an egress policy in xr1 in the same manner as in r3 still sends labels. 

  • "Send-label" equivalent in XR is "labelled-unicast" address-family (SAFi=4).

    Regards,

    AB.

  • It's not send label he is talking about, it's set MPLS label in a route map. 

  • Hi,

     

    I have the problem where my Inter AS MPLS L3 VPN is broken after I add a route-map outbound

    even I have set mpls label on every route-map sequence.

     

    After I double checked I found out that on R5 to for example R1 (10.0.0.1) I have a out label over R3 link, but not over R5-->XR1 link.

    When I shutdown the R5<->XR1 link everything is working.

    So what did I wrong?

    I have LDP everywhere in AS1000, so it should work. Even show mpls for shows that I have a label for 10.0.0.1,

    but not when I type show bgp ipv4 unicast 10.0.0.1/32.

     



  • Did you use on XR1 a static route pointing to R3? For MPLS label imposition you need a /32 ipv4 prefix and XR does not do it automatically for you.

     

    To answer also to the very first question, that was because you alter the community values FROM R3 TO XR1,R5 and not viceversa. That is why you need them only in that direction. If you were applying the RFC1998 in both directions you had to implement set mpls-label also on R5 route-map.

     

    Alessio

  • Hi,

     

    yes I configured a static route on XR1.

    I took care about everything but it was still not working. In the next few days I will re do the lab again and check if I have the same problem.

  • After I double checked I found out that on R5 to for example R1 (10.0.0.1) I have a out label over R3 link, but not over R5-->XR1 link.

    When I shutdown the R5<->XR1 link everything is working.

    So what did I wrong?

    I have LDP everywhere in AS1000, so it should work. Even show mpls for shows that I have a label for 10.0.0.1,

    but not when I type show bgp ipv4 unicast 10.0.0.1/32.

     




    Did you redistribute the "remote AS" loopbacks into the IGP's? Remember that labels are not generated by LDP if the prefixes are learnt via BGP - most likely this is what is causing it to fail to work.

     

    /Mark

Sign In or Register to comment.