Lab 4 - Issues with Task 4.1 again

Hi all,

 

I've found myself spending an inordinate amount of time trying to get the basic Inter-AS and CSC working in Lab 4 and it's making me want to pack this whole thing in! I'm having real issues, apparently centred around XR2, where I cannot get reachability through to the R7 and R8 loopbacks inside vrf FOO. There are prefixes and labels being advertised out but the traffic just doesn't get there. If anyone can shed some light on this I'd really appreciate it

 

RP/0/3/CPU0:XR2#sh ip ro vrf FOO 172.16.0.7

Sat Oct 25 12:30:46.058 UTC

 

Routing entry for 172.16.0.7/32

  Known via "bgp 1000", distance 20, metric 0

  Tag 3000, type external

  Installed Oct 25 12:23:46.953 for 00:06:59

  Routing Descriptor Blocks

    172.16.207.7, from 172.16.207.7

      Route metric is 0

  No advertising protos.

 

 

RP/0/3/CPU0:XR2#sh bgp vrf FOO

Sat Oct 25 12:35:15.380 UTC

BGP VRF FOO, state: Active

BGP Route Distinguisher: 10.0.0.20:1

VRF ID: 0x60000003

BGP router identifier 10.0.0.20, local AS number 1000

BGP table state: Active

Table ID: 0xe0000003

BGP main routing table version 170

 

Status codes: s suppressed, d damped, h history, * valid, > best

              i - internal, r RIB-failure, S stale

Origin codes: i - IGP, e - EGP, ? - incomplete

   Network            Next Hop            Metric LocPrf Weight Path

Route Distinguisher: 10.0.0.20:1 (default for vrf FOO)

*> 172.16.0.1/32      10.0.0.1                               0 2000 i

*>i172.16.0.2/32      10.0.0.2                 0    100      0 i

*> 172.16.0.3/32      10.0.0.3                               0 2000 i

*> 172.16.0.4/32      10.0.0.4                 0             0 2000 i

*>i172.16.0.5/32      10.0.0.5                 0    100      0 i

*> 172.16.0.6/32      10.0.0.1                               0 2000 ?

*> 172.16.0.7/32      172.16.207.7             0             0 3000 i

*> 172.16.0.8/32      172.16.208.8             0             0 3000 i

*>i172.16.0.19/32     10.0.0.19                0    100      0 i

*> 172.16.0.20/32     0.0.0.0                  0         32768 i

*> 172.16.46.0/24     10.0.0.1                               0 2000 ?

*> 172.16.78.0/24     172.16.207.7             0             0 3000 i

*                     172.16.208.8             0             0 3000 i

*> 172.16.207.0/24    172.16.207.7             0             0 3000 i

*> 172.16.208.0/24    172.16.208.8             0             0 3000 i

 

RP/0/3/CPU0:XR2#sh bgp vrf FOO 172.16.0.7

Sat Oct 25 12:35:57.173 UTC

BGP routing table entry for 172.16.0.7/32, Route Distinguisher: 10.0.0.20:1

Versions:

  Process           bRIB/RIB  SendTblVer

  Speaker                169         169

    Local Label: 16010

Last Modified: Oct 25 12:08:13.531 for 00:27:43

Paths: (1 available, best #1)

  Advertised to PE update-groups (with more than one peer):

    0.3

  Advertised to PE peers (in unique update groups):

    10.0.0.4

  Advertised to CE update-groups (with more than one peer):

    0.1

  Path #1: Received by speaker 0

  3000

    172.16.207.7 from 172.16.207.7 (172.16.0.7)

      Received Label 3

      Origin IGP, metric 0, localpref 100, valid, external, best, import-candidate

      Extended community: RT:1000:1

 

As you can see XR2 is learning the prefixes and is being given label 3 to use. However when it comes to using that label it's a different matter.

 

RP/0/3/CPU0:XR2#sh mpls forwarding vrf FOO

Sat Oct 25 12:29:18.248 UTC

Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes

Label  Label       or ID              Interface                    Switched

------ ----------- ------------------ ------------ --------------- ------------

16006  Aggregate   FOO: Per-VRF Aggr[V]  

                                      FOO                          4680

16009  Aggregate   172.16.207.0/24[V] FOO                          0

16012  Aggregate   172.16.208.0/24[V] FOO                          0

16013  Pop         172.16.78.0/24[V]               172.16.207.7    0

16014  19          172.16.0.1/32[V]                10.0.0.1        0

16015  19          172.16.0.2/32[V]                10.0.0.2        0

16016  21          172.16.0.3/32[V]                10.0.0.3        0

16017  21          172.16.0.4/32[V]                10.0.0.4        0

16018  22          172.16.0.5/32[V]                10.0.0.5        0

16019  28          172.16.0.6/32[V]                10.0.0.1        0

16020  16007       172.16.0.19/32[V]               10.0.0.19       0

16021  29          172.16.46.0/24[V]               10.0.0.1        0

 

If I add a static route inside vrf FOO for the R7/R8 loopbacks then I get a forwarding entry however obviously this isn't a solution in the lab and anyway the CSC still doesn't work.

 

Doing a debug I can see R5, directly connected, is trying to send traffic to XR2 with a label of 16010 however this doesn't appear in the mpls forwarding table above. XR2 is actively advertising this label out! Output below is from another PE router

 

R1(config-subif)#do sh mpls fo vrf FOO 172.16.0.7

Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop

Label      Label      or Tunnel Id     Switched      interface

30         16010      172.16.0.7/32[V] 9522          Fa0/0.13   10.0.13.3

 

This is confirmed on XR2

 

RP/0/3/CPU0:XR2#sh bgp vrf FOO labels | include 172.16.0.7

Sat Oct 25 13:01:11.580 UTC

*> 172.16.0.7/32      172.16.207.7    3               16010

 

I'm completely stuck now. The outputs do look similar for XR2s loopback inside vrf FOO however that works as expected.

 

Here is the BGP config from XR2:

 

 

router bgp 1000

 address-family ipv4 unicast

  network 10.0.0.20/32

 !

 address-family vpnv4 unicast

 !

 address-family ipv6 unicast

  network 2001:10::20/128

 !

 neighbor 10.0.0.2

  remote-as 1000

  update-source Loopback0

  address-family ipv4 unicast

  !

  address-family vpnv4 unicast

   route-reflector-client

  !

 !

 neighbor 10.0.0.4

  remote-as 2000

  ebgp-multihop 255

  update-source Loopback0

  address-family vpnv4 unicast

   route-policy PASS in

   route-policy PASS out

   next-hop-unchanged

  !

 !

 neighbor 10.0.0.5

  remote-as 1000

  update-source Loopback0

  address-family vpnv4 unicast

   route-reflector-client

  !

 !

 neighbor 10.0.0.19

  remote-as 1000

  update-source Loopback0

  address-family vpnv4 unicast

   route-reflector-client

  !

 !

 neighbor 2001:10::19

  remote-as 1000

  update-source Loopback0

  address-family ipv6 unicast

  !

 !

 vrf FOO

  rd 10.0.0.20:1

  address-family ipv4 unicast

   network 172.16.0.20/32

   allocate-label all

  !

  neighbor 172.16.207.7

   remote-as 3000

   address-family ipv4 labeled-unicast

    route-policy PASS in

    route-policy PASS out

   !

  !

  neighbor 172.16.208.8

   remote-as 3000

   address-family ipv4 labeled-unicast

    route-policy PASS in

    route-policy PASS out

   !

  !

 !

!

 

 

And the static routes for good measure

 

 

router static

 vrf FOO

  address-family ipv4 unicast

   172.16.0.7/32 GigabitEthernet0/4/0/0.207

   172.16.0.8/32 GigabitEthernet0/4/0/0.208

!   172.16.207.7/32 GigabitEthernet0/4/0/0.207

!   172.16.208.8/32 GigabitEthernet0/4/0/0.208

  !

 !

!

 

 

 

 

R7 BGP config

 

 

R7(config-router-af)#do sh run | s bgp

 mpls bgp forwarding

router bgp 3000

 no bgp default ipv4-unicast

 bgp log-neighbor-changes

 neighbor 172.16.0.6 remote-as 3000

 neighbor 172.16.0.6 update-source Loopback0

 neighbor 172.16.0.8 remote-as 3000

 neighbor 172.16.0.8 update-source Loopback0

 neighbor 172.16.207.20 remote-as 1000

 !

 address-family ipv4

  network 172.16.0.7 mask 255.255.255.255

  network 172.16.78.0 mask 255.255.255.0

  neighbor 172.16.0.8 activate

  neighbor 172.16.0.8 send-label

  neighbor 172.16.207.20 activate

  neighbor 172.16.207.20 send-label

  no auto-summary

 exit-address-family

 !

 address-family vpnv4

  neighbor 172.16.0.6 activate

  neighbor 172.16.0.6 send-community extended

  neighbor 172.16.0.8 activate

  neighbor 172.16.0.8 send-community extended

 exit-address-family

 !

 address-family ipv4 vrf BAR

  network 192.168.0.7 mask 255.255.255.255

 exit-address-family

 

 

Comments

  • Hi,

    Check this thread http://ieoc.com/forums/t/22729.aspx. I was also tearing hair on my had before I chanced to find it.

    Best regards,
     Danil Zhigalin

    25 ???. 2014 ?., ? 19:24, muh <[email protected]> ???????(?):

    Hi all,

     

    I've found myself spending an inordinate amount of time trying to get the basic Inter-AS and CSC working in Lab 4 and it's making me want to pack this whole thing in! I'm having real issues, apparently centred around XR2, where I cannot get reachability through to the R7 and R8 loopbacks inside vrf FOO. There are prefixes and labels being advertised out but the traffic just doesn't get there. If anyone can shed some light on this I'd really appreciate it

     

    RP/0/3/CPU0:XR2#sh ip ro vrf FOO 172.16.0.7

    Sat Oct 25 12:30:46.058 UTC

     

    Routing entry for 172.16.0.7/32

      Known via "bgp 1000", distance 20, metric 0

      Tag 3000, type external

      Installed Oct 25 12:23:46.953 for 00:06:59

      Routing Descriptor Blocks

        172.16.207.7, from 172.16.207.7

          Route metric is 0

      No advertising protos.

     

     

    RP/0/3/CPU0:XR2#sh bgp vrf FOO

    Sat Oct 25 12:35:15.380 UTC

    BGP VRF FOO, state: Active

    BGP Route Distinguisher: 10.0.0.20:1

    VRF ID: 0x60000003

    BGP router identifier 10.0.0.20, local AS number 1000

    BGP table state: Active

    Table ID: 0xe0000003

    BGP main routing table version 170

     

    Status codes: s suppressed, d damped, h history, * valid, > best

                  i - internal, r RIB-failure, S stale

    Origin codes: i - IGP, e - EGP, ? - incomplete

       Network            Next Hop            Metric LocPrf Weight Path

    Route Distinguisher: 10.0.0.20:1 (default for vrf FOO)

    *> 172.16.0.1/32      10.0.0.1                               0 2000 i

    *>i172.16.0.2/32      10.0.0.2                 0    100      0 i

    *> 172.16.0.3/32      10.0.0.3                               0 2000 i

    *> 172.16.0.4/32      10.0.0.4                 0             0 2000 i

    *>i172.16.0.5/32      10.0.0.5                 0    100      0 i

    *> 172.16.0.6/32      10.0.0.1                               0 2000 ?

    *> 172.16.0.7/32      172.16.207.7             0             0 3000 i

    *> 172.16.0.8/32      172.16.208.8             0             0 3000 i

    *>i172.16.0.19/32     10.0.0.19                0    100      0 i

    *> 172.16.0.20/32     0.0.0.0                  0         32768 i

    *> 172.16.46.0/24     10.0.0.1                               0 2000 ?

    *> 172.16.78.0/24     172.16.207.7             0             0 3000 i

    *                     172.16.208.8             0             0 3000 i

    *> 172.16.207.0/24    172.16.207.7             0             0 3000 i

    *> 172.16.208.0/24    172.16.208.8             0             0 3000 i

     

    RP/0/3/CPU0:XR2#sh bgp vrf FOO 172.16.0.7

    Sat Oct 25 12:35:57.173 UTC

    BGP routing table entry for 172.16.0.7/32, Route Distinguisher: 10.0.0.20:1

    Versions:

      Process           bRIB/RIB  SendTblVer

      Speaker                169         169

        Local Label: 16010

    Last Modified: Oct 25 12:08:13.531 for 00:27:43

    Paths: (1 available, best #1)

      Advertised to PE update-groups (with more than one peer):

        0.3

      Advertised to PE peers (in unique update groups):

        10.0.0.4

      Advertised to CE update-groups (with more than one peer):

        0.1

      Path #1: Received by speaker 0

      3000

        172.16.207.7 from 172.16.207.7 (172.16.0.7)

          Received Label 3

          Origin IGP, metric 0, localpref 100, valid, external, best, import-candidate

          Extended community: RT:1000:1

     

    As you can see XR2 is learning the prefixes and is being given label 3 to use. However when it comes to using that label it's a different matter.

     

    RP/0/3/CPU0:XR2#sh mpls forwarding vrf FOO

    Sat Oct 25 12:29:18.248 UTC

    Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes

    Label  Label       or ID              Interface                    Switched

    ------ ----------- ------------------ ------------ --------------- ------------

    16006  Aggregate   FOO: Per-VRF Aggr[V]  

                                          FOO                          4680

    16009  Aggregate   172.16.207.0/24[V] FOO                          0

    16012  Aggregate   172.16.208.0/24[V] FOO                          0

    16013  Pop         172.16.78.0/24[V]               172.16.207.7    0

    16014  19          172.16.0.1/32[V]                10.0.0.1        0

    16015  19          172.16.0.2/32[V]                10.0.0.2        0

    16016  21          172.16.0.3/32[V]                10.0.0.3        0

    16017  21          172.16.0.4/32[V]                10.0.0.4        0

    16018  22          172.16.0.5/32[V]                10.0.0.5        0

    16019  28          172.16.0.6/32[V]                10.0.0.1        0

    16020  16007       172.16.0.19/32[V]               10.0.0.19       0

    16021  29          172.16.46.0/24[V]               10.0.0.1        0

     

    If I add a static route inside vrf FOO for the R7/R8 loopbacks then I get a forwarding entry however obviously this isn't a solution in the lab and anyway the CSC still doesn't work.

     

    Doing a debug I can see R5, directly connected, is trying to send traffic to XR2 with a label of 16010 however this doesn't appear in the mpls forwarding table above. XR2 is actively advertising this label out! Output below is from another PE router

     

    R1(config-subif)#do sh mpls fo vrf FOO 172.16.0.7

    Local      Outgoing   Prefix           Bytes Label   Outgoing   Next Hop

    Label      Label      or Tunnel Id     Switched      interface

    30         16010      172.16.0.7/32[V] 9522          Fa0/0.13   10.0.13.3

     

    This is confirmed on XR2

     

    RP/0/3/CPU0:XR2#sh bgp vrf FOO labels | include 172.16.0.7

    Sat Oct 25 13:01:11.580 UTC

    *> 172.16.0.7/32      172.16.207.7    3               16010

     

    I'm completely stuck now. The outputs do look similar for XR2s loopback inside vrf FOO however that works as expected.

     

    Here is the BGP config from XR2:

     

     

    router bgp 1000

     address-family ipv4 unicast

      network 10.0.0.20/32

     !

     address-family vpnv4 unicast

     !

     address-family ipv6 unicast

      network 2001:10::20/128

     !

     neighbor 10.0.0.2

      remote-as 1000

      update-source Loopback0

      address-family ipv4 unicast

      !

      address-family vpnv4 unicast

       route-reflector-client

      !

     !

     neighbor 10.0.0.4

      remote-as 2000

      ebgp-multihop 255

      update-source Loopback0

      address-family vpnv4 unicast

       route-policy PASS in

       route-policy PASS out

       next-hop-unchanged

      !

     !

     neighbor 10.0.0.5

      remote-as 1000

      update-source Loopback0

      address-family vpnv4 unicast

       route-reflector-client

      !

     !

     neighbor 10.0.0.19

      remote-as 1000

      update-source Loopback0

      address-family vpnv4 unicast

       route-reflector-client

      !

     !

     neighbor 2001:10::19

      remote-as 1000

      update-source Loopback0

      address-family ipv6 unicast

      !

     !

     vrf FOO

      rd 10.0.0.20:1

      address-family ipv4 unicast

       network 172.16.0.20/32

       allocate-label all

      !

      neighbor 172.16.207.7

       remote-as 3000

       address-family ipv4 labeled-unicast

        route-policy PASS in

        route-policy PASS out

       !

      !

      neighbor 172.16.208.8

       remote-as 3000

       address-family ipv4 labeled-unicast

        route-policy PASS in

        route-policy PASS out

       !

      !

     !

    !

     

     

    And the static routes for good measure

     

     

    router static

     vrf FOO

      address-family ipv4 unicast

       172.16.0.7/32 GigabitEthernet0/4/0/0.207

       172.16.0.8/32 GigabitEthernet0/4/0/0.208

    !   172.16.207.7/32 GigabitEthernet0/4/0/0.207

    !   172.16.208.8/32 GigabitEthernet0/4/0/0.208

      !

     !

    !

     

     

     

     

    R7 BGP config

     

     

    R7(config-router-af)#do sh run | s bgp

     mpls bgp forwarding

    router bgp 3000

     no bgp default ipv4-unicast

     bgp log-neighbor-changes

     neighbor 172.16.0.6 remote-as 3000

     neighbor 172.16.0.6 update-source Loopback0

     neighbor 172.16.0.8 remote-as 3000

     neighbor 172.16.0.8 update-source Loopback0

     neighbor 172.16.207.20 remote-as 1000

     !

     address-family ipv4

      network 172.16.0.7 mask 255.255.255.255

      network 172.16.78.0 mask 255.255.255.0

      neighbor 172.16.0.8 activate

      neighbor 172.16.0.8 send-label

      neighbor 172.16.207.20 activate

      neighbor 172.16.207.20 send-label

      no auto-summary

     exit-address-family

     !

     address-family vpnv4

      neighbor 172.16.0.6 activate

      neighbor 172.16.0.6 send-community extended

      neighbor 172.16.0.8 activate

      neighbor 172.16.0.8 send-community extended

     exit-address-family

     !

     address-family ipv4 vrf BAR

      network 192.168.0.7 mask 255.255.255.255

     exit-address-family

     

     




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  • Hi Danil,

     

    Thanks for the reply, I think I read one of your threads earlier. I thought this could have been the issue however XR2 is definitely advertising a label for the R7 loopback. As you can see in the outputs there is a VPN label of 16010 being sent out! It really looks as though XR2 just isn't installing it in his own LFIB

     

    The outputs were taken from a rack rental earlier today. I have since built the entire thing again in GNS3 and IOS XRV and I just can't recreate the issue. I'm starting to lean towards a software bug in 3.9.1 as the same config works well in 5.2.1 but if anything this is even more frustrating - what if it happens in the lab!?

     

    If only there was a nice way to debug on the XR...

     

    Pete

  • Hi all,

     

    Responding to my own thread as I've just run into this exact same issue again, again it's on a rack rental and it looks like a software bug, however this time I seem to have hit a magic button

     

    So the XR is doing it's thing again, popping labels instead of using the perfectly valid labels it receives via LDP:

     

    RP/0/3/CPU0:XR2(config-bgp)#do sh mpls fo labels 20006

    Tue Dec  2 21:15:33.728 UTC

    Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes

    Label  Label       or ID              Interface                    Switched

    ------ ----------- ------------------ ------------ --------------- ------------

    20006  Pop         10.0.0.1/32        PO0/7/0/0.1920 10.19.20.19     0          

           Pop         10.0.0.1/32        Gi0/4/0/0.205 10.0.205.5      540

     

    RP/0/3/CPU0:XR2(config-bgp)#do sh mpls ldp bindings 10.0.0.1/32

    Tue Dec  2 21:16:04.275 UTC

    10.0.0.1/32, rev 30

            Local binding: label: 20006

            Remote bindings: (3 peers)

                Peer                Label

                -----------------   --------

                10.0.0.2:0          2001

                10.0.0.5:0          5002

                10.0.0.19:0         19001

     

    I've removed the config for BGP and ISIS and reapplied it, same thing, I've applied a route-policy facing R2 to drop all bgp routes just to see if it's because there's a labelless BGP route being installed instead of ISIS, etc etc, basically just messing around. Then finally "clear isis route" - BLAM

     

    RP/0/3/CPU0:XR2(config-bgp-nbr-af)#do sh mpls fo labels 20006

    Tue Dec  2 21:39:11.718 UTC

    Local  Outgoing    Prefix             Outgoing     Next Hop        Bytes

    Label  Label       or ID              Interface                    Switched

    ------ ----------- ------------------ ------------ --------------- ------------

    20006  5002        10.0.0.1/32        Gi0/4/0/0.205 10.0.205.5      0

           19001       10.0.0.1/32        PO0/7/0/0.1920 10.19.20.19     1080       

     

    Hope this helps someone, this scared me pretty bad thinking if I saw this on the big day I'd be screwed. I think at the first sign of any wierdness like this I'll clear every routing process I have!

     

    Cheers

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