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Saturday, December 10, 2016

CCIE SP [ 6VPE- InterAS Option C - CSC ]

Hello All ,
 

I want to share with you one of my practical studies on ipv6 , InterAS option C and CSC
I made all of them in one document with the configuration needed to be a reference for all of us.
with some of troubleshooting and wireshark capture of mpls labels.

lets take now a deep dive of the topology
Hint : all the lab is built by the use of  CSR1000v  and XRv over Vmware ESXi 6.0.
Here as shown below we have 2 large ISPs AS9 and AS1009
and CSC ISPs AS109(R11) and AS1109 (R16,R19).

vrf ABC to inter-as customers (R11,R16)
vrf XYZ  to CSC customers  (R17,R19)

at both large ISPs I am running ISIS + LDP.

Here is the IP scheme used.

Routerloopback0
R19.9.0.1
R29.9.0.2
R39.9.0.3
R79.9.0.7
R89.9.0.8
R109.9.0.10
R11172.9.0.11
R16172.9.0.16
R17192.9.0.17
R19192.9.0.19

IP scheme :
At  AS9 and AS1009 is 9.9.X.X
between AS9 and AS109 is  172.9.X.X
between AS1009 and AS1109 is 172.9.X.X
between AS109 and R17  is 192.9.X.X
between AS1109 and R19 is 192.9.X.X


Configuration section


OSPFv3  300

                                R17    [CE]
                          R11    [PE]
interface Loopback0
ipv6 address 2002:192:9::17/128
ipv6 enable
ospfv3 300 ipv6 area 0
!
interface GigabitEthernet1
ipv6 address 2002:192:9:117::17/64
ipv6 enable
ospfv3 300 ipv6 area 0
!
router ospfv3 300
!
address-family ipv6 unicast
exit-address-family
!




















R17#sh ipv6 route ospf
IPv6 Routing Table - default - 9 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
      B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2
      IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external
      ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect
      O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
      ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2, a - Application
OI  2002:192:9::16/128 [110/2]
    via FE80::20C:29FF:FE31:CB96, GigabitEthernet1
OI  2002:192:9::19/128 [110/2]
    via FE80::20C:29FF:FE31:CB96, GigabitEthernet1
OI  2002:192:9:169::/64 [110/2]
    via FE80::20C:29FF:FE31:CB96, GigabitEthernet1
vrf definition XYZ
rd 2:2
!
  address-family ipv6
  route-target export 1:1
  route-target import 1:1
exit-address-family
!
interface GigabitEthernet3
vrf forwarding XYZ
ipv6 address 2002:192:9:117::11/64
ipv6 enable
ospfv3 300 ipv6 area 0
!
interface Loopback1
vrf forwarding XYZ
ip address 192.9.0.11 255.255.255.255
ipv6 address 2002:192:9::11/128
ipv6 enable
ospfv3 300 ipv6 area 0
!
router ospfv3 300
!
address-family ipv6 unicast vrf XYZ
  redistribute bgp 109
exit-address-family
!
router bgp 109

address-family ipv6 vrf XYZ
  redistribute ospf 300 match internal external 1 external 2
exit-address-family
!

R11#  show ipv6 route vrf XYZ
IPv6 Routing Table - XYZ - 7 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
      B - BGP, R - RIP, H - NHRP, I1 - ISIS L1
      I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary, D - EIGRP
      EX - EIGRP external, ND - ND Default, NDp - ND Prefix, DCE - Destination
      NDr - Redirect, O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1
      OE2 - OSPF ext 2, ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
      ls - LISP site, ld - LISP dyn-EID, a - Application
B  2002:192:9::16/128 [20/0]
    via 172.9.0.16%default, indirectly connected
O  2002:192:9::17/128 [110/1]
    via FE80::20C:29FF:FE72:AB09, GigabitEthernet3
B  2002:192:9::19/128 [20/1]
    via 172.9.0.16%default, indirectly connected
C  2002:192:9:117::/64 [0/0]
    via GigabitEthernet3, directly connected
L  2002:192:9:117::11/128 [0/0]
    via GigabitEthernet3, receive
B  2002:192:9:169::/64 [20/0]
    via 172.9.0.16%default, indirectly connected
L  FF00::/8 [0/0]
    via Null0, receive




BGP v6

  R3 [PE]
R11  [CE]
vrf ABC
address-family ipv6 unicast
  import route-target
  1:1
  !
  export route-target
  1:1
  !
!
!
interface GigabitEthernet0/0/0/3
vrf ABC
ipv6 address 2002:172:9:113::3/64
ipv6 enable
!


router bgp 9
address-family vpnv6 unicast
!
address-family ipv6 unicast
!
vrf ABC
  rd 1:1
  address-family ipv6 unicast
  !
  neighbor 2002:172:9:113::11
  remote-as 109
  address-family ipv6 unicast
    route-policy pass in
    route-policy pass out
  !
  !
!
!

RP/0/0/CPU0:R3# show bgp vrf ABC ipv6 unicast
Sun Oct 30 15:02:06.119 UTC
BGP VRF ABC, state: Active
BGP Route Distinguisher: 1:1
VRF ID: 0x60000002
BGP router identifier 9.9.0.3, local AS number 9
BGP table state: Active
Table ID: 0xe0800002  RD version: 14
BGP main routing table version 14

Status codes: s suppressed, d damped, h history, * valid, > best
              i - internal, r RIB-failure, S stale, N Nexthop-discard
Origin codes: i - IGP, e - EGP, ? - incomplete
  Network            Next Hop            Metric LocPrf Weight Path
Route Distinguisher: 1:1 (default for vrf ABC)
*> 2002:172:9::11/128 2002:172:9:113::11
0            0 109 i
*>i2002:172:9::16/128 9.9.0.10                0    100 0 1009 ?
*> 2002:172:9:113::/64
                      2002:172:9:113::11
0            0 109 ?
*>i2002:172:9:160::/64
                      9.9.0.10                0    100 0 1009 ?

Processed 4 prefixes, 4 paths
interface GigabitEthernet1
negotiation auto
ipv6 address 2002:172:9:113::11/64
ipv6 enable
!

router bgp 109
bgp router-id 172.9.0.11
neighbor 2002:172:9:113::3 remote-as 9
address-family ipv6
  redistribute connected
  neighbor 2002:172:9:113::3 activate
exit-address-family
!






















R11#show bgp ipv6 unicast
BGP table version is 11, local router ID is 172.9.0.11
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
              r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter,
              x best-external, a additional-path, c RIB-compressed,
Origin codes: i - IGP, e - EGP, ? - incomplete
RPKI validation codes: V valid, I invalid, N Not found

    Network          Next Hop            Metric LocPrf Weight Path
*> 2002:172:9::11/128
                      ::                      0        32768 i
*> 2002:172:9::16/128
                      2002:172:9:113::3
0 9 1009 ?
*> 2002:172:9:113::/64
                      ::                      0        32768 ?
*> 2002:172:9:160::/64
                      2002:172:9:113::3
0 9 1009 ?


Ospfv3 200

R19    [CE]
R16    [PE]
interface Loopback0
ipv6 address 2002:192:9::19/128
ipv6 enable
ospfv3 200 ipv6 area 0
!
interface GigabitEthernet2
ipv6 address 2002:192:9:169::19/64
ipv6 enable
ospfv3 200 ipv6 area 0
!
router ospfv3 200
!
address-family ipv6 unicast
exit-address-family

























R19#show ipv6 route ospf
IPv6 Routing Table - default - 8 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
      B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2
      IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external
      ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect
      O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
      ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2, a - Application
O  2002:192:9::16/128 [110/1]
    via FE80::20C:29FF:FEC4:8AC8, GigabitEthernet2
OI  2002:192:9::17/128 [110/2]
    via FE80::20C:29FF:FEC4:8AC8, GigabitEthernet2
vrf definition XYZ
rd 2:2
!
address-family ipv6
  route-target export 1:1
  route-target import 1:1
exit-address-family
!
interface Loopback1
vrf forwarding XYZ
ip address 192.9.0.16 255.255.255.255
ipv6 address 2002:192:9::16/128
ipv6 enable
ospfv3 200 ipv6 area 0
!
interface GigabitEthernet3
vrf forwarding XYZ
ipv6 address 2002:192:9:169::16/64
ipv6 enable
ospfv3 200 ipv6 area 0
!
router ospfv3 200
router-id 192.9.0.16
!
address-family ipv6 unicast vrf XYZ
  redistribute bgp 1109
exit-address-family
!
router bgp 1109
address-family ipv6 vrf XYZ
  redistribute ospf 200 match internal external 1 external 2 include-connected
exit-address-family
!







R16#show ipv6 route vrf XYZ
IPv6 Routing Table - XYZ - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
      B - BGP, R - RIP, H - NHRP, I1 - ISIS L1
      I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary, D - EIGRP
      EX - EIGRP external, ND - ND Default, NDp - ND Prefix, DCE - Destination
      NDr - Redirect, O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1
      OE2 - OSPF ext 2, ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
      ls - LISP site, ld - LISP dyn-EID, a - Application
LC  2002:192:9::16/128 [0/0]
    via Loopback1, receive
B  2002:192:9::17/128 [20/1]
    via 172.9.0.11%default, indirectly connected
O  2002:192:9::19/128 [110/1]
    via FE80::20C:29FF:FEB8:8806, GigabitEthernet3
C  2002:192:9:169::/64 [0/0]
    via GigabitEthernet3, directly connected
L  2002:192:9:169::16/128 [0/0]
    via GigabitEthernet3, receive
L  FF00::/8 [0/0]
    via Null0, receive

EIGRP v6

hint: take care of the place of the redistribution of BGP under the topology base.

R10    [PE]
R16  [CE]
vrf definition ABC
rd 1:1
!
address-family ipv6
  route-target export 1:1
  route-target import 1:1
exit-address-family
!

interface GigabitEthernet3
vrf forwarding ABC
ipv6 address 2002:172:9:160::10/64
ipv6 enable

router eigrp ABC
!
address-family ipv6 unicast vrf ABC autonomous-system 200
  !
  topology base
  redistribute bgp 1009 metric 1000 100 255 200 1500
  exit-af-topology
  eigrp router-id 9.9.0.10
exit-address-family

router bgp 1009
address-family ipv6 vrf ABC
  redistribute connected
  redistribute eigrp 200
exit-address-family




R10#    show ipv6 route vrf ABC
IPv6 Routing Table - ABC - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
      B - BGP, R - RIP, H - NHRP, I1 - ISIS L1
      I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary, D - EIGRP
      EX - EIGRP external, ND - ND Default, NDp - ND Prefix, DCE - Destination
      NDr - Redirect, O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1
      OE2 - OSPF ext 2, ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
      ls - LISP site, ld - LISP dyn-EID, a - Application
B  2002:172:9::11/128 [200/0]
    via 9.9.0.3%default, indirectly connected
D  2002:172:9::16/128 [90/2570240]
    via FE80::20C:29FF:FEC4:8AB4, GigabitEthernet3
B  2002:172:9:113::/64 [200/0]
    via 9.9.0.3%default, indirectly connected
C  2002:172:9:160::/64 [0/0]
    via GigabitEthernet3, directly connected
L  2002:172:9:160::10/128 [0/0]
    via GigabitEthernet3, receive
L  FF00::/8 [0/0]
    via Null0, receive


interface GigabitEthernet1
ipv6 address 2002:172:9:160::16/64
ipv6 enable
ipv6 eigrp 200

ipv6 router eigrp 200
eigrp router-id 172.9.0.16


























R16#show ipv6 route eigrp
IPv6 Routing Table - default - 6 entries
Codes: C - Connected, L - Local, S - Static, U - Per-user Static route
      B - BGP, R - RIP, H - NHRP, I1 - ISIS L1
      I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary, D - EIGRP
      EX - EIGRP external, ND - ND Default, NDp - ND Prefix, DCE - Destination
      NDr - Redirect, O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1
      OE2 - OSPF ext 2, ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
      ls - LISP site, ld - LISP dyn-EID, a - Application
EX  2002:172:9::11/128 [170/2585856]
    via FE80::20C:29FF:FE9D:E281, GigabitEthernet1
EX  2002:172:9:113::/64 [170/2585856]
    via FE80::20C:29FF:FE9D:E281, GigabitEthernet1



(VPNv6) & (BGP+send label) relationship between R7 & R3


                                  R3
                                    R7
router bgp 9
bgp router-id 9.9.0.3
address-family ipv4 unicast
  allocate-label all
!
address-family ipv6 unicast
!
address-family vpnv6 unicast
!
neighbor 9.9.0.7
  remote-as 9
  update-source Loopback0
  address-family ipv4 labeled-unicast
  !
  address-family vpnv6 unicast
  !
!
router bgp 9
bgp router-id 9.9.0.7
neighbor 9.9.0.3 remote-as 9
neighbor 9.9.0.3 update-source Loopback0
!
address-family ipv4
  neighbor 9.9.0.3 activate
  neighbor 9.9.0.3 send-community both
  neighbor 9.9.0.3 route-reflector-client
  neighbor 9.9.0.3 send-label
  exit-address-family
!
  address-family vpnv6
  neighbor 9.9.0.3 activate
  neighbor 9.9.0.3 send-community extended
  neighbor 9.9.0.3 route-reflector-client
exit-address-family

(VPNv6) & (BGP+send label) relationship between R10 & R8

R10
                                        R8
router bgp 1009
bgp router-id 9.9.0.10
neighbor 9.9.0.8 remote-as 1009
neighbor 9.9.0.8 update-source Loopback0
!
address-family ipv4
  neighbor 9.9.0.8 activate
  neighbor 9.9.0.8 send-community both
  neighbor 9.9.0.8 send-label
exit-address-family
!
address-family vpnv6
  neighbor 9.9.0.8 activate
  neighbor 9.9.0.8 send-community extended
exit-address-family
!
router bgp 1009
bgp router-id 9.9.0.8
neighbor 9.9.0.10 remote-as 1009
neighbor 9.9.0.10 update-source Loopback0
!
address-family ipv4
  neighbor 9.9.0.10 activate
  neighbor 9.9.0.10 send-community both
  neighbor 9.9.0.10 route-reflector-client
  neighbor 9.9.0.10 send-label
exit-address-family
!
address-family vpnv6
neighbor 9.9.0.10 activate
  neighbor 9.9.0.10 send-community extended
  neighbor 9.9.0.10 route-reflector-client
exit-address-family


VPNv6 relationship between R11 & R16 to transfer the routes of CSC customers (R17 & R19).

R11
R16
router bgp 109
bgp router-id 172.9.0.11
neighbor 172.9.0.16 remote-as 1109
neighbor 172.9.0.16 ebgp-multihop 255
neighbor 172.9.0.16 update-source Loopback0
!
address-family vpnv6
  neighbor 172.9.0.16 activate
  neighbor 172.9.0.16 send-community extended
exit-address-family
!
router bgp 1109
bgp router-id 172.9.0.16
neighbor 172.9.0.11 remote-as 109
neighbor 172.9.0.11 ebgp-multihop 255
neighbor 172.9.0.11 update-source Loopback0
  !
  address-family vpnv6
  neighbor 172.9.0.11 activate
  neighbor 172.9.0.11 send-community extended
exit-address-family
!

The configuration at ASBRs
===========================
we noticed here the advertising of the loopbacks from each AS to the other
to make the BGP to can assign them labels to confirm the reachability end-to-end.

the static route here should be done to make the XR see the /32 at the IGP and can assign to it label
this behavior is done by default at native IOS and XE routers.

  R1    ASBR
  R2        ASBR
router bgp 1009
bgp router-id 9.9.0.1
address-family ipv4 unicast
  network 9.9.0.1/32
  network 9.9.0.8/32

  network 9.9.0.10/32
  allocate-label all
!
address-family vpnv4 unicast
!
neighbor 9.9.0.8
  remote-as 1009
  update-source Loopback0
  address-family ipv4 labeled-unicast
   next-hop-self
  !
  address-family vpnv4 unicast
   next-hop-self
  !
!
neighbor 9.9.12.2
  remote-as 9
  address-family ipv4 labeled-unicast
   route-policy pass in
   route-policy pass out
  !
!
!


router static
address-family ipv4 unicast
  9.9.12.2/32 GigabitEthernet0/0/0/0
!
!
router bgp 9
bgp router-id 9.9.0.2
address-family ipv4 unicast
  network 9.9.0.2/32
  network 9.9.0.3/32
  network 9.9.0.7/32
  allocate-label all
!
address-family vpnv4 unicast
!
neighbor 9.9.0.7
  remote-as 9
  update-source Loopback0
  address-family ipv4 labeled-unicast
   next-hop-self
  !
  address-family vpnv4 unicast
   next-hop-self
  !
!

neighbor 9.9.12.1
  remote-as 1009
  address-family ipv4 labeled-unicast
   route-policy pass in
   route-policy pass out
  !
!
!


router static
address-family ipv4 unicast
  9.9.12.1/32 GigabitEthernet0/0/0/0
!
!



Troubleshooting the Inter-AS between R11 and R16 customers :
=================================================================================================

we can see from the traceroute below that inter-as  needs only 2 lables , 1 label as Transport label and the other as VPN label.
the transport label will be on the top of the stack which point to the loopback of Egress PE in the other AS.

How R11 reaches to R16's loopback
==============================================================

R11#ping ipv6 2002:172:9::16
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2002:172:9::16, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/8 ms

R11#traceroute ipv6 2002:172:9::16
Type escape sequence to abort.
Tracing the route to 2002:172:9::16

  1 2002:172:9:113::3 2 msec 1 msec 1 msec
  2 ::FFFF:9.9.0.2 [MPLS: Labels 16011/23 Exp 0] 3 msec 3 msec 2 msec
  3 2002:9:9:18::1 [MPLS: Labels 16000/23 Exp 0] 2 msec 3 msec 2 msec
  4 2002:172:9:160::10 [AS 1009] [MPLS: Label 23 Exp 0] 2 msec 5 msec 2 msec
  5 2002:172:9:160::16 [AS 1009] 2 msec 5 msec 3 msec

R10#show mpls forwarding-table vrf ABC
Local      Outgoing Prefix          Bytes Label  Outgoing Next Hop
Label      Label or Tunnel Id    Switched      interface
16        Pop Label  172.9.156.0/24[V]  \
                                      0            Gi3        172.9.160.16
21        16009      172.9.0.11/32[V] 191852        Gi1        9.9.101.1
23        No Label  2002:172:9::16/128[V]  \
6432          Gi3        FE80::20C:29FF:FEC4:8AB4
24        Pop Label  2002:172:9:160::/64[V]  \
4344          aggregate/ABC
25        Pop Label  172.9.0.16/32[V] 162645        Gi3        172.9.160.16
26        Pop Label  172.9.160.0/24[V]  \
                                      570          aggregate/ABC

RP/0/0/CPU0:R1#show mpls forwarding prefix 9.9.0.10/32
Sun Oct 30 15:59:58.274 UTC
Local  Outgoing Prefix            Outgoing    Next Hop        Bytes
Label  Label or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
16000  Pop 9.9.0.10/32        Gi0/0/0/2    9.9.101.10      7464205



RP/0/0/CPU0:R2#show mpls forwarding prefix 9.9.0.10/32
Sun Oct 30 15:59:32.663 UTC
Local  Outgoing Prefix            Outgoing    Next Hop        Bytes
Label  Label or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
16011  16000 9.9.0.10/32        Gi0/0/0/0    9.9.12.1        6201056
RP/0/0/CPU0:R3#show mpls forwarding prefix 9.9.0.10/32
Sun Oct 30 16:01:19.755 UTC
Local  Outgoing Prefix            Outgoing    Next Hop        Bytes
Label  Label or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
16012  16011 9.9.0.10/32 9.9.0.2        0

How R16 reaches to R11's loopback
=============================================
R16#ping ipv6 2002:172:9::11
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2002:172:9::11, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/3/8 ms

R16#traceroute ipv6 2002:172:9::11
Type escape sequence to abort.
Tracing the route to 2002:172:9::11

  1 2002:172:9:160::10 1 msec 1 msec 1 msec
  2 2002:9:9:101::1 [MPLS: Labels 16003/16020 Exp 0] 2 msec 2 msec 2 msec
  3 ::FFFF:9.9.0.2 [MPLS: Labels 16003/16020 Exp 0] 2 msec 3 msec 2 msec
  4 2002:172:9:113::3 [MPLS: Label 16020 Exp 0] 2 msec 4 msec 2 msec
  5 2002:172:9:113::11 2 msec 4 msec 4 msec

RP/0/0/CPU0:R3#show mpls forwarding vrf ABC
Sun Oct 30 16:07:12.541 UTC
Local  Outgoing Prefix            Outgoing    Next Hop        Bytes
Label  Label or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
16003  Pop 172.9.113.11/32[V] Gi0/0/0/3 172.9.113.11    1979294
16009  Pop 172.9.0.11/32[V]  Gi0/0/0/3    172.9.113.11    163648
16016  25 172.9.0.16/32[V] 9.9.0.10        11170
16018  16 172.9.156.0/24[V] 9.9.0.10        0
16019  26 172.9.160.0/24[V] 9.9.0.10        0
16020  Unlabelled 2002:172:9::11/128[V]  \
Gi0/0/0/3 fe80::20c:29ff:fe31:cb82  \
17384400
16021  Aggregate 2002:172:9:113::/64[V]  \
ABC                          13352
RP/0/0/CPU0:R1#show mpls forwarding prefix 9.9.0.3/32
Sun Oct 30 16:03:41.409 UTC
Local  Outgoing Prefix            Outgoing    Next Hop        Bytes
Label  Label or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
16003  16003 9.9.0.3/32        Gi0/0/0/0    9.9.12.2        18779294

RP/0/0/CPU0:R2#show mpls forwarding  prefix 9.9.0.3/32
Sun Oct 30 16:10:11.549 UTC
Local  Outgoing Prefix            Outgoing    Next Hop        Bytes
Label  Label or ID              Interface                    Switched
------ ----------- ------------------ ------------ --------------- ------------
16003 Pop 9.9.0.3/32        Gi0/0/0/1    9.9.23.3        18099293

Troubleshooting CSC
====================

we can see from the  end-to-end traceroute below that we use 3 labels
1 label as a VPN label
above it there is a transport label to reach loopback ip of PE in the other small ISP
then on the top of the stack the transport label needed to reach the loopback ip of PE of large ISP.

R16#ping vrf XYZ ipv6 2002:192:9::17
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2002:192:9::17, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/2/3 ms



This is captured at R10 interface Gi1 going to R1


R16#traceroute vrf XYZ ipv6 2002:192:9::17
Type escape sequence to abort.
Tracing the route to 2002:192:9::17

  1 ::FFFF:172.9.160.10 [MPLS: Labels 21/24 Exp 0] 3 msec 4 msec 2 msec
  2 2002:9:9:101::1 [MPLS: Labels 16003/16009/24 Exp 0] 1 msec 4 msec 2 msec
  3 ::FFFF:9.9.0.2 [MPLS: Labels 16003/16009/24 Exp 0] 2 msec 4 msec 2 msec
  4 2002:9:9:34::3 [MPLS: Labels 16009/24 Exp 0] 2 msec 3 msec 2 msec
  5 2002:192:9:117::11 [MPLS: Label 24 Exp 0] 2 msec 4 msec 2 msec
  6 2002:192:9:117::17 2 msec 3 msec 2 msec



R11#ping vrf XYZ ipv6 2002:192:9::19
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2002:192:9::19, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 2/2/3 ms

R11#traceroute vrf XYZ ipv6 2002:192:9::19
Type escape sequence to abort.
Tracing the route to 2002:192:9::19

  1 2002:172:9:113::3 [MPLS: Labels 16016/35 Exp 0] 4 msec 3 msec 2 msec
  2 ::FFFF:9.9.0.2 [MPLS: Labels 16011/25/35 Exp 0] 2 msec 4 msec 3 msec
  3 2002:9:9:18::1 [MPLS: Labels 16000/25/35 Exp 0] 2 msec 4 msec 2 msec
  4 ::FFFF:9.9.101.10 [MPLS: Labels 25/35 Exp 0] 2 msec 3 msec 2 msec
  5 2002:192:9:169::16 [AS 1109] [MPLS: Label 35 Exp 0] 2 msec 3 msec 2 msec
  6 2002:192:9:169::19 [AS 1109] 2 msec 3 msec 2 msec


Finally , i hope that this Document will be informative to you
and be noticed that this post may be needs more declaration we can discuss here in the comments.
your feedback for sure is highly appreciated

Regards,
Mostafa Hassan Ahmed
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