eng-mssk

Saturday, December 22, 2012

MPLS TE with Explicit Paths

Issue

In this example we will go through MPLS L3VPN using RSVP as our label protocol as well as going through TE and how we will control our traffic as needed using explicit paths and using dynamic path option as our backup in case of link failure inside the backbone

The IGP inside the network used is ISIS and static routing is PE-CE routing protocols

Configuration

R1#sh run int f1/0

interface FastEthernet1/0

ip address 192.1.12.1 255.255.255.0

speed 100

duplex full

R1#sh run int lo0

interface Loopback0

ip address 1.1.1.1 255.255.255.255

R1#sh run | sec ip route

ip route 0.0.0.0 0.0.0.0 192.1.12.2

R2#sh run int f1/0

interface FastEthernet1/0

vrf forwarding MSSK

ip address 192.1.12.2 255.255.255.0

speed 100

duplex full

R2#sh run int f1/1

interface FastEthernet1/1

ip address 192.1.23.2 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

isis metric 20

ip rsvp bandwidth

R2#sh run int f2/0

interface FastEthernet2/0

ip address 192.1.25.2 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R2#sh run int lo0

interface Loopback0

ip address 2.2.2.2 255.255.255.255

R2#sh run int tun0

tunnel mode mpls traffic-eng

ip unnumbered loopback0

tunnel destination 4.4.4.4

tunnel mpls traffic-eng autoroute announce

tunnel mpls traffic-eng path-option 1 explicit name PATH

tunnel mpls traffic-eng path-option 2 dynamic

R2#sh run | sec ip route

ip route vrf MSSK 1.1.1.1 255.255.255.255 192.1.12.1

R2#sh run | sec vrf def

vrf definition MSSK

rd 100:1

route-target export 100:1

route-target import 100:1

address-family ipv4

exit-address-family

R2#sh run | sec router isis

router isis 1

net 49.0001.0000.0000.0002.00

is-type level-2-only

metric-style wide

passive-interface Loopback0

mpls traffic-eng router-id Loopback0

mpls traffic-eng level-2

R2#sh run | sec router bgp

router bgp 100

bgp log-neighbor-changes

no bgp default ipv4-unicast

neighbor 4.4.4.4 remote-as 100

neighbor 4.4.4.4 update-source Loopback0

address-family ipv4

exit-address-family

address-family vpnv4

neighbor 4.4.4.4 activate

neighbor 4.4.4.4 send-community both

exit-address-family

address-family ipv4 vrf MSSK

network 1.1.1.1 mask 255.255.255.255

network 192.1.12.0

exit-address-family

R2#sh run | inc mpls

mpls traffic-eng tunnels

ip explicit-paths name PATH

next-address 192.1.23.3

next-address 192.1.35.5

next-address 192.1.45.4

next-address 4.4.4.4

R3#sh run int f1/0

interface FastEthernet1/0

ip address 192.1.23.3 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R3#sh run int f1/1

interface FastEthernet1/1

ip address 192.1.34.3 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R3#sh run int f2/0

interface FastEthernet2/0

ip address 192.1.35.3 255.255.255.0

ip router isis 1

shutdown

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R3#sh run int lo0

interface Loopback0

ip address 3.3.3.3 255.255.255.255

R3#sh run | sec router isis

router isis 1

net 49.0001.0000.0000.0003.00

is-type level-2-only

metric-style wide

passive-interface Loopback0

mpls traffic-eng router-id Loopback0

mpls traffic-eng level-2

R3#sh run | inc mpls

mpls traffic-eng tunnels

R4#sh run int f1/0

interface FastEthernet1/0

vrf forwarding MSSK

ip address 192.1.46.4 255.255.255.0

speed 100

duplex full

R4#sh run int f1/1

interface FastEthernet1/1

ip address 192.1.34.4 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R4#sh run int f2/0

interface FastEthernet2/0

ip address 192.1.45.4 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R4#sh run int lo0

interface Loopback0

ip address 4.4.4.4 255.255.255.255

R4#sh run int tun0

tunnel mode mpls traffic-eng

ip unnumbered loopback0

tunnel destination 2.2.2.2

tunnel mpls traffic-eng autoroute announce

tunnel mpls traffic-eng path-option 1 explicit name PATH

tunnel mpls traffic-eng path-option 2 dynamic

R4#sh run | sec router isis

router isis 1

net 49.0001.0000.0000.0004.00

is-type level-2-only

metric-style wide

passive-interface Loopback0

mpls traffic-eng router-id Loopback0

mpls traffic-eng level-2

R4#sh run | sec router bgp

router bgp 100

bgp log-neighbor-changes

no bgp default ipv4-unicast

neighbor 2.2.2.2 remote-as 100

neighbor 2.2.2.2 update-source Loopback0

address-family ipv4

exit-address-family

address-family vpnv4

neighbor 2.2.2.2 activate

neighbor 2.2.2.2 send-community both

exit-address-family

address-family ipv4 vrf MSSK

network 6.6.6.6 mask 255.255.255.255

network 192.1.46.0

exit-address-family

R4#sh run | inc mpls

mpls traffic-eng tunnels

R4#sh run | inc ip route

ip route vrf MSSK 6.6.6.6 255.255.255.255 192.1.46.6

ip explicit-paths name PATH

next-address 192.1.45.5

next-address 192.1.35.3

next-address 192.1.23.2

next-address 2.2.2.2

R5#sh run int f1/0

interface FastEthernet1/0

ip address 192.1.25.5 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R5#sh run int f1/1

interface FastEthernet1/1

ip address 192.1.45.5 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R5#sh run int f2/0

interface FastEthernet2/0

ip address 192.1.35.5 255.255.255.0

ip router isis 1

speed 100

duplex full

mpls traffic-eng tunnels

ip rsvp bandwidth

R5#sh run int lo0

interface Loopback0

ip address 5.5.5.5 255.255.255.255

R5#sh run | sec router isis

router isis 1

net 49.0001.0000.0000.0005.00

is-type level-2-only

metric-style wide

passive-interface Loopback0

mpls traffic-eng router-id Loopback0

mpls traffic-eng level-2

R5#sh run | inc mpls

mpls traffic-eng tunnels

R6#sh run int f1/0

interface FastEthernet1/0

ip address 192.1.46.6 255.255.255.0

speed 100

duplex full

R6#sh run int lo0

interface Loopback0

ip address 6.6.6.6 255.255.255.255

R6#sh run | inc ip route

ip route 0.0.0.0 0.0.0.0 192.1.46.4

Verification

Testing reachablity between our CEs

R1#ping 6.6.6.6 source 1.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 6.6.6.6, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 20/22/28 ms

R1#traceroute 6.6.6.6 source lo0

Type escape sequence to abort.

Tracing the route to 6.6.6.6

VRF info: (vrf in name/id, vrf out name/id)

1 192.1.12.2 4 msec 4 msec 4 msec

2 192.1.23.3 [MPLS: Labels 16/16 Exp 0] 28 msec 20 msec 20 msec

3 192.1.35.5 [MPLS: Labels 17/16 Exp 0] 24 msec 20 msec 20 msec

4 192.1.46.4 [MPLS: Label 16 Exp 0] 20 msec 16 msec 16 msec

5 192.1.46.6 20 msec 20 msec *

Checking our explicit path configured

R2#sh ip explicit-paths

PATH PATH (strict source route, path complete, generation 13)

1: next-address 192.1.23.3

2: next-address 192.1.35.5

3: next-address 192.1.45.4

4: next-address 4.4.4.4

R6#traceroute 1.1.1.1 sou lo0

Type escape sequence to abort.

Tracing the route to 1.1.1.1

VRF info: (vrf in name/id, vrf out name/id)

1 192.1.46.4 8 msec 0 msec 4 msec

2 192.1.45.5 [MPLS: Labels 19/16 Exp 0] 24 msec 20 msec 20 msec

3 192.1.35.3 [MPLS: Labels 18/16 Exp 0] 20 msec 20 msec 20 msec

4 192.1.12.2 [MPLS: Label 16 Exp 0] 20 msec 16 msec 16 msec

5 192.1.12.1 20 msec 20 msec *

R4#sh ip explicit-paths

PATH PATH (strict source route, path complete, generation 11)

1: next-address 192.1.45.5

2: next-address 192.1.35.3

3: next-address 192.1.23.2

4: next-address 2.2.2.2

R2#sh mpls traffic-eng tunnels

P2P TUNNELS/LSPs:

Name: R2_t0 (Tunnel0) Destination: 4.4.4.4

Status:

Admin: up Oper: up Path: valid Signalling: connected

path option 1, type explicit PATH (Basis for Setup, path weight 40)

Config Parameters:

Bandwidth: 0 kbps (Global) Priority: 7 7 Affinity: 0x0/0xFFFF

Metric Type: TE (default)

AutoRoute: enabled LockDown: disabled Loadshare: 0 [0] bw-based

auto-bw: disabled

Active Path Option Parameters:

State: explicit path option 1 is active

BandwidthOverride: disabled LockDown: disabled Verbatim: disabled

InLabel : -

OutLabel : FastEthernet1/1, 16

Next Hop : 192.1.23.3

RSVP Signalling Info:

Src 2.2.2.2, Dst 4.4.4.4, Tun_Id 0, Tun_Instance 8812

RSVP Path Info:

My Address: 192.1.23.2

Explicit Route: 192.1.23.3 192.1.35.3 192.1.35.5 192.1.45.5

192.1.45.4 4.4.4.4

Record Route: NONE

Tspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

RSVP Resv Info:

Record Route: NONE

Fspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

History:

Tunnel:

Time since created: 3 days, 59 minutes

Time since path change: 5 minutes, 8 seconds

Number of LSP IDs (Tun_Instances) used: 8812

Current LSP: [ID: 8812]

Uptime: 4 minutes, 58 seconds

Selection: reoptimization

Prior LSP: [ID: 8811]

ID: path option unknown

Removal Trigger: configuration changed

LSP Tunnel R4_t0 is signalled, connection is up

InLabel : FastEthernet1/1, implicit-null

Prev Hop : 192.1.23.3

OutLabel : -

RSVP Signalling Info:

Src 4.4.4.4, Dst 2.2.2.2, Tun_Id 0, Tun_Instance 8805

RSVP Path Info:

My Address: 2.2.2.2

Explicit Route: NONE

Record Route: NONE

Tspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

RSVP Resv Info:

Record Route: NONE

Fspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

P2MP TUNNELS:

P2MP SUB-LSPS:

R2#sh mpls forwarding-table

Local Outgoing Prefix Bytes Label Outgoing Next Hop

Label Label or Tunnel Id Switched interface

16 No Label 1.1.1.1/32[V] 12776 Fa1/0 192.1.12.1

17 No Label 192.1.12.0/24[V] 0 aggregate/MSSK

R3#sh mpls forwarding-table

Local Outgoing Prefix Bytes Label Outgoing Next Hop

Label Label or Tunnel Id Switched interface

16 17 2.2.2.2 0 [8812] 3934 Fa2/0 192.1.35.5

18 Pop Label 4.4.4.4 0 [8805] 4152 Fa1/0 192.1.23.2

Now, we want to configure backup using lower priority path option

R2(config)#int tun0

R2(config-if)#tunnel mpls traffic-eng path-option 2 dynamic

R4(config)#int tun0

R4(config-if)#tunnel mpls traffic-eng path-option 2 dynamic

Now, shutting down one of the links across the explicit path

R3#conf t

Enter configuration commands, one per line. End with CNTL/Z.

R3(config)#int f2/0

R3(config-if)#shutdown

R2#sh mpls traffic-eng tunnels

P2P TUNNELS/LSPs:

Name: R2_t0 (Tunnel0) Destination: 4.4.4.4

Status:

Admin: up Oper: up Path: valid Signalling: connected

path option 2, type dynamic (Basis for Setup, path weight 20)

path option 1, type explicit PATH

Config Parameters:

Bandwidth: 0 kbps (Global) Priority: 7 7 Affinity: 0x0/0xFFFF

Metric Type: TE (default)

AutoRoute: enabled LockDown: disabled Loadshare: 0 [0] bw-based

auto-bw: disabled

Active Path Option Parameters:

State: dynamic path option 2 is active

BandwidthOverride: disabled LockDown: disabled Verbatim: disabled

InLabel : -

OutLabel : FastEthernet2/0, 18

Next Hop : 192.1.25.5

RSVP Signalling Info:

Src 2.2.2.2, Dst 4.4.4.4, Tun_Id 0, Tun_Instance 8814

RSVP Path Info:

My Address: 192.1.25.2

Explicit Route: 192.1.25.5 192.1.45.5 192.1.45.4 4.4.4.4

Record Route: NONE

Tspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

RSVP Resv Info:

Record Route: NONE

Fspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

History:

Tunnel:

Time since created: 3 days, 1 hours, 3 minutes

Time since path change: 59 seconds

Number of LSP IDs (Tun_Instances) used: 8814

Current LSP: [ID: 8814]

Uptime: 59 seconds

Selection: reoptimization

Prior LSP: [ID: 8812]

ID: path option unknown

Removal Trigger: path error

LSP Tunnel R4_t0 is signalled, connection is up

InLabel : FastEthernet1/1, implicit-null

Prev Hop : 192.1.23.3

OutLabel : -

RSVP Signalling Info:

Src 4.4.4.4, Dst 2.2.2.2, Tun_Id 0, Tun_Instance 8807

RSVP Path Info:

My Address: 2.2.2.2

Explicit Route: NONE

Record Route: NONE

Tspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

RSVP Resv Info:

Record Route: NONE

Fspec: ave rate=0 kbits, burst=1000 bytes, peak rate=0 kbits

P2MP TUNNELS:

P2MP SUB-LSPS:

R1#traceroute 6.6.6.6 source lo0

Type escape sequence to abort.

Tracing the route to 6.6.6.6

VRF info: (vrf in name/id, vrf out name/id)

1 192.1.12.2 4 msec 0 msec 4 msec

2 192.1.25.5 [MPLS: Labels 18/16 Exp 0] 20 msec 16 msec 16 msec

3 192.1.46.4 [MPLS: Label 16 Exp 0] 24 msec 8 msec 12 msec

4 192.1.46.6 16 msec 16 msec *

As we can see end to end reachability is maintained but the path now is different as we are using the dynamic one

Friday, December 14, 2012

MPLS L2VPN With AToM - Eth to Eth

Issue

In this example we will examine L2VPN with AToM

Our CEs in this example are R1 and R5

Our PEs are R2 and R4, and R3 is the P

We will run OSPF as the IGP inside the MPLS backbone and we will configure OSPF also as the routing protocol running between the CEs

Configuration

R1#sh run int f1/0

interface FastEthernet1/0

ip address 192.1.15.1 255.255.255.0

speed 100

duplex full

R1#sh run int lo0

interface Loopback0

ip address 1.1.1.1 255.255.255.255

R1#sh run | sec router ospf

router ospf 1

router-id 1.1.1.1

network 1.1.1.1 0.0.0.0 area 0

network 192.1.15.1 0.0.0.0 area 0

mpls label protocol ldp

mpls ldp router-id Loopback0 force

R2#sh run int f1/0

interface FastEthernet1/0

no ip address

speed 100

duplex full

no keepalive

xconnect 4.4.4.4 15 encapsulation mpls pw-class MSSK

end

R2#sh run int f1/1

Building configuration...

Current configuration : 103 bytes

interface FastEthernet1/1

ip address 192.1.23.2 255.255.255.0

speed 100

duplex full

mpls ip

end

R2#sh run int lo0

Building configuration...

Current configuration : 63 bytes

interface Loopback0

ip address 2.2.2.2 255.255.255.255

end

R2#sh run | sec router ospf

router ospf 1

router-id 2.2.2.2

network 2.2.2.2 0.0.0.0 area 0

network 192.1.23.2 0.0.0.0 area 0

mpls label protocol ldp

mpls ldp router-id Loopback0 force

R3#sh run int f1/0

Building configuration...

Current configuration : 103 bytes

interface FastEthernet1/0

ip address 192.1.23.3 255.255.255.0

speed 100

duplex full

mpls ip

end

R3#sh run int f1/1

Building configuration...

Current configuration : 103 bytes

interface FastEthernet1/1

ip address 192.1.34.3 255.255.255.0

speed 100

duplex full

mpls ip

end

R3#sh run int lo0

Building configuration...

Current configuration : 63 bytes

interface Loopback0

ip address 3.3.3.3 255.255.255.255

end

R3#sh run | sec router ospf

router ospf 1

router-id 3.3.3.3

network 3.3.3.3 0.0.0.0 area 0

network 192.1.23.3 0.0.0.0 area 0

network 192.1.34.3 0.0.0.0 area 0

mpls label protocol ldp

mpls ldp router-id Loopback0 force

R4#sh run int f1/0

interface FastEthernet1/0

ip address 192.1.34.4 255.255.255.0

speed 100

duplex full

mpls ip

R4#sh run int f1/1

interface FastEthernet1/1

no ip address

speed 100

duplex full

no keepalive

xconnect 2.2.2.2 15 encapsulation mpls pw-class MSSK

R4#sh run int lo0

Building configuration...

Current configuration : 63 bytes

interface Loopback0

ip address 4.4.4.4 255.255.255.255

R4#sh run | sec router ospf

router ospf 1

router-id 4.4.4.4

network 4.4.4.4 0.0.0.0 area 0

network 192.1.34.4 0.0.0.0 area 0

R5#sh run int f1/0

interface FastEthernet1/0

ip address 192.1.15.5 255.255.255.0

speed 100

duplex full

R5#sh run int lo0

interface Loopback0

ip address 5.5.5.5 255.255.255.255

R5#sh run | sec router ospf

router ospf 1

router-id 5.5.5.5

network 5.5.5.5 0.0.0.0 area 0

network 192.1.15.5 0.0.0.0 area 0

Verification

We will start our verification from the PE routers

R2#sh mpls ldp neighbor 4.4.4.4

Peer LDP Ident: 4.4.4.4:0; Local LDP Ident 2.2.2.2:0

TCP connection: 4.4.4.4.50601 - 2.2.2.2.646

State: Oper; Msgs sent/rcvd: 2105/2103; Downstream

Up time: 1d06h

LDP discovery sources:

Targeted Hello 2.2.2.2 -> 4.4.4.4, active, passive

Addresses bound to peer LDP Ident:

192.1.34.4 4.4.4.4

R2#sh mpls l2transport summary

Destination address: 4.4.4.4, total number of vc: 1

0 unknown, 1 up, 0 down, 0 admin down, 0 recovering, 0 standby, 0 hotstandby

1 active vc on MPLS interface Fa1/1

R4#sh mpls l2transport summary

Destination address: 2.2.2.2, total number of vc: 1

0 unknown, 1 up, 0 down, 0 admin down, 0 recovering, 0 standby, 0 hotstandby

1 active vc on MPLS interface Fa1/0

As we can see the status is up, the pseudowire adjacency will be formed once the xconnect is configured on the attachment circuit, i.e. the link facing the CE

Now, R1 and R5 are as they were directly connected, let us check reachability

R1#ping 192.1.15.5

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 192.1.15.5, timeout is 2 seconds:

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 16/18/28 ms

Now, OSPF adjacency between R1 and R5 should be established

R1#sh ip ospf neighbor

Neighbor ID Pri State Dead Time Address Interface

5.5.5.5 1 FULL/DR 00:00:35 192.1.15.5 FastEthernet1/0

R1#sh ip route ospf

Codes: L - local, C - connected, S - static, R - RIP, M - mobile, B - BGP

D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

E1 - OSPF external type 1, E2 - OSPF external type 2

i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

ia - IS-IS inter area, * - candidate default, U - per-user static route

o - ODR, P - periodic downloaded static route, H - NHRP, l - LISP

+ - replicated route, % - next hop override

Gateway of last resort is not set

5.0.0.0/32 is subnetted, 1 subnets

O 5.5.5.5 [110/2] via 192.1.15.5, 1d01h, FastEthernet1/0

R1#ping 5.5.5.5 source 1.1.1.1

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 16/16/16 ms

R1#sh ip ospf database

OSPF Router with ID (1.1.1.1) (Process ID 1)

Router Link States (Area 0)

Link ID ADV Router Age Seq# Checksum Link count

1.1.1.1 1.1.1.1 1724 0x80000030 0x00ED51 2

5.5.5.5 5.5.5.5 2019 0x80000030 0x00AD5D 2

Net Link States (Area 0)

Link ID ADV Router Age Seq# Checksum

192.1.15.5 5.5.5.5 2019 0x8000002E 0x00DD2D

If we wanted to check the data plane

R3#debug mpls packet

R1#ping 5.5.5.5 sou lo0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 5.5.5.5, timeout is 2 seconds:

Packet sent with a source address of 1.1.1.1

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 16/16/20 ms

*Dec 14 22:20:15.692: MPLS turbo: Fa1/0: rx: Len 391 Stack {17 0 255} {19 0 255} CW {f:0 l:0 s:0}

*Dec 14 22:20:15.692: MPLS turbo: Fa1/1: tx: Len 387 Stack {19 0 254} CW {f:0 l:0 s:0}

*Dec 14 22:20:16.952: MPLS turbo: Fa1/1: rx: Len 80 Stack {16 6 255} - ipv4 data s:4.4.4.4 d:2.2.2.2 ttl:255 tos:C0 prot:11

*Dec 14 22:20:17.280: MPLS turbo: Fa1/0: rx: Len 86 Stack {17 0 255} {19 0 255} CW {f:0 l:0 s:0}

*Dec 14 22:20:17.280: MPLS turbo: Fa1/1: tx: Len 82 Stack {19 0 254} CW {f:0 l:0 s:0}

*Dec 14 22:20:17.472: MPLS turbo: Fa1/0: rx: Len 80 Stack {17 6 255} - ipv4 data s:2.2.2.2 d:4.4.4.4 ttl:255 tos:C0 prot:11

*Dec 14 22:20:18.432: MPLS turbo: Fa1/1: rx: Len 86 Stack {16 0 255} {19 0 255} CW {f:0 l:0 s:0}

*Dec 14 22:20:18.432: MPLS turbo: Fa1/0: tx: Len 82 Stack {19 0 254} CW {f:0 l:0 s:0}

*Dec 14 22:20:20.340: MPLS turbo: Fa1/0: rx: Len 120 Stack {17 0 255} {19 0 255} CW {f:0 l:0 s:0}

*Dec 14 22:20:20.340: MPLS turbo: Fa1/1: tx: Len 116 Stack {19 0 254} CW {f:0 l:0 s:0}

*Dec 14 22:20:23.628: MPLS turbo: Fa1/1: rx: Len 120 Stack {16 0 255} {19 0 255} CW {f:0 l:0 s:0}

*Dec 14 22:20:23.628: MPLS turbo: Fa1/0: tx: Len 116 Stack {19 0 254} CW {f:0 l:0 s:0}

*Dec 14 22:20:24.332: MPLS turbo: Fa1/0: rx: Len 140 Stack {17 0 255} {19 0 255} CW {f:0 l:0 s:0}

R3#sh mpls forwarding-table

Local Outgoing Prefix Bytes Label Outgoing Next Hop

Label Label or Tunnel Id Switched interface

16 Pop Label 2.2.2.2/32 4318680 Fa1/0 192.1.23.2

17 Pop Label 4.4.4.4/32 4314590 Fa1/1 192.1.34.4

The 16 and 17 label values can be seen from the debug output above as well as the 19 value which can be demonstrated more in the output below

R2#sh mpls l2transport vc detail

Local interface: Fa1/0 up, line protocol up, Ethernet up

Destination address: 4.4.4.4, VC ID: 15, VC status: up

Output interface: Fa1/1, imposed label stack {17 19}

Preferred path: not configured

Default path: active

Next hop: 192.1.23.3

Create time: 1d06h, last status change time: 1d06h

Last label FSM state change time: 1d06h

Signaling protocol: LDP, peer 4.4.4.4:0 up

Targeted Hello: 2.2.2.2(LDP Id) -> 4.4.4.4, LDP is UP

Status TLV support (local/remote) : enabled/supported

LDP route watch : enabled

Label/status state machine : established, LruRru

Last local dataplane status rcvd: No fault

Last BFD dataplane status rcvd: Not sent

Last BFD peer monitor status rcvd: No fault

Last local AC circuit status rcvd: No fault

Last local AC circuit status sent: No fault

Last local PW i/f circ status rcvd: No fault

Last local LDP TLV status sent: No fault

Last remote LDP TLV status rcvd: No fault

Last remote LDP ADJ status rcvd: No fault

MPLS VC labels: local 19, remote 19

R2#sh mpls forwarding-table

Local Outgoing Prefix Bytes Label Outgoing Next Hop

Label Label or Tunnel Id Switched interface

16 Pop Label 3.3.3.3/32 0 Fa1/1 192.1.23.3

17 Pop Label 192.1.34.0/24 0 Fa1/1 192.1.23.3

18 17 4.4.4.4/32 0 Fa1/1 192.1.23.3

19 No Label l2ckt(1) 2538066 Fa1/0 point2point

Note the l2ckt keyword in the output above has a label value of 19, and the show mpls l2transport vc detail the remote and local label value is 19