eng-mssk: MPLS Tunneling

Issue

We will configure MPLS through our backbone, EBGP as the CE-PE routing protocol and transport the CE prefixes over the MPLS backbone

ISIS will be the IGP inside the MPLS backbone

No VRF or L2VPN parameters will be configured, just enabling MPLS in the backbone and transport the routes between the CEs

Configuration

R1#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.12.1 255.255.255.0

speed 100

full-duplex

R1#sh run int lo0

interface Loopback0

ip address 1.1.1.1 255.255.255.255

R2#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.12.2 255.255.255.0

speed 100

full-duplex

R2#sh run int f0/1

interface FastEthernet0/1

ip address 192.168.23.2 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R2#sh run int lo0

interface Loopback0

ip address 2.2.2.2 255.255.255.255

R2#sh run | sec router isis

router isis 1

net 49.0000.0000.0000.0002.00

is-type level-2-only

passive-interface Loopback0

R3#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.23.3 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R3#sh run int f0/1

interface FastEthernet0/1

ip address 192.168.34.3 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

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 49.0000.0000.0000.0003.00

is-type level-2-only

passive-interface Loopback0

mpls label protocol ldp

mpls ldp router-id Loopback0 force

R4#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.34.4 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R4#sh run int f0/1

interface FastEthernet0/1

ip address 192.168.45.4 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R4#sh run int lo0

interface Loopback0

ip address 4.4.4.4 255.255.255.255

R4#sh run | sec router isis

router isis 1

net 49.0000.0000.0000.0004.00

is-type level-2-only

passive-interface Loopback0

mpls label protocol ldp

mpls ldp router-id Loopback0 force

R5#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.45.5 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R5#sh run int f0/1

interface FastEthernet0/1

ip address 192.168.56.5 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

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 49.0000.0000.0000.0005.00

is-type level-2-only

passive-interface Loopback0

mpls label protocol ldp

mpls ldp router-id Loopback0 force

R6#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.56.6 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R6#sh run int f0/1

interface FastEthernet0/1

ip address 192.168.19.6 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R6#sh run int lo0

interface Loopback0

ip address 6.6.6.6 255.255.255.255

R6#sh run | sec router isis

router isis 1

net 49.0000.0000.0000.0006.00

is-type level-2-only

passive-interface Loopback0

mpls label protocol ldp

mpls ldp router-id Loopback0 force

R7#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.19.19 255.255.255.0

ip router isis 1

speed 100

full-duplex

mpls ip

R7#sh run int f0/1

interface FastEthernet0/1

ip address 192.168.20.19 255.255.255.0

speed 100

full-duplex

R7#sh run int lo0

interface Loopback0

ip address 19.19.19.19 255.255.255.255

R7#sh run | sec router isis

router isis 1

net 49.0000.0000.0000.0019.00

is-type level-2-only

passive-interface Loopback0

R8#sh run int f0/0

interface FastEthernet0/0

ip address 192.168.20.20 255.255.255.0

speed 100

full-duplex

R8#sh run int lo0

interface Loopback0

ip address 20.20.20.20 255.255.255.255

Verification

R2#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

R3 L2 Fa0/1 192.168.23.3 UP 7 R3.01

R2#sh mpls ldp neighbor

Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 2.2.2.2:0

TCP connection: 3.3.3.3.11021 - 2.2.2.2.646

State: Oper; Msgs sent/rcvd: 30/29; Downstream

Up time: 00:13:18

LDP discovery sources:

FastEthernet0/1, Src IP addr: 192.168.23.3

Addresses bound to peer LDP Ident:

192.168.23.3 192.168.34.3 3.3.3.3

R3#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

R2 L2 Fa0/0 192.168.23.2 UP 24 R3.01

R4 L2 Fa0/1 192.168.34.4 UP 7 R4.01

R3#sh mpls ldp neighbor

Peer LDP Ident: 4.4.4.4:0; Local LDP Ident 3.3.3.3:0

TCP connection: 4.4.4.4.60496 - 3.3.3.3.646

State: Oper; Msgs sent/rcvd: 42/44; Downstream

Up time: 00:25:35

LDP discovery sources:

FastEthernet0/1, Src IP addr: 192.168.34.4

Addresses bound to peer LDP Ident:

192.168.34.4 4.4.4.4 192.168.45.4

Peer LDP Ident: 2.2.2.2:0; Local LDP Ident 3.3.3.3:0

TCP connection: 2.2.2.2.646 - 3.3.3.3.11021

State: Oper; Msgs sent/rcvd: 29/29; Downstream

Up time: 00:12:34

LDP discovery sources:

FastEthernet0/0, Src IP addr: 192.168.23.2

Addresses bound to peer LDP Ident:

192.168.12.2 192.168.23.2 2.2.2.2

R4#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

R5 L2 Fa0/1 192.168.45.5 UP 7 R5.01

R3 L2 Fa0/0 192.168.34.3 UP 27 R4.01

R4#sh mpls ldp neighbor

Peer LDP Ident: 3.3.3.3:0; Local LDP Ident 4.4.4.4:0

TCP connection: 3.3.3.3.646 - 4.4.4.4.60496

State: Oper; Msgs sent/rcvd: 44/42; Downstream

Up time: 00:25:49

LDP discovery sources:

FastEthernet0/0, Src IP addr: 192.168.34.3

Addresses bound to peer LDP Ident:

192.168.23.3 192.168.34.3 3.3.3.3

Peer LDP Ident: 5.5.5.5:0; Local LDP Ident 4.4.4.4:0

TCP connection: 5.5.5.5.53841 - 4.4.4.4.646

State: Oper; Msgs sent/rcvd: 33/33; Downstream

Up time: 00:17:03

LDP discovery sources:

FastEthernet0/1, Src IP addr: 192.168.45.5

Addresses bound to peer LDP Ident:

192.168.45.5 192.168.56.5 5.5.5.5

R5#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

R4 L2 Fa0/0 192.168.45.4 UP 28 R5.01

R6 L2 Fa0/1 192.168.56.6 UP 8 R6.01

R5#sh mpls ldp neighbor

Peer LDP Ident: 192.168.56.6:0; Local LDP Ident 5.5.5.5:0

TCP connection: 192.168.56.6.19552 - 5.5.5.5.646

State: Oper; Msgs sent/rcvd: 41/42; Downstream

Up time: 00:24:15

LDP discovery sources:

FastEthernet0/1, Src IP addr: 192.168.56.6

Addresses bound to peer LDP Ident:

192.168.56.6 6.6.6.6 192.168.19.6

Peer LDP Ident: 4.4.4.4:0; Local LDP Ident 5.5.5.5:0

TCP connection: 4.4.4.4.646 - 5.5.5.5.53841

State: Oper; Msgs sent/rcvd: 33/33; Downstream

Up time: 00:17:20

LDP discovery sources:

FastEthernet0/0, Src IP addr: 192.168.45.4

Addresses bound to peer LDP Ident:

192.168.34.4 4.4.4.4 192.168.45.4

R6#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

R7 L2 Fa0/1 192.168.19.19 UP 7 R7.01

R5 L2 Fa0/0 192.168.56.5 UP 22 R6.01

R6#sh mpls ldp neighbor

Peer LDP Ident: 5.5.5.5:0; Local LDP Ident 192.168.56.6:0

TCP connection: 5.5.5.5.646 - 192.168.56.6.19552

State: Oper; Msgs sent/rcvd: 43/42; Downstream

Up time: 00:25:01

LDP discovery sources:

FastEthernet0/0, Src IP addr: 192.168.56.5

Addresses bound to peer LDP Ident:

192.168.45.5 192.168.56.5 5.5.5.5

Peer LDP Ident: 192.168.19.19:0; Local LDP Ident 192.168.56.6:0

TCP connection: 192.168.19.19.646 - 192.168.56.6.13701

State: Oper; Msgs sent/rcvd: 32/33; Downstream

Up time: 00:16:43

LDP discovery sources:

FastEthernet0/1, Src IP addr: 192.168.19.19

Addresses bound to peer LDP Ident:

192.168.19.19 192.168.20.19 19.19.19.19

R7#sh isis neighbors

System Id Type Interface IP Address State Holdtime Circuit Id

R6 L2 Fa0/0 192.168.19.6 UP 26 R7.01

R7#sh mpls ldp neighbor

Peer LDP Ident: 192.168.56.6:0; Local LDP Ident 192.168.19.19:0

TCP connection: 192.168.56.6.13701 - 192.168.19.19.646

State: Oper; Msgs sent/rcvd: 34/32; Downstream

Up time: 00:16:58

LDP discovery sources:

FastEthernet0/0, Src IP addr: 192.168.19.6

Addresses bound to peer LDP Ident:

192.168.56.6 6.6.6.6 192.168.19.6

Now, we will establish EBGP peering between R1 and R2, R7 and R8

As well, between the PEs: R2 and R7 which will be an iBGP session

R1#sh run | sec router bgp

router bgp 1

no synchronization

bgp log-neighbor-changes

network 1.1.1.1 mask 255.255.255.255

neighbor 192.168.12.2 remote-as 100

no auto-summary

R2#sh run | sec router bgp

router bgp 100

no synchronization

bgp log-neighbor-changes

neighbor 19.19.19.19 remote-as 100

neighbor 19.19.19.19 update-source Loopback0

neighbor 19.19.19.19 next-hop-self

neighbor 192.168.12.1 remote-as 1

no auto-summary

R8#sh run | sec router bgp

router bgp 20

no synchronization

bgp log-neighbor-changes

network 20.20.20.20 mask 255.255.255.255

neighbor 192.168.20.19 remote-as 100

no auto-summary

R7#sh run | sec router bgp

router bgp 100

no synchronization

bgp log-neighbor-changes

neighbor 2.2.2.2 remote-as 100

neighbor 2.2.2.2 update-source Loopback0

neighbor 2.2.2.2 next-hop-self

neighbor 192.168.20.20 remote-as 20

no auto-summary

As the connection between R7 and R8 is EBGP session, and that connection is not advertised in the BGP session, we need to configure next-hop-self for iBGP peering inside the MPLS backbone

R1#sh ip bgp summary

BGP router identifier 1.1.1.1, local AS number 1

BGP table version is 3, main routing table version 3

2 network entries using 234 bytes of memory

2 path entries using 104 bytes of memory

3/2 BGP path/bestpath attribute entries using 372 bytes of memory

1 BGP AS-PATH entries using 24 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 734 total bytes of memory

BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

192.168.12.2 4 100 30 30 3 0 0 00:25:13 1

R1#sh ip bgp

BGP table version is 3, local router ID is 1.1.1.1

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

*> 1.1.1.1/32 0.0.0.0 0 32768 i

*> 20.20.20.20/32 192.168.12.2 0 100 20 i

R2#sh ip bgp summary

BGP router identifier 2.2.2.2, local AS number 100

BGP table version is 3, main routing table version 3

2 network entries using 234 bytes of memory

2 path entries using 104 bytes of memory

3/2 BGP path/bestpath attribute entries using 372 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 758 total bytes of memory

BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

19.19.19.19 4 100 22 22 3 0 0 00:18:00 1

192.168.12.1 4 1 32 32 3 0 0 00:27:04 1

R2#sh ip bgp neighbors 192.168.12.1 advertised-routes

BGP table version is 3, local router ID is 2.2.2.2

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

*>i20.20.20.20/32 19.19.19.19 0 100 0 20 i

Total number of prefixes 1

R2#sh ip bgp neighbors 19.19.19.19 advertised-routes

BGP table version is 3, local router ID is 2.2.2.2

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

*> 1.1.1.1/32 192.168.12.1 0 0 1 i

Total number of prefixes 1

R2#sh ip bgp

BGP table version is 3, local router ID is 2.2.2.2

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

*> 1.1.1.1/32 192.168.12.1 0 0 1 i

*>i20.20.20.20/32 19.19.19.19 0 100 0 20 i

R7#sh ip bgp summary

BGP router identifier 19.19.19.19, local AS number 100

BGP table version is 3, main routing table version 3

2 network entries using 234 bytes of memory

2 path entries using 104 bytes of memory

3/2 BGP path/bestpath attribute entries using 372 bytes of memory

2 BGP AS-PATH entries using 48 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 758 total bytes of memory

BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

2.2.2.2 4 100 23 23 3 0 0 00:18:45 1

192.168.20.20 4 20 32 32 3 0 0 00:28:21 1

R7#sh ip bg

R7#sh ip bgp neigh

R7#sh ip bgp neighbors 2.2.2.2 advert

R7#sh ip bgp neighbors 2.2.2.2 advertised-routes

BGP table version is 3, local router ID is 19.19.19.19

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

*> 20.20.20.20/32 192.168.20.20 0 0 20 i

Total number of prefixes 1

R7#sh ip bg

R7#sh ip bgp nei

R7#sh ip bgp neighbors 192.168.20.20 advert

R7#sh ip bgp neighbors 192.168.20.20 advertised-routes

BGP table version is 3, local router ID is 19.19.19.19

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

*>i1.1.1.1/32 2.2.2.2 0 100 0 1 i

Total number of prefixes 1

R7#sh ip bg

R7#sh ip bgp

BGP table version is 3, local router ID is 19.19.19.19

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

*>i1.1.1.1/32 2.2.2.2 0 100 0 1 i

*> 20.20.20.20/32 192.168.20.20 0 0 20 i

R8#sh ip bgp summary

BGP router identifier 20.20.20.20, local AS number 20

BGP table version is 3, main routing table version 3

2 network entries using 234 bytes of memory

2 path entries using 104 bytes of memory

3/2 BGP path/bestpath attribute entries using 372 bytes of memory

1 BGP AS-PATH entries using 24 bytes of memory

0 BGP route-map cache entries using 0 bytes of memory

0 BGP filter-list cache entries using 0 bytes of memory

BGP using 734 total bytes of memory

BGP activity 2/0 prefixes, 2/0 paths, scan interval 60 secs

Neighbor V AS MsgRcvd MsgSent TblVer InQ OutQ Up/Down State/PfxRcd

192.168.20.19 4 100 32 32 3 0 0 00:28:46 1

R8#sh ip bgp

BGP table version is 3, local router ID is 20.20.20.20

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

*> 1.1.1.1/32 192.168.20.19 0 100 1 i

*> 20.20.20.20/32 0.0.0.0 0 32768 i

R1#ping 20.20.20.20 source loopback 0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 20.20.20.20, 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 = 28/30/32 ms

R8#ping 1.1.1.1 source loopback 0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 1.1.1.1, timeout is 2 seconds:

Packet sent with a source address of 20.20.20.20

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 28/29/32 ms

Now, if we wanted to trace the packet as it traverses through the backbone and check label assignments, we will enable debug mpls packets on the MPLS routers (R3 through R6) and initiate an ICMP packet from R8 towards R1

R3 – R6

debug mpls packets

R7#sh mpls forwarding-table

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 6.6.6.6/32 0 Fa0/0 192.168.19.6

17 16 5.5.5.5/32 0 Fa0/0 192.168.19.6

18 18 4.4.4.4/32 0 Fa0/0 192.168.19.6

19 20 3.3.3.3/32 0 Fa0/0 192.168.19.6

20 Pop tag 192.168.56.0/24 0 Fa0/0 192.168.19.6

21 17 192.168.45.0/24 0 Fa0/0 192.168.19.6

22 19 192.168.34.0/24 0 Fa0/0 192.168.19.6

23 21 192.168.23.0/24 0 Fa0/0 192.168.19.6

24 23 2.2.2.2/32 0 Fa0/0 192.168.19.6

*Mar 2 00:57:59.197: MPLS: Fa0/1: recvd: CoS=0, TTL=254, Label(s)=23

*Mar 2 00:57:59.201: MPLS: Fa0/0: xmit: CoS=0, TTL=253, Label(s)=23

Note: we can see the TTL decrements

R6#sh mpls forwarding-table

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 5.5.5.5/32 0 Fa0/0 192.168.56.5

17 Pop tag 192.168.45.0/24 570 Fa0/0 192.168.56.5

18 17 4.4.4.4/32 0 Fa0/0 192.168.56.5

19 18 192.168.34.0/24 590 Fa0/0 192.168.56.5

20 19 3.3.3.3/32 0 Fa0/0 192.168.56.5

21 20 192.168.23.0/24 0 Fa0/0 192.168.56.5

22 Pop tag 19.19.19.19/32 189257 Fa0/1 192.168.19.19

23 23 2.2.2.2/32 116949 Fa0/0 192.168.56.5

*Mar 2 00:57:59.429: MPLS: Fa0/1: recvd: CoS=0, TTL=253, Label(s)=23

*Mar 2 00:57:59.429: MPLS: Fa0/0: xmit: CoS=0, TTL=252, Label(s)=23

R5#sh mpls forwarding-table

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 6.6.6.6/32 0 Fa0/1 192.168.56.6

17 Pop tag 4.4.4.4/32 0 Fa0/0 192.168.45.4

18 Pop tag 192.168.34.0/24 570 Fa0/0 192.168.45.4

19 16 3.3.3.3/32 0 Fa0/0 192.168.45.4

20 17 192.168.23.0/24 0 Fa0/0 192.168.45.4

21 22 19.19.19.19/32 201541 Fa0/1 192.168.56.6

22 Pop tag 192.168.19.0/24 0 Fa0/1 192.168.56.6

23 23 2.2.2.2/32 117675 Fa0/0 192.168.45.4

*Mar 2 00:58:01.133: MPLS: Fa0/1: recvd: CoS=0, TTL=252, Label(s)=23

*Mar 2 00:58:01.137: MPLS: Fa0/0: xmit: CoS=0, TTL=251, Label(s)=23

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 3.3.3.3/32 0 Fa0/0 192.168.34.3

17 Pop tag 192.168.23.0/24 0 Fa0/0 192.168.34.3

18 Pop tag 5.5.5.5/32 0 Fa0/1 192.168.45.5

19 Pop tag 192.168.56.0/24 0 Fa0/1 192.168.45.5

20 16 6.6.6.6/32 0 Fa0/1 192.168.45.5

21 21 19.19.19.19/32 200951 Fa0/1 192.168.45.5

22 22 192.168.19.0/24 0 Fa0/1 192.168.45.5

23 23 2.2.2.2/32 117103 Fa0/0 192.168.34.3

*Mar 2 00:58:03.237: MPLS: Fa0/1: recvd: CoS=0, TTL=251, Label(s)=23

*Mar 2 00:58:03.237: MPLS: Fa0/0: xmit: (no label)

Note: we can see the no label keyword which is due to PHP

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 4.4.4.4/32 0 Fa0/1 192.168.34.4

17 18 5.5.5.5/32 0 Fa0/1 192.168.34.4

18 Pop tag 192.168.45.0/24 0 Fa0/1 192.168.34.4

19 19 192.168.56.0/24 0 Fa0/1 192.168.34.4

20 20 6.6.6.6/32 0 Fa0/1 192.168.34.4

21 21 19.19.19.19/32 200498 Fa0/1 192.168.34.4

22 22 192.168.19.0/24 0 Fa0/1 192.168.34.4

23 Pop tag 2.2.2.2/32 111092 Fa0/0 192.168.23.2

Then checking the reverse direction (Echo reply)

*Mar 2 01:01:31.829: MPLS: Fa0/0: recvd: CoS=0, TTL=254, Label(s)=21

*Mar 2 01:01:31.829: MPLS: Fa0/1: xmit: CoS=0, TTL=253, Label(s)=21

R3#sh mpls forwarding-table

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 4.4.4.4/32 0 Fa0/1 192.168.34.4

17 18 5.5.5.5/32 0 Fa0/1 192.168.34.4

18 Pop tag 192.168.45.0/24 0 Fa0/1 192.168.34.4

19 19 192.168.56.0/24 0 Fa0/1 192.168.34.4

20 20 6.6.6.6/32 0 Fa0/1 192.168.34.4

21 21 19.19.19.19/32 201225 Fa0/1 192.168.34.4

22 22 192.168.19.0/24 0 Fa0/1 192.168.34.4

23 Pop tag 2.2.2.2/32 111735 Fa0/0 192.168.23.2

*Mar 2 01:01:29.729: MPLS: Fa0/0: recvd: CoS=0, TTL=253, Label(s)=21

*Mar 2 01:01:29.729: MPLS: Fa0/1: xmit: CoS=0, TTL=252, Label(s)=21

R4#sh mpl for

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 3.3.3.3/32 0 Fa0/0 192.168.34.3

17 Pop tag 192.168.23.0/24 0 Fa0/0 192.168.34.3

18 Pop tag 5.5.5.5/32 0 Fa0/1 192.168.45.5

19 Pop tag 192.168.56.0/24 0 Fa0/1 192.168.45.5

20 16 6.6.6.6/32 0 Fa0/1 192.168.45.5

21 21 19.19.19.19/32 201952 Fa0/1 192.168.45.5

22 22 192.168.19.0/24 0 Fa0/1 192.168.45.5

23 23 2.2.2.2/32 117924 Fa0/0 192.168.34.3

*Mar 2 01:01:28.029: MPLS: Fa0/0: recvd: CoS=0, TTL=252, Label(s)=21

*Mar 2 01:01:28.029: MPLS: Fa0/1: xmit: CoS=0, TTL=251, Label(s)=22

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 6.6.6.6/32 0 Fa0/1 192.168.56.6

17 Pop tag 4.4.4.4/32 0 Fa0/0 192.168.45.4

18 Pop tag 192.168.34.0/24 570 Fa0/0 192.168.45.4

19 16 3.3.3.3/32 0 Fa0/0 192.168.45.4

20 17 192.168.23.0/24 0 Fa0/0 192.168.45.4

21 22 19.19.19.19/32 202679 Fa0/1 192.168.56.6

22 Pop tag 192.168.19.0/24 0 Fa0/1 192.168.56.6

23 23 2.2.2.2/32 118573 Fa0/0 192.168.45.4

*Mar 2 01:01:27.801: MPLS: Fa0/0: recvd: CoS=0, TTL=251, Label(s)=22

*Mar 2 01:01:27.801: MPLS: Fa0/1: xmit: (no label)

Local Outgoing Prefix Bytes tag Outgoing Next Hop

tag tag or VC or Tunnel Id switched interface

16 Pop tag 5.5.5.5/32 0 Fa0/0 192.168.56.5

17 Pop tag 192.168.45.0/24 570 Fa0/0 192.168.56.5

18 17 4.4.4.4/32 0 Fa0/0 192.168.56.5

19 18 192.168.34.0/24 590 Fa0/0 192.168.56.5

20 19 3.3.3.3/32 0 Fa0/0 192.168.56.5

21 20 192.168.23.0/24 0 Fa0/0 192.168.56.5

22 Pop tag 19.19.19.19/32 190601 Fa0/1 192.168.19.19

23 23 2.2.2.2/32 118001 Fa0/0 192.168.56.5

As can be seen from the debug outputs above that the precedence value is 0 which is copied from the packet header to the MPLS header (CoS)

R1(config)#access-list 100 permit ip any any precedence critical

R1(config)#access-list 100 permit ip any any precedence flash

R1(config)#access-list 100 permit ip any any precedence flash-override

R1(config)#access-list 100 permit ip any any precedence immediate

R1(config)#access-list 100 permit ip any any precedence internet

R1(config)#access-list 100 permit ip any any precedence network

R1(config)#access-list 100 permit ip any any precedence priority

R1(config)#access-list 100 permit ip any any precedence routine

R1(config)#int f0/0

R1(config-if)#ip access-group 100 in

R1#sh access-lists 100

Extended IP access list 100

10 permit ip any any precedence critical

20 permit ip any any precedence flash

30 permit ip any any precedence flash-override

40 permit ip any any precedence immediate

50 permit ip any any precedence internet

60 permit ip any any precedence network

70 permit ip any any precedence priority

80 permit ip any any precedence routine (15 matches)

.net file

For anyone want to lab it up, please find the .net file below

autostart = False

[127.0.0.1:7200]

workingdir = /tmp

udp = 10001

[[3725]]

image = INE/c3725-adventerprisek9-mz.124-18.bin

ram = 128

ghostios = True

[[ROUTER R4]]

model = 3725

console = 2004

f0/0 = R3 f0/1

f0/1 = R5 f0/0

x = -129.0

y = 106.0

[[ROUTER R5]]

model = 3725

console = 2005

f0/0 = R4 f0/1

f0/1 = R6 f0/0

x = 57.0

y = 110.0

[[ROUTER R6]]

model = 3725

console = 2006

f0/0 = R5 f0/1

f0/1 = R7 f0/0

x = 61.0

y = 14.0

[[ROUTER R7]]

model = 3725

console = 2007

f0/0 = R6 f0/1

f0/1 = R8 f0/0

x = 201.0

y = -37.0

[[ROUTER R1]]

model = 3725

console = 2001

f0/0 = R2 f0/0

x = -249.0

y = -139.0

[[ROUTER R2]]

model = 3725

console = 2002

f0/0 = R1 f0/0

f0/1 = R3 f0/0

x = -246.0

y = -37.0

[[ROUTER R3]]

model = 3725

console = 2003

f0/0 = R2 f0/1

f0/1 = R4 f0/0

x = -125.0

y = 17.0

[[ROUTER R8]]

model = 3725

console = 2008

f0/0 = R7 f0/1

x = 203.0

y = -140.0

eng-mssk

Saturday, October 13, 2012

MPLS Tunneling

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