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
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
R2
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
R3
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
R4
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
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
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