In the next series of post I want to go through setting up a MPLS VRF system, and work on from MPLS TE, which is a subject which I have not worked on. Yeah, I read through a couple of docs but have never implemented it myself. My goal at the end of their series of post it to cover the MPLS TE topics as I learn them.

Before setting up a anything to do with MPLS TE, the basic MPLS network needs to be created. This is the topology I have set up.

All of the layer 2 and 3 work as been completed. PE_WEST has a loopback of 100.100.100.100 and PE_EAST has a loopback of 200.200.200.200.

Testing end to end.

PE_WEST#ping 200.200.200.200 so lo0

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 200.200.200.200, timeout is 2 seconds:
Packet sent with a source address of 100.100.100.100
!!!!!

Now, time to enable basic MPLS.

On all P/PE routers, we’ll enable MPLS and force the router-ID to be loopback0.

mpls ip
mpls ldp router-id lo0 force

After this, enable MPLS on all if the links withing the P network.

PE_WEST(config)#interface FastEthernet2/0
PE_WEST(config-if)# mpls ip
PE_WEST(config-if)#

Let’s verify on PE_WEST that the links are up.

PE_WEST#show mpls int
Interface              IP            Tunnel   BGP Static Operational
FastEthernet2/0        Yes (ldp)     No       No  No     Yes
FastEthernet2/1        Yes (ldp)     No       No  No     Yes

Looking at the LDP neighbors from PE_WEST.

PE_WEST#show mpls ldp nei
Peer LDP Ident: 2.2.2.2:0; Local LDP Ident 100.100.100.100:0
TCP connection: 2.2.2.2.646 - 100.100.100.100.11001
State: Oper; Msgs sent/rcvd: 1669/1665; Downstream
Up time: 1d00h
LDP discovery sources:
FastEthernet2/1, Src IP addr: 10.20.22.2
Targeted Hello 100.100.100.100 -> 2.2.2.2, active, passive
Addresses bound to peer LDP Ident:
10.20.22.2      10.24.24.2      10.12.12.2      2.2.2.2
Peer LDP Ident: 1.1.1.1:0; Local LDP Ident 100.100.100.100:0
TCP connection: 1.1.1.1.646 - 100.100.100.100.11002
State: Oper; Msgs sent/rcvd: 1668/1669; Downstream
Up time: 1d00h
LDP discovery sources:
FastEthernet2/0, Src IP addr: 10.10.11.2
Addresses bound to peer LDP Ident:
10.10.11.2      10.13.13.1      10.12.12.1      1.1.1.1

 

Another item to note is how LDP is established. In this case when two neighbors are directly connected, the router sends out a hello message via UDP to the multicast address for all routers on a subnet (224.0.0.2). To initiate the TCP sessions, the router with the higher transport address (in this case loopback ID) will take the active role and and initiate the TCP sessions. This can be seen in the output above by the target hello line showing the active and passive router. Also, look at the TCP connection < TCP connection: 2.2.2.2.646 – 100.100.100.100.11001 >. From this we know 100.100.100.100 is initiating the session.

 

Next I finished enabling MPLS across the SP network. All the checks should be done across the SP network. In our case all the LDP peers are up. I won’t post them for brevity.