Mpls Lab #1 : Basic Mpls configuration

Hi all, after a successful BGP exam, now it's time to start with MPLS... nothing better than a basic lab to practice the configurations and show commands.

Here the topology, most of my lab routers doesn't support mpls (2600 series) that's why I used GNS3 with 3600s...

STEP 1: configure all point to point links and use EIGRP with various AS to route all links and loopbacks. Ensure that you can ping every interface from every router.

STEP 2: basic mpls configuration, for each router you must:
-enable ip cef with:

ip cef

-set some mpls parameters like:

mpls label protocol ldp   !-- optional... by default is ldp
mpls ldp router-id loopback0   !-- optional, but it's not a bad idea use a loopback as router-id

-enable mpls for eache interface

interface Serial0/0
description R0 <-> R1
ip address 172.17.45.5 255.255.255.252
 mpls ip

Well done, now our network is using mpls, time to check it with several show commands:
-we must ensure that mpls is enabled for the correct interfaces:

R0#sh mpls interfaces
Interface              IP            Tunnel   Operational
Serial0/0              Yes (ldp)     No       Yes
Serial0/1              Yes (ldp)     No       Yes

-then we must check if we have ldp sessions with neighbours:

R0#sh mpls ldp neighbor
  Peer LDP Ident: 172.17.50.13:0; Local LDP Ident 10.26.0.1:0
      TCP connection: 172.17.50.13.61893 - 10.26.0.1.646
      State: Oper; Msgs sent/rcvd: 89/90; Downstream
      Up time: 00:55:11
      LDP discovery sources:
        Serial0/1, Src IP addr: 172.17.45.2
      Addresses bound to peer LDP Ident:
        172.17.50.2     172.17.50.13    172.17.45.2     172.17.45.9
  Peer LDP Ident: 172.17.50.9:0; Local LDP Ident 10.26.0.1:0
      TCP connection: 172.17.50.9.45695 - 10.26.0.1.646
      State: Oper; Msgs sent/rcvd: 88/87; Downstream
      Up time: 00:55:10
      LDP discovery sources:
        Serial0/0, Src IP addr: 172.17.45.6
      Addresses bound to peer LDP Ident:
        172.17.50.1     172.17.50.9     172.17.45.6     172.17.45.13

Note that the "Addresses bound to peer ldp ident" are all the ip addresses assigned to the interfaces of the neighbour. This is used to find the next hop for each prefix in the routing table and identify the ldp neighbour for outgoing label selection.
-now we can see the whole LFIB with:

R0#sh mpls forwarding-table
Local  Outgoing    Prefix            Bytes tag  Outgoing   Next Hop
tag    tag or VC   or Tunnel Id      switched   interface
16     Untagged    172.17.45.6/32    0          Se0/0      point2point
17     Untagged    172.17.45.2/32    0          Se0/1      point2point
18     Pop tag     172.17.50.8/30    0          Se0/0      point2point
19     Pop tag     172.17.50.0/30    0          Se0/0      point2point
       Pop tag     172.17.50.0/30    0          Se0/1      point2point
20     17          10.40.0.0/24      0          Se0/0      point2point
21     18          10.40.10.0/24     0          Se0/0      point2point
22     19          172.17.45.18/32   0          Se0/0      point2point
23     20          172.17.45.16/30   0          Se0/0      point2point
24     25          172.17.45.14/32   0          Se0/0      point2point
25     Pop tag     172.17.45.12/30   0          Se0/0      point2point
26     Pop tag     172.17.50.12/30   0          Se0/1      point2point
27     17          172.17.45.10/32   0          Se0/1      point2point
28     Pop tag     172.17.45.8/30    0          Se0/1      point2point
29     31          172.17.50.4/30    0          Se0/1      point2point
30     32          172.17.45.17/32   0          Se0/1      point2point
31     32          172.17.45.9/32    0          Se0/0      point2point
32     29          10.31.0.0/24      0          Se0/1      point2point
33     30          10.32.0.0/24      0          Se0/1      point2point
34     33          172.17.45.13/32   0          Se0/1      point2point