Sunday, February 22, 2009

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

2 comments:

Scott said...

While searching for like content, I found your article and just wanted to promote a similar set of articles that I wrote in case someone wants to read more about the basic configuration of MPLS.

http://www.xpresslearn.com/cisco/mpls-cisco/configure-a-basic-mpls-network

Marco Rizzi said...

you are wellcome Scott!

have fun with mpls
Marco