A Network Artist : Building MPLS Layer 3 VPN Series Part 2

Saturday, June 9, 2012

Building MPLS Layer 3 VPN Series Part 2 - Building SP Core

So let's continue with Second Post of the series. In today's post we will be building SP Core. Which will include following:

1. Establishing the basic IP Connectivity in the SP Core.
2. Enabling CEF
3. Enabling Label Distribution Protocol
4. Enabling MPLS in the SP Core

So let's bring the topology quickly:

So let's first quickly setup the IP Connectivity between R1-R2-R3 (SP Core Devices)

%%%%%%%%%%%%%%%%%%%%%%%%%%

###

conf t

ho R1

no ip domain-lookup

int f0/0

ip add 12.12.12.1 255.255.255.0

no sh

exit

int lo0

ip add 1.1.1.1 255.255.255.255

exit

router ospf 500

network 12.12.12.1 0.0.0.0 area 500

network 1.1.1.1 0.0.0.0 area 500

exit

end

*********************************

###

conf t

ho R2

no ip domain-lookup

int lo0

ip add 2.2.2.2 255.255.255.255

exit

int f0/0

ip add 12.12.12.2 255.255.255.0

no sh

exit

int f1/0

ip add 23.23.23.2 255.255.255.0

no sh

exit

router ospf 500

net 12.12.12.2 0.0.0.0 area 500

net 23.23.23.2 0.0.0.0 area 500

net 2.2.2.2 0.0.0.0 area 500

exit

end

*********************************

###

conf t

ho R3

no ip do lo

int lo0

ip add 3.3.3.3 255.255.255.255

exit

int f0/0

ip add 23.23.23.3 255.255.255.0

no sh

exit

router ospf 500

net 3.3.3.3 0.0.0.0 area 500

net 23.23.23.3 0.0.0.0 area 500

exit

end

%%%%%%%%%%%%%%%%%%%%%%%%%%

Next let's quickly verify the connectivity:

R1#ping 3.3.3.3 source loopback0

Type escape sequence to abort.

Sending 5, 100-byte ICMP Echos to 3.3.3.3, 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 = 28/62/116 ms

R3#ping 1.1.1.1 so lo0

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 3.3.3.3

!!!!!

Success rate is 100 percent (5/5), round-trip min/avg/max = 20/52/80 ms

So far so good ? ...... ;-)

Let's proceed with enabling the MPLS in SP Core Network:

Step 1 > Will be to enable CEF globally on the router. Though CEF is by default enabled on Cisco Routers these days. But it never hurts to type one small command which can save your whole day. Specially it will be something stupid when you find that everything in MPLS VPN was setup correctly and in last you find that it was only CEF which was disabled. Which caused MPLS VPN to fail.

R1(config)#ip cef

Step 2 > Is to Enable Label distribution protocol. There are technically 4 protocols which can help with this named as - TDP (Tag Distribution Protocol - Cisco Proprietary), LDP (Label Distribution Protocol), BGP & RSVP. TDP is Cisco baby so most likely not going to appear in R&S Lab. LDP on the other hand is industry standard which most likely you gonna find on exam. Using BGP/RSVP for label distribution is out of scope from R&S Lab prospective.

R1(config)#mpls label protocol ?

ldp Use LDP (default)

tdp Use TDP

R1(config)#mpls label protocol ldp

Next we fix Router ID that LDP will be using:

R1(config)#mpls ldp router-id loopback 0

Step 3 > Enable MPLS on SP Core Interfaces:

R1(config)#int f0/0

R1(config-if)#mpls ip

R1(config-if)#exit

Lets follow the same steps on R2/R3 :

R2(config)#ip cef

R2(config)#mpls label protocol ldp

R2(config)#mpls ldp router-id loopback0

R2(config)#int f0/0

R2(config-if)#mpls ip

R2(config-if)#exit

R2(config)#int f1/0

R2(config-if)#mpls ip

R2(config-if)#exit

R3(config)#ip cef

R3(config)#mpls label protocol ldp

R3(config)#mpls ldp router-id loopback0

R3(config)#int f0/0

R3(config-if)#mpls ip

R3(config-if)#exit

Let's quickly verify the LDP sessions and other basic MPLS configuration:

R1#sh mpls interfaces

Interface IP Tunnel Operational

FastEthernet0/0 Yes (ldp) No Yes

R1#sh mpls ldp neighbor

Peer LDP Ident: 2.2.2.2:0; Local LDP Ident 1.1.1.1:0

TCP connection: 2.2.2.2.46225 - 1.1.1.1.646

State: Oper; Msgs sent/rcvd: 15/15; Downstream

Up time: 00:06:23

LDP discovery sources:

FastEthernet0/0, Src IP addr: 12.12.12.2

Addresses bound to peer LDP Ident:

12.12.12.2 23.23.23.2 2.2.2.2

R2#sh mpls interfaces

Interface IP Tunnel Operational

FastEthernet0/0 Yes (ldp) No Yes

FastEthernet1/0 Yes (ldp) No Yes

R2#sh mpls ldp neighbor

Peer LDP Ident: 1.1.1.1:0; Local LDP Ident 2.2.2.2:0

TCP connection: 1.1.1.1.646 - 2.2.2.2.46225

State: Oper; Msgs sent/rcvd: 16/16; Downstream

Up time: 00:07:01

LDP discovery sources:

FastEthernet0/0, Src IP addr: 12.12.12.1

Addresses bound to peer LDP Ident:

12.12.12.1 1.1.1.1

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

TCP connection: 3.3.3.3.64294 - 2.2.2.2.646

State: Oper; Msgs sent/rcvd: 14/14; Downstream

Up time: 00:05:19

LDP discovery sources:

FastEthernet1/0, Src IP addr: 23.23.23.3

Addresses bound to peer LDP Ident:

23.23.23.3 3.3.3.3

R3#sh mpls interfaces

Interface IP Tunnel Operational

FastEthernet0/0 Yes (ldp) No Yes

R3#sh mpls ldp neighbor

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

TCP connection: 2.2.2.2.646 - 3.3.3.3.64294

State: Oper; Msgs sent/rcvd: 15/15; Downstream

Up time: 00:06:04

LDP discovery sources:

FastEthernet0/0, Src IP addr: 23.23.23.2

Addresses bound to peer LDP Ident:

12.12.12.2 23.23.23.2 2.2.2.2

So last step for today - Let's quickly verify MPLS Label operation using traceroute command:

R1#traceroute 3.3.3.3 source loopback 0

Type escape sequence to abort.

Tracing the route to 3.3.3.3

1 12.12.12.2 [MPLS: Label 17 Exp 0] 140 msec 132 msec 128 msec

2 23.23.23.3 152 msec * 144 msec

R3#traceroute 1.1.1.1 source loopback 0

Type escape sequence to abort.

Tracing the route to 1.1.1.1

1 23.23.23.2 [MPLS: Label 16 Exp 0] 212 msec 228 msec 144 msec

2 12.12.12.1 64 msec * 132 msec

So far so cool.

In Next Post we will be setting up Normal BGP Session and VRF Sessions.

Stay Tuned.........

HTH...

Deepak Arora

Evil CCIE

Saturday, June 9, 2012

Building MPLS Layer 3 VPN Series Part 2 - Building SP Core

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