MPLS: Frame-mode MPLS configuration

Step 1: Enable CEF

1841-1#
ip cef

1841-2#
ip cef

3825-1#
ip cef

Step 2: Configure IGP

1841-1#
router ospf 1
 router-id 11.11.11.11
 log-adjacency-changes
 passive-interface default
 no passive-interface FastEthernet0/0
 network 192.168.0.1 0.0.0.0 area 0

3825-1#
router ospf 1
 router-id 22.22.22.22
 log-adjacency-changes
 passive-interface default
 no passive-interface GigabitEthernet0/0
 no passive-interface GigabitEthernet0/1
 network 192.168.0.2 0.0.0.0 area 0
 network 192.168.0.5 0.0.0.0 area 0

1841-2#
router ospf 1
 router-id 33.33.33.33
 log-adjacency-changes
 passive-interface default
 no passive-interface FastEthernet0/1
 network 192.168.0.6 0.0.0.0 area 0

Step 3: Enable MPLS label forwarding on interface

1841-1#
interface FastEthernet0/0
 ip address 192.168.0.1 255.255.255.252
 ip ospf network point-to-point
 duplex auto
 speed auto
 mpls ip
end

3825-1#
interface GigabitEthernet0/0
 ip address 192.168.0.2 255.255.255.252
 ip ospf network point-to-point
 duplex auto
 speed auto
 media-type rj45
 mpls ip
end

interface GigabitEthernet0/1
 ip address 192.168.0.5 255.255.255.252
 ip ospf network point-to-point
 duplex auto
 speed auto
 media-type rj45
 mpls ip
end

1841-2#
interface FastEthernet0/1
 ip address 192.168.0.6 255.255.255.252
 ip ospf network point-to-point
 duplex auto
 speed auto
 mpls ip
end

Note:

1. Default label switching protocol is LDP, hence it is not necessary to explicitly enable LDP in global configuration mode.

mpls label protocol ?
ldp  Use LDP (default)
tdp  Use TDP

2. MPLS router-id uses the highest loopback address as its router-id, if no loopback interface exists the highest physical interface ip address will be used as router-id.

In this lab, I have defined the loopback interface for each router.

3. The ingress LSR will impose a label and swap the label with the next hop router.

4. The egress LSR will pop the label and send out the packet entered from the ingress LSR.

5. The penultimate LSR is the router before the egress (popping) LSR.

MPLS verification

1841-1#sh mpls interfaces
Interface              IP            Tunnel   BGP Static Operational
FastEthernet0/0        Yes (ldp)     No       No  No     Yes

3825-1#sh mpls interface
Interface              IP            Tunnel   Operational
GigabitEthernet0/0     Yes (ldp)     No       Yes
GigabitEthernet0/1     Yes (ldp)     No       Yes

1841-2#sh mpls interface
Interface              IP            Tunnel   BGP Static Operational
FastEthernet0/1        Yes (ldp)     No       No  No     Yes