MPLS Part 1 ( Control Plane and Data Plane) And different Kind of Labels associated

Control plane: Responsible for Exchanging layer 3 routing information and labels.

Control plane consists complex mechanism to exchange routing information such as OSPF, EIGRP, IS-IS, and BGP and to exchange label such as TDP, LDP, BGP and RSVP.

Data plane: Responsible to forward packet based on labels and IP header.

Data plane has simple forwarding engine it maintains LFIB and FIB.

Control Plane:

Routing protocol: Responsible for exchange of routing information .It prepares IP routing table.

IP routing table: Responsible to build IP forwarding table (FIB) in Data Plane (Forwarding plane).

LDP: Responsible for exchange of labels between the peers. After exchanging the labels with LDP peer LFIB is formed in Data Plane (Forwarding Plane).

Data Plane:

1.  As the IP packet comes in it will do a IP routing lookup and check is any label is associated with particular FEC. If yes then label is imposed in the packet and process by LFIB as labeled packet.
2. If no label is associated with IP Packet then it is processed as normal IP Packet by FIB.
3. If incoming packet is labeled then by using LFIB the label is swapped and the packet is processed

RIB Table

show ip route

CEF Table

show ip cef - shows the cef table. The major difference is that the next hop is figured out in the cef output.

LIB Table

show mpls ldp bindings - shows all the labels bounded to the networks, contains all good and bad networks labels. Here Liberal retention mode is used. That means even not the best labels are remembered

LFIB  Table

# show mpls forwarding – LFIB is winner circle. Best paths for the label forwarding go in the LFIB