- Layer 1 (e.g.: SLT)
- Layer 2 (e.g.: Etisalat, Mobitel, Dialog)
- Layer 3 (not present in Sri Lanka)
Friday, June 28, 2013
For describing purposes lets divide Internet Service Providers into three categories. They are:
Using Label Distribution Protocol (LDP) routers distribute their labels. LDP is not a routing protocol as OSPF (Open Shortest Path First) or IS-IS (Intermediate System to Intermediate System). As in previous case (in IP routing) in MPLS routers build two tables namely LIB (Label Information Base) and LIFB (Label Information Forwarding Base). LIB consists of labels of connected networks. And LIFB consist of label mapping of the networks. No data loss occurs as in previous case, only label switching happens. Now a large table with labels build up. To overcome, we can use a protocol like BGP (Border Gateway Protocol). Following figure will give you an idea of how a LFIB - MPLS table looks like.