In Frame Relay, Same DLCI number & difference DLCI number , which is better?

Unanswered Question
Aug 12th, 2010

I want to know about

DLCI number.

I have 3 cisco 2811 routers,          connected with  Framerelay, bandwidth is 512kbps.

Router A (dlci 101 ) is connected to Router B dlci (101) << same dlci

Router A (dlci 102 ) is connected to Router C dlci 102 <<same dlci

Router B (dlci 103 ) is connected to Router C dlci 103 << same dlci.

so i want to know why setting up same dlci number between two routers ?

Which is better in same DLCI & different DLCI ?

Framelay is using tcp & rtp header compression.

help me to know the reasons.

thz a lot.

I have this problem too.
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Reza Sharifi Thu, 08/12/2010 - 20:07

DLCI numbers are locally significant so you can have the same DLCI on both sides or different DLCI on each side.  It is easier to troubleshot when you have the same DLCI on both sides.  When you use the same DLCI, it is easier to map them to each other.

HTH

Reza

Richard Burts Fri, 08/13/2010 - 08:21

Reza correctly point out that the DLCI is locally significant so that assigning a DLCI on one end has no effect on assigning the DLCI on the other end. This makes it possible to have the same DLCI on both ends or to have different DLCI on each end.

I would agree with Reza that there may be some advantage to the people involved if the DLCI is the same on each end of the Frame Relay connection since it makes it easier to associate a particular DLCI to a particular connection. When doing labs with Frame Relay I would usually do this.

But this solution does not scale well. It works very well on small networks (like the 3 routers in the original post). But it gets very difficult to implement as the network gets larger. Think about assigning DLCIs for 15 routers, especially if some routers have connections to multiple other routers. Then think about assigning DLCIs for 100 routers, especially if some routers have connections to multiple other routers.

In summary, having the same DLCI on both ends of the connection is convenient for the people involved but makes no difference to the routers involved. And it works for small networks but not so well for larger networks.

HTH

Rick

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