DLCI in Frame Relay

Unanswered Question
Apr 18th, 2009

Hi,

Did the DLCI that show in (show frame-relay pvc) and (show frame-relay map) is the local address or global address.

BR,

Auos.

I have this problem too.
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Giuseppe Larosa Sat, 04/18/2009 - 22:35

Hello Auos,

a DLCI is always a local identifier valid between your router interface and the FR switch.

The so called global addressing is only a way to pretend that DLCIs are like MAC addresses.

if the service provider gives you global addresses means that from every site y to reach site x you have to use DLCIx but it is only an emulation.

So to understand if your service provider is using global addressing you need to examine multiple sites:

if you see that the same DLCI is used on different sites to reach the same remote sites "global addressing" is in use.

else if different DLCIs are used at different sites to reach the same remote site global addressing is not in use.

Hope to help

Giuseppe

auosdavid2000 Sat, 04/18/2009 - 23:19

Hello giuslar,

Great thanks for your Clarification, but suppose below diagram

R1(500) ---- (501)FR(502) ---- (500)R2

(503)

|

|

|

(500)

R3

Frame Relay used local addressing to setup three PVC, using (501) to connect with R1, (502) to connect to R2 and (503) to connect to R3. But in other side all router (R1, R2 and R3) using local address (500) to connect to FR.

As you said "The same DLCI is used on different sites to reach the same remote sites (global addressing) is in use", in this case R1 and R2 when they need to reach R3 they using local DLCI (500) and it is local not global. Did I wrong?

Giuseppe Larosa Sat, 04/18/2009 - 23:32

Hello Auos,

if in your drawing each router uses the nearest DLCI R1 uses 503 to reach R3 and 500 to reach R2.

R2 has to use dlci 500 to reach both R1 and R3.

this may need an additional map command.

R2

int s0/0

frame-relay map ip 10.10.10.1 500 broadcast

frame-relay map ip 10.10.10.3 500

this in order to be able to ping R3 ip address.

Other note:

We usually talk of global addressing in a full mesh scenario.

in this case we have a partial mesh with R1 that acts as hub and R2 and R3 that are spokes: R2 has to use the same DLCI to reach both R1 and R3.

Hope to help

Giuseppe

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