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Frame relay question

Sorry for the silly question but I confused myself on this one...ok I have a T1 frame relay circuit terminating on my main interface of s0/0/0 now from this frame relay circuit I have 8 subinterfaces configured all at 128k. Now the question is of the 8 subinterfaces lets say dlci 22 want to upgrade itself from 128k to a full T1. I cannot terminate a T1 on that subinterface I would have to put it on its own separate T1 card correct? If the dlci 22 was going to be upgraded to say 256k then yes we can terminate it on the same interface as it will not exceed the main interface speed s0/0/0 of 1536k. Am I thinking correctly or am I lost?

2 ACCEPTED SOLUTIONS

Accepted Solutions
Hall of Fame Super Gold

Re: Frame relay question

Hi Wgranada,

in reality you could have branches upgraded to T1 and still have T1 at the HQ plus the speed from other brands. That is, the sum of the CIRs for all the PVCs exceeds the physical interface speed.T

This is called oversubscription and is made to save on cost of additional circuits.

The best thing is that you talk to for FR SP and see what different option (Multilink FR, PVC splitting on new interface, oversubscription) and costs you have. Of course, more bandwidth the better.

Hope this helps, if so please rate post!

Re: Frame relay question

That's OK. Typing in 'yes' didn't take too long :-)

Yes, you need to configure channels 1-24 at the branch if the port speed of the circuit is a full T1.

HTH

Sundar

8 REPLIES
Hall of Fame Super Gold

Re: Frame relay question

Hi Wgranada,

in reality you could have branches upgraded to T1 and still have T1 at the HQ plus the speed from other brands. That is, the sum of the CIRs for all the PVCs exceeds the physical interface speed.T

This is called oversubscription and is made to save on cost of additional circuits.

The best thing is that you talk to for FR SP and see what different option (Multilink FR, PVC splitting on new interface, oversubscription) and costs you have. Of course, more bandwidth the better.

Hope this helps, if so please rate post!

Community Member

Re: Frame relay question

so what you are telling me is that even though I have a T1 frame relay connection terminating on my main interface of s0/0/0

and 8 subinterfaces off of that at 128K. If

s0/0/0.22 at 128k wanted to upgrade to a full T1 I still can terminate that full T1 connection on s0/0/0.22?!? So I will have 2 T1 terminating on the WIC T1V2 card? I thought I couldn't do that?

Re: Frame relay question

As Paolo stated it's technically possible to upgrade DLCI 22 to 1.536 mbps. However, this one DLCI can result in deprivation of bandiwth for the other branches. If you expect any of the branches to use up a sizable amount of bandwidth on the T1 then you may want to look at adding another T1.

The response to your 2nd post is you would only terminate 1 physical circuit (T1) to the interface but the DLCI 22 can be provisioned with a CIR of 1536k by the SP. All the DLCI aka PVCs are virtual. CIR is the bandwidth guaranteed by the provider for each DLCI. If you want to add another T1 (physical) circuit then yes, it has to be terminated on the 2nd Serial port.

HTH

Sundar

Community Member

Re: Frame relay question

Hi Sundar ok I think I understand now, you cannot terminate 2 Physical T1s on the same WIC card which makes sense. Now since DLCI/PVC are virtual circuits it is possible to provision one of my DLCI/PVC, in this case DLCI 22, to a CIR of 1536k as that is what the SP is guaranteeing this particular DLCI to be. So currently this circuit is set at 256k inorder for me to change the bandwidth to match the SP 1536k I would have to go to the distant end router on its serial interface and change it from using TS 1-4 to use all the TS 1-24 and the circuit would come up as a T1?

Re: Frame relay question

Yes :-)

Community Member

Re: Frame relay question

Sorry Sundar I was retyping my message are you saying yes my first message or the one that I just finished? Sorry about that I didn't think you would get to my question that fast. The one I just updated is at 1:10 PST

Re: Frame relay question

That's OK. Typing in 'yes' didn't take too long :-)

Yes, you need to configure channels 1-24 at the branch if the port speed of the circuit is a full T1.

HTH

Sundar

Community Member

Re: Frame relay question

ok I understand now...I was confusing myself between physical and virtual. It helps to speek to someone when you go crazy like this thanks for straightening me out

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