Ascend Archive
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Re: (ASCEND) Max4000 and TWO telcos ?
>At 09:36 AM 6/29/98 -0700, Peter Lalor wrote:
>>>From: Shiloh Costa <costa@mdi.ca>
>>>If you have 23 Channels with one D on the first T1, with TELCO A
>>>...and you have another 23 channels with one D on the second T1,
>>>with TELCO B
>>>
>>>Is it possible to utilize two different Telcos on a Max4000 or Max4048 ?
>>>
>>>Basically we're locked into a contract with a more expensive PRI on the
>>>first Telco, and from now on we'll be buying from the second Telco.
>>>
>>>Is there any problems with this, or any loopholes to look out for ?
>>
>>Your Max needs to take it's clock from a PRI (as opposed to a T1), but it
>>can't have two clock sources at the same time and the clocks on each of
>>your telcos aren't going to be in sync. This will cause frame slips and
>>poor throughput, etc.
>
>Might, can, should etc. This may have been your particular observation, but
>*MANY* other installations use this configuration quite happily.
I thought I was one of them for quite a while until I looked at my T1 stats
on the TNT and saw a lot of errors. IMO, everything can _appear_ fine, but
be very not-fine-at-all.
I originally looked into this becuase a client with a Pipeline 130
connected to me via 128k Frame Relay was reporting heavy packet loss under
load. I put it down to the Pipeline 130, as I've seen complaints about them
on the list for ages.
What resolved my problems was this:
1. Take timing off a PRI.
2. Have other telcos (than the one providing the PRI) set loop timing.
3. Have all other routers take timing off me.
>>Because of this, you'll need to have one of the telcos use your Max as
>>their clock source ("loop timing"), thereby syncing the two PRIs and your
>>Max together.
>
>Hmm? I don't know of any case where this has been done. On a local PBX
>maybe, but not loop-timed back to the telco....?
>
>>I haven't done this with a 4000, but we take circuits from three telcos
>>into a TNT and this was crucial in eliminating timing problems.
>
>I'll have to look into that, as I am not aware of this issue....
This is what Ivan (who knows of what he speaks) in Ascend Support said at
the time, and it was exactly the fix for frame slips on a Frame Relay T1:
>This is a timing synchronization problem between the TNT and the frame
>relay switch. Since the TNT is taking timing off the PRI, it cannot also
>take timing from the FR T1. What you need to do is to contact the
>carrier that provides you the FR T1 and ask him to take timing off the TNT.
Whether you always need to do this I don't know, but it worked for me.
Peter Lalor Infoasis
plalor@infoasis.com http://www.infoasis.com/
415-459-7991 x102 415-459-7992 fax
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