Ascend Archive
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Re: (ASCEND) shared D-Channels on PRI
> Related to this, I had a 3com vendor tell me yesterday that NFAS was a
> BAD thing, that above 1 PRI's worth of ISDN calls, that performance
> would drop off, both for call setup and throughput. He also claimed
> that this was true for all equipment including Ascend MAXs.
BS.
(I wonder if it is Lucent who told you this? - They don't support NFAS)
There is plenty of bandwidth in a 64K channel to handle the call load on
massive amounts of B channels. I would imagine that even if a large
number of them were setting up or tearing down calls, it would still be
enough.
> My first thought was to politely tell him how wrong he was, and then
> realized that I didn't have enough real world data to form an opinion.
I don't know how big an ISDN conversation is to set up a call, assuming
it comes with CallerID information and some other goodies, but let's
say it's about 100 bytes.
100 bytes * 80 calls per second = 8000 Kilobytes per second = 64Kbps
Do you have 80 calls per second coming in?
Now I _have_ seen some systems that have that kind of a call load or
more on just 3-4 PRIs, but it's not NASes that are connected to those
lines.
> Also are these values effected by wheither or not the PRIs are
> terminated in 1 chassis or multiple chassis? Is there an effect
> that can be tied to type of calls, Modem vs. ISDN?
Call setup *should* be identical for modem/ISDN.
I *do* imagine, as I said in another message, that terminating the PRIs
on different boxes is something I wouldn't do. I hypothesize that it
would incur delays. Not to mention what would happen if you lose a Max
or have bad collisions on your LAN.
-Phil
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