From: Nauman Khan (mustafa@247emails.com)
Date: Sat Jan 24 2004 - 06:18:58 GMT-3
Jay Hennigan wrote:
>I believe you are wrong, but this may be one of those "it depends" type
>of things. SPIDs are layer 2 communication between the ISDN TE and the
>switch, related to the actual raw B channel. If the switch requires a
>spid for one channel, it will require it for the other as well. Note
>that the real world may vary from a simulator and from the specific lab
>environment.
Hi Jay,
Thanks for correcting me.
I also think I am wrong when I say that:
> You would need the second spid numbers if you want to bring the second >channel up without considering load threshold. If you only specify one >spid, then the second channel will only come up once your configured >load threshold is corssed. (Somebody can correct me if I am wrong)
which then means, that the only way to bring the second channel up is the use of dialer load-threshold command ?
but I was just trying to find out why we would ever need to specify
2 spids, as Yasser asked. The only time I have seen 2 spid's needing to be specified (in real world) is when using a bas-ni switch type.
Although it works with one spid too... (depending on how switch is setup
from the telco side)
Regarding your following comments:
>SPIDs are layer 2 communication between the ISDN TE and the
>switch, related to the actual raw B channel. If the switch requires a
>spid for one channel, it will require it for the other as well. Note
>that the real world may vary from a simulator and from the specific lab
>environment.
Its not necessary (in real world configuration) to have 2 spids to bring up the second channel.
For e.g. in DMS100 switch case, generally telco gives you only 1 spid number. But that does not mean you have only one spid. You still dial out on 2 channels.
The way it works is there is a thing called automatic rollover or B channel hunt group that Telco configures on their switch. No router configuration involved.
What it does is when we dial xxx string (which lets say is the only string that we got from Telco), it connects on first B channel. Now when router has to bring up 2nd channel, it again tries xxx string, and since telco has both b channels in one single hunt group or in automatic rollover,you will connect on 2nd channel with the same xxx string.
This is alternate to have multiple dial strings on the source router for each B channel.
Cheers,
Nauman
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