Problem using 2nd B-Channel

[JH24]

Hi, i wonder if anyone can help with this problem??

I am connecting via a Cisco 3640 Router to an ASP, i have set both ISDN channels to come up and make data calls when interesting traffic occurs from a terminal in my office.
This works fine, however when files are being recieved from the ASP only the 1st B-Channel is recieving the packets of data
e.g
Bri 0/1:1 gets to 245/255
Bri 0/1:2 stays at 0/255

The only thing that ever passes down the 2nd B-Channel is control packets.

Is this normal??

Thanks

 

[jgercken]

Is the device on the other end Cisco?
-Jeff
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Wasabi Pop Tarts! Write Kellogs today!

 

[JH24]

yes it is a cisco the other end.
I get a download rate of about 7k per sec, would i be right in thinking it should be about 14k if both B-channels were transmiting?

 

[dnels]

First I'd check with the ASP to make sure he has routing set up properly (the ISDN channels have an equal cost routing metric to your network) and his thresholds are set to bring up the second channel.

The problem may be the switching path that the router at the ASP end is using. If he is fast-switching or CEF switching, it will not load balance packets in a single source/dest stream (you should verify this on ISDN, it's been a few years since I've worked on this kind of implementation). He would need to implement process-switching (no ip route-cache) on the ISDN interfaces in order to load balance a single source/dest stream across both channels. This may not be a problem if the router on the ASP side is dedicated to you. However if this is an aggregation point for the ASP he may not want to do it because process-switching will drive the CPU up on the router.

Regards,
Dave

 

[StarTAC]

just to add, download rate should be about 16Kbps if you're getting a full 128Kbps bandwidth...

of course, with overheads and everything, u may get to see only about 15Kbps..

good luck..