Cisco 2801 - E1/ISDN dial-in

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Apr 11th, 2008
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Hi all,


A simple setup - c2801 box with Channelized E1 WIC + E1/ISDN PRI line. Task is pretty simple as well - to configure router to accept incoming ISDN data calls (dial-up backup for data links). I have done similar things in past, but have no experience with ISR platforms in this context. Question is - at the moment I am trying to add E1 timeslots to 'pri-group' with 'pri-group timeslots 1-31' command, Im getting an error message:


% Not enough DSP resources available to configure pri-group on controller E1 0/2/0

% The remaining dsp resources are enough for 0 time slots.

% For current codec complexity, 2 extra dsp(s) are required to create this voice port.



Rest of controller's configuration is:


controller E1 0/2/0

framing NO-CRC4



.. and telco says line is fine. Somehow I trust them, as line was working a couple days ago.


As far as I understand - router tries to allocate resources to those voice ports, but there are not enough resources to do it. Thing is - I dont need any voice capabilities, it will be used for data transmission only.


Ideas on how to proceed? Basicaly - any replies will be highly appreciated :)



Thanks,

Andris

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paolo bevilacqua Fri, 04/11/2008 - 12:16
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Hi, load an "ip base" image in the router and you *could* be able to configure the pri-group.

You shoudl also configure network-clock-select and network-clock-participate commands.


Note, that may not be supported by cisco, the proper card to do pri isdn data is not vwic, but hwic-1t1e1-pri.


Hope this helps, please rate post if it does!

andris.zarins Sat, 04/12/2008 - 05:17
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IP BASE image is not an option, as I need security features, and ADV-SEC image is not an option as it requires 192M of RAM, but I have only 128. Anyway - I dont think downgrading IOS to cut off voice features would be the best way to deal with it ;)


Just checked - I have VWIC-1MFT-E1 card installed. CCO says, I cant configure it for data transmission using 'pri-group' command, as 'pri-group' is meant for voice traffic.



I'm checking documentation at the moment, hopefuly will find anything useful, any configuration examples for c2801/VWIC-1MFT-E1 for data transmission, or hyperlinks to useful resources would be highly appreciated ;) .

paolo bevilacqua Sat, 04/12/2008 - 06:14
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Hi, I can really tell you that the only possibility you have, is to load an image without voice support, or use the new hwic that I've mentioned above.


Here's the link for data pri using vwic or vwic2, however this approach requires full dsp resources that you don't have, from which the problem in discussion.

http://www.cisco.com/en/US/docs/ios/12_4t/12_4t11/intserv.html


Instead, when you you run a no voice image, the configuration is limited to normal dialer interfaces, that I suggest you to try.








andris.zarins Sat, 04/12/2008 - 06:33
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Still - no offence mate, but I'd like to hear a second option before I change VWIC to WIC, or buy and extra RAM to run ADV-SEC soft.

paolo bevilacqua Sat, 04/12/2008 - 08:43
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Do you realize that nowhere in datasheet or documentation, cisco claims you can do isdn for data on a 2801 ?


Anybody will tell you that you can't, unless they know about one of the three solutions:


- install dsp in the box

- use a non-voice image

- use the proper HWIC


what other option do you expect ?


Good luck.

andris.zarins Sat, 04/12/2008 - 08:47
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A possibility to turn off unneeded voice features would be just perfect.



paolo bevilacqua Sat, 04/12/2008 - 08:58
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Right in theory, unfortunately doesn't exists in practice.

andris.zarins Sat, 04/12/2008 - 09:05
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If one more person agrees - I'll buy it ;) . Please understand me correctly, but I dont want to base such decisions on just one person's opinion ;)

paolo bevilacqua Sat, 04/12/2008 - 09:54
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Check the size of the non voice images, chances are, these are smaller of what you're using now.


You'll find that when it comes to ciscos, experience matters more than opinions. That is something I've personally gained in 15 years of blood, sweat and tears. Oh and some fun too.

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