voice lab question with 1760s and IOS ?

itdaddyitdaddy Member Posts: 2,089 ■■■■□□□□□□
Hey dudes,
was wondering if you can help me.

Okay this is my lab in a nutshell. Just 2 border routers (1760s)
separated by T1 csu/dsu line. then on both sides of the border routers
I am goingto have 3550 hooked to a ip phone and on the other border
router will have a vwic-fxs card with a POTS phone connected. And I will
run a gatekeeper 2610xm and Call Manager on one of my servers.

Okay there yo have my cheesy voice lab just to learn the basics but
my question is this. on the 1760s what IOS do I run? I mean
do I need ipservices or what IOS do I need the bare minimum. I mean
my 1760s are way low on ram like I think the are 64MB and the images I find that say tthey are 15MB decompress to 3.5 or 4.5 times there original size and then my router says memory overload crap so I can only run say and IOS that is 13MB which is decompressed to like 67MB max only

so any tips on what is the bare miniumum I need to run on the boarder routers? only 2 1760s. again one will have the vwic-fxs connected pots
with a DSP module 256 installed on that 1760 as welll..
I just dont know what features I need and what is the minium IOS I need.



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    azaghulazaghul Member Posts: 569 ■■■■□□□□□□
    I was running a similar setup for CCNA-Voice.

    I think the minimum IOS feature set is ipvoice (which is about 20MB uncompressed), and the minimum RAM is 32F/128D on the 1760's. If you want to add CME and/or SDM things can get tight. But flash and DRAM are fairly cheap on eBay these days. I'm running adventerprise feature set, with 48F/64F and 128D/160D, gives me the IOS for most future certs. The latest version of IOS as well doesn't go astray, 12.4T.

    Best place to check features and flash/DRAM requirements is the IOS feature navigator.


    Not being in the country where T1 is used, I think that the T1 DSU/CSU's will only support data, so you wont be able to test CAS/CCS/PRI features.
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    itdaddyitdaddy Member Posts: 2,089 ■■■■□□□□□□

    hey bud thanks for yoru input...hey what do you mean the latest IOS doesnt go astray, 12.4 ?

    what type of connection do you have between your routers? fastethernet? or serial vs my T1 csu/DSU

    I know voice is converted to ip via the routers or somethinglike that
    so it can traverse the T1 csu/dsu types. at work here we have that doen. I think some kind of card in the routers or DSP module does that? I think? what do you think?

    I just want to get the basics down for now. I realize I cant do any PBX stuff etc...I just want to make phone calls between my POTS and 1 ip phone. I will have call manager 7 or 8 on a server running from there not on a cisco device...what do you think of this? I am just piecing it together. I learn best by trial and error and maybe lots of error ahhaha hhaicon_lol.gif
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    tierstentiersten Member Posts: 4,505
    itdaddy wrote: »
    hey what do you mean the latest IOS doesnt go astray, 12.4 ?
    azaghul means that it doesn't hurt to have 12.4T running instead of some older version.
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    itdaddyitdaddy Member Posts: 2,089 ■■■■□□□□□□
    hahahah thanks sir ..aahhahha yeah ;)
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    azaghulazaghul Member Posts: 569 ■■■■□□□□□□
    My "Lite" lab is 2 x 1760's working as branch office routers running CME with both serial to simulate the WAN and E1/T1 to simulate the PSTN, and a 2691 working as my PSTN/frame-relay WAN cloud. One 1760 also has FXS and FXO for analogue handsets and "real" PSTN connection. I use a 3550PWR switch shared, interfaces 1-12 vlan'd for router1, 13-24 vlan'd for router2, this cuts cost, noise and power usage.

    As for IOS ver 12.4T, its always best to have the latest version you can find. Earlier IOS versions may have a different command syntax and may be missing some commands as well when features weren't developed. Also the 1760's themselves do some things very differently, E1/T1 clocking and DSP resource allocation spring to mind.

    As for using T1 csu/dsu, I don't think DSP's are needed (as they are data only), as the VoIP stream is not being transcoded to G.711 but just staying as packets.

    CUCM running in vmWare is fine, but you'll still need a PC with a bit of grunt to run it and the host OS. I've run it in vmWare on a P4 3.0 and it can be a bit slow.

    I'm in the same boat, I like to lab with real hardware, and learning by trial and error is a great way to learn. If nothing goes wrong in a lab, where's the fun in that...:D
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    itdaddyitdaddy Member Posts: 2,089 ■■■■□□□□□□

    wow that is a lot of info I understood 85 % of it.
    really I dont need dsp module huh? well I plan to have 1 vwic with a pots connected to it then I think i need a dsp 256 module right?

    i want to connect a fxs card in the vwic of the 1760 border router
    to call the ip phone...right?
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    azaghulazaghul Member Posts: 569 ■■■■□□□□□□
    For straight IP phones you can get away without DSP resources, thats why some people run a no-hardware Voice Lab in GNS3, and to save on costs.

    However DSP's are needed for:

    VWIC-MFT-E1/T1 (not WIC T1 csu/dsu)
    and probably a couple others I've missed

    Even though I'm in an E1 country, I've bought VWIC-MFT-T1's (to round out the lab) for as low as US$36, combined with a E1/T1 cross-over cable for US$4, makes it very cheap to simulate the PSTN. But you'll need DSP's on each router of course for that (see above).

    Just checked my home made 1760 DSP calc, to support 2 FXS ports, 2 FXO ports, 1 conference and 3 E1/T1 channels, you'd need a PVDM-256K-12. Without conferencing or the E1/T1, you can get by with a PVDM-256K-4.

    Only understood 85% of my previous post? Not a problem, I sometime suffer from TMI syndrome (too much information icon_lol.gif).
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    itdaddyitdaddy Member Posts: 2,089 ■■■■□□□□□□
    funny. no i am glad you go nutz and explain everything on the top of your head it helps me learn. I appreicate your help and your time. thank you.
    yeah i am going to get a pvdm-256-4 only for my fxs vic card for my pots phone and run and IP hone off of my 3550 poe and run it across frame relay and a t1 csu/dsu...just the basics for now.
    thank you icon_thumright.gif
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