Questions about using two VG200 gateways back-to-back

[christopher.baldwin]

First off, please forgive me as I'm very new to Cisco products, and came into some information that might lead me to believe the VG200 product will do what I need.

I have a private microwave IP-based network and the need to transport bi-directional audio across it. This is for two-way radio communications (RoIP).

What I'd like to know is, can two Cisco VG200's equipped with VIC-2E&M cards be set up to work back-to-back (what goes in one on one end of the link comes out of the other on the opposite end and vice-versa), or do I need to have a Call Manager in between them?

Any help would be appreciated. I realize I can only buy these aftermarket, but I don't want to buy them if they won't do the job.

Our IT specialist is familiar with programming Cisco products, but he's never worked with the VG200 specifically. Since I'm heading up the project, I'm tasked with asking all the questions.

Lastly, if these gateways can be configured "back to back", what's the latency like as far as the audio is concerned across a dedicated 10MBPS network with nothing else but these devices on it? Is it pretty much instantaneous, or is there some significant delay?

Any help is most sincerely appreciated.

Regards,

Chris Baldwin, CET

[paolo bevilacqua]

VG200 do not accept optional cards of any type, so for E&M you will have to use ISR G1 or G2 routers.

These do not need a CM to communicate.

[christopher.baldwin]

So it is FXS/FXO on VG200 only? No E&M? There is mention in the Cisco documentation about using E&M cards on VG200.

http://www.cisco.com/en/US/tech/tk652/tk653/technologies_tech_note09186a0080094ab9.shtml#plat

This mentions all releases of VG200 support E&M. I just want to know if I purchase two VG200's, can I get the E&M ports on one unit to connect to the E&M ports on the other unit without call manager.

I just want to use two VG200's as a dumb bidirectional (4-wire) audio pipe with a total of four ports (2x VIC-2E&M installed on NM-1V).

Please help! Thanks for your response Paolo!

Chris    

[paolo bevilacqua]

The problem here is that you're referring to a very old product that went End os Sales aready in 2003.

For sure and solid results you should absolutely avoid using such obsolete hardware. As mentioned before, using ISR G1 or G2 routers with VIC2-2E/M, you should be able to accompish the design succesufully.

Note: E&M applications are not for the beginner. It is recommended that you consult with someone with specific experience.

[Robert Craig]

I've never really used the VG series because I've only had small deployments in terms of analog based devices (voip is the way to go). Having said that, the VIC-2E&M card was really designed to interface with a PBX. You could do this with an FXO port, but an 2E&M card is designed for high amounts of circuits. I'm not sure if that card will interface with your equipment or not. Hopefully someone else can shed some light on that part. In regards to the latency, that all depends on the transport. Latency is ultimately determined by the transport of the IP packet. After all, once the signal gets into the VG200 (or whatever device providing the signal conversion), it's an IP packet that is subject to the same rules and treatment of any other data packet in the network. Your network may support a max of 10mbps, but if the transport has packet loss, or is 20 miles away, latency will increase, if not cause the audio (your radio signal) to sound choppy. So, you can prioritize your packets based on DSCP, or even match it with an ACL, but the physical transport and all of the devices it goes through will factor into the quality (latency) of the signal.

[christopher.baldwin]

Robert,

Thanks for the reply. The E&M card is the most suited interface to the radio equipment, in fact Cisco recommends it in their LMR (land mobile radio) interfacing documents for the 2600 series.

I've just noticed that the 2600 series requires very specific IOS, cards, DSP's, etc to make work, and wanted to know if I bought a pair of VG200's with NM-2V's in them, and installed E&M cards and performed the proper programming, if the equipment will support transporting the circuits over IP without the call manager, etc.

I know nothing about these - I'll have someone else do the programming once I'm told the hardware will do what I want.

So what do you think?         

[Robert Craig]

Just from quickly looking at the VG series on Cisco, no. The VG series was designed to be used in conjunction with a Callmanager of some type. Now, sinnce you mention using a 2600 series router, you could get a 2651XM which has enough memory to run CME and then use that with a VG, but it would probably need to be configured as a pair on both sides. So, I'm sure you could register a VG across that link to a single 2651XM, but that tends to be less reliable than you want. In the VOIP world, we call those long locals, but is usually applied to one or two phones, not a voice gateway. If you can get yourself a 2651XM to pair with each VG200, then it will work provided your configure CME on both routers.

[paolo bevilacqua]

Robert Craig wrote:
 Just from quickly looking at the VG series on Cisco, no. The VG series was designed to be used in conjunction with a Callmanager of some type. Now, sinnce you mention using a 2600 series router, you could get a 2651XM which has enough memory to run CME and then use that with a VG, but it would probably need to be configured as a pair on both sides. So, I'm sure you could register a VG across that link to a single 2651XM, but that tends to be less reliable than you want. In the VOIP world, we call those long locals, but is usually applied to one or two phones, not a voice gateway. If you can get yourself a 2651XM to pair with each VG200, then it will work provided your configure CME on both routers. 

That is incorrect. The VG200 as well the VG224, VG202, VG204 etc, can perfectly work as standalone device. Furthermore, to transport vocie circuits (of any type, analog or digital)) from A to B, and LMR application, no CME or CM configuration is necessary.

[paolo bevilacqua]

Robert Craig wrote:
You could do this with an FXO port, but an 2E&M card is designed for high amounts of circuits. I'm not sure if that card will interface with your equipment or not.

That is incorrect. First of all, one cannot use FXO when the device to be interfaced has E&M.

Secondly, E&M is not "designed for high amount of circuits". To the contrary, the card, in a VIC form facotr, has just two ports, each one can carry a single voice channel.

[Robert Craig]

Ahhh, I stand corrected. Thanks for the info. I've never used one of those cards or any of the VG series. So, really, what is the difference between an E&M card and an FXO? From what I see, they both accomplish the same thing, but just use different technology, yet limited to the same physical limitations.

[paolo bevilacqua]

Ahhh, I stand corrected. Thanks for the info. I've never used one of those cards or any of the VG series. So, really, what is the difference between an E&M card and an FXO? From what I see, they both accomplish the same thing, but just use different technology, yet limited to the same physical limitations.

E&M:

http://www.cisco.com/en/US/tech/tk1077/technologies_tech_note09186a0080093f60.shtml

All signalling subjects:

http://www.cisco.com/en/US/tech/tk652/tk653/tk754/tsd_technology_support_sub-protocol_home.html

[christopher.baldwin]

So, Paolo, while it is legacy hardware that is more or less unsupported, any VG200 with the VIC-2E&M cards in it *WILL* do the job, correct?

This is more or less a proof of concept project at this point, so budget is an issue.

[paolo bevilacqua]

Again: I  strong recommend you avoid using obsolte hardware that is completely unsupported and dead, if you want good chances of results.

As a very minimum you can use a 2801 with PVDM2-16.

[christopher.baldwin]

I understand the deficits of using the VG200 from a support standpoint, but it will do what I want it to do, correct? I'd rather prove the concept on dirt cheap hardware than newer, expensive hardware to find out it won't work anyway.    

[paolo bevilacqua]

Sorry, I can't really stress further the importance of the concept that I've been trying to deliver above.

Thanks for the nice rating and good luck!