Bill G and Others, What IP Hardware Do You Like

[Birken Vogt]

I am wanting your advice on what the best hardware for this sort of setup. I am moving away from the idea of DS0s and more toward IP for flexibility and future-proofness.

1. Centracom/Spectratac (for now) at central location
2. About 50% of the links will be T1s or spanned DS0s (partial T1s) provided by others
3. The remaining will be digital MW of ours which can either be high speed ethernet or T1.
4. Ring topology so if any one link breaks we will still be in business, hopefully with an alarm so we know about it
5. We like to run this off +12v as much as possible or +24v but there is not a lot of -48 to work with.

So I am wondering what devices you have good experience for

1. Ethernet routers
2. Ethernet <--> E&M audio interface
3. Ethernet <--> T1

Thanks
Birken

[Bill_G]

Routers - I use what's provided for the project. Most of the time it's a Cisco product. Sometimes It's HP or Agilent. Sometimes it's a plain old cheap switch. A few times it's been the fun little RouterBoard

Eth to e&m - The closest you'll get to a ETH/E&M converter is the Raytheon NXU2-A. Simple little PTP or PMP box that can extend 2W, 4W, E&M, or local audio across an IP transport. Very simple to set up. No frills. Never breaks. Great solution for a single circuit. Doesn't scale up well after the third DS0. Then you need a gateway product like the Telex IP224, or the Zetron 6300. There are other OEM's doing the same thing. Most of these only handle two circuits/radios at a time. If you want to transport more than a half dozen voice circuits, then you start looking at Harris Broadcast Intraplex IP Link product. A little spendy, and it has a learning curve, but it does it all.

Eth to T1 - For single circuits, the Kentrox CSU/DSU. Which ever way you're going to go - T1 over an ip transport, or ip over T1, use a Kentrox. You can get them as single units like a modem, or you can get a nest that holds several channel cards. But, as soon as you start scaling up, or switch media, then you need something bigger like Huawei or Cisco fiber muxes that can handle the bandwidth.

[Birken Vogt]

Thanks, Bill-

I looked at the products on your list. The Raytheon seems like the right thing mostly, but I am concerned about how this will all integrate back at the dispatch office. There are roughly 12 sites with receivers and 6 with transmitters, and it seems like it would become a bit of a mess in the back room with all those NXUs. I guess if we use the Telex or Zetron units the number would be roughly half, but can two separate receive sites come out one back office unit this way?

I did not understand your reference to the Intraplex IP product. What I saw looks like a studio link for 4 channels but only from one place to another.

My dilemma is getting them all to come in to one place and not taking up half the room, which is of course already too crowded. I wonder if there is a way to rack these up together while providing access and making sure they do not overheat.

[Bill_G]

If you just have twelve sites (6 rx only, 6 tx/rx), then two dozen NXU2-A's (12 at the sites, 12 at the head end) would be perfect. They'll fit on a standard 3ru shelf. You'll need a simple 16 port switch (1 ru), and a 12v 10A supply to run them (2 ru). You'll need a firewall / router / internet appliance to connect to the sites. Not a lot of space required. You'll have to build the cables from the BIM blocks to the NXU's, and then from the NXU's to the radios. Set the levels. Done. The NXU's have a link light. Makes it easy to tell if they are up or down.

I'll work on finding you a better link to the Intraplex. If you have just one radio at each site, the Harris becomes cost prohibitive.

[Birken Vogt]

You saying Kentrox means a lot to me, but at remote sites it concerns me to have to run something off AC power which is all it appears Kentrox have available. I would much rather run off the radio batteries and use a Wilmore supply if necessary than to have to maintain a UPS at the site. Is there a good Ethernet-T1 device you know of that will run off dc battery power?

Otherwise I think your ideas are the way to go.

[Bill_G]

DCB T2500 CSU/DSU has a 48VDC option. They are a good company, and I've used their encrypted tunnel products quite a bit to carry multicast console traffic cheaper and easier than Cisco or Juniper. I bet if you contact them, they can help you figure out how to power it by 12V. And if they can't, Wilmore can.

So, a question for you Birken - are you going to try tone control over ip? If you are, then don't use the NXU. The least little frame loss will cause your tones to wobble which can cause voters to false, and xmit LLGT to drop. You'll want the Telex IP224 in console mode so it can interpret your tone control, turn it into ip, get it from here to there, and then turn it back into tone control again. Never skips a beat even until the BER hits 1e4. Twice as expensive as NXU's. About $2900 each retail. You can get it down to $2000 each with the right dealer.

[Birken Vogt]

Yes, this is a Spectratac system. I had thought that they got the IP devices good enough to where they could all handle these sorts of tones. One thing we will not be doing is sharing this network with anything. It will be completely dark except for these audio streams. But the purpose of doing the IP thing is to get rid of the leased lines for increased reliability. If IP makes it more flaky that is no good.

I was aware of the IP224 doing the tone reconstruction thing. It sounds good so long as it does not introduce too much delay. When systems get more intricate little tone keying delays really start to add up. Does the Zetron do that or is Telex the only one?

[Bill_G]

Only the Telex. It transports the voice, and regens the tones. People can deal with voice wobble. Most of the time you don't notice. But, precision tone detectors do. Real fast.

If you're getting rid of the leased lines, what are you going to?

[Birken Vogt]

My plan, if finances will allow, is to use IP over microwave where possible/necessary and use point-to-point copper T1s that have recently gone dark from their original purpose for some data links that no longer exist.

Originally I had planned to use DS0s over T1s but I have been told enough times that IP has reached the level now that we can use it for this purpose. I figure it will be more future proof.

[Bill_G]

Ah. So, the microwave is something you'll be putting in, and something you control. What about the copper? Is that existing enterprise network? DSL? WAN? The more segments under your control (ie: traffic and bandwidth), the more likely you can use NXU's. Even fast best effort enterprises can blow up tone control over NXU's once in a blue moon, but you may land in four nine reliability. If it's just you and nobody else across the link, you'll hit five nines.

[Birken Vogt]

The idea will be to use private MW, point to point T1s from the telco, and T1s leased from a neighboring county and radio shop. Ditching the analog leased lines.

At no point will anybody else's traffic be on our network, nor any network segments be variable based on outside traffic. The original idea was to make it DS0s over T1 but IP sounds like a better idea for configurablility and future upgrades. Five nines is the goal.

I am still working on getting ideas for the best IP hardware and looping it together so if any one link goes down, it can still function. Concepts like Spanning Tree Protocol or MPLS but how to actually implement these in hardware is the question.

[Astro Spectra]

Go with Cisco. Their numerous router platforms will support redundancy with failover and protocols like VRRP. Hardware will support IP and T1. If you need analog interfaces then 4wire E&M cards are available and some of the larger routers will support 8 or 16 analog circuits. 24/48VDC operation is an option but it's generally cheaper to run everything on AC and use a good UPS hooked to the station battery. There is so much Cisco hardware around you can buy refurbished kit from third parties and still get Cisco support contracts.