What’s the best solution for datacenter modem dialling

alertingdialupmodemrackmountvirtualization

We have some physical servers that we cannot virtualise because they are connected to analog modems for alert paging.

We need to retain this functionality, but virtualise the servers and reduce the pile of individual modems down to something that can be rackmounted in a minimal number of U.

So I guess I'm seeking a stack something like this:

Rackmount bank of 8-16 modems
Network connectivity from the modem bank onto the network
Some kind of client software on the VMs that allow them to create a modem COM port, via the IP connection

I'm already familiar with a partial solution – MOXA make an IP-connected serial server that can connect to a bunch of modems. This works in exactly the manner we need, but it doesn't go as far as integrating the modems – So we still have a bunch of them sat on rack shelves.

Can anyone point me in the right direction on this?

Edit: I'm thinking I can probably get closest to what I'm after by stacking one of these with one of these. I was hoping there would be an integrated, single-unit solution but maybe not.

Best Answer

I'm not sure if there's a client, but it sounds like you should be able to use reverse telnet to a Cisco AS5300. The AS5300 takes a PRI (T1 with ISDN framing, so 24 phone lines worth) and should support dial-out (I think), in a single rack space.

Related Solutions

Networking – Difference Between Switch, Router, and Modem Explained

Routers: these devices connect different networks, operating at Layer 3 (the network layer) of the OSI model. They maintain routing tables which map IP addresses (more correctly, IP prefixes) to an outgoing interface. Note that an interface may contain one or more ports (See below).

Switches: these maintain forwarding tables which map MAC addresses to physical ports, operating at Layer 2 (the data link layer) of the OSI model. This is not necessarily a one-to-one mapping; many MAC addresses can be bound to the same physical port. This is the case where you have multi-layer switched networks (think a Netgear or Belkin switch plugged into your office or university network), or a hub connected to a switch port.

Hubs: these are essentially multi-port signal repeaters, operating at Layer 1 (the phyiscal layer) of the OSI model. They can be either unpowered (simply providing a physical connection for the existing signal to propagate along), or powered, where they actually regenerate and/or amplify the signal they receive. The point to note here is that hubs are a single collision domain. A collision domain represents a set of devices all connected to the same physical transmission medium, such that only one of them can transmit at any given time (ignoring multiplexing technologies like wavelength division multiplexing, frequency-division multiplexing, time-division multiplexing, etc etc.).

In practice, hubs are found less and less in today's data networks, as they have poor performance (as only one user can transmit at a time) and poor security (anyone connected to the same hub can hear everything all other users transmit and receive).

Modems: MOdulator-DEModulator. Responsible for establishing a digital channel over an analogue medium, most commonly the telephone network. Modems again operate at Layer 2 (the data link layer), but use different protocols than Ethernet to communicate. They then offer protocols such as PPP to the network layer, to allow IP traffic to flow over their links.

Linux – Using modem for sending voice recording

Linux uses vgetty for voice data over a modem (mostly as an answering machine). It looks like there's a perl module over at CPAN that comes with an example script like what you want.

Callme script

In the examples subdirectory of the source distribution there is a callme.pl script. This dials the given number and plays the given message. Use the following command to run it:

    vm shell -S /usr/bin/perl callme.pl <number> <message>.rmd

Related Topic

Linux – Modem emulator for Ubuntu