Automatic switching between Cable and DSL

Discussion in 'Hardware' started by MrX, Oct 7, 2001.

  1. MrX


    Question for all you networking gurus out there.

    I have a cable modem set up right now and it works great, most of the time. As I am writing this I am using my netzero dial up because my cable modem is down :mad:

    My question is that I am thinking about getting DSL as a backup and would like to know if it's possible to run them both at the same time so if one goes out the other kicks in automatically.

    I was thinking maybe 2 network cards or a router/switch that automatically senses which connection to uses maybe even picks the faster one that would be sweet. :D

    Anyway, thanks in advance

    Mr X
  2. I have run both DSL and Cable over the last year on a NT4 trading platform. I considered a number of configurations and ended up using two Asante routers with different IP (gateway) addresses hooked to my office network. In my workstation, I use one NIC assigned two IP addresses and two gateway addresses. Technically, NT will automatically switch from one gateway (DSL) to the other (Cable) when one service fails. The problem is that failure here means the unlikely failure of the local network or router itself and not the internet path. When I want to switch between DSL and Cable, I use two small batch programs on my desktop to flip the primary gateway.

    route delete
    route add mask

    Where is the IP of the gateway (router). This manual configuration gives me control over the timing of the switch over.

    While the Nexland router looks like an affordable backup product , it doesn't fill my needs as a trader. I typically have a data feed and 3 to 5 broker applications running. All of these are connected to different IPs with different routes. A failure is any unacceptable condition on any route lasting more than 10 to 20 seconds. Unacceptable performance includes high latency (ping > 500ms), lost packets (> 10%) or failure of any link in the route to my supplier's server. As far as I know, the Nexland device will look for hard failure of the path to one server every 20 seconds. I doubt that it would efficiently evaluate multiple or even degraded paths.

    I could write a piece of software to monitor each path; however, the switch over itself has some undesirable results. When a connection is lost, my data feed and broker interfaces go into a time-out mode (not visible) and then each application attempts to relog-in. Unfortunately, during the time-out period, you may not even know you are down. The total process takes up to 90 seconds before everything is back on-line. If the route failure is common to both ISP paths (for example, the broker's server), then an automated system would alternatively switch between ISPs trying to find a connection. Thus, the loss of one of five applications takes my whole platform down. For these reasons, I prefer to manually switch between ISPs when I have evaluated the nature of the problem using a route tool like ping plotter.
  3. rcreal


    Finally picked up one of these from Nexland.

    Sales folks were very helpful and gave a good deal ...

    $250 + 15 s/h via fedex.

    Currently have cable modem, will be getting dsl once i move in a month or two.
  4. Bob777


    When it comes to quote providers, trading software, etc., you need to manually switch over anyway if your ISP goes down. I'm still trying to figure out what good a Nexland router would be for anything other than web surfing.

    For example, Lets say I have cable access with @home (which I do and I hope they don't shutdown tonight). I have DSL service with Quest. And my quote provider is Esignal.

    I'm connected to Esignal using @home's network. If @home's connection goes down, so will my Esignal connection. It's not going to automatically switch over using DSL/Quest. I'm still going to have to reestablish a connection with Esignal using my DSL provider.

    I'm not trying to knock the Nexland router. Between today and next spring, I'll be losing my cable access with @home, so I'm looking for a good backup system and setup.

  5. I can't see the value of the router either.

    All of my applications will detect loss of connectivity within 30 seconds and attempt to relog-in. If I switch over to the other ISP in the intervening time period, my applications will re-establish themselves. I suspect your data feed will act in a similar manner. The problem is the 60 second down time. An automated system will only make maters worse in a noisy environment.
  6. aldrums


    I have an @home connection and I used to have an Earthlink DSL connection. The @home connection connects automatically when the computer boots up.
    I used to start all my trading programs and then start my DSL connection last. When I did this all the programs would automatically use the DSL connection. If the DSL went down, everything would automatically revert to the @home connection. It wasn’t so smooth if the @home connection went down. Even though all my programs were technically still connected through the DSL, Realtick and all my other programs would start to disconnect, and I would have to disable the @home connection, close all my programs and start them back up again.
    A lot of this depends on how these connections are configured on your computer. I know one guy who had cable modem and DSL and was able to quickly switch connections by pulling up an MS-DOS window and typing a route command. I was not able to do this because the PPOE software I needed to run my DSL connection prevented it.

    Best of luck,

  7. Turok


  8. aldrums


    Gee...first I had to deal with Covad's problems and now this. I guess I can always re-activate my DSL. I still have all the equipment hooked up.

    P.S. I just read Desert Trader's first post on this thread. The batch program he spoke of was what I was trying I was referring to as the "route command" in my post.
  9. aldrums

    If you ever want to go to a dual ISP configuration, PPOE should not be a problem. Each ISP's modem should interface with its own router. Most routers will emulate the PPOE software on your machine and each router needs to have a seperate gateway address. The routers are connected to a network. Each computer on the network can talk to either ISP by setting the computers gateway to the routers IP. This is done by writing small batch programs and draging their icons to the desktop. A quick double click on the icon is all that is required to switch ISPs. Unfortunately it will take 60 seconds for everything to catch-up.

    I use this configuraton for the following reasons:

    The ISPs are always on

    Each router provides a hardware firewall for security

    I can use one NIC per computer (with dual IPs)

    I can send other traffic over the network (file and print
    sharing). This is not allowed for cable networks without a firewall.
    #10     Dec 1, 2001