Re: [pacnog] Router & Satellite modem connection

  • To: "Mr. Siumafua Moala" <siumafua.moala at tcc dot to>
  • Subject: Re: [pacnog] Router & Satellite modem connection
  • From: Joe Abley <jabley at ca dot afilias dot info>
  • Date: Thu, 18 May 2006 19:44:02 -0400
  • Cc: 'PacNOG' <pacnog at pacnog dot org>
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    • 
      On 18-May-2006, at 17:23, Mr. Siumafua Moala wrote:
      
      
      Thanks for your help, ideas, suggestions, etc.
      
      
      We are using SDM-300 Sat modems with a UB-530 interface board. This has an EI-530 interface which can be wired to V.35 standards. We have our core routers at the SES (only < .5 mtr away) and using Ethernet take it to the distribution/access network where one is 500mtrs and another is 2km. We keep the internet traffic on a separate VLAN to distribute it. This way you
      need not have to run it into a Mux or converter...  Saves you money.
      
      
      
      We use the same setup at the moment (with 3/2 down/up) but I was wondering if we could increase the length of the V.35 link so we can move the router to our computer room from the earth station for ease of maintenance, etc.
      
      
      I look through the blackbox site and they had converters, extenders, etc but with max of 2mbps.
      
      
      About eight years ago, before southern cross was lit and as the Internet in New Zealand was having one of its little growth spurts, we landed a 10Mbit/s carrier from Intelsat 177E to an earthstation in Carlaw Park in Auckland. The uplink was from Steel Valley in California, which was operated by Vyvx.
      
      
      I just found one of the test traces we ran, as we were testing the carrier.
      
        http://www.patho.gen.nz/~jabley/pix/cn_beg.gif
      
      
      We used an SDM-2020 modulator in California and the corresponding demod in Auckland, each of which presented HSSI interfaces to a cisco router (a 7204 and a 7505, respectively). Since this was a unidirectional US -> NZ link we had to mangle some $150 cisco cables and loop various conductors within them to convince the routers in each site that the interfaces were actually up.
      
      
      We would have liked to avoid putting what (at the time) were expensive routers in the earthstations, but we had great trouble finding a good alternative: we couldn't extend them using sync telco circuits because we kept running into sync/clocking issues: it was (fairly obviously) next to impossible to arrange for the achieved signal rate over the bird to match any of the available transmission rates of any DSU we could buy.
      
      
      When it came to troubleshooting transmission problems through either earthstation, it was very handy to have a local router there to diagnose problems. The more boxes there are between your antenna and your router, the harder it is to know whether you need to be talking to the uplink operator, the satellite operator, the earthstation operator or the person providing transmission from the earthstation back to your main site. Unless you have good, hard evidence as to what is going on, they will all just keep pointing fingers at each other and whistling, innocently.
      
      
      So, I would say that having routers close to your antennas is a good idea.
      
      
      Joe