1MB, 4MB, 8MB lines

billybob01

A question arose yesterday that had me thinking. How many people can physically use either a 1MB, 4MB, or 8MB ADSL line? before contention becomes an issue?

Forsaken_GA

DSL isn't a shared media, so contention isn't an issue, not until you get back to the DSLAM anyway. It's possible that the backhaul from the DSLAM is oversubscribed, but that's not a problem to be dealt with on the copper loop

bellhead

billybob01 wrote: »

A question arose yesterday that had me thinking. How many people can physically use either a 1MB, 4MB, or 8MB ADSL line? before contention becomes an issue?

By contention I think you mean saturation of the bandwidth correct?

Cisco setup
The network configuration for a dslam is setup this way there is usually one dslam acting as the controller at the top of the tree, below there are other dslams. They are connected into the controlling dslam by either a ds3 or oc3 circuit depending on the type, age, and vendor. The top dslam in the config. in the network I worked on took a oc3 into a gigabyte backbone switch, a 6400 series cisco switch with multiple blades on it for each connection. Then back to a main co by a gigabyte ethernet connection.

Lucent
A much cleaner setup each dslam went into the 6400 by a oc3 connection then back to the main co. The lucents also had a lot more ports available than the ciscos per dslam.

Bandwidth was never an issue per dslam, if it came to be then load balancing could be achieved very easily just by moving connections around between dslams.

dtlokee

I think the OP was talking in terms of end users on the DSL connection not the head end. The question is difficult to answer because I have seen small offices with a 25MB/s connection and it was barely keeping up with them and I have seen 500 user networks with 2 T1 circuits and it was fine. It really depends on what how you are using the bandwidth.

bellhead

dtlokee wrote: »

I think the OP was talking in terms of end users on the DSL connection not the head end. The question is difficult to answer because I have seen small offices with a 25MB/s connection and it was barely keeping up with them and I have seen 500 user networks with 2 T1 circuits and it was fine. It really depends on what how you are using the bandwidth.

I have seen business's with 100 people on a 5mg/768k dsl line and it worked fine. The thing is when you throw something else in on it like voip then it fails. The reason I think it fails is because of the async data on it, not the speeds. Right before I left the rboc, there was a job where a company was moving into a office complex. They had about 40 users, the IT guy if you want to call him was trying to connect a voip pbx switch back to their main office over DSL. I had done the initial DSL install and was trying to tell him at the time it was unsuitable for voip applications such as the one he was trying to accomplish, he needed at least a t-1. Suffice to say he didn't listen until after the 2nd visit for a repair after he was complaining of calls dropping. I told him there was nothing wrong with the dsl circuit but the problem was on his end. He didn't like it but ultimately he bought a T-1 and was much happier when I talked to him a month later. PS I picked up a nice bonus on the T-1 sale.