Building a TDMA Network?

  • Hi Guys,

    Don't know if this is crazy question, but here goes…

    Not all of us are able to afford that 20mb or even a 10mb connection and in some local area networks, with as little as 30 computers, there are bottlenecks, and delays when nat'ing through to a public IP Address and was wondering...

    If there is such a thing as Time Division Multiple Access for LAN's.

    Can such a thing work? Is there software version that can be used with pfsense, or in conjunction with network cards?


  • its not TDMA, but VLANs may do the trick… what are you trying to accomplish?

  • I guess I'm trying to find out if pfsense will have TDMA type capability, software or otherwise, in the future, and if so, will Network cards also have to ship with TDMA capabilities.

    What will be the benefits of such a thing for the LAN operating environment with a /24 or greater network, putting aside traffic shaping and squid caching for the moment?

    I guess another way of looking at it, is altering, minimizing, or eliminating congestion and collisions LAN side, improving user experience and perceptions, and maximizing response time efficiency on the LAN through to NAT with any limitations you may have on internet bandwidth?

    Am I making ANY sense?


  • @jits:

    Am I making ANY sense?

    Frankly, no, sorry. That just reads to me like a corporate BS generator that spits out random networking-related words. ;D

    Collisions LAN-side? You should have gotten rid of your hubs 10 years ago. Congestion LAN-side? Extremely few people have a fast enough Internet connection that anything other than the Internet connection is a bottleneck, that would mean your Internet connection is faster than your LAN Ethernet port, in which case you would have issues, yes, but they have nothing to do with anything other than having too slow of a NIC.

  • oh come on, surely someone before me has said those exact same words…somewhere.

    I hate capturing packets and since you won't do the TDMA thingy, life just got harder. thanks!  ;D

    In any case, progress is slow, but improvements are being seen.


  • Cable Internet does kinda a TDMA method for getting your data to and from you to their part of the network…    :P

    Bottlenecks on the LAN?  Use gigabit NIC's and switch.

  • I ran wireshark and found majority of traffic on network was broadcast traffic, well aside from the torrents, but nothing I can do about that. Isolated one broadcast from Promise RAID Array on our network, using 192.168.4.x source address. At least two other machines are doing constant broadcasts. Also, found that our 8 mbit dedicated internet connection is actually operating at half-duplex instead of full.

    At some point very close in the future, I'm gonna have to pay for some pfsense support because we need to get VOIP working.

    Be in touch.


  • Well if you continually harness an expanded array of models I'm sure that everyone would work flawlessly… No? Okay.... (My random generated sentence)

    To answer the question about TDMA, ethernet does not need TDMA. The reason is that ethernet doesn't need to worry about trying to divide up their traffic into time shares. The main purpose behind TDMA is not for balancing bandwidth, but to avoid collisions between packets. Ethernet uses a different  method called CDMA. They basically just send out the packets as necessary and if there is a collision they will resend the packets at a random interval. TDMA will not increase bandwidth in the slightest, and if anything might limit the bandwidth available. Like cmb said, unless you're using a hub you won't have that many collisions because the switches will only send data out the ports which the traffic pertains to.

    If you have a ton of broadcast traffic that you think is slowing down your lan, then you can segment it off into smaller parts. It sounds like your bottleneck has nothing to do with your lan side, but rather you're having issues with the amount of bandwidth on your wan connection with 30 computers. All of that broadcast traffic on your lan will be dropped at your gateway as broadcast traffic cannot be routed. So none of that should be traversing your lans unless something is misconfigured.

  • Pretty much every network in the world has a good deal of broadcast noise. Until you get up to hundreds or thousands of hosts it's not enough to impact anything short of a host gone nuts spewing huge amounts of broadcast traffic (thousands of pps, which I've only seen happen a couple times that can be classified as just "host gone nuts", it's very rare). That's the reason you generally don't want more than a /24 per broadcast domain, more than 254 active devices on a network and you may have enough broadcast noise that it becomes an issue (though usually not until you get to several times that many hosts).

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