Announcement

Collapse
No announcement yet.

Port trunk between two switches

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Port trunk between two switches

    Hi,

    I'm trying to find out the best way to improve bandwidth between two of my switches. They are both managed switches, but they are not in the same stack ansd they are different models (NetGear FSM700S & NetGear GS724TS).

    Currently the two switches are daisy chained using a single CAT5E cable.

    ASAIK what I want is a LAG Group consisting of 2 or maybe 4 ports on each switch. I've been reading though, and everyone keeps talking about VLANs being assigned to LAG Groups, and I'm not sure if that's what I need or not.

    Do I need to create a VLAN on each switch, assign it to a LAG Group, and then assign ports as members of the LAG Group. Or, can I just assign ports to the LAG Group without worrying about the VLAN part of it?

    Basically, my only goal is to increase bandwidth between those two switches, I don't want to segregate the network or create broadcast domains etc.

    Thanks in advance.
    I nerd therefore I am!

  • #2
    Re: Port trunk between two switches

    Pardon my being blunt but have you looked at the utilization of the ports connecting the two switches? I often find that people are quick to throw hardware at perceived performance problems before they've had time to adequately analyze the problem. If the utilization is not consistently above 50% then IMHO opinion there's no point in using aggregated links and any performance problem you have is not due to saturation of the current link.

    Also, in terms of network link utilization, the common train of thought is that if your link shows 35% utilization (for instance) that 65% of the link is available for more data. This is incorrect. Whenever data is passing through the link it's always 100% utilized at that moment. There are electrons passing through the physical wires and when they are, those wires are 100% utilized at that moment. What the utilization metric is showing is that during the polling interval the physical wires were 100% utilized (electrons flowing) 35% of the time. This sounds counterintuitive but this is the way utilization really works. So if your utilization shows 50% it means that the physical wires were 100% utilized with flowing electrons 50% of the time (based on the polling interval) and at 50% utilization IMHO the link could be a bottleneck.

    Electrons flow in a serial manner not in a parallel manner. When an electron is placed on the wire, no other electron can occupy that space and that space is 100% utilized. When a data stream (electron stream) is traversing the wire, that data stream is utilizing 100% of the wire at that moment and no other streams can occupy that space at that moment.
    Last edited by joeqwerty; 28th May 2009, 04:23.

    Comment


    • #3
      Re: Port trunk between two switches

      Thanks Joe, and I agree in principle. However, there are a few reasons why I think the trunk is justified.

      1) Redundancy. Currently there's only one cable. If it goes or is accidentally unplugged, no link. With trunking I should be able to introduce some failover.

      2) The link between the switches is basically the link between the server rack and the rest of the network. I'm keen to increase the bandwidth above 1Gbps to cope with the large file transfers that are performed at peak times without adversely affecting the rest of the network. Normally, as you say, 1Gbps is enough. However there are times when that link is fully utilised.

      3) I'm interested in how it works and I'd like to learn something as I configure it
      I nerd therefore I am!

      Comment


      • #4
        Re: Port trunk between two switches

        I get it. I'm not sure about LAG providing for redundancy as I use redundant links and STP for that, but it makes sense. Keep us posted as to your progress.

        Comment


        • #5
          Re: Port trunk between two switches

          Will do, thanks.

          I'm still at a bit of a loss as to the asnwer to the main question here though:

          "Do I need to create a VLAN on each switch, assign it to a LAG Group, and then assign ports as members of the LAG Group. Or, can I just assign ports to the LAG Group without worrying about the VLAN part of it?"

          Is there anyone else who can shed any light? I would love to just go for it and see what happens but the switch is in production and I can't really play too much at the moment without coming in during the night :P
          I nerd therefore I am!

          Comment

          Working...
          X