5 2960G and 1 3560G

Discussion in 'Cisco' started by Ng Son, May 21, 2008.

  1. Ng Son

    Ng Son Guest

    Hi Group,
    Please let me know if the following configration will work or not
    5 access switches 2960G 48 ports
    1 core switch 3560G 24 ports

    if I use 4 cat6 utp cables to connect one 2960G to 3650G per access
    switch and repeat this for other 4 remaining access switches

    Can I use gigabit etherchannel to make a 4G connection between access
    and core switch?
    So far I have mixed replies:
    One says yes but core switch has bottle head (A)
    One says no, the maximum bandwidth between access and core for these
    module is only 1G (B)

    WHo is right?
    Ng Son
    Ng Son, May 21, 2008
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  2. Ng Son

    Trendkill Guest

    Technically, this will work and you will have 5, 4 gig etherchannels.
    Your issue is more on switch backplane and performance. I don't deal
    with the smaller switches too much, but using a 6148 blade for a 6500
    as an example, each segment of 8 ports shares an ASIC behind the
    scenes. Each ASIC is only rated at 1 gigabit, meaning that if you did
    two four gig ethernchannels or 4 two gig etherchannels, the maximum
    throughput is still only 1 gig. Each of the 2 four gig channels would
    only get 500 megabit if running full throttle. While I don't know the
    make-up of the 2960s or 3560s, both sides are likely to have similar
    constraints. Even if the 3560 can support 4 gigs on consecutive
    ports, can the 2950? If you stagger out the ports so each channel has
    one port in 1-7, 8-15, and 16-23, you may be able to get 3-4 gigs on a
    channel to one switch at a time, but multiple channels will
    cannibalize any common hardware thresholds.

    The point is, I would consider getting two 3560s, and doing a gig or
    two from each to each 2960. This is much better for redundancy, would
    allow you to have layer 3 redundancy with HSRP, and spreads your usage
    out. I would also either split your vlans even/odd across the two
    3560s, or distribute the vlans out to the 2960s if they support layer
    3. Just my two cents.

    Perhaps someone else can speak to actual hardware thresholds on these
    Trendkill, May 21, 2008
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