3750G Question

Discussion in 'Cisco' started by ec, Apr 6, 2004.

  1. ec

    ec Guest

    I am looking at a 500 node network with a 4510R at the MDF. I need to
    replace 3 IDF switches, each of which has 10-24 switches uplinked to it.
    Right now they are linked to the IDF at 100Mbps, and I am upgrading the
    backbone to Gigabit using the 6 GBIC line cards for the 4510, so would like
    to extend at least 1Gbps to each access switch. I have 4 strands of fiber at
    each IDF which I can use to uplink the new switches at 2Gbps GEtherchannel
    tot he 4510. So, it would be: Access switch -> IDF Switch -> MDF. This
    network is a campus network, and the cabling design cannot be changed at
    this time. I was wondering about using the 3750G-24TS at the IDF's. It has
    24 10/100/1000 ports and 4 SFP ports. The access switches are all
    2950T-24's. These are 24 port 10/100 switches with copper gigabit uplinks.
    My question is, would the 3750G-24TS be good in the IDF? The client will not
    buy a more expensive modular switch like the 4506 or similar which I would
    prefer for the IDF's. I can't find in the Cisco docs on the 3750 if all 24
    of those ports can be trunk links, ie, are they non blocking or not. Can
    anyone shed some light here?
    ec, Apr 6, 2004
    #1
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  2. ec

    Jeff C Guest

    "ec" <> wrote in news:iOncc.44125$wl1.43291@fed1read06:

    > I am looking at a 500 node network with a 4510R at the MDF. I need to
    > replace 3 IDF switches, each of which has 10-24 switches uplinked to
    > it. Right now they are linked to the IDF at 100Mbps, and I am
    > upgrading the backbone to Gigabit using the 6 GBIC line cards for the
    > 4510, so would like to extend at least 1Gbps to each access switch. I
    > have 4 strands of fiber at each IDF which I can use to uplink the new
    > switches at 2Gbps GEtherchannel tot he 4510. So, it would be: Access
    > switch -> IDF Switch -> MDF. This network is a campus network, and the
    > cabling design cannot be changed at this time. I was wondering about
    > using the 3750G-24TS at the IDF's. It has 24 10/100/1000 ports and 4
    > SFP ports. The access switches are all 2950T-24's. These are 24 port
    > 10/100 switches with copper gigabit uplinks. My question is, would the
    > 3750G-24TS be good in the IDF? The client will not buy a more
    > expensive modular switch like the 4506 or similar which I would prefer
    > for the IDF's. I can't find in the Cisco docs on the 3750 if all 24
    > of those ports can be trunk links, ie, are they non blocking or not.
    >


    With a backplane speed of 32 Gbps (IIRC) all of the ports on the 3750 are
    "non-blocking" of course if you are aggregating 24 gigabit copper ports
    to 2 gigabit uplink ports so there is going to be a bottleneck in the
    design. All of the ports can function as trunk ports from what I recall
    but I have never installed one in that manner.

    The 3750 has a few different limitations including a maximum of 12
    etherchannel connections (fine you say there are only 24 ports that is
    until you "stack" multiple switches together)

    In reguards to this I think I saw a document on Cisco's site concerning
    network design indicating a suggested 8 to one ratio between access and
    distribution and 4 to one ratio from distribution to core.

    Some of the above is from memory and some from experiance. Double check
    anything I say before you make any final decisions as I am not an
    engineer.

    -Jeff C
    Jeff C, Apr 6, 2004
    #2
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  3. Jeff C <> wrote in message news:<x4rcc.26822$Q45.22859@fed1read02>...
    > "ec" <> wrote in news:iOncc.44125$wl1.43291@fed1read06:
    >
    > > I am looking at a 500 node network with a 4510R at the MDF. I need to
    > > replace 3 IDF switches, each of which has 10-24 switches uplinked to
    > > it. Right now they are linked to the IDF at 100Mbps, and I am
    > > upgrading the backbone to Gigabit using the 6 GBIC line cards for the
    > > 4510, so would like to extend at least 1Gbps to each access switch. I
    > > have 4 strands of fiber at each IDF which I can use to uplink the new
    > > switches at 2Gbps GEtherchannel tot he 4510. So, it would be: Access
    > > switch -> IDF Switch -> MDF. This network is a campus network, and the
    > > cabling design cannot be changed at this time. I was wondering about
    > > using the 3750G-24TS at the IDF's. It has 24 10/100/1000 ports and 4
    > > SFP ports. The access switches are all 2950T-24's. These are 24 port
    > > 10/100 switches with copper gigabit uplinks. My question is, would the
    > > 3750G-24TS be good in the IDF? The client will not buy a more
    > > expensive modular switch like the 4506 or similar which I would prefer
    > > for the IDF's. I can't find in the Cisco docs on the 3750 if all 24
    > > of those ports can be trunk links, ie, are they non blocking or not.
    > >

    >
    > With a backplane speed of 32 Gbps (IIRC) all of the ports on the 3750 are
    > "non-blocking" of course if you are aggregating 24 gigabit copper ports
    > to 2 gigabit uplink ports so there is going to be a bottleneck in the
    > design. All of the ports can function as trunk ports from what I recall
    > but I have never installed one in that manner.
    >
    > The 3750 has a few different limitations including a maximum of 12
    > etherchannel connections (fine you say there are only 24 ports that is
    > until you "stack" multiple switches together)
    >
    > In reguards to this I think I saw a document on Cisco's site concerning
    > network design indicating a suggested 8 to one ratio between access and
    > distribution and 4 to one ratio from distribution to core.
    >
    > Some of the above is from memory and some from experiance. Double check
    > anything I say before you make any final decisions as I am not an
    > engineer.
    >
    > -Jeff C


    I like the 8 to 1 number, but in a webinar on Gig to the desktop they
    claimed 20 to 1, and that there was no noticable problem at 40 to 1.
    I'm not sure I beleive it. I prefer to design with the 8 to 1.
    Trent Collicutt, Apr 17, 2004
    #3
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