Cat 4000/4500/5000/6000: router or switch?

Discussion in 'Cisco' started by Walter Roberson, Oct 22, 2004.

  1. I wonder if someone could explain briefly why the Cat 4000,
    4500, 5000, and 6000 are classified by Cisco as Switches instead of
    Routers?

    I can see the point for the 5000 line, in that the 5000
    just does layer 2 unless you add in the optional RSM, and
    people really do use the 5000 as a pure switch. Probably
    some of the 4000 line too.

    In particular why is the new 4503 classed as a switch, when
    the lowest supervisor engine you can get for it (Supervisor II+)
    has layer 3 routing and supports traditional router-only
    features such as GRE (in software until you get to the IV engine) ?

    I'm accustomed to the 3550 and 3750 series being referred to
    as "multilayer switches", as they do not support software
    interfaces such as loopbacks and GRE tunnels... but the 450x line
    does support those.

    And where does the new 4948 "multilayer switch" fit into this?
    It is fixed configuration (like the 2950/3550/3750 in that
    regard), but with the -E software supports OSPF, EIGRP and
    some other unspecified goodies [I can't find the list of
    differences.]

    The feature navigator claims that the 4500 with the new
    Supervisor Engine II+TS does not support GRE tunnels, but the
    release (20) release notes say that all the 4500 support GRE.
    The feature navigator either doesn't know about the 4948 yet or
    else classifies it as being part of some other family
    (e.g., the 4000)


    A semi-related question: if I am looking for gigabit ports
    (mostly TX but some SPF or GBIC), layer 3 routing, and QoS
    with traffic control, and (not sure yet) perhaps room for
    expansion into VOIP, and I do not need any non-ethernet connections
    (such as T1), then what would be reason I would go for the new 3845
    "router" instead of (say) the new C4503-II+TS-48GB
    bundle, which is a 4503 chassis and power supply, software,
    and a 48 port 10/100/1000 card that has some SPFs thrown in?
    (This bundle does not appear to be documented by Cisco, but it
    is listed by some stores.) ?
     
    Walter Roberson, Oct 22, 2004
    #1
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  2. Hello, Walter!
    You wrote on 22 Oct 2004 19:40:23 GMT:

    WR> I wonder if someone could explain briefly why the Cat 4000,
    WR> 4500, 5000, and 6000 are classified by Cisco as Switches instead
    WR> of Routers?

    For marketing and historical reasons?

    WR> And where does the new 4948 "multilayer switch" fit into this?
    WR> It is fixed configuration (like the 2950/3550/3750 in that
    WR> regard), but with the -E software supports OSPF, EIGRP and
    WR> some other unspecified goodies [I can't find the list of
    WR> differences.]

    4948 looks like Sup V in a stackable form. It's more powerful than 3750 - more
    TCAM, more RAM - but has a smaller footprint than normal 4500.

    WR> A semi-related question: if I am looking for gigabit ports
    WR> (mostly TX but some SPF or GBIC), layer 3 routing, and QoS
    WR> with traffic control, and (not sure yet) perhaps room for
    WR> expansion into VOIP, and I do not need any non-ethernet
    WR> connections (such as T1), then what would be reason I would go
    WR> for the new 3845 "router" instead of (say) the new
    WR> C4503-II+TS-48GB bundle, which is a 4503 chassis and power
    WR> supply, software, and a 48 port 10/100/1000 card that has some
    WR> SPFs thrown in? (This bundle does not appear to be documented by
    WR> Cisco, but it is listed by some stores.) ?

    One reason would be if you need PSTN gateway for VoIP and want to have
    everything in one box. Than 3845 will be a better solution for a small office.
    Be careful with Sup II-PLUS-TS though - it only works in 4503. 48 10/100/1000
    card has it's own trick - since each slot in 4500 series has only 6Gbps
    connection to Supervisor, ports on this card are heavily oversubscribed - 8:1.

    With best regards,
    Andrey.
     
    Andrey Tarasov, Oct 22, 2004
    #2
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  3. :Be careful with Sup II-PLUS-TS though - it only works in 4503. 48 10/100/1000
    :card has it's own trick - since each slot in 4500 series has only 6Gbps
    :connection to Supervisor, ports on this card are heavily oversubscribed - 8:1.

    That's a good piece of information to have.

    According to the data sheets, the Sup II+, Sup IV, and Sup V in the 4503
    are 28 Gbps and are 64 Gbps in the 4506 or 4507R; also the data sheets
    indicate that the Sup II+TS in the 4503 is 64 Gbps.

    http://www.cisco.com/en/US/products/hw/switches/ps4324/products_data_sheet0900aecd801792b1.html

    If we ignore the Sup II+TS for the moment, and split the 21 Gbps over 3
    slots, the implication would be 7 Gbps. If 6 is the maximum the bus
    will put through, then the implication could just be that the switch
    fabric is faster than the bus and so that the Supervisor has "spare steam".
    But when I look at the 64 rating for the 6 or 7 slot units, 64/6 and
    64/7 are both more than the 6 Gbps that you mention. The Sup II+ is
    not supported in the 10 slot unit.. if it were, 64/10 would at least be
    close to the 6 Gbps you mention. The 10 slot unit requires Sup V,
    which is rated at 96 Gbps, which would still be more than 6 Gbps per slot.
    It does not make sense to me that they would bother requiring a higher
    speed supervisor when the lower end one already has spare capacity??

    I've looked through several of the datasheets now, and I do not see 6 Gbps
    per slot mentioned anywhere. Would you have a link to that figure?


    Either way, the fact does still remain that with the 4503 and its
    28 Gbps limit, a 48 port gig card is going to oversubscribe the fabric
    by about 2:1 [unless the switching doesn't have to go through the fabric
    if the destination is on the same line card... then it would be down to
    traffic patterns] and the problem would only get worse if one
    expanded to 96 ports (2 x 48). The 4948 I see has 96 Gbps switch
    fabric, which is undersubscribed 1:2... but one could imagine
    something like that it had two separate 48 Gbps fabrics, one for input
    and the other for output.
     
    Walter Roberson, Oct 22, 2004
    #3
  4. :4948 looks like Sup V in a stackable form. It's more powerful than 3750 - more
    :TCAM, more RAM - but has a smaller footprint than normal 4500.

    I just had another look at the specs on the 4948; I do not see any
    stackability ?


    : WR> no connections (such as T1), then what would be reason I would go
    : WR> for the new 3845 "router" instead of (say) the new
    : WR> C4503-II+TS-48GB bundle, which is a 4503 chassis and power

    :One reason would be if you need PSTN gateway for VoIP and want to have
    :everything in one box. Than 3845 will be a better solution for a small office.

    Looking at the 4000/4500 series cards -- is there a difference between
    the PSTN gateway you mention, and the facilities provided by the VIC-2FXS
    or VIC-2FXO, or VIX-2FXO-EU ?
     
    Walter Roberson, Oct 22, 2004
    #4
  5. Hello, Walter!
    You wrote on 22 Oct 2004 21:50:49 GMT:

    WR> According to the data sheets, the Sup II+, Sup IV, and Sup V in
    WR> the 4503 are 28 Gbps and are 64 Gbps in the 4506 or 4507R; also
    WR> the data sheets indicate that the Sup II+TS in the 4503 is 64
    WR> Gbps.

    And that goes like this - (6Gbps x 2 slots + 1Gbs x 2 ports on Sup) x 2 for
    full-duplex = 28Gbps in case of 4503. For 4506 and 4507R it would be (6 x 5 + 1
    x 2) x 2 = 64Gbps.

    WR> Gbps you mention. The 10 slot unit requires Sup V, which is rated
    WR> at 96 Gbps, which would still be more than 6 Gbps per slot. It
    WR> does not make sense to me that they would bother requiring a
    WR> higher speed supervisor when the lower end one already has spare
    WR> capacity??

    With Sup V it's a little bit different - 8 slots x 6Gbps + 4 ports x 1Gbps
    (because you can have 2 Sups and both ports will be active, which is not the
    case for Sup IV) should give us 104Gbps but there is only 96. And I just found
    an explanation how Cisco pulls it off -
    ....
    *When Supervisor V is used in the 4510R chassis, Slot 10 (Flex-slot) will
    support a sub-set of linecards: 2-port GBIC (WS-X4302-GB) and Access Gateway
    Module (WS-X4604-GWY). Future Supervisor Engines will allow Slot 10 to
    accommodate any and all linecards.
    ....

    So correct formula is (7 x 6 + 4 x 1 + 2 x 1) x 2 = 96.

    WR> I've looked through several of the datasheets now, and I do not
    WR> see 6 Gbps per slot mentioned anywhere. Would you have a link to
    WR> that figure?

    It's in description of line cards and configuration guide for Etherchannel -

    ....
    The Catalyst 4000/4500 Series 6-port Gigabit Ethernet line card provides six
    ports of dedicated 1000BASE-X Gigabit Ethernet uplinks for high-speed backbone
    ....
    The Cisco Catalyst 4000/4500 Series 18-Port Gigabit Ethernet line card provides
    two ports of dedicated 1000BASE-X GBIC-based Gigabit Ethernet uplinks, as well
    as up to 16 GBIC-based ports for high-performance Gigabit Ethernet server
    connectivity. The 16 server ports can burst to Gigabit Ethernet line rate and
    share 8 Gbps of full-duplex bandwidth into the switching fabric.
    ....
    The Cisco Catalyst 4000/4500 Series 48-port 10/100/1000BASE-T line card ... The
    48 ports can burst to Gigabit Ethernet line rate and share 6 Gbps of full-duplex
    bandwidth into the switching fabric. The amount of oversubscription can be
    controlled by varying the number of ports used at 1000 Mbps.
    ....

    WR> only get worse if one expanded to 96 ports (2 x 48). The 4948 I
    WR> see has 96 Gbps switch fabric, which is undersubscribed 1:2...
    WR> but one could imagine something like that it had two separate 48
    WR> Gbps fabrics, one for input and the other for output.

    No, 4948 is indeed has 96Gbps fabric. 48 ports x 1Gbps x 2 for full-duplex.

    With best regards,
    Andrey.
     
    Andrey Tarasov, Oct 23, 2004
    #5
  6. Hello, Walter!
    You wrote on 22 Oct 2004 21:59:04 GMT:

    WR> I just had another look at the specs on the 4948; I do not see
    WR> any stackability ?

    I don't think it will provide one. You still can daisy-chain them via regular
    GigE ports.

    WR> Looking at the 4000/4500 series cards -- is there a difference
    WR> between the PSTN gateway you mention, and the facilities provided
    WR> by the VIC-2FXS or VIC-2FXO, or VIX-2FXO-EU ?

    Well, I had something along T1 or PRI card in mind. There is AGM module for 4500
    where you can plug those (and FXO/FXS cards also) but I don't know much about
    it.

    With best regards,
    Andrey.
     
    Andrey Tarasov, Oct 23, 2004
    #6
  7. Walter Roberson

    AnyBody43 Guest

    I received the "8 Gbps" story for this card from a supplier but
    I did not like the looks of it at all. I assumed that it was an
    error since I suspect that "since each slot in 4500 series
    has only 6Gbps" is true.

    We have 18 ports

    2 x 1G dedicated
    16 x 1G per block of 4 ports

    = 6G and not 8G.

    Just a thought.

    As regards the subject line, since neither are precisely defined
    it is difficult to make much of it at all. Just go with the marketing
    flow, read the specs, get in tow with someone who gets access to the NDA
    material and keeps up to date.

    Cisco for example used to (and may well still do) give their Gold
    partners consutlants detailed technical briefings on the inner
    workings of all of the kit. The material was often not available
    in written form:( The problem with this approach was that unless you
    are spending quite a bit it is difficult to get access to the material
    at all since the only people who have access to it are talking to
    customers that are spending millions.
     
    AnyBody43, Oct 23, 2004
    #7
  8. Hello, AnyBody43!
    You wrote on 23 Oct 2004 13:24:43 -0700:

    ??>> The Cisco Catalyst 4000/4500 Series 18-Port Gigabit Ethernet
    ??>> line card provides two ports of dedicated 1000BASE-X GBIC-based
    ??>> Gigabit Ethernet uplinks, as well as up to 16 GBIC-based ports
    ??>> for high-performance Gigabit Ethernet server connectivity. The
    ??>> 16 server ports can burst to Gigabit Ethernet line rate and
    ??>> share 8 Gbps of full-duplex bandwidth into the switching fabric.

    A> I received the "8 Gbps" story for this card from a supplier but
    A> I did not like the looks of it at all. I assumed that it was an
    A> error since I suspect that "since each slot in 4500 series
    A> has only 6Gbps" is true.

    A> We have 18 ports

    A> 2 x 1G dedicated
    A> 16 x 1G per block of 4 ports

    A> = 6G and not 8G.

    A> Just a thought.

    8Gbps _full-duplex_ So it's 4Gbps connection shared by 1 ports. 4:1
    oversubscription.

    With best regards,
    Andrey.
     
    Andrey Tarasov, Oct 23, 2004
    #8
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