Re: LAN<-->WAN<-->LAN ; L3 switches or Routers??

Discussion in 'Cisco' started by qazmlp1209@rediffmail.com, Jul 26, 2006.

  1. Guest

    > > So something to consider is what hardware you need to interface to the WAN.
    >
    > This is a good point as while Cisco high-end switches like the 6500
    > have FLEXWAN card to support more than just Ethernet connectivity this
    > is not the case on their low end switches.
    >
    > So you might need routers and switches depending on the WAN transport
    > options available.

    As I am aware, the following are the possible WAN transport options:
    - Point to point private links
    - Gigabit Ethernet
    - ATM
    - Frame Relay
    - SDH/SONET

    What do you suggest for each of the above-mentioned WAN transport
    options? Why?
    Also, should the replacement cost also be considered while taking this
    decision?
    , Jul 26, 2006
    #1
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  2. stephen Guest

    <> wrote in message
    news:...
    > > > So something to consider is what hardware you need to interface to the

    WAN.
    > >
    > > This is a good point as while Cisco high-end switches like the 6500
    > > have FLEXWAN card to support more than just Ethernet connectivity this
    > > is not the case on their low end switches.
    > >
    > > So you might need routers and switches depending on the WAN transport
    > > options available.

    > As I am aware, the following are the possible WAN transport options:


    i was trying to point out that just because this is possible on a 6500
    doesnt mean it is a good idea.

    Personally i would try to use "real" routers for low end stuff, and LAN
    optimised kit like a 6509 for Ethernet WAN connections.

    > - Point to point private links


    this could be almost anything - usually PDH or SDH links - E1, T1, E3,
    STM-1. easiest used to be flexWAN with 7200 style port adaptors (basically a
    VIP if you know the 75xx routers). SPA can do the same for some interfaces.

    for "low speed" say up to 2 Mbps / 34 Mbps it may be cheaper and more
    flexible to use a separate router.

    > - Gigabit Ethernet

    just plug it into the Cat. Main issue is if you buy a rate limited port (ie.
    20 Mbps of bandwidth presented on a 1 Gbps link). Normal LAN type ports on
    the Cat cannot do traffic rate limiting in conjunction with QoS, but the
    high end modules such OSM support this if you need it.

    i understand cisco now recommend the SPA for this.

    Same reasoning goes for the different speed ports 10G, 100M and 10M as long
    as they are presented as Ethernet.

    > - ATM

    flexWAN adaptor or SPA.

    pretty much obsolete for new links, but lots around and you might want it if
    you already have
    > - Frame Relay

    same as a serial (up to 34 Mbps, although not many high speed F/R links.
    > - SDH/SONET


    OSM or SPA.

    If you have lots of SDH, then you probably dont want a 6509.

    However that much derided animal the SDH mux can give you very cheap wire
    speed GigE thru SDH...... and if you have 10G SDH (STM-64 or SONET 192),
    then a modern lambda transport will normally also support 10G Ethernet LAN
    PHY - so use the Ethernet presentation instead.
    >
    > What do you suggest for each of the above-mentioned WAN transport
    > options? Why?
    > Also, should the replacement cost also be considered while taking this
    > decision?


    not sure what you mean here - there is an "oppotunity cost" - ie putting low
    speed ports into a high speed chassis like a 6509 eats up slots but doesnt
    give much thruput.

    But - the cost of a slot in a 6509 is much less than in a more conventional
    router - at work the "real" high end routers used to be7513s, and GSR12008.
    Now new units are 10008s, GSR1241x, CRS-1.... (this is where the phrase
    "carrier class" is used to justify 5 times the price for 1/3 or less ports,
    although to be fair the boxes support much richer QoS, aggregated interfaces
    and so on).

    For some of the big iron routers a single card with a couple of ports costs
    more than a 6509 full of LAN blades, so if the relatively reduced feature
    set of the 6509 is "good enough", the cost per Gbps of the 6509 is much
    better
    >

    --
    Regards

    - replace xyz with ntl
    stephen, Jul 26, 2006
    #2
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