To BGP or not to BGP (multihoming with ISPs over uneven links speed)?!?

Discussion in 'Cisco' started by papi, Mar 26, 2005.

  1. papi

    papi Guest

    I have two providers, of whom one offers me a DS3, and the other a T1. I
    was thinking of using BGP, but I am not sure if there are ways of load
    balancing in such a way that inbound and outbound traffic happen in the
    same proportion as the port speed I have with each. If not - what other
    options would you see being available for such a setup? My last resort is
    to use the T1 as backup (passive), and run all traffic exclusively over
    the DS3, under normal circumstances ... but this would be such a waste ...

    TIA,
    Papi
     
    papi, Mar 26, 2005
    #1
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  2. Re: To BGP or not to BGP (multihoming with ISPs over uneven linksspeed)?!?

    On 26.03.2005 18:34 papi wrote

    > I have two providers, of whom one offers me a DS3, and the other a T1. I
    > was thinking of using BGP, but I am not sure if there are ways of load
    > balancing in such a way that inbound and outbound traffic happen in the
    > same proportion as the port speed I have with each. If not - what other
    > options would you see being available for such a setup? My last resort is
    > to use the T1 as backup (passive), and run all traffic exclusively over
    > the DS3, under normal circumstances ... but this would be such a waste ...


    So what is your normal need? A T1 or a DS3? If it is more a DS3 then get
    rid of the T1 and get another DS3. If it is more T1 than you might want
    to get rid of the DS3. Otherwise just turn on your BGP and watch how
    traffic settles.

    BGP was in no way designed to do traffic engineering. It's a
    reachability protocol. It's only metric is AS hop.

    Of course there are several ways to trim you BGP. But doing this with a
    T1 and a DS3 is a complete waste of time.


    Arnold
    btw: Who told you that you will be able to use both links?
    --
    Arnold Nipper, AN45
     
    Arnold Nipper, Mar 26, 2005
    #2
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  3. papi

    papi Guest

    On Sat, 26 Mar 2005 18:56:47 +0100, Arnold Nipper wrote:

    > On 26.03.2005 18:34 papi wrote
    >
    >> I have two providers, of whom one offers me a DS3, and the other a T1. I
    >> was thinking of using BGP, but I am not sure if there are ways of load
    >> balancing in such a way that inbound and outbound traffic happen in the
    >> same proportion as the port speed I have with each. If not - what other
    >> options would you see being available for such a setup? My last resort is
    >> to use the T1 as backup (passive), and run all traffic exclusively over
    >> the DS3, under normal circumstances ... but this would be such a waste ...

    >
    > So what is your normal need? A T1 or a DS3? If it is more a DS3 then get
    > rid of the T1 and get another DS3. If it is more T1 than you might want
    > to get rid of the DS3. Otherwise just turn on your BGP and watch how
    > traffic settles.
    >
    > BGP was in no way designed to do traffic engineering. It's a
    > reachability protocol. It's only metric is AS hop.
    >
    > Of course there are several ways to trim you BGP. But doing this with a
    > T1 and a DS3 is a complete waste of time.
    >
    >
    > Arnold
    > btw: Who told you that you will be able to use both links?


    1. I have right now a setup with two ISPs, with different fiber runs
    and POPs, belonging to two major carriers (for redundancy), each with
    a T1, running "simple" BGP
    2. I am upgrading one of the T1s to a DS3
    3. The initial thought was to run everything over the DS3, and have the T1
    to the other provider as a "backup"
    4. While planning for "3." above - I thought of putting the remaining T1,
    actually, to some use, instead of letting it got "to waste" (i.e. no
    interruption in the DS3 ==> no use for the T1 ==> waste)

    Papi
     
    papi, Mar 26, 2005
    #3
  4. Re: To BGP or not to BGP (multihoming with ISPs over uneven linksspeed)?!?

    On 26.03.2005 19:54 papi wrote

    > 1. I have right now a setup with two ISPs, with different fiber runs
    > and POPs, belonging to two major carriers (for redundancy), each with
    > a T1, running "simple" BGP
    > 2. I am upgrading one of the T1s to a DS3
    > 3. The initial thought was to run everything over the DS3, and have the T1
    > to the other provider as a "backup"
    > 4. While planning for "3." above - I thought of putting the remaining T1,
    > actually, to some use, instead of letting it got "to waste" (i.e. no
    > interruption in the DS3 ==> no use for the T1 ==> waste)
    >


    Again: if you really need more than a T1, upgrade the second to DS3 as
    well (or fractional DS3). If not you will run in big trouble when your
    DS3 fails. In that case most customers find it better to have no
    connectivity instead of a very lousy.

    Of course you could also engineer the T1 to allow only premium traffic
    and traffic anything else on the florr. Generally this is PITA.



    Nopte buna, Arnold
    --
    Arnold Nipper, AN45
     
    Arnold Nipper, Mar 26, 2005
    #4
  5. papi

    theapplebee

    Joined:
    Jun 19, 2009
    Messages:
    67
    Location:
    USA
    Unfortunately, BGP is not good for load-sharing by traffic ratio.
    If you have unequal bandwidth link, you need to play with your route announcement for in/outbound traffic.
    Yes, it is pain in the butt

    See below article about Cisco BGP configuration

    http://showipbgp.com/bgp-configurations/cisco.html
     
    Last edited: Sep 11, 2009
    theapplebee, Sep 8, 2009
    #5
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