Load balancing multiple bgp full feeds + some backups

Discussion in 'Cisco' started by pshemko, Dec 7, 2006.

  1. pshemko

    pshemko Guest

    Hi,

    I'm facing the following problem: we have two border routers (let's call
    them bdr1 and bdr2). We receive 3 full BGP feeds from 3 different
    providers (A,B,C), for providers A and C we have backup links (capacity
    equal to primary links) with BGP on them, but we can't use them (due to
    commercial reasons) unless the primary link for given provider is down.
    To make things more complicated links are of different capacity
    (A - 400Mb, B and C - 100Mb). Our traffic is about 60% in/ 40% out.

    So the whole picture looks like this:

    A B Cb Ab C
    | | | | |
    | | | | |
    ++-+-+--+ ++--+---+
    | bdr1 +-----+ bdr2 |
    +-------+ +-------+


    b - backup

    Currently we simply shut down BGP on the backup links manually to
    prevent any traffic on them (we got both backup links quite recently).
    But we would like to get it going in an automated manner. So far traffic
    is being load-balanced by prepending on outbound and inbound.
    I made a few experiments - I set up MED on outbound to attract traffic
    only onto primary links - that works well, but how do I prevent the
    outbound traffic from choosing the backup links (for example Ab on bdr2)?
    If I set the local preference for backup links (Ab,Cb) to a lower value
    then A,B,C then if the primary A goes down outbound traffic won't choose
    Ab as the local preference of B and C is still higher (even though they
    don't have enough capacity to handle outbound), inbound traffic will
    come through Ab as our provider honours the MED.
    Any ideas or pointers are welcome.

    kind regards
    pshemko



    --
    If want to contact me, use:
    pshem.k #@# g m a i l #.# c o m
     
    pshemko, Dec 7, 2006
    #1
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  2. pshemko

    jj19 Guest

    Have your tried prepending your local AS to the backup ISP? That way
    the AS path is lengthen on this ISP circuit.


    pshemko wrote:
    > Hi,
    >
    > I'm facing the following problem: we have two border routers (let's call
    > them bdr1 and bdr2). We receive 3 full BGP feeds from 3 different
    > providers (A,B,C), for providers A and C we have backup links (capacity
    > equal to primary links) with BGP on them, but we can't use them (due to
    > commercial reasons) unless the primary link for given provider is down.
    > To make things more complicated links are of different capacity
    > (A - 400Mb, B and C - 100Mb). Our traffic is about 60% in/ 40% out.
    >
    > So the whole picture looks like this:
    >
    > A B Cb Ab C
    > | | | | |
    > | | | | |
    > ++-+-+--+ ++--+---+
    > | bdr1 +-----+ bdr2 |
    > +-------+ +-------+
    >
    >
    > b - backup
    >
    > Currently we simply shut down BGP on the backup links manually to
    > prevent any traffic on them (we got both backup links quite recently).
    > But we would like to get it going in an automated manner. So far traffic
    > is being load-balanced by prepending on outbound and inbound.
    > I made a few experiments - I set up MED on outbound to attract traffic
    > only onto primary links - that works well, but how do I prevent the
    > outbound traffic from choosing the backup links (for example Ab on bdr2)?
    > If I set the local preference for backup links (Ab,Cb) to a lower value
    > then A,B,C then if the primary A goes down outbound traffic won't choose
    > Ab as the local preference of B and C is still higher (even though they
    > don't have enough capacity to handle outbound), inbound traffic will
    > come through Ab as our provider honours the MED.
    > Any ideas or pointers are welcome.
    >
    > kind regards
    > pshemko
    >
    >
    >
    > --
    > If want to contact me, use:
    > pshem.k #@# g m a i l #.# c o m
     
    jj19, Dec 8, 2006
    #2
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