3750 and routing question.

Discussion in 'Cisco' started by newsacct8080, Sep 9, 2010.

  1. newsacct8080

    newsacct8080 Guest

    we have a location mile away from the headquarter and until last week,
    it had a 100M wifi link, We just got another set of radios installed
    so there is a gig link (unused at the moment) now between the 2
    buildings too.

    all 4 radios terminate in a 3750 on either side and I am wondering if
    there is smarter way to use those links and not just channel bond them
    so they fail over for each other. I can push routing to those switches
    if need be but I am interested in using the 100M link just for
    critical traffic (remote desktop and telnet) and the gig link for
    commodity browsing and backups etc. so 100M link is really dedicated
    just for this one application that is housed at that building.
    Currently we can't back anything up over there because 100M link is
    nearly maxed out with just browser traffic.

    anyone got any suggestion? I am happy to do some reading but just need
    some direction.

    Thanks,
     
    newsacct8080, Sep 9, 2010
    #1
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  2. newsacct8080

    bod43 Guest

    On 9 Sep, 20:50, newsacct8080 <> wrote:
    > we have a location mile away from the headquarter and until last week,
    > it had a 100M wifi link, We just got another set of radios installed
    > so there is a gig link (unused at the moment) now between the 2
    > buildings too.
    >
    > all 4 radios terminate in a 3750 on either side and I am wondering if
    > there is smarter way to use those links and not just channel bond them
    > so they fail over for each other. I can push routing to those switches
    > if need be but I am interested in using the 100M link just for
    > critical traffic (remote desktop and telnet) and the gig link for
    > commodity browsing and backups etc. so 100M link is really dedicated
    > just for this one application that is housed at that building.
    > Currently we can't back anything up over there because 100M link is
    > nearly maxed out with just browser traffic.
    >
    > anyone got any suggestion? I am happy to do some reading but just need
    > some direction.
    >
    > Thanks,


    Zerothly, I wouldn't bother with this unless it
    was proved nevessary.

    Firstly be aware that the 3750 is a hardware router
    that can use software routing in some circumstances.
    The software routing performance will be rather poor.

    I have no idea if PBR is handled in hardware on the 3750
    but I doubt it very much.


    I think you will need to use Policy Based Routing.

    PBR is manually configured and can choose output
    interface or next-hop IP depending on arbitrary
    access-list matching.

    If an interface is down it can fall back to routing via the
    routing table.

    If your hardware does not force the router interface down
    on radio link loss you could perhaps use the SLA facility to
    force the interface down if the link is lost..

    http://www.cisco.com/en/US/tech/tk920/tsd_technology_support_sub-protocol_home.html

    Cisco IOS IP Service Level Agreements An Overview, External (PPT - 2
    MB)
    Cisco IOS IP Service Level Agreements Technical Overview (PPT - 2 MB)

    Good luck.
     
    bod43, Sep 9, 2010
    #2
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  3. newsacct8080

    donb80

    Joined:
    Sep 10, 2010
    Messages:
    2
    If you have routing interfaces at both sides then you can do a failover via administratively distanced routes

    IE:

    10.252.10.1 being the other end of the gigabit radio
    10.252.11.1 being the other end of the 100mbit radio
    10.0.0.0/24 being your network

    ip route 10.0.0.0 255.255.255.0 10.252.10.1 100
    ip route 10.0.0.0 255.255.255.0 10.252.11.1 101

    Then just add reciprocal/default routes at the other side. If the gig goes down, the route with the admin distance of 101 will install into your routing table at each end.

    You can also setup OSPF and assign appropriate costs to each interface. If the physical ethernet media is different (ie one's port is 100M and the other is 1000M) then OSPF should be able to setup failover without setting interface costs. If they're both 1000M ports then it's going to try to load balance them by default. In this case you will need to setup costs.

    If you're wanting to send certain traffic in/out a certain interface during normal operation, you will need to use PBR.
     
    donb80, Sep 10, 2010
    #3
  4. newsacct8080

    Stephen Guest

    On Thu, 9 Sep 2010 12:50:27 -0700 (PDT), newsacct8080
    <> wrote:

    >we have a location mile away from the headquarter and until last week,
    >it had a 100M wifi link, We just got another set of radios installed
    >so there is a gig link (unused at the moment) now between the 2
    >buildings too.
    >
    >all 4 radios terminate in a 3750 on either side and I am wondering if
    >there is smarter way to use those links and not just channel bond them
    >so they fail over for each other.


    You do not want to channel bond links with widely different speeds.

    Ganging Ethernet pipes together uses various ways to share traffic,
    but all the simple schemes (which is all that will work on a switch at
    GigE) assume all pipes have the same speed.

    The net effect will be approx N x slowest link = 200 Mbps in your
    case.

    whereas your fastest link is 1 G - so more complications and hassle
    for 1/5 the throughput.......

    I can push routing to those switches
    >if need be but I am interested in using the 100M link just for
    >critical traffic (remote desktop and telnet) and the gig link for
    >commodity browsing and backups etc. so 100M link is really dedicated
    >just for this one application that is housed at that building.
    >Currently we can't back anything up over there because 100M link is
    >nearly maxed out with just browser traffic.


    Run the 2 links as routed.

    set the costs so your traffic "prefers" the GigE link, and use the
    100M as a backup (note this assumes that when you lose something there
    is a fighting chance the GigE breaks but the 100M doesnt - if not,
    dont bother).

    use QoS and possibly shaping to handle the special app - that way you
    can have different bandwidth setups, and rate limit how much it takes
    so other traffic gets serviced.

    3750 has pretty good QoS, but not much buffering - but with higher
    speed links that doesnt matter so much. Tinker with the buffer pools
    at your peril....

    it is also one of the few relatively cheap switches that can rate
    limit and also do QoS on the same port.
    So - if your GigE radio link is really say 400 Mbps, the switch can be
    set up to cope with that and still use QoS.....
    >
    >anyone got any suggestion? I am happy to do some reading but just need
    >some direction.
    >
    >Thanks,

    --
    Regards

    - replace xyz with ntl
     
    Stephen, Sep 11, 2010
    #4
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