7204 vxr fa mtu

Discussion in 'Cisco' started by no@no.no, Feb 22, 2006.

  1. Guest

    I have two locations connected over ATM network. On both locations I have
    systems that communicate over IP and need mtu to be not less then 2500 over
    whole path (fiber over IP switches from Cisco). But I cannot set mtu to
    2500 on fast eth ports on 7204 (NP225). What are my options?

    Thanks!
    , Feb 22, 2006
    #1
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  2. Merv Guest

    Do you own all of the equipment end -to-end ?

    What are the Cisco switch model numbers ?
    Merv, Feb 22, 2006
    #2
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  3. Merv Guest

    Oh and what else do the 7204's connect to ?
    Merv, Feb 22, 2006
    #3
  4. Guest

    On 22 Feb 2006 14:22:13 -0800, Merv wrote:

    > Oh and what else do the 7204's connect to ?


    yes I do own it and I am not sure about switches exactly, routers are
    connected to 4506 and those fiberoverip switches are connected to 4506
    also. Point is that fiberoverip link is not working and storage people are
    telling me that mtu MUST be 2500. But we did some tests with both storage
    systems on one location, connected over 10M half duplex eth and default
    1500 mtu and everything worked ok.
    , Feb 22, 2006
    #4
  5. Merv Guest

    Do the data flows have to go thru your router or can they just flow
    over you 4506 switches ?

    What supervisor do you have on the 4506 - SUP V ?

    If you have a SUP V, are you using the GE ports ?

    Do you know the make and model of the SAN storage devices ?

    Do you know the performance and throughput requirements for the storage
    devices ?
    Merv, Feb 23, 2006
    #5
  6. Drx Guest

    On 23 Feb 2006 01:33:31 -0800, Merv wrote:

    > Do the data flows have to go thru your router or can they just flow
    > over you 4506 switches ?
    >
    > What supervisor do you have on the 4506 - SUP V ?
    >
    > If you have a SUP V, are you using the GE ports ?
    >
    > Do you know the make and model of the SAN storage devices ?
    >
    > Do you know the performance and throughput requirements for the storage
    > devices ?


    they have to go through switches. SAN switches are MDS 9216. On 4506 sup
    mod is II+ and SAN switch is connected to ports that support jumbo frames
    (2 GBIC on sup mod). SAN devices are some kind of EMC disks. I do not know
    throughput requirements but in this stage I need to solve jumbo frames on
    complete path between SANs, wich means MDS - 4506 - 7204 - ATM network -
    7204 - 4506 - MDS. So far I am stuck with 7204 eth ports.
    Drx, Feb 23, 2006
    #6
  7. Merv Guest

    Your last post really clarified your setup - thanks.

    Is the only role that the 7204 plays is to connect 4506 to ATM WAN ?

    Or are there other devices connected to 4506?
    Merv, Feb 23, 2006
    #7
  8. Drx Guest

    On 23 Feb 2006 01:45:45 -0800, Merv wrote:

    > Your last post really clarified your setup - thanks.
    >
    > Is the only role that the 7204 plays is to connect 4506 to ATM WAN ?
    >
    > Or are there other devices connected to 4506?


    other devices also. Both locations I am talking about has cca 200 people
    working on it. ATM link is 6Mb between locations. There is QOS on link and
    I can ping between MDS switches
    Drx, Feb 23, 2006
    #8
  9. Merv Guest

    7204 options for Gigabit Ethernet connection to 4506 switch

    MTU can be as high as 4470

    a) NPE-GE1

    b) PA-GE
    Merv, Feb 23, 2006
    #9
  10. Drx Guest

    On 23 Feb 2006 02:04:09 -0800, Merv wrote:

    > 7204 options for Gigabit Ethernet connection to 4506 switch
    >
    > MTU can be as high as 4470
    >
    > a) NPE-GE1
    >
    > b) PA-GE


    I know but I do not have those interfaces. So I have two options

    1. eithere buy them
    2. or convince SAN guys that MTU higher then 2500 is not MANDATORY

    I've read som doc about this and I think that MTU highrt then 2500 is not
    mandatory. What do you think?
    Drx, Feb 23, 2006
    #10
  11. Merv Guest

    Merv, Feb 23, 2006
    #11
  12. Drx Guest

    On 23 Feb 2006 02:43:05 -0800, Merv wrote:

    > A bigger MTU will probably provide higher throughput between the SAN
    > devices.
    >
    > What is essential is not to end up fragmenting packets.
    >
    > For starter take a look at the following Cisco doc:
    > http://www.cisco.com/application/pdf/en/us/guest/netsol/ns378/c649/cdccont_0900aecd800ed145.pdf


    this is my opinio also. But because link between locations is ATM, we
    cannot avoid fragmentation. Am I right? And on one side it is E3 connection
    to ATM network and on other location it is 8xE1 IMA group, yet another
    source of fragmentation and mybe "out-of-order" packets. But mybe because
    fragmentation is on layer 2, mybe TCP packet i reasamled ok? What do you
    think?

    Thanks!
    Drx, Feb 23, 2006
    #12
  13. Merv Guest

    When I was speaking of fragmentation it was at layer 3 (i.e. IP
    fragmentation).

    Clearly with ATM there is L2 fragmentation.

    I would suggest that you baseline the busy-hour ATM link utilization
    and latency before the SAN load is imposed.

    >From page 7 of the Cisco doc you can see why "they" are asking for an

    MTU of 2500.
    Lower MTU(i.e. 1500) will work but throughput for SAN will not be as
    good.

    You should also consider whether you want the SAN traffic going thru
    your 4506 switches or whether it should go directly into the 7204 using
    a PA-FC-1G. Also you will need to determin if the 7204 will need a
    processor upgrade.

    Are your running VOIP over the ATM link ?
    Merv, Feb 23, 2006
    #13
  14. Drx Guest

    On 23 Feb 2006 05:49:06 -0800, Merv wrote:

    > When I was speaking of fragmentation it was at layer 3 (i.e. IP
    > fragmentation).
    >
    > Clearly with ATM there is L2 fragmentation.
    >
    > I would suggest that you baseline the busy-hour ATM link utilization
    > and latency before the SAN load is imposed.
    >
    >>From page 7 of the Cisco doc you can see why "they" are asking for an

    > MTU of 2500.
    > Lower MTU(i.e. 1500) will work but throughput for SAN will not be as
    > good.
    >
    > You should also consider whether you want the SAN traffic going thru
    > your 4506 switches or whether it should go directly into the 7204 using
    > a PA-FC-1G. Also you will need to determin if the 7204 will need a
    > processor upgrade.
    >
    > Are your running VOIP over the ATM link ?


    :)) yes we are running voip. I guess we can replace MDS switches on both side wirh PA-FC-1G modules?
    Drx, Feb 23, 2006
    #14
  15. Merv Guest

    1. Do you have low latency queueing(LLQ) configured for VOIP

    2. Do you have a Cisco SE or do you acquire your gear thru a
    distributor?

    3. Do you have a detailed VISIO diagram for the current setup ( I can
    provided private email id)
    Merv, Feb 23, 2006
    #15
  16. Merv Guest

    OBTW what are the availability requirements for the SAN to SAN
    connection over your WAN ?
    Merv, Feb 23, 2006
    #16
  17. Guest

    On 23 Feb 2006 07:23:50 -0800, Merv wrote:

    > 1. Do you have low latency queueing(LLQ) configured for VOIP
    >
    > 2. Do you have a Cisco SE or do you acquire your gear thru a
    > distributor?
    >
    > 3. Do you have a detailed VISIO diagram for the current setup ( I can
    > provided private email id)


    1. yes
    2. distributor
    3. will see tommorow
    , Feb 23, 2006
    #17
  18. Guest

    On 23 Feb 2006 07:49:07 -0800, Merv wrote:

    > OBTW what are the availability requirements for the SAN to SAN
    > connection over your WAN ?


    offline sinc, over night, not real time
    , Feb 23, 2006
    #18
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