Performance tuning and diagnosis of eth0?

Discussion in 'Cisco' started by Helmut Wollmersdorfer.at, Feb 23, 2005.

  1. This is my (simplified) configuration:

    +------------+ +--------+ +-------+
    | server .2 |------| Cisco |----| cable |
    +------------+ +-| 831 | | modem |
    | +--------+ +-------+
    +------------+ |
    | server .11 |--+ |
    +------------+ | | +--------+
    | +-| |
    +------------+ +---| switch |
    | PC .21 |------| |
    +------------+ +--------+

    The speed of the cable modem is limited to 1024 kbit/sec download and
    512 upload, connection to cisco is 10 Mbit ethernet.

    LAN is 100 Mbit including switch and NICs in the machines.

    Unfortunately I configured the LAN to eth0, which is a virtual interface
    AFAIK:

    interface Ethernet0
    ip address 192.168.0.1 255.255.255.0
    ip access-group 112 in
    no ip proxy-arp
    ip nat inside
    no ip route-cache
    no cdp enable
    hold-queue 32 in

    FastEthernet1 to 4 have no IP configured.

    interface FastEthernet1
    no ip address
    duplex auto
    speed auto

    Now the measured speeds with bing are:
    PC .21 to Cisco .1 6 Mbit
    PC .21 to Server .2 8 Mbit
    PC .21 to server .11 45 Mbit
    Server .11 to Cisco .1 10 Mbit
    Server .2 to Cisco .1 40 Mbit

    As I watched full speed to good connected sites with my old router, and
    now with the Cisco between 400 - 700 kbit, I want to do the best possible.

    Do I understand right, that I have to configure the FastEthernet
    interfaces? This will need splitting into subnets too?

    What is the appropriate manual for interfaces configuration and tuning?

    TIA

    Helmut Wollmersdorfer
     
    Helmut Wollmersdorfer.at, Feb 23, 2005
    #1
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  2. No! On the 8xx series the fastethernet interfaces exist ONLY to set
    MAC-level parameters of the internal switch like speed and duplex.

    That said, make sure the autonegotiation worked and that you don't have a
    duplex mismatch between the router and switch (try manual settings). Some
    switches are not soo good at autonegotiation. I tore my hair out on a
    performance problem for over a week until I discovered that the cheapie
    disposable ethernet switch was failing is a very subtle way. So try a
    switch swap if practical.
     
    Phillip Remaker, Feb 24, 2005
    #2
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