MTU problem DSL/CABLE Router - Firwall upgrade

Archived from groups: comp.security.firewalls (More info?)

This is a Good advice for other newbies like me trying to tweak a new
Broadband Router/Firewall

I noticed a Major Bandwith performance decrease right after I upgraded my
good old Linksys BEFR41 to a Netgear FR114P.

It took me couple days to find out it was only a bad MTU setting.

Make sure you set the router/firewall MTU to its optimal value.

I found a good article which explain out to do it.

http://www.dslreports.com/faq/5793

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4 answers Last reply
More about problem cable router firwall upgrade
  1. Archived from groups: comp.security.firewalls (More info?)

    Yaff <novirus@junkaei.ca> wrote:
    > It took me couple days to find out it was only a bad MTU setting.

    I think, the setting was OK, but many DSL providers require a smaller
    setting. You can find this in the documentation of the DSL provider
    usually.

    > Make sure you set the router/firewall MTU to its optimal value.

    Optimal? You mean, small enough, because some providers have such
    problems.

    Yours,
    VB.
    --
    "Es kann nicht sein, dass die Frustrierten in Rom bestimmen, was in
    deutschen Schlafzimmern passiert".
    Harald Schmidt zum "Weltjugendtag"
  2. Archived from groups: comp.security.firewalls (More info?)

    On 28-Aug-2005, Volker Birk <bumens@dingens.org> wrote:

    > Optimal? You mean, small enough, because some providers have such
    > problems.

    Optimal means not too small and not too large. The default MTU at 1500 in
    the Netgear was too large.
    Optimal value in my case is 1456 according to the test describe in the link
    above.

    "Setting your computer's MTU value too low would make downloading less
    efficient because a greater percentage of the packet is taken up by the
    packet header which contains a variety of information about the packet,
    source, and destination. However, setting the MTU too high can also decrease
    efficiency. Other computers on the Internet might not be able to handle MTU
    values of a certain size. If you set your computer's MTU value too high,
    some computers along the delivery path would be required to break these
    packets into smaller pieces before accepting them and passing them to the
    next computer. This "Stop. Break. Go." processing of packets can
    dramatically slow down data transfers."
  3. Archived from groups: comp.security.firewalls (More info?)

    Yaff <novirus@junkaei.ca> wrote:
    > > Optimal? You mean, small enough, because some providers have such
    > > problems.
    > Optimal means not too small and not too large.

    I'd not call a compromize "optimal". But I don't want to nitpick ;-)

    Yours,
    VB.
    --
    "Es kann nicht sein, dass die Frustrierten in Rom bestimmen, was in
    deutschen Schlafzimmern passiert".
    Harald Schmidt zum "Weltjugendtag"
  4. Archived from groups: comp.security.firewalls (More info?)

    Ok... we are playing on words now :)

    For my setup, 1456 is the largest MTU I can set without having fragmented
    packets.

    Also, I started to notice decreased performance under 1400.

    According to what I've read, the optimal value is the largest MTU that
    doesn't cause packet fragmentation.
    So is it really a compromize?

    Cheers,
    C++. ;)
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