Linux-Hams archive - July 1997: Re: Path MTU Discovery and X1Jv4 nodes

Re: Path MTU Discovery and X1Jv4 nodes

Paul Lewis (osuxzk.vhiumdulkw@mail.dy.fi)
Thu, 3 Jul 1997 20:35:34 +0100


In message <terhi.victor@logonet.com>, Carl Makin
<mkmhkh@mx.dy.fi> writes
>
>We have a bizarre and silly network here that requires me to use an IP
>tunnel route via an X1Jv4 node to get to my local gateway. It seems to
>have real problems at times with delays even though a straight AX.25
>connection seems to run OK.
>
>I was wondering what effect Path MTU discovery would have on this sort of
>link and what happens when a router in the path does NOT sent back ICMP
>messages.
>
>Any ideas?
>
>Carl.
>
>--
>Carl Makin (vk1kcm)
>terhi.victor@logonet.com
>
>
Hello Carl,
As a side issue to your question.

re using the x1j4, the default MTU values in the x1j4 eprom
are reset back to default values as blown in to the eprom on soft or
power off/on.

On my system I had increased the MTU values to handle larger frames,
only to find when the x1j4 router been power off or did a soft reset
these values where reset. All other params were still OK.

The end result large frames where being sent and truncated through the
router until the problem had been identified. ALso sending large frames
via BPQ IP router in an adjacent router also caused that BPQ node to
fail.

Having 'blown' in the larger values that we wanted to use between our
local tcpip hosts, all appears to working well.

i.e linux host/x1j4 router/linux host

regards de Paul g4apl

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