Uploading across the VPN

Eric Zarling zarling at BERBEE.COM
Wed Jul 19 13:48:33 EDT 2000


What you are probably seeing is an MTU issue.  Are you using a VPN client
or VPN router or gateway?  I have come across an issue with uploading files
through a Cisco router running DES.  What happens the router needs to
fragment the IP packet because of the encryption overhead, the OS (in this
case Microsoft) sets the "Do not Fragment" bit on.  The router will not
breakup the packet and will send what basically is a host unreachable ICMP
packet back the machine and it will error out.

The work around for this is to set the MTU lower than 1500.  I set the MTU
to 1400 and it works fine.

The only issue I have come across iwith certain NIC cards is where this can
be set.  It usually is a registry setting.  But I have been fighting with
Xircom on whose responsibility it is to set the MTU.  Xircom claims it is a
Microsoft setting.  With other NICs (3COM), I have set it in the registry
under the NIC entry.

Give this a shot and let me know what happens,

Eric


At 01:00 PM 7/19/2000 -0400, Cindy Slosar wrote:
>Hi,
>
>Is anyone else having problems uploading files across
>a VPN?  I can't seem to figure out what the problem
>is.  I get an error saying "Cannot copy filename:  The
>specified network name is no longer available."  I can
>download files no problem.
>
>Thanks in advance.
>
>Cindy
>
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Eric Zarling CCIE #5499 <zarling at berbee.com>
Berbee
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