[nsp] Help: Packet TCP checksum errors (IP checksum is OK)

Oliver Boehmer (oboehmer) oboehmer at cisco.com
Thu Feb 12 04:30:57 EST 2004

> My scenario is:
> [Host-1]--L1--[Cat6500]------L2-----[Cat4500]--L3--[Host-2]
> Host 1 & 2 are unix gears.
> L1 & L3 are 100Mb Ethernet
> L2 is 100Mb ethernet encapsulated by a HUNT to ATM over SDH (STM1) and
> vice versa.
> Reported problem: FTP file transfers fails from Host-1 to Host-2.
> L2 is a leased line, the provider says he don't see any problem with
> the link, the "hunt" is not under my management.
> Any ideas what to investigate ? how to fix ? Workarounds ?

Can you investigate whether the ATM link has payload scrambling enabled?
It should have. See


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