[c-nsp] (Unknown error 0) when upgrading 7609 SUP720

[Peter Olsson]

A customer has bought two 7609, each with redundant SUP720.
Both shipped with one SUP720 mounted in slot 5, and the
other SUP720 we had to mount ourselves, in slot 6.

Both 7609 boots fine, and all SUP720 seems fine. However,
the two redundant SUP720 in slot 6 both have a different
IOS than the pre-mounted SUP720 in slot 5.
Slot 5 SUP720 in both 7609: c7600s72033-advipservicesk9-mz.122-33.SRB2.bin
Slot 6 SUP720 in 7609 #1: s72033-ipservices_wan-vz.122-18.SXF11.bin
Slot 6 SUP720 in 7609 #2: s72033-ipservicesk9_wan-mz.122-18.SXF11.bin

In order to get the redundancy we want, we have to upgrade the
slot 6 SUP720's to the SRB image. But this fails. I have upgraded
the slot 5 SUP720's to SRB3, no problems. But as soon as I try to
upgrade the slot 6 SUP720's with the same image file, they refuse with
"(Unknown error 0)". After a lot of wasted time I discovered that if I
rename the image file from c7600s72033-advipservicesk9-mz.122-33.SRB3.bin
to s72033-advipservicesk9-mz.122-33.SRB3.bin, the slot 6 SUP720 accept
the file. However, I haven't dared reload with that file active, I have
already got one of the slot 6 SUP720's stuck in rommon because of
previous testing of this problem.
(By the way, I can't understand what reason there is behind not having
tftpdnld in rommon in 7609.)

Can anyone shed some light on this upgrade problem?

Thanks!

-- 
Peter Olsson                    pol at leissner.se