[c-nsp] corrupted IOS image when transferring using

[Matti Saarinen]

Jon Lewis <jlewis at lewis.org> writes:

> On Wed, 13 Apr 2005, Network.Security wrote:
>
>> Last version of 3Com's I tried has a 32MB limit to transfers.
>>
>
> I've had that issue with tftpd on linux as well and had to use ftp
> to get [>32mb] images onto our 6500s.

 That is because it is really hard to convice (original) tftp to go
 over 32MB. According to the RFC1350 tftp sends the file in 512 byte
 blocks and there is a two byte field for numbering the blocks. So, if
 I used bc correctly, the maximum number of bytes without the counter
 wrapping around is 33553920. 32 MB is 33554432 bytes, 512 less than
 the maximum. So the maximum size would be 32MB + 511 bytes (not 512
 due to the end of file detection in tftp).
 
 The extensions provided in RFCs 2347 - 2349 may help the matters but
 I've no idea how widely they are supported. In any case, ftp, rcp and
 scp are far superior to tftp (except in protocol overhead).

 Cheers,

-- 
- Matti -