Remote boot (time transfer)

  • Thread starter Thread starter Greg
  • Start date Start date
G

Greg

Hi,

I successfully boot XPE from the network (using RAM
boot).
I wonder if it exists a mean to "customize" the first
program downloaded (startrom.n12) in order to negociate
TFTP packet size larger than 1492 Bytes (this is the
packet size negociated by default). In that way, the
transfer time of the sdi image will drastically decrease.

Thanks for your help

Greg
 
Do you have Gigabit Network? Forget this question.

Do you have support for Jumbo frames enabled on both network adapters and
does your switch support it.
And what size did you set?

Default MTU size for all 802.3 LAN's is 1536 bytes take out packet headers
and size of 1492 is very probable.

So if you are already using larger MTU's, then I don't know how to configure
TFTP.

Best regards,
Slobodan
..
 
I don't understand your remark.

I'm on an Ethenet network with a 1500 Byte MTU.

Even on this case, if TFTP packet are larger than MTU,
(there is overhead added due to IP fragmentation), but
the transfer time will decrease because less TFTP packets
(and less ACKs) are sent. This is why TFTP block size has
been implemented (refer to RFC 2348: example of transfer
on an Ethernet network with 'TFTP Block size' > 'Ethernet
MTU')

bye

Greg
 
I don't understand your remark.
English is not my native language, sorry.
I just tried to say that you should determine MTU size of you network, you
said that this is 1536 bytes. That makes my remark successful we determined
MTU size of your network.
My simple network has MTU size of 16128 bytes. So every packet can be up to
this length as you probably know.


Abstract from RFC 2348

The Trivial File Transfer Protocol [1] is a simple, lock-step, file
transfer protocol which allows a client to get or put a file onto a
remote host. One of its primary uses is the booting of diskless
nodes on a Local Area Network. TFTP is used because it is very
simple to implement in a small node's limited ROM space. However,
the choice of a 512-octet blocksize is not the most efficient for use
on a LAN whose MTU may 1500 octets or greater.

This document describes a TFTP option which allows the client and
server to negotiate a blocksize more applicable to the network
medium. The TFTP Option Extension mechanism is described in [2].


This standard as I understand will enable negotiation of best maximum packet
size on network, but not greater than MTU size.
I don't see mention of fragmentation and reassembly in this standard.


But even if your network supports Jumbo frames, I don't know if TFTP RFC
2348 is supported in your case.

I don't use yet TFTP but soon I will need it, so in any case that you
succeeded or not I would appreciate to know results.



Best regards,
Slobodan
 
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