USB to Ethernet relay agent (Was: Duplicate lease, different ip.)

Simon Hobson dhcp1 at
Fri May 4 09:01:23 UTC 2007

Kaustuv De (w/PGDIT) wrote:

>I am going to build a relay which will send and receive from usb to
>ethernet and viceversa.How do I manage packetization of data from USB, as
>it is a stream...

What on earth does this have to do with the original subject line/thread ?

First rule of posting queries to mailing lists - start a new thread 
for a new topic. Do NOT just hijack an existing thread, and do NOT 
reply to an existing message and just change the subject line 
(replies have a reference to the original message ID so that mail 
user agents and archivers can 'thread' the messages).

As to your query, this is not a DHCP problem, this is a programming problem.

Once you have an address for your USB device, how do you plan to 
packetise the data for the networking it is going to do ? DHCP is 
little different in that respect since apart from dealing with the 
GIAddr field, your relay is doing little more than just forward the 

Once you've dealt with the general problem of packetising your data, 
the extra step to building a relay agent is quite minor - I'm sure 
the source for the ISC relay agent would give you enough information 
to deal with that.

I'm also unclear what you are actually trying to do, USB doesn't 
strike me as a likely candidate for a networking interface - for one 
thing it's a very hierarchical interface with ONE controller and a 
number of controlled nodes. As such I don't see where the opportunity 
for networking comes in since there are already protocols in place to 
communicate between controller and devices. If you are trying to 
build a "USB 'network' switch" to network a number of devices via USB 
ports, then to be perfectly honest I think you would be wasting your 
time - the cost & ubiquity of ethernet devices is such that the 
market for such a USB network would be VERY limited.

A more likely scenario is that you run a package on the host which 
handles mediation between a USB device and whatever you want to have 
communicating over the network - eg for sharing a peripheral via the 
network. This would simply use the hosts existing network address(es).

If I've missed the mark and you really do have a novel and useful new 
use for USB then I'm sure we'd be interested in helping - please tell 
us more.

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