On Sun, Nov 19, 2006 at 12:41:10PM -0500, Andrew Schweitzer wrote:
> > I wanted to know what exactly is a PDU. Where is the length of the pdu
> > defined in the PDU.
>
> I believe a PDU is a "Protocol Data Unit". I believe it is the
> application layer packet that has been wrapped into TCP or UDP, or the
> "payload" of TCP or UDP. It's length is specified by whatever protocol
> is used to fill that payload, so it varies from protocol to protocol.
A pdu is not specifically linked to protocols atop tcp or udp. For
example, think of a BPDU (Bridge Protocol Data Unit). Which sits just
on top op de data-link layer.
>From wikipedia:
In telecommunications, the term protocol data unit (PDU) has the following meanings:
1. Information that is delivered as a unit among peer entities of a network and that may contain control information, address information, or data.
2. In layered systems, a unit of data that is specified in a protocol of a given layer and that consists of protocol-control information of the given layer and possibly user data of that layer. For example: Bridge PDU or iSCSI PDU
Source: from Federal Standard 1037C
(http://en.wikipedia.org/wiki/Protocol_data_unit)
Cheers,
Sake