On Mon, Mar 09, 2009 at 11:12:39AM +0530, ravi kumar wrote: > RFC 3315 specifies that Vendor-specific option (option 17) is used by *clients > and servers* to exchange vendor-specific information. This is correct, and RFC 3315 should be considered the only reference on the subject. Note the statement is not normative, and the table in Appendix A (also not normative?) clearly indicates Relay-Forw and Relay-Reply permit the VCIO and VSIO options. > Dhcp Server includes this option in Reply message, when client request for > options configured for vendor class. But when do Client include this option > ? Whenever they want to. Some vendor options may require negotiation, in which case the client needs to advertise its desired value (or range). Generally clients don't need to do this, as vendor options are usually specific assignments and the "default values" are known in advance (if this option isn't present, the client defaults to X) because it is the vendor's client, after all. So usually the client just sends VCIO options, and the server replies with relevant VSIO options, containing only those parameters that need defaults over-ridden. > In contrast to RFC 3315, RFC 3736 specifies that option-17 is used to pass > information to clients in options defined by vendors. This is a summarization, "the common use," as RFC 3736 is citing RFC 3315. > I would like to know, if Client can include Vendor-specific option in > messages sent to Server and in which scenarios do Client include this > option? If a client needs to deliver any information the server can not assume in advance, then probably the client would also send VSIO options. -- David W. Hankins "If you don't do it right the first time, Software Engineer you'll just have to do it again." Internet Systems Consortium, Inc. -- Jack T. Hankins
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