Has anyone got an answer to the following question? Its not really an important question, just wondering... Why there is a version field in IP at all. The layer 2 payload type identifier (ether-type field, SAP value, etc.) defines IP version 4 and IP version 6 seperately (note also that tunneled IP in IP distinguishes between the two versions). If the answer is to provide for future expansion by allowing the nodes to distinguish between IP version 4 and IP version 6 headers then why is a different ethertype field used, which also provides that differentiation. You may also answer that it is in case there may be layer two protocols which do not have a distinguishing layer 3 type field, but you'd be wrong. There isn't a single layer 2 protocol which I can find which neither has a type field (anything defined by IEEE 802 protocols, anything based on HDLC - PPP, X25, AX25), nor implicitly defines the layer 3 protocol by carrying only one protocol. (SLIP for instance). I'm wondering what the rationale is, given that it is absorbing four bits of information which could otherwise make the traffic class and flow label better aligned, and contain four bits more information. --------------------------------------------------------------------- The IPv6 Users Mailing List Unsubscribe by sending "unsubscribe users" to [EMAIL PROTECTED]
