See inline below.
-----Original Message----- From: Tom Herbert [mailto:[email protected]] Sent: Thursday, September 24, 2015 10:08 AM To: Lucy yong Cc: Anoop Ghanwani; Larry Kreeger (kreeger); Sandeep Kumar (Sandeep) Relan; [email protected]; Shahram Davari Subject: Re: [nvo3] destination UDP port : draft-ietf-nvo3-vxlan-gpe-00 > What we may want to say, then, is that if a P bit of 0 is used then > none of the other flags must be set. This would prevent someone from > generating a packet with a P bit of 0 and trying to use new GPE features. > > [Lucy] The P bit is used for version purpose too. The rule is if the > GPE need support new features to Ethernet payload, it has to set P bit > and use the protocol field to indicate Ethernet payload. > > The rule is: GPE accepts a special case of P=0 mode as valid for > Ethernet Payload., and P =1 (mode) & Protocol = Ethernet (0x03). When > a P bit of 0 is used, none of the other flags must be set. > > > > This works under condition/rule that VXLAN protocol enhancement MUST > be stopped. > Lucy, I'm not sure why the constraint needs to be so stringent. The P bit can be used to discriminate between VXLAN and VXLAN-GPE received on the same port. i.e if P bit is set, it is a VXLAN-GPE packet. If it is not set it is VXLAN packet and the rest of the fields are processed accordingly. New features can be added to either protocol in this way using the other reserved bits independently. This allows backwards compatibility to receive VXLAN on a VXLAN-GPE port (doesn't help with the forward compatibility problem though). [Lucy] What you say is the draft intention. My comment is to say, if we add this rule as Anoop suggested "When a P bit of 0 is used, none of the other flags must be set.", it will only work if no more VXLAN enhancement in future, e.g. using a new bit for something. If there will be, it will cause an issue for interworking between two. I just want to point out for caution. Lucy Tom _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
