Hi Fabio, Thanks for the reply. I read the version 08, and it is OK now. At first glance, I though Next Protocol of values from 0x0 to 0x7F was only for dataplane processing. But later I found GBP moved from 0x6 to 0x80 which broke my assumption. Could you help to explain why GBP do such change since you are also author of GBP? Agree that some suggestions for the assignment is difficult. But from the implementation point of view, if some shim headers are not critical (As Remy mentioned), it would be better to have a way to skip them, and get to the Next Protocol of values from 0x0 to 0x7F directly. That will ease the ASIC design, some new defined non-critical shim headers will not break existing GPE implementation.
Regards Lizhong On Thu, Oct 24, 2019 at 6:14 AM Fabio Maino (fmaino) <[email protected]> wrote: > Hi Lizhong, > > Sorry for the delay. > > > > Vxlan-gpe version 08 should now contain the appropriate reference to > [I-D.lemon-vxlan-lisp-gpe-gbp]. Let me know if I’m missing anything. > > > > I know designing ASICs with the added flexibility required by the shim > headers comes at a cost. Ultimately implementations will have to choose > which extensions to support, and how much buffer to dedicate for > unsupported extensions. I don’t think there’s a general rule that can be > applied. Do you have any suggestion? Restricting to control plane functions > might be too much, even some of the OAM features might end up being > implemented in the dataplane. > > > > Wrt GBP it’s a fairly well known use case, but not universally deployed > so we wanted to leave to implementors the decision to support or not that > extension. > > > > Thanks, > > Fabio > > > > > > > > > > > > *From: *Lizhong Jin <[email protected]> > *Date: *Saturday, October 12, 2019 at 7:29 PM > *To: *"[email protected]" < > [email protected]> > *Cc: *"[email protected]" < > [email protected]>, "[email protected]" <[email protected]> > *Subject: *Shim header of vxlan-gpe > *Resent-From: *<[email protected]> > *Resent-To: *Fabio Maino <[email protected]>, Larry Kreeger < > [email protected]>, <[email protected]> > *Resent-Date: *Saturday, October 12, 2019 at 7:29 PM > > > > > > Hi GPE authors, > > I recently review the GPE draft and the shim header design. I saw the > "Next Protocol" assigned to GBP changed from 0x6 to 0x80, and the reference > of [I-D.lemon-vxlan-lisp-gpe-gbp] should be updated from version 01 to > version 02 which confused me in my first reading. I am not clear why GBP do > such kind of update, do you have any design principles for the "Next > Protocol" assignment for range from 0x80 to 0xFF? Some practical design > principles in the document would benefit the industry. > > And since shim header is a TLV style, I tend to ask if it would be > practical to restrict the shim header to be used only for OAM and control > purpose. That would greatly simplify the ASIC design. > > > > Regards > > Lizhong >
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