<removed LISP list>
On Jul 30, 2014, at 8:16 PM, Tom Herbert <[email protected]> wrote: > On Wed, Jul 30, 2014 at 3:00 PM, Larry Kreeger (kreeger) > <[email protected]> wrote: >> Hi Tom, >> >> First, the VXLAN-GPE Next Protocol field would indicate the value 0x4 for >> NSH (as specified in draft-quinn-vxlan-gpe-03). Then, directly following >> the VXLAN-GPE header would be an NSH header. One would need to define a >> new MD Type (not the SFC value of 0x1, specified in draft-quinn-nsh-03). >> Then you need to make a decision as to whether you want to possibility of >> your authentication value to be processed by hardware or only software. >> If you want hardware support, then I would recommend that it not be >> encoded as a TLV. If you only care about software support, then you could >> encode the authentication in a TLV using your own organization's TLV >> Class, or perhaps an IETF TLV Class if you are standardizing it. If you >> expect hardware to parse and validate the VNI authentication, then I would >> encode it somewhere within the 20 bytes following the base NSH header and >> not in a TLV. >> > Any optional data I define which proves useful in the datapath I may > eventually want to implement in HW, and I really wouldn't want to have > to make such a decision up front-- so I'll assume anything we'd want > to define would need to go into NSH headers in order to keep HW > support an option. So then in this model is it correct to say that the > we could arbitrarily extend the protocol by using a chain of NSH > headers each of which provides 20 bytes of data we can use for > optional data and still be "HW friendly"? You can’t generalize hardware parsing like that. The key for easy of parsing is fixed sizes and known offsets. Stacking headers changes that. That isn’t to say you couldn’t do what you suggest, but it would be more complex and limits the value of the simple fixed size header. _______________________________________________ nvo3 mailing list [email protected] https://www.ietf.org/mailman/listinfo/nvo3
