[sfc] clarification on Service Path ID for draft-penno-sfc-packet

["Kent Leung (kleung)" <[e-mail]>]

Hi. We are working on a revision for this draft. There were 4 proposed solution options in section 5. During some discussions, most folks seem to favor the use of algorithmic method in section 5.4. However, there are 2 sub-options. One is based on same Service Path ID and using Service Index to determine flow direction (sect. 5.4.1). The other is based on setting high order bit on Serve Path ID, which determines flow direction (sect. 5.4.2). There are mixed opinions. One reason is that there may be the assumption the Service Path ID is uni-directional. No explicit wording of that nature has been encountered in the RFCs, maybe we missed something?

If Serve Path ID is required to be uni-directional, then the answer is easy (=> 5.4.2). We would like to solicit WG comments to get rough consensus and revised the next version with that solution. This problem is critical to address for Service Function that generate packet in reverse direction, especially security service functions as mentioned in draft-wang-sfc-ns-use-cases.

Thanks.

Kent