Meeting Minutes: October 4, 2018

Meeting Time and Location

10 am to 11:30 am PDT (GMT - 7), Barefoot Networks, 4750 Patrick Henry Dr, Santa Clara, CA 95054

Attendees

Barefoot Networks: Jeongkeun Lee, Mickey Spiegel, Roberto Mari
Cisco Systems: Ramesh Sivakolundu
Mellanox: Barak Gafni
Surfnet: Ronald Vanderpol
VMware: Mukesh Hira

INT using IPv6 Extension Header

Edits proposed by Ramesh Sivakolundu, Cisco Systems, were reviewed. Following decisions were made regarding this. Ramesh will incorporate these in his edits.

• Only Hop By Hop header is to be used. IPv6 Destination header cannot be used to carry INT Destination Headers as the INT Sink may not be the ultimate IPv6 destination.
• INT in IPv6 extension header can only be supported when Hop Metadata Length is a multiple of 8 Bytes, so as to make the extension header a multiple of 8 bytes and satisfy IPv6 header alignment requirements. A Null instruction bit is to be defined for scenarios where the INT source intends to collect an odd number of metadata elements at each hop. In such cases, the source will need to set the Null instruction to expand per-hop metadata length to a multiple of 8 bytes.
• Value of Next Header Type for INT in IPv6 header is yet to be determined.

Egress Buffer Occupancy

Edits proposed by Ramesh Sivakolundu, Cisco Systems, were reviewed. Following decisions were made regarding this. Ramesh will incorporate these in his edits.

• Spell out explicitly that this is "egress" buffer occupancy
• Need buffer ID to be reported along with buffer occupancy. We decided to go with 32 bits of metadata consisting of 8-bit buffer ID and 24-bit buffer occupancy
• For scenarios where the buffer may be deeper than (2^24-1) bytes/cells, a switch may report buffer occupancy in multiples of bytes/cells with the multiple communicated to the monitoring platform via the YANG model.

Other Discussions

Following other items were discussed at the meeting:

• Need for another instruction to report queue threshold, specially with dynamic thresholding. It would be useful to know not only the queue occupancy and buffer occupancy that a packet experienced, but also what the queue discard threshold was at that time.
• Edits for domain specific extensions cover INT data plane changes, but relevant changes to the report format specification and YANG model need to be covered as well.

Next Steps

• We shall review above pull requests over GitHub and meet again in two weeks on October 18
• Support for INT in IPv6 and support for any new instruction bits such as buffer occupancy or queue threshold will go into INT v1.x as this is backward compatible with INT v1.0. Domain specific extensions will be added to the specifications after INT v1.x is tagged, and this will be part of INT v2.0 as the proposed edits for domain specific extensions break backward compatibility with v1.x.