On Thu, Apr 12, 2018 at 9:54 AM, Greg Mirsky <gregimir...@gmail.com> wrote: > Hi Frank, > thank you for sharing your points. Please find my notes in-line and tagged > GIM>>. I believe that this is very much relevant to work of other working > groups that directly work on the overlay encapsulations in the center of the > discussion and hence I've added them to the list. Hope we'll have more > opinions to reach the conclusion that is acceptable to all. > > Regards, > Greg > > On Wed, Apr 11, 2018 at 12:02 PM, Frank Brockners (fbrockne) > <fbroc...@cisco.com> wrote: >> >> Back at the IPPM meeting in London, we discussed several drafts dealing >> with the encapsulation of IOAM data in various protocols >> (draft-brockners-ippm-ioam-vxlan-gpe-00, >> draft-brockners-ippm-ioam-geneve-00, draft-weis-ippm-ioam-gre-00). One >> discussion topic that we decided to take to the list was the question on >> whether draft-ooamdt-rtgwg-ooam-header could be leveraged. After carefully >> considering draft-ooamdt-rtgwg-ooam-header, I came to the conclusion that >> the “OOAM header” does not meet the needs of IOAM: >> >> * Efficiency: IOAM adds data to live user traffic. As such, an >> encapsulation needs to be as efficient as possible. The “OOAM header” is 8 >> bytes long. The approach for IOAM data encapsulation in the above mentioned >> drafts only requires 4 bytes. Using the OOAM header approach would add an >> unnecessary overhead of 4 bytes – which is significant. Greg,
I'm missing something here. I looked at the drafts you referenced and each of them looks like the overhead for OAM is greater that four bytes. In each there is some overhead equivalent to type/length, for instance in Geneve four bytes are needed for option class, type, and length. Unless the the OAM data is zero length, I don't see how this adds up to only four bytes of overhead. Tom > > GIM>> The difference in four octets is because OOAM Header: > > provides more flexibility, e.g. Flags field and Reserved fields; > supports larger OAM packets than iOAM header; > is future proof by supporting versioning (Version field). >> >> * Maturity: IOAM has several implementations, which were also shown at >> recent IETF hackathons – and we’re expecting additional implementations to >> be publicized soon. Interoperable implementations need timely >> specifications. Despite the question being asked, the recent thread on OOAM >> in the NVO3 list hasn’t revealed any implementation of the OOAM header. In >> addition, the thread revealed that several fundamental questions about the >> OOAM header are still open, such as whether or how active OAM mechanisms >> within protocols such as Geneve would apply to the OOAM header. This >> ultimately means that we won’t get to a timely specification. > > GIM>> May I ask which encapsulations supported by the implementations you > refer to. Until very recently all iOAM proposals were to use meta-data TLV > in, e.g. Geneve and NSH. And if these or some of these implementations > already updated to the newly proposed iOAM shim, I don't see problem in > making them use OOAM Header. Would you agree? > >> >> * Scope: It isn’t entirely clear to which protocols the OOAM header would >> ultimately apply to. The way the OOAM header is defined, OOAM uses a 8-bit >> field for “Next Prot”, the next protocol. Some protocols that IOAM data >> needs to be encapsulated into use 16-bits for their next protocol code >> points. See e.g. the GRE encapsulation – as specified in >> draft-weis-ippm-ioam-gre-00. > > GIM>> The first paragraph of the Introduction section states: > New protocols that support overlay networks like VxLAN-GPE > [I-D.ietf-nvo3-vxlan-gpe], GUE [I-D.ietf-nvo3-gue], Geneve > [I-D.ietf-nvo3-geneve], BIER [I-D.ietf-bier-mpls-encapsulation], and > NSH [I-D.ietf-sfc-nsh] support multi-protocol payload, e.g. > Ethernet, IPv4/IPv6, and recognize Operations, Administration, and > Maintenance (OAM) as one of distinct types. That ensures that > Overlay OAM (OOAM)packets are sharing fate with Overlay data packet > traversing the underlay. > I'm updating the OOAM Header draft and along with cleaning nits will update > reference to GUE. I think that the list and the statemnt are quite clear in > identifying the scope of networks that may benefit from using not only > common OOAM Header but common OOAM mechanisms, e.g. Echo Request/Reply. > >> With the above in mind, I’d suggest that the WG moves forward with >> specific definitions for encapsulating IOAM data into protocols – per the >> above mentioned drafts. >> >> >> >> Regards, Frank >> >> >> _______________________________________________ >> ippm mailing list >> i...@ietf.org >> https://www.ietf.org/mailman/listinfo/ippm >> > > > _______________________________________________ > Int-area mailing list > int-a...@ietf.org > https://www.ietf.org/mailman/listinfo/int-area > _______________________________________________ nvo3 mailing list nvo3@ietf.org https://www.ietf.org/mailman/listinfo/nvo3