[rddp] RDDP WG Vienna minutes
Black_David@emc.com Wed, 06 August 2003 23:27 UTC
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Subject: [rddp] RDDP WG Vienna minutes
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RDDP WG minutes - Vienna, Austria, July 2003 -------------------------------------------- Thanks to Tom Talpey for taking the initial minutes. Letters in [square brackets] indicate first letter in name of corresponding presentation in proceedings. Tuesday, July 15 5-6pm ---------------------- David Black (WG chair) introduces agenda changes, no bashing, agenda accepted [A] Review of WG draft intentions and status - see presentation [B] + RDDP Applicability statement, Lode Coene [C] Review of document content - draft considered by authors to be in good shape, waiting for comments from WG. David Black requests that TCP mapping issues (drawbacks of TCP by comparison to SCTP) be included in the applicability statement. + SCTP Mapping draft [D] On its third revision. A DDP Stream establishment issue has been identified, can a protection domain assignment be deferred or no? Needs documentation at a minimum. A draft revision under author review concerns single-message exchange for "private data", compatible with current MPA draft, but this is part of the open startup issues in the MPA draft. No others issues are currently identified, speak up now... New version expected in next few weeks. + Shared receive queues vs Shared buffer pool [D] David Black presented this issue from the mailing list on behalf of Caitlin Bestler, who was unable to travel to Vienna. Shared receive queues are proposed in draft-hilland-verbs-00. Their presence/absence has impact on other drafts: Architecture document should it define a "post receive"? Security issues The problem: need to underprovision receive buffers, but how to control per-receive queue quotas? Two proposals: Shared receive queue (draft-hilland) Shared buffer pool (email on list) The proposals are described and a lengthy discussion ensues. David Black suggests trying the following tack: need to resolve robustness to DOS attack on shared buffers. Tag this as the only open portion of this issue and look at countermeasures in security draft. Examine offline and continue this issue on Thursday. A question is asked about why this issue is holding up the architecture draft, which is *not* an interface specification. David Black answers that the architecture draft goes into sufficient detail on pseudo-interfaces that some discussion of resource sharing is necessary there. + RDMAP/DDP Security draft - Jim Pinkerton [E] Presents the new security draft for first time. Draft is focused on wire protocol issues, in a generic way with out referencing verbs, etc. Sketches components necessary to implement security over RDMA. - privileged resource manager, controlling the RNIC itself as well as two classes of application - priv and non-priv applications. Identifies resources to be analyzed (and controlled): connection context, data buffers, translation tables, STags, completion queues, plus RDMA Read request queue. Describes the "dimensions of trust": local resource sharing, local trust and remote trust. There are 8 combinations of trust, 4 are addressed in the paper. The 4 were chosen as most applicable to IETF areas of interest, due to brevity and also lack of relevant applications which might fall into the other 4. Enumerates tools for countermeasures: protection domain, limiting STag scope, (4 others) <presentation abbreviated due to end of WG meeting time> David Black requests that for Thursday's session, protocols should decide which "trust bucket" each lands in, determines if bucket is addressed in draft, and if so are the issues accurate? Thursday, July 17, 3:30-5:30pm ------------------------------ + Architecture draft resolution ddp_post_receive goes back in Allow sharing of buffers for untagged receives Work out how to avoid tacking limit per stream/socket problem in arch draft; problem will be addressed in security draft In ddp draft, ok to not fail immediately on shared overdraw question from floor - have we addressed the issues raised by VJ delay-bandwidth results? Enough buffers to allow the flow to use all available bw? A (David Black): The fact that RDDP moves control of buffering resources upwards in the protocol stack doesn't change the need to provide bandwidth-delay product quantity of buffering to enable full use of the available network bandwidth. This is an issue for receivers to appropriately provision receive buffers. Consider adding a statement to this effect to the architecture draft. + Return to Security document discussion, Jim Pinkerton. [This meeting time conflicts with SAAG meeting so security experts may not be in attendance.] Current open issues summarized: - IPSec section is currently a placeholder, and will be filled in (Bernard Aboba to help out) - Also, summary section at end still in progress. - From reflector, elaborate some issues in "trust model". - Multiple Protection Domains - Scope of STags - Other resources to add to security discussion (async event queue, PD, etc) - STag disable/enable by non-privileged app. Question from floor - we need an analysis of issues introduced by RDMA into existing protocols, e.g. NFSv4. When transfers are done purely by RDMA they may not be protected by existing security. A (David Black): This may indeed require additional security coverage such as IPsec which may be enabled by existing CCM NFSv4 proposal. It as also noted that the integrity protection is present in NFSv4, RPCSEC_GSS integrity, can verify that RDMA transfers actually occur as promised, while IPsec can be used to enforce the authorizations themselves. Two different issues, important to keep separate. Question - should performance analysis be included in our analysis? Especially where IPSec overhead is involved. A (David Black): First of all, let's complete the security analysis. At that point, the specific performance implications may be worth analyzing. But not before. Next major revision of this document should become an official WG draft. No objections. + Status of TCP mapping issues WG chair summarizes marker issues resolved to date: Sender alignment Marker usage, intervals, optionality CRC use (5+ issues) Further discussion to go into applicability draft Question from floor - have we worked out when it's ok not to use MPA CRC yet? Prefers to have it always present for simplicity. A (David Black): Rough consensus is for CRC to be optional. Discussion of when it may be disabled and what ULP designers/implementers should assume goes into the applicability statement draft. Last(?) CRC Issue - one CRC or two? Case for two - faster placement, fast header validation Case for one - tractable, simpler, doesn't abuse layering Statement from floor - there are more reasons to have two CRCs: DDP Routers don't have to rebuild data crc Don't have to wait for whole segment to begin processing header Large amount of controversy whether it's valid to rewrite DDP headers. WG Chair declares that rough consensus exists for one CRC; while there are advantages to two, they don't outweigh increased complexity. Further discussion will be on the list. + MPA discussion - Paul Culley Changes to most recent draft recapped: optional, receiver-specified markers optional, mutually agreed CRC MPA streaming mode "key" validation mechanism at connect new informational sections Authors' additional proposals no "alignment" of market to TCP sequence #, as alignment would violate layering CRC field always present, not filed in or checked when not used - simplicity no private data in MPA (carried only in TCP mode), quiescing stream required at MPA init MPA 128-bit start key, carrying a fixed MPA signal + CRC/marker bits, etc. passive/active rules specified Question - what happens if both "active"? Needs to be addressed Resolved - Start Key should at a minimum assert Active vs. Passive. Discussion of connection startup models - immediate RDMA enabled, RDMA enabled midstream, RDMA midstream with private data (blob follows MPA key). This whole area of how to initiate a connection, including private data, is open and needs to go to list Chair proposes that this document is ready to go to official WG draft for TCP mapping of RDDP (with significant issues to be worked out of course). No objections. Question: Is the MPA draft as informational or standards track? A (WG Chair) Informational: per ADs from recent rechartering. Can be reconsidered when draft is complete and ready for publication as an RFC. Q: Didn't acceptance of Start Key mechanism enable standards track status? A (WG Chair): No, refusal to accept Start Key mechanism would have resulted in TCP mapping work being removed from RDDP WG charter. NOTE: WG Chair has subsequently verified w/ADs that standards track status for the TCP mapping (MPA) can be reconsidered when the draft is complete. Among the reasons for this is a strong desire to see exactly what is being proposed and understand its effects on TCP before approving standards track status. _______________________________________________ rddp mailing list rddp@ietf.org https://www1.ietf.org/mailman/listinfo/rddp
- [rddp] RDDP WG Vienna minutes Black_David