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
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
Architecture document should it define a "post receive"? Security issues
The problem: need to under provision 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
+ 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
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
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
+ 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
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.