Hi Tom,
In section 2.3, the 16bit 0s is redundant for a packet. I prefer the format
like below:
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 0x0 | Hlen |V|SEC|R|R|P|P|E| Protocol |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
When Ebit = 0, protocol = 8bit IP protocol number.
When Ebit = 1, protocol = 16bit EtherType.
Then the ASIC could always use the combined 17bit (1bit Ebit + 16bit Protocol)
as an index to parse the payload.
In my mind, one of the potential use cases of the private fields is congestion
control. Currently, there is only TCP have congestion control mechanism. Some
other non-TCP traffics in DC also require flow based congestion control.
Regards
Lizhong
> -----Original Message-----
> From: Tom Herbert [mailto:[email protected]]
> Sent: 2014年3月5日 4:05
> To: [email protected]
> Cc: [email protected]
> Subject: [nvo3] Fwd: New Version Notification for draft-herbert-gue-01.txt
>
> Hi,
>
> i posted a new version of GUE (Generic UDP Encpasulation). I appreciate
> comments, however please bear in mind:
>
> 1) This is not just for network visualization, we anticipate other use cases.
> Network virtualization is a very important use case.
> 2) I do not claim that this solves all of the problems or addresses all
> requirements of encapsulation or networking virtualization. As far as I can
> tell,
> it does satisfy most of our needs for a generic and ubiquitous encapsulation
> (in one large data center environment). Even so, we still have need for other
> encapsulation protocols in different contexts.
> 3) Please take this as input for some requirements and potential solutions
> when contemplating standard encap protocols.
> 4) We did consider many alternate encapsulation protocols (see motivation
> section). GRE was the closest to what we need, and in fact the basic concepts
> of GUE are derived from GRE. GRE is very simple, generic, stateless, allows
> for extensions, is amenable to efficient HW implementation, and is suitable
> for high PPS applications. We can't use directly GRE because adding new
> fields (extensibility) breaks middleboxes which need to parse inner headers
> (header length ambiguity with new fields). So in GUE we have a header
> length field that can allow a device to skip over unknown options. Also, we
> chose to encapsulate by IP protocol as opposed to the EtherType which is
> more efficient and appropriate when doing L3oL3 encap (our majority use
> case).
> 6) GRE-like flag-fields are very limited and constrained compared to
> something like TLVs which allow open ended extensibility. Their use
> represents a trade-off. To their advantage flag-fields are very efficient and
> simple to to parse. They are very compact, order of fields in the packet is
> fixed, each field type occurs at most once in the packet, and random access
> of specific fields is possible. I don't foresee the need to add a whole bunch
> of
> new fields, and those add will likely be generic supporting "pluggable"
> semantics (like the security field in the draft). Other similar generic fields
> we've contemplated are a long inner flow identifier, QoS/classification, and
> congestion control.
> 7) We have deployed a variant of this protocol at scale and it is working
> pretty
> well!
> 8) I have posted patches for the initial GUE draft on Linux netdev.
> These implement IPIP/GUE, SIT/GUE, and GRE/GUE (also implements
> GRE/UDP draft). In testing we did demonstrate the value of UDP
> encapsulation to improve load balancing and steering in the network.
>
> Thanks,
> Tom
>
> ---------- Forwarded message ----------
> From: <[email protected]>
> Date: Tue, Mar 4, 2014 at 11:02 AM
> Subject: New Version Notification for draft-herbert-gue-01.txt
> To: Tom Herbert <[email protected]>
>
>
>
> A new version of I-D, draft-herbert-gue-01.txt has been successfully
> submitted by Tom Herbert and posted to the IETF repository.
>
> Name: draft-herbert-gue
> Revision: 01
> Title: Generic UDP Encapsulation
> Document date: 2014-03-05
> Group: Individual Submission
> Pages: 20
> URL: http://www.ietf.org/internet-drafts/draft-herbert-gue-01.txt
> Status: https://datatracker.ietf.org/doc/draft-herbert-gue/
> Htmlized: http://tools.ietf.org/html/draft-herbert-gue-01
> Diff: http://www.ietf.org/rfcdiff?url2=draft-herbert-gue-01
>
> Abstract:
> This specification describes Generic UDP Encapsulation (GUE), which
> is a scheme for using UDP to encapsulate packets of arbitrary IP
> protocols for transport across layer 3 networks. By encapsulating
> packets in UDP, specialized capabilities in networking hardware for
> efficient handling of UDP packets can be leveraged. GUE specifies
> basic encapsulation methods upon which higher level constructs, such
> tunnels and overlay networks, can be constructed.
>
>
>
>
> Please note that it may take a couple of minutes from the time of submission
> until the htmlized version and diff are available at tools.ietf.org.
>
> The IETF Secretariat
>
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