This is something I tried to say at the mic today, but I was too late.
If we put potentially valuable use cases into the bucket of "Exceptions", this
becomes yet another excuse to delay or avoid adoption of IPv6 by the very large
percentage of Enterprises who have yet to do so (and have no serious plans)
today.
I am hopeful that work in the IETF will provide features and hence motivation
for us sadly delinquent Enterprises to begin actually using IPv6. I am
concerned that perception of solutions being "Exceptions" or non standard, will
cause consternation (warranted or not) and avoidance.
-----Original Message-----
From: ipv6 [mailto:ipv6-bounces(_at_)ietf(_dot_)org] On Behalf Of Suresh
Krishnan
Sent: Thursday, March 30, 2017 9:30 AM
To: Leddy, John <John_Leddy(_at_)comcast(_dot_)com>
Cc: draft-ietf-6man-rfc2460bis(_dot_)all(_at_)ietf(_dot_)org; 6man WG
<ipv6(_at_)ietf(_dot_)org>; ietf(_at_)ietf(_dot_)org
Subject: Re: IETF Last Call conclusion for draft-ietf-6man-rfc2460bis-08
Hi John,
Thanks for chiming in. I recognize that you might have use cases that might
be better off with header insertion but I think they should be handled as and
when they come up for consideration (e.g. in the SRv6 discussions). Holding up
this document is not going to help in any way in reinterpreting what RFC2460
intended. My suggestion for proponents of safe header insertion to write up how
it is expected to work and have the discussion then.
Thanks
Suresh
On Mar 29, 2017, at 9:59 PM, Leddy, John <John_Leddy(_at_)comcast(_dot_)com>
wrote:
On Mar 14, 2017, at 9:47 PM, Suresh Krishnan
<suresh(_dot_)krishnan(_at_)ericsson(_dot_)com> wrote:
NEW:
With one exception, extension headers are not examined, processed,
inserted, or deleted by any node along a packet's delivery path,
until the packet reaches the node (or each of the set of nodes, in
the case of multicast) identified in the Destination Address field of
the IPv6 header...
Please feel free to comment either privately or on list if you have any
concerns with this resolution going forward.
Suresh,
I still have concerns that we are eliminating a tool that may prove very
helpful in migrations without understanding its value.
The Internet transition of IPV4 -> Dual Stack V4/V6 -> IPV6 Only; has been
long, operationally complex and full of unexpected challenges.
We are only now starting to make the transition from Dual Stack to IPV6 Only,
there are still many unknowns on how to complete this migration.
As we contemplate finishing this major Network shift – We find ourselves in
the early stages of another.
The transition from Physical to Virtual Infrastructure. Again, the migration
will be long, operationally complex and full of unexpected challenges.
In the old world with Servers running Applications in Physical locations
designed for very predictable loads; using an encap/decap tunnel to emulate a
physical circuit between locations has many attractive properties – but that
is compared to actually ordering and provisioning real circuits between
locations.
In the new world of dynamic resources spun up on demand in distributed
environments across multiple providers, Applications having the Intelligence
and State to bring up their own required connectivity is very natural. This
is where we are putting the majority of our efforts. SRv6 enables very
attractive solutions by Applications building their own headers.
The challenges come as we try to migrate and require these two
infrastructures to Interoperate for a long time.
Burdening the new Virtual world with Old, Static circuit paradigms is not
optimal.
Supplementing the legacy infrastructure with an assist function seems
a reasonable solution. (Ext Hdr insertion/deletion or encap/decap
tunnels)
The preferred assist mechanism seems to be the one that allows the New
World to operate in its final preferred state, sending and receiving packets
with their own headers. (SRv6) But what does an Application in the new world
due when it is attempting to communicate with an Application in the Old World?
Shouldn’t it build an SRv6 header? That would mean that the assist function
would need to be the last SID in the Segment List and be capable of removing
the SRH.
Wouldn’t it make sense for the assist function to do the same thing in the
reverse direction; an Old World Server talking to a New Virtual World
Application? Insert an SRH.
If this insert/delete of an SRH is prematurely prohibited; What is a
recommended solution to the Real World problem above. Not use case, we are
implementing.
Again; I’m worried we are eliminating a tool that may prove very
helpful, preclude its use in future IETF work and shutdown a path for
Innovation in Networking,
Thank you for asking and listening to my concerns,
John Leddy
Comcast
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