On 9 Dec 2008, at 09:08, Scott Brim wrote:
Excerpts from RJ Atkinson at 09:00:09 -0500 on Tue 9 Dec 2008:
Off the top of my head, it seems to me that this issue already exists
in the deployed IPv4 Internet and also in the deployed IPv6 Internet.
If one considers a multi-homed end-system (i.e. one that is
directly connected to multiple IP subnetworks), that host needs
to make a decision about which source IP address to use
to communicate.
If it is communicating with a remote node that is also multi-homed
(same definition), then it needs to make a decision about which
destination IP address to use to communicate (typically this is
a choice from the set of A/AAAA records that the first host found
in the DNS for the remote node).
Few multi-homed hosts participate in intra-domain routing.
Fewer participate in inter-domain routing. So nearly all hosts
wanting to correspond cannot use knowledge from the routing
system to make a better informed decision about either the
source address to use or the destination address to use.
This is a good point -- individual devices that are multihomed already
face that situation. Is there any deployed use of multiple
simultaneous paths?
We should all think about that question.
A quick answer is that at least deployments of applications
using SCTP will use multiple paths today. A basic multi-path
multi-homing capability has been in SCTP all along. More
recently, dynamic multi-homing capability has been added.
If I understood my namesake when I last chatted with him,
SCTP's dynamic multi-homing capability has multiple independent
implementations already.
SCTP is not the most widely used transport protocol.
However, it is deployed and it has real-world use today.
I am reliably told that the multi-homing capability is
critical to most currently deployed uses of SCTP.
I am also mindful of Mark Handley's proposal for a multi-homed,
multi-path TCP extension. Such an extension seems sensible to me,
at least conceptually, particularly given that there are now
experimental results from SCTP indicating that such a thing
can work reasonably well.
What is new is the opportunity to do something more with it given
locator/identifier separation.
Hmm. I'm not quite sure.
"Here's this cool new tool, but to use
it you have to install new wiring in your house and by the way your
electric bill will double."
(I haven't finished my coffee yet, so maybe it is just me,
but I have no idea what that quoted text means. :-)
Cheers,
Ran
[EMAIL PROTECTED]
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