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Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating MPLS in UDP) to Proposed Standard

2014-01-21 09:57:38

Lloyd,

If we really want to get silly we can claim that a UDP control block
or socket state on a UDP listen is state and therefore UDP is not a
stateless protocol.

But we don't want to get silly.  Do we?  Or are we long past that
point?

Curtis

PS - type "man setsocopt" on a BSD system to see a list of state, most
of which applies to any socket including UDP sockets.


In message 
<290E20B455C66743BE178C5C84F1240847E63346CE(_at_)EXMB01CMS(_dot_)surrey(_dot_)ac(_dot_)uk>
l(_dot_)wood(_at_)surrey(_dot_)ac(_dot_)uk writes:
 
Surely you mean minimised state?
 
The tunnels have to know where the other tunnel endpoint is -
state. This is distinct from having a congestion-aware state machine
that e.g. TCP includes...
 
Lloyd Wood
http://about.me/lloydwood
________________________________________
From: mpls [mpls-bounces(_at_)ietf(_dot_)org] On Behalf Of Ross Callon 
[rcallon(_at_)juniper(_dot_)net]
Sent: 16 January 2014 22:32
To: Eggert, Lars
Cc: EXT - joelja(_at_)bogus(_dot_)com; mpls(_at_)ietf(_dot_)org; IETF 
discussion list
Subject: Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating 
MPLS in UDP) to Proposed Standard
 
These tunnels are stateless

yep. (But they don't have to be.)
 
The tunnels strictly speaking do not have to be stateless. However, if you 
want routers to actually implement them, and you want to scale in both 
forwarding speed and number of tunnels, then yes they do have to be stateless.
 
Ross
(speaking only as an individual contributor)
 
-----Original Message-----
From: mpls [mailto:mpls-bounces(_at_)ietf(_dot_)org] On Behalf Of Eggert, Lars
Sent: Thursday, January 16, 2014 12:20 PM
To: EXT - joelja(_at_)bogus(_dot_)com
Cc: mpls(_at_)ietf(_dot_)org; IETF discussion list
Subject: Re: [mpls] Last Call: <draft-ietf-mpls-in-udp-04.txt> (Encapsulating 
MPLS in UDP) to Proposed Standard
 
Hi,
 
On 2014-1-16, at 18:06, joel jaeggli <joelja(_at_)bogus(_dot_)com> wrote:
These tunnels are stateless
 
yep. (But they don't have to be.)
 
 The endpoints not the encapsulators have visibility into the
end-to-end loss latency properties of the path.
 
Yep. But when you tunnel some L2 in UDP, apps that were limited to L2 domains 
- where not reacting to congestion may be OK - can now go over the wider 
Internet, where this is not OK.
 
I'd be great if those apps would change. But in the meantime, it's the duty 
of the encapsulator - who enables this traffic to break out of an L2 domain 
and go over the wider net - to make sure the traffic it emits conforms to our 
BCPs.
 
 the encapsulator is an intermediate hop, similar to any other router
in the path.
 
It's not. For the rest of the network, that encapsulator is indistinguishable 
from any other app that sends UDP traffic.
 
UDP is a transport-layer protocol, and we have practices how it is to be used 
on the net. If you want to use it for encapsulation, you bind yourself to 
these BCPs.
 
Look at it the other way: if transport area folks would want to send MPLS 
packets into the network in some problematic way, I'm sure the routing and 
ops folks would not be amused.
 
Lars

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