Subject: Re: [rrg] Locator Path Liveness concerns

From: [email-masked]
Date: Tue, 9 Dec 2008 15:48:39 EST

I think rerouting inside the path between multi-homed source user A  and  
multi-homed destination user B ought to be possible at which ever  point prior 
getting to B. It may be at A and at any router in the  path. It should not 
involve B nor the application being run at B. And it should  not involve the 
application at A either.
 
Rerouting may either be done such that the packets are  still forwarded 
towards the same destination location, or, if  this becomes necessary/advantageous 
(e.g. for reasons of traffic balancing),  that
the destination location is changed-  e.g somewhere in the middle of  the 
path or at/by the egress router in the first place.
 
Is this a wanted objective ? If so, any architecture, including TARA, needs  
to do something about it.
E.g. a natural approach is to convey an armed destination location as well  
the potential alternatives while a packet is transmitted. Right ?
 
Heiner

_______________________________________________
rrg mailing list
[email-masked]
https://www.irtf.org/mailman/listinfo/rrg

---

From: "Teco Boot" <[email-masked]>
Date: Wed, 10 Dec 2008 08:48:18 +0100

Hi Heiner,

I agree reroute shall not affect application layer, nor the session.
On the transmission layer, I doubt. Maybe A could be informed that the
<A-a1,B-b1> path is not available anymore. Node A could initiate a
<A-a2,B-b1> connection for the same session. A better approach would be set
up both connections on forehand and select the best or use load distribution
(Mark Handley e.o.). SA based routing to DFZ (e.g. BRDP based routing)
circumvents problems with ingress filters and firewalls.
There could be other mechanisms monitoring the path between host A and the
border routers for A-a1 and A-a2. For example, NTP could be used providing
connectivity, delay and jitter statistics to some NTP servers. 
I think the IGP should validate paths and nodes should be provided accurate
information on what source addresses should be used. BRDP does just that.
For destination address selection, I don't know how the (local) IGP could
help.

Teco.

-----Oorspronkelijk bericht-----
Van: [email-masked] [mailto:[email-masked]] Namens
[email-masked]
Verzonden: dinsdag 9 december 2008 21:49
Aan: [email-masked]; [email-masked]
CC: [email-masked]
Onderwerp: Re: [rrg] Locator Path Liveness concerns

I think rerouting inside the path between multi-homed source user A and
 multi-homed destination user B ought to be possible at which ever point
prior getting to B. It may be at A and at any router in the path. It should
not involve B nor the application being run at B. And it should not involve
the application at A either.
 
Rerouting may either be done such that the packets are still forwarded
towards the same destination location, or, if this becomes
necessary/advantageous (e.g. for reasons of traffic balancing), that
the destination location is changed-  e.g somewhere in the middle of the
path or at/by the egress router in the first place.

Heiner