Subject: Re: [rrg] and while we're at it, here's a view from the ground...

From: [email-masked]
Date: Sun, 2 Nov 2008 10:44:30 EST

In einer eMail vom 01.11.2008 02:29:14 Westeuropäische Normalzeit schreibt  
[email-masked]:

On Fri,  Oct 31, 2008 at 2:33 PM,  <[email-masked]> wrote:

>  Oh no. The way I would use geographical coordinates is completely
>  transparent to any geographical meaning (like continent, country,  state,

and I read your example of driving or paper-mailing things  pretty much
as examples, akin to: "Route your traffic to AS1239, let them  find the
right internal place to deliver to..."

which seemed sane  enough, and in fact quite a bit like LISP or some of
the other loc/id split  techniques.

Strong objection.TARA doesn't disseminate user reachability information -  
neither directy nor indirectly.

> city,...) It is only a means to select the right  "proxy  destination node"
> in the case that your true destination  node is not yet "on your radar
> screen". Based on it you determine the  next hop. There is no change of the
> economic make up. It is only that  the next hop is determined in a different

so yea, that again sounds  like LISP... ETRs/ITRs..
No again. I guess you know the German storytelling about the lie baron  
Muenchhausen. LISP reminds me of Muenchhausen who boasted how he rescued  himself 
from drowning: "I grabbed my hair and pulled myself out of the  water". For 
comparison,  the  geographical coordinates are a  helping hand from solid ground.
 
BTW what is really understood by economic make up? I objected because I  
would only determine the next hop in a different way - comparable to seafarers  
who may watch the stars or the magnetic needle for determining the right  
direction to sail. Nothing else. But I still wonder what this economic make up  
really is.
 
With TARA I could imagine further going economic make ups: like different  
routing during the day as opposed during the night. Or safest routing, or  
.....or....or....

> and scaling way and can, in the data plane, be retrieved  much faster than 
by
> searching thru a 300 000 entries sized  table.
>

300k isn't so much a problem for most core devices  today, 3m though... could 
be.

> In a preceding email I once stated  that the next hop determination (in the
> data plane) takes only one  single table offset lookup. Admitted, I have to
> backup a little bit:  If the destination is within a different spherical
> rectangle (limited  by two consecutive longitudes and two consecutive
> latitudes) yes then  it takes only 1 table offset lookup. However, otherwise

how do  longtitude and latitude matter for networks exactly? Save a few
minor  examples no one builds a network on lat/long boundaries... and
often costs  associated with paths in a network are more related to
underlying fiber  costs or peering costs than distances.

> it will take 3. This  wouldn't by any different even if the internet would 
be
> a million  times bigger.
>
> And this would only be the beginning for better  routing:
> With respect to a particular destination any router can  subdivide its
> adjacent links into 3 classes A, B, C.
> Class A:  the remote node is one hop closer to the destination
> Class B: the  remote node is equidistant away from the destination
> Class C: the  remote node is one hop further away from the destination
> Multipath:  With DV-based routing you can only use the links of class A. 
With
> TARA  you can also use the links of classes B and C - which includes
>  detecting whether or not the link leads into a dead end area, and/or  
whether
> or not there is a chance to wind up in a loop and how to avoid  it if
> applicable.
>

how is route stretch measured?  latency? jitter? how are services that
depend upon lower latency and  consistent (low jitter) latency supposed
to survive in this climate? One of  the reasons for the existing state
in the global table (some of it at  least) is for traffic-engineering
concerns, I don't see the above scenario  addressing those, but maybe
you've just oversimplified.
Stretch: Do you think that a traveller who has all the time just the  
currently appropriate maps at hand (for the current city, county, state,  
country,continent -  and a world map) is doomed to make ANY detour? Or  even a detour 
which is 3 times as long as the shortest path - which is called  stretch 3? Do 
you really believe so ?

Heiner

-chris

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