Subject: Re: EUI-48 globally unique site-locals (GUSL)

From: Bob Hinden <[email-masked]>
Date: Sun, 01 Dec 2002 09:46:58 -0800

Aidan,

>For each link, a router may automatically assign a site-local
>address from an EUI-48 (ie a MAC address) using the following
>address format:
>
>    | 12 bits |     48 bits      |  4 bits  |       64 bits        |
>    +---------+------------------+----------+----------------------+
>    |   fef   | router device ID |  sub ID  | machine interface ID |
>    +---------+------------------+----------+----------------------+
>                   Figure 1: Address Format: fef0::/12

BTW, two bits in an EUI-48 (i.e., the g and u bits) are not needed if using 
this as a global token, so it could be easily compressed to 46 bits leaving 
two more bits for the subnet.

I am not sure this helps very much with the other problems raised.

Bob

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From: Bob Hinden <[email-masked]>
Date: Sun, 01 Dec 2002 09:46:58 -0800

Aidan,

Bob

---

From: Bob Hinden <[email-masked]>
Date: Sun, 01 Dec 2002 09:46:58 -0800

Aidan,

Bob

---

From: "Tony Hain" <[email-masked]>
Date: Wed, 4 Dec 2002 16:03:41 -0800

I agree with Brian that there are issues with DNS & configured
databases, but the event frequency of this is generally low enough I
would consider it worth the risk. The problem I do have with it is the
lack of aggregation in the IGP that would result. While flat routing is
not a problem for a small network, it wouldn't work when the network
reached any significant size. 

From my perspective, there is room here to support an automated set as
well as an aggregatable set. If we took one /16 from the fec/10, say
feff, and used the next 48 bits from the router EUI to create the /64,
there would be no management required, but the networks that wanted
explicit control could filter that /16 in the IGP, and still have plenty
of SL space to manage as aggregates. How that works after the EUI-48's
run out is a different question...

Tony

> -----Original Message-----
> From: [email-masked] 
> [mailto:[email-masked]] On Behalf Of Bob Hinden
> Sent: Sunday, December 01, 2002 9:47 AM
> To: Aidan Williams
> Cc: [email-masked]
> Subject: Re: EUI-48 globally unique site-locals (GUSL)
> 
> 
> Aidan,
> 
> >For each link, a router may automatically assign a 
> site-local address 
> >from an EUI-48 (ie a MAC address) using the following address format:
> >

---

From: Andrew White <[email-masked]>
Date: Thu, 05 Dec 2002 11:59:44 +1100

Tony Hain wrote:
> 
> The problem I do have with it is the

Define 'significant'.  According to Brian Carpenter (28/11/2002):
> 
> The question is, at what scale does route aggregation
> begin to matter? The sort of VPN-based or merger-and-
> acquisition based networks we are talking about don't seem
> to be anywhere near that scale; we know that flat routing
> of thousands of prefixes is possible. So it may be
> philosophically unsettling, but I don't think it is
> operationally unsettling.

I freely admit my experience with routing tables is insufficient to know
where this cut-off is, but the gist I've been getting is 'hundreds - easy',
'thousands - doable'.

Am I hearing wrong?

-- 
Andrew White                [email-masked]

---

From: "Tony Hain" <[email-masked]>
Date: Wed, 4 Dec 2002 18:06:23 -0800

You are correct, but approaching 10,000 flat routes will cause the IGPs
to show their limits. (In case you were thinking that was an outrageous
number, there are IPv4 networks with that many subnets, and they can
only exist through aggregation.) The point is that we need to allow for
managed aggregation in the scheme, but that does not preclude
automatomation for a subset of the SL space.

Tony

> [mailto:[email-masked]] On Behalf Of Andrew White
> Sent: Wednesday, December 04, 2002 5:00 PM
> To: [email-masked]
> > lack of aggregation in the IGP that would result. While 
> flat routing 
> > is not a problem for a small network, it wouldn't work when the 
> > network reached any significant size.
> 
> > begin to matter? The sort of VPN-based or merger-and- acquisition 
> > based networks we are talking about don't seem to be anywhere near 
> > that scale; we know that flat routing of thousands of prefixes is 
> > possible. So it may be philosophically unsettling, but I 
> don't think 
> > it is operationally unsettling.
> 
> I freely admit my experience with routing tables is 
> insufficient to know where this cut-off is, but the gist I've 
> been getting is 'hundreds - easy', 'thousands - doable'.
> 
> Am I hearing wrong?
> 
> --