a radical proposal (Re: protocols that don't meet the need...)

Fred Baker fred at cisco.com
Wed Feb 15 23:15:12 UTC 2006

On Feb 15, 2006, at 9:13 AM, Edward B. DREGER wrote:
> Of course not.  Let SBC and Cox obtain a _joint_ ASN and _joint_  
> address
> space.  Each provider announces the aggregate co-op space via the  
> joint
> ASN as a downstream.

Interesting. This is what has been called metropolitan addressing.  
I'm certainly not the one who first proposed it, although I have  
thought about it for a while, dating at least as far back as 2001.

The crux of the concept as several *have* proposed it is that a  
regional authority - a city, perhaps, or a consortium of ISPs, or in  
the latest version of the proposal I have seen the country of Korea -  
gets a prefix, and sets up an arrangement. SOHOs that want to  
multihome within its territory are able to get small (/48? /56?)  
prefixes from it, and providers that deliver service in the area may  
opt in to supporting such SOHO prefixes. If they opt in, they are  
agreeing to:

  - join a local IXP, which may be a physical switch or
    virtualized by a set of bilateral agreements.
  - outside the region, they advertise the prefix of the
    regional authority
  - within the region, for customers that have gotten such a
    prefix, if they have connectivity to the customer they
    advertise the customer's prefix to the ISPs at the IXP.

Note that the customer is not expected to run BGP or get an AS  
number, but either the regional authority gets an AS number or each  
serving ISP is deemed authorized to originate the prefix in its BGP  
announcements. But if a SOHO has two ISPs, both advertise its prefix  
within the region, and when a packet is sent to the prefix from  
wherever, any ISP that is delivering service to the SOHO can  
legitimately deliver it, and if one gets the packet but is not the  
servicing ISP, it knows how to hand the packet to the appropriate ISP  
at the IXP.

This turns the business model of routing on its head. Typically today  
if Alice is using ISP AliceNet and Bob is using ISP BobNet, Alice  
hands her packet to AliceNet, AliceNet gets it to BobNet in the  
cheapest way it can, and BobNet carries it halfway around the world  
to Bob. Bob's ISP carries the burden of most of the work. But in this  
model, if AliceNet happens to also provide service in Bob's region,  
AliceNet might carry the packet to the region and only give it to  
BobNet for the last 500 feet.

Whenever I have talked about the model with an ISP, I have gotten  
blasted. Basically, I have been told that

(1) any idea on operations proposed in the IETF is a bad idea because  
the IETF doesn't listen to operators
(2) the ISPs aren't going to be willing to make settlement payments  
among themselves in accordance with the plan
(3) routing isn't good enough to support it
(4) and in any event, this makes it too easy to change ISPs

In short, "hell no".

So, since nobody in the IETF (according to you) is supporting this  
model, what I understand from your remark and this thread is that the  
IETF is not responsive to ideas proposed by operators and doesn't  
come up with things operators can use, taking as an example that it  
hasn't told you how to implement metropolitan addressing.

Did I get that right?

I'm not sure how to proceed, given the level of invective I get in  
any discussion with anyone on the topic.

Note 1: PI addressing for edge networks that can qualify under a  
sensible set of rules (current ones are inadequate) for an AS number  
is the preferred way to handle an enterprise of a size r complexity  
comparable to a small (or large) ISP.

Note 2: Provider-provisioned addresses continue to make sense for  
folks that don't plan to multihome.

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