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Re: Last Call: 'Classless Inter-Domain Routing (CIDR): The Internet Address Assignment and Aggregation Plan' to Proposed Standard

2005-11-23 03:53:56
On Tue, Nov 22, 2005 at 10:52:23AM -0500, The IESG wrote:
The IESG has received a request from the Global Routing Operations WG to 
consider the following document:

- 'Classless Inter-Domain Routing (CIDR): The Internet Address Assignment and 
   Aggregation Plan '
   <draft-ietf-grow-rfc1519bis-03.txt> as a Proposed Standard

The IESG plans to make a decision in the next few weeks, and solicits
final comments on this action.  Please send any comments to the
iesg(_at_)ietf(_dot_)org or ietf(_at_)ietf(_dot_)org mailing lists by 


I think this is an interesting update.  

Some minor points that may wish to be considered but feel free to
pass over.

One is on section 2 - I think the issue is perhaps more the efficiency
of usage of IPv4 address space.   I know that is tied to rate of
consumption, but for many end site admins the impact of CIDR is a lot
of paperwork to demonstrate efficient use of allocated (or requested)
address space.

The rate of growth of the routing tables is perhaps also about the PI vs PA
issue.   Perhaps these terms could be explained in the text.

Another point is the use of private address space in the documentation for 
example purposes.  I know this is hard to avoid, but a statement like

 "For example, the legacy "class B" network, with an implied
  network mask of, is defined as the prefix"

seems odd when I normally see and think of it as a /12.

A third point is on the negative impacts of CIDR.  

For example, in squeezing out every bit of the prefix address space, 
administrators often spend extra time resizing internal (globally addressed) 
subnets because their provider insists on them maximising the efficiency 
of their address plans (understandably).    Or when a site grows, its
ISP offers it a different larger block (requiring renumebring) or 
non-contiguous ones, adding some internal complexity.

I would also suggest that this pressure has led to increased adoption of
NAT.   I don't see NAT mentioned anywhere in the text - perhaps it is
avoided for 'religious' reasons :)

I think in contrast to IPv6 address space allocation, in IPv6 we have 
aggregation from the outset, with a /48 per site (or maybe a /56 for some 
sites :) and in effect 'infinitely' sized subnets, so the above concerns 
are not really present for a typical IPv6 deployment.   Perhaps again 
though an aside into IPv6 comparisons with aggregation would be a 
distraction :)


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