[arin-ppml] ARIN Draft Policy 2011-5: Shared Transition Space

Owen DeLong owen at delong.com
Tue Jul 5 17:30:31 EDT 2011

On Jul 5, 2011, at 2:24 PM, William Herrin wrote:

> On Tue, Jul 5, 2011 at 5:13 PM, Owen DeLong <owen at delong.com> wrote:
>> On Jul 5, 2011, at 2:01 PM, William Herrin wrote:
>>> 2. Router interface numbering is a potential use case. Filtering of
>>> RFC1918 is too widespread to overcome, so using it outside the NAT
>>> breaks path MTU detection. That's not inherently true of this new
>>> space and nonfiltering could be encouraged in a way that renders it
>>> usable in a few years.
>> Not really... How would you know which ISP to route the packet
>> back to?
> Hi Owen,
> You don't care. The packets you care about receiving from the router
> are ICMP type 3 (destination unreachable) and ICMP type 11 (time
> exceeded) . Those flow only one direction -- from the router back
> towards you.

Not really...

If a packet is inbound towards me and needs fragmentation, for PMTU
discovery, then, an ICMP type 3 would be sent back towards the
originator of said packet.


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