Telechat Review of draft-ietf-6man-eh-limits-19
review-ietf-6man-eh-limits-19-intdir-telechat-combes-2025-04-03-00

Hi,

I am an assigned INT directorate reviewer for draft-ietf-6man-eh-limits-19.
These comments were written primarily for the benefit of the Internet Area
Directors. Document editors and shepherd(s) should treat these comments just
like they would treat comments from any other IETF contributors and resolve
them along with any other Last Call comments that have been received. For more
details on the INT Directorate, see
https://datatracker.ietf.org/group/intdir/about/
<https://datatracker.ietf.org/group/intdir/about/>.

I would appreciate clarifications about “Intermediate node” concept, based on
the following text:

<document>
1.3.  Terminology

This section provides definitions for some terms used in this document.

Node: a device that implements IPv6

Router: a node that forwards IPv6 packets not explicitly addressed to itself

Intermediate node: a node that is addressed by an entry in a Routing Header
list where the entry is not the last one in the list

Host: any node that is not a router or intermediate node

IPv6 header chain: the IPv6 header and the set of following IPv6 Extension
Headers that precede the upper layer protocol in a packet

2.  Overview of extension header limits

<snip>

Limits are defined for both senders (sending hosts) and receivers (receiving
hosts, intermediate nodes, or routers).  A receiver limit is set to limit the
amount of processing or the amount of data in received extension headers. 
Sender limits are set to limit the use of extension headers being sent.  The
purpose of sender limits is to increase the probability of successful delivery.
</document>

Why the “intermediate node” concept has been specified?
Indeed, except if I missed something, the “intermediate node” could be
considered as a “receiving host” when receiving a packet and, after RH
extension process, as a “sending host” when sending the packet. Correct?

BTW, is there something that prevents any “intermediate node” to modify
extension headers (e.g., numbers, length) inside the packet? If not, IMHO,
limits for senders should apply to any "intermediate node" too.

Thanks in advance for the clarifications.

Best regards,

JMC.