[Int-dir] Re: draft-ietf-v6ops-framework-md-ipv6only-underlay-25 telechat Intdir review

[Chongfeng Xie <[e-mail]>]

Hi Min,
Thank you for your review and raising the comments, please see my feedback inline[Chongfeng],
 
From: 【外部账号】Xiao Min via Datatracker
Date: 2026-08-17 08:47
To: [e-mail]
CC: draft-ietf-v6ops-framework-md-ipv6only-underlay.all; last-call; v6ops
Subject: draft-ietf-v6ops-framework-md-ipv6only-underlay-25 telechat Intdir review
Document: draft-ietf-v6ops-framework-md-ipv6only-underlay
Title: Framework for Multi-domain IPv6-only Underlay Network and IPv4-as-a-Service
Reviewer: Xiao Min
Review result: Almost Ready
 
Hi,
 
I have been assigned as the int-dir reviewer for this draft. For background on int-dir,
please see the FAQ (https://wiki.ietf.org/en/group/intdir) Please resolve these 
comments along with any other comments you may receive.
 
This draft describes a framework for a multi-domain IPv6-only underlay network 
from the perspective of network providers. I think this draft is well-written. At the 
same time, I have some comments for the authors to consider.
 
## Major Comments
 
None.
 
## Minor Comments
 
### Section 2
 
There is a term IPv4-embedded IPv6 address defined here. However IPv6 mapping 
prefix is not mentioned and that concept appears multiple times later, sometimes 
combined with IPv4-embedded IPv6 address. Suggest to add some text describing 
the relationship between IPv4-embedded IPv6 address and IPv6 mapping prefix.

[Chongfeng]: IPv4-embedded IPv6 address is a term defined in RFC6052， it refers to
An IPv6 address embedded with a 32-bit IPv4 address used to represent an IPv4 node 
in an IPv6 network, its relationship with IPv6 mapping prefix is shown in table 1. 
For the case of an multi-domain IPv6-only network，IPv6 mapping prefix equals 
to "Network Specific Prefix" of RFC6052, this has been illustrated in section 4.1 

### Section 3
 
For Figure 1, I couldn't find the expansion for BR.
 
### Section 4.1
 
Is the Pref6(PE) allocation must be unique within the multi-domain network? If yes, 
suggest to make it explicit.

[Chongfeng]: Yes, the following change has been made in section 6,
OLD：
These prefixes are to be allocated from the Network Specific Prefix (NSP).

NEW：
These prefixes are unique within the multi-domain network, and they are to
be allocated from the NSPs.

 
### Section 4.2
 
For Figure 2, I couldn't find the expansion for NW.

[Chongfeng]: It has been changed to "NP-3"
 
### Section 6
 
It says "This allows IPv4-embedded IPv6 packets to be forwarded using existing aggregate 
routes, avoiding the need for additional FIB entries in the IPv6 core". It seems there is a 
precondition in multi-domain environment that each domain needs to employ the same 
length of IPv6 mapping prefix, if that's the case, suggest to make it explicit.

[Chongfeng]: I agree with your point. In section 6，there has been the following statement,

    "For NPs, having all IPv6 mapping prefixes share the same length  
    during deployment will likely avoid the unnecessary processing cost
    and complexity caused by prefix length diversity."

    It has reflected your point. 

Based on your comments, a new version (-26) has been submitted.
If you have further comments, please feel free to let me know.  

Best regards
Chongfeng