Speaking as individual contributor.

Thank you for the document and in particular for the new -09.

With regards to §7.1 " Trusted Domains and Filtering"

I think that in the general case there may be multiple SRv6 domains:
-a- totally separated (e.g., SP A & SP B with no interconnection). Usually, 
this is the assumed case.
-b- hierarchical (à la Carrier's carrier). §7.1.2 is referring to this case
-c- overlapping. E.g., with one node belonging to two SRv6 domains. (could be a 
mobile SRv6 domain and a packet SRv6 domain with some nodes belonging in both. 
Could also be one internal domain (P, PE node), and another domain for PE and 
customers/CE (with a reduced set of segments, e.g., a few bindings segments 
offered as API). §7.1.3 can probably be read to cover this.

I feel that at minimal, the texts from this document should cover all cases, 
and should be generally applicable. This may require to carefully craft some 
wording.
Ideally, in my opinion, the document would explicitly touch on this point.

Please find below some proposed minimal changes
" SRv6 is deployed within a trusted domain" seems to only cover a single "SRv6" 
(domain).
OLD: the current document assumes that SRv6 is deployed within a trusted domain
NEW: the document assumes that the SRv6 domain is a trusted domain

§7.1.3
In general, the boundary of the domain seems to be at the interface level, 
rather than at the node level. (In particular, but not limited to, a node part 
of multiple SRv6 domains)
May be
OLD: The IPv6 destination address can be filtered at the SR ingress node
NEW: The IPv6 destination address can be filtered at the external interface of 
the SR ingress node of the SRv6 domain.

(as a side effect, this highlight that the filter is applied on a per interface 
basis, which can be less scalable for some hardware).

§7.1.3
In the scope of deployment "-b-", may be this section could say that the 
filter/@block is associated to the/one SRv6 domain. (and different SRv6 domains 
have different a block/filter)

May be §7.3 (HMAC) could also cover this. E.g.
OLD:  the same key might be reused by multiple systems
NEW:  the same key might be reused by multiple systems of a SRv6 domain

(but definitely not the same key for different domains, including on the same 
system/node)

BTW, this sentence starts with the term "node" and finish by using the term 
"systems". It's not clear to me what distinction is implied. If none, may I 
suggest using the same term? (e.g. node)

§7.2
" Encapsulation of packets at the SR ingress node and
decapsulation at the SR egress node mitigates the ability of external
attackers to attack the domain and also allows for encapsulation of
both IPv4 and IPv6 packets."

Again, node boundary is not enough: decapsulation at the SR egress node, 
followed by a lookup on that node does not provides protection. We need 
decapsulation on the egress followed by the sending of the packet outside of 
the SRv6 domain without further lookup. MPLS has some similar security 
consideration and possibly 
https://datatracker.ietf.org/doc/html/rfc4364#section-6 may be of some help.

§7.3 (HMAC TLV)
"An internal attacker who does not have access to the pre-shared
key can capture legitimate packets, and later replay the SRH and
HMAC from these recorded packets."

Agreed. May be adding "for the lifetime of the pre-shared key validity."
(possibly adding that a mitigation would be to change the key 
periodically/frequently.)


Thanks,
Regards,
--Bruno



-----Original Message-----
From: [email protected] <[email protected]>
Sent: Thursday, November 6, 2025 3:39 PM
To: [email protected]
Cc: [email protected]
Subject: [spring] I-D Action: draft-ietf-spring-srv6-security-09.txt

Internet-Draft draft-ietf-spring-srv6-security-09.txt is now available. It is
a work item of the Source Packet Routing in Networking (SPRING) WG of the
IETF.

   Title:   Segment Routing IPv6 Security Considerations
   Authors: Nick Buraglio
            Tal Mizrahi
            Tian Tong
            Luis M. Contreras
            Fernando Gont
   Name:    draft-ietf-spring-srv6-security-09.txt
   Pages:   30
   Dates:   2025-11-06

Abstract:

   SRv6 is a traffic engineering, encapsulation and steering mechanism
   utilizing IPv6 addresses to identify segments in a pre-defined
   policy.  This document discusses security considerations in SRv6
   networks, including the potential threats and the possible mitigation
   methods.  The document does not define any new security protocols or
   extensions to existing protocols.

The IETF datatracker status page for this Internet-Draft is:
https://datatracker.ietf.org/doc/draft-ietf-spring-srv6-security/

There is also an HTML version available at:
https://www.ietf.org/archive/id/draft-ietf-spring-srv6-security-09.html

A diff from the previous version is available at:
https://author-tools.ietf.org/iddiff?url2=draft-ietf-spring-srv6-security-09

Internet-Drafts are also available by rsync at:
rsync.ietf.org::internet-drafts


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