Hi Bill,
thanks for your comments, please see inline (##PP):
On 13/05/2023 22:38, Acee Lindem wrote:
Hi Bill,
Thanks for the Ops review. I reformatted your Email for readability and
continued discussion.
Thanks,
Acee
Reviewer: Qin Wu
Review result: Has Issues
I have reviewed this document as part of the Ops area directorate's ongoing
effort to review all IETF documents being processed by the IESG. These
comments were written primarily for the benefit of the Ops area directors.
Document editors and WG chairs should treat these comments just like any other
last-call comments.
This document extends Flex-Algorithm that is originally used for SR MPLS and
SRv6 data plane, allowing it to compute paths to IPv4 and IPv6 prefixes. This
draft is well written, however I do have a few comments on the latest version
before seeing this work being moved forward:
1. Abstract:Is regular IPv4 and IPv6 forwarding related to Native IP data plane,
IP dataplane has been describe once in section 5, but most of other places use
IP forwarding, which lack consistency.
##PP
we use data-plane all over the document, whether we refer to IP, MPLS or
SRv6 one.
"IP forwarding" is only used for OSPFv2 "IP Forwarding address" which is
a term defined in RFC2328.
2. Introduction, last paragraph: It looks there are some contradiction here, On
one hand, Flex algorithm can be used independent of data plane technologies
such as SR MPLS, SRv6, Native IPv4/IPv6 On the other hand, it said: Flex
algorithm is tied to SR MPLS or SRv6 data plane technology, lack consistency.
##PP
where do you see it saying that "Flex algorithm can be used independent
of data plane technologies"?
The text says:
"Flex-Algorithm definition (FAD), as described in [RFC9350], is data-
plane independent and is used by all Flex-Algorithm data-planes."
but that refers to FAD, which is indeed DP independent.
3. Section 3 Do we use specific GTP data plane technology in this 5G use case?
##PP
no.
If not the case, is there IGP protocol enabled on both gNodeB and UPF?
##PP
yes.
GTP/Native IP/ IP network with IGP protocol support Please be more explcit
in the use case section.
##PP
I'm not, by any means, a 5G expert, please suggest the exact text.
4.Section 6.1: Last Paragraph Lack RFC reference for IPv4 Prefix Reachability
TLV and IPv6 Prefix Reachability TLV.
##PP added
Why IPv4 prefix reachability TLV can not
be used to Carry algo prefix reachability related information? Suppose both
IPv4 prefix reachability TLV and IPv4 Algorithm Prefix reachability TLV can
be used to carry the similar information, then the question is when we use
IPv4 Prefix Rechability TLV? When we use IPv4 Algorithm Prefix Reachability
TLV? Do we over design for this?
##PP
legacy IPv4/v6 prefix reachability TLVs advertise the prefix
reachability in default algorithm 0. They can not be used to advertise
the reachability for any other algorithm, because routers that do not
understand extensions defined in this draft would consider it as
reachability in algo 0. That would potentially result in permanent loop.
5. Section 6.2: Last two Paragraphs It looks both ISIS SRv6 locator TLV an
ISIS IPv6 algorithm Prefix rechability TLV serve the similar purpose? Why
we should introduce ISIS IPv6 Algorithm Rechability TLV?
##PP
ISIS SRv6 locator TLV has been defined for SRv6 and may carry SRv6
specific sub-TLVs, which IP algorithm TLVs MUST not carry.
The question of reusing the locator TLV has been discussed by the WG and
the decision was to define an independent TLV for IP Flex-algo.
thanks,
Peter
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