Hi Fan,

Thanks for your detailed review of this draft. They are helpful for polishing 
the document.

Please see some replies inline:

From: Fan Zhang <[email protected]>
Sent: Tuesday, December 2, 2025 11:24 AM
To: [email protected]
Cc: RTGWG <[email protected]>; FANTEL <[email protected]>
Subject: [fantel] Some comments on draft-dong-fantel-problem-statement-02

Hi authors,

Thanks for the draft. It's good to have a draft that helps clarify the problems 
and scope of FANTEL. I've read it and have some comments below.

[Comments]

1) "fast network notification" and "fast notification" are both used in the 
document. Is there any difference between them? If not, it may be better to 
align the terminology.
[Jie] Thanks for pointing this out. I agree it is better to align the 
terminology. IMO this is a good question and we would like to hear opinions 
from participants on both the RTGWG and FANTEL lists:
[Jie] "fast notification" is what was firstly used in FANTEL BoF, "network 
notification" is what we used in initial versions of this draft following the 
guidance from our AD, and  "fast network notification" is what we hear people 
proposing during the RTGWG meeting at IETF 124.
[Jie] Which one should we use in future version of this draft and other related 
drafts? We are open to feedbacks.

2) Section 3-Overhead and Scalability Challenges: Telemetry usually works in a 
publish/subscribe mode, rather than "flooding". "telemetry streaming" may be 
better.
[Jie] I agree telemetry streaming is more accurate, thanks for the suggestion, 
will fix it in next revision.

3) Section 4: "before congestion or micro-loops develop". "develop" might imply 
a gradual progress. Perhaps "occur" would be clearer.
[Jie] My personal opinion is develop may be better here. “develop” indicates 
the congestion and micro-loop can become more significant if it takes longer 
time to send the notification. With fast notification and action, it is 
possible to avoid severe congestion and micro-loop, while they may still exist 
for a short period.

4) Section 4.1.1-BFD: "nor can it notify the failure or congestion to other 
nodes". IMHO, BFD can trigger the local IGP process to notify the failure to 
other nodes.
[Jie] Yes BFD can be used for the detection of IGP neighbor failure, then IGP 
will act accordingly and propagate state updates to other nodes in the network. 
While BFD itself is not used as a notification to other nodes about the 
failure. Also BFD is not used for the notification of congestion or other state 
changes.

5) Section 4.1.2: "Fast notification alerts upstream nodes". I agree that it's 
obvious that upstream nodes might need to be notified in some cases. But I'm 
wondering whether there are other cases where fast notification might alert 
other nodes (such as neighbors)?
[Jie] In the example described in section 4, the notification is used to notify 
the nodes which are sending traffic towards the failure point, so as to shift 
the traffic to alternate link/path, thus from the perspective of traffic flow, 
the notification needs to be sent to the upstream nodes. Depending on the 
traffic flows to be shifted, the notification may be sent to different nodes 
(which are considered as the upstream nodes of the traffic flow under 
consideration). We will consider how to make this clearer.

[Nits, take it or leave it]

1) Section 4.1: "exchange terabits per second of data" --> "exchange terabits 
of data per second"

2) Section 4.1.1-FRR: "The former lacks of global network situation" --> "The 
former lacks a global view of the network state"

3) Section 4.1.1: "may already be missed" --> "may have already been missed"

4) Section 5.2: "protocols, analytics, NMS, etc." --> "protocols, analytics 
systems, NMS, etc."

5) Section 5.4: "but not limit to" --> "but not limited to"

6) Section 5.4: "Switch all traffic" --> "Switches all traffic". Might need to 
align with other bullets.
7) Section 6: "too slow, too coarse, or too resource-intensive" --> "too slow, 
too coarse, or too resource-intensive to ......" Might need to clarify the 
specific consequences.

[Jie] Thanks for catching the nits, they will definitely help in improving the 
readability of this document.

Best regards,
Jie

Regards,
Fan
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