Subject: [sfc] Some questions about NSH

From: [email-masked]
Date: Wed, 19 Apr 2017 10:02:17 +0800

Hi authors，

After I reviewed the NSH draft, I have some questions and comments. 

1.Section 4: In Figure 8, I think Classifier should also have function to 
select SFP, the Classifier need to know how to forward the traffic to the 
first SFF of the SFP.

2.Section 7.1: There is a mapping between next hop and transport in every 
SFF. So the traffic forwarded from one SFF to anther SFF is on a kind of 
transport tunnel. I think there should be an example to illustrated the 
packet format from SFF on a transport. That is how to choose a specific 
tunnel according to the next hop and tranport in Figure 9, so that the 
packet can be forwarded to right next SFF. And in this part, it is assumed 
that the NVE( function for tunnel) and SFF are co-located. What if they 
are split? There is no specification about it. In my opinion, only if SFF 
forwarding is independent with NVE, so we can say that NSH is agonostic 
with transport. 

3.Section 8.2: There are already Metadata Augment and Metadata Update. 
What about the Metadata Delete? For some cases, one metadata once be used 
by a SF, and the metadata will not by used anymore, maybe the SF should 
delete that metadata if it is not useful anymore.

Best Regards.
Ting