Subject: [spring] One comment on <srv6-network-programming>

From: Xiejingrong <[email-masked]>
Date: Tue, 12 Mar 2019 14:28:00 +0000

Dear authors of <srv6-network-programming>:

Thanks for introducing this great concept about how to develop the 128-bit IPv6 address.

One comment/question:
Next header value 59 is used when an Ethernet-packet is as the IPv6 payload in SRv6-L2VPN scenario.
It is confusing, because 59 is generally used to indicate that there is *no* payload after the IPv6 header and the extension headers. RFC4380 has such an example.
Though RFC8200 allow a packet with Next Header 59 with some payload, but it is not the normal case.
For example, a firewall, or acl rules on a legacy router may drop a packet with next header 59.
The IP/IPv6 should use Next Header to indicate the payload format *explicitly* as its original paradigm.
This document also has a good example to use this correctly:
Next Header value 4/41 for IPv4/IPv6 payload in SRv6-L3VPN like End.DT4 or End.DT6.

Should this value 59 be changed to TBD and be allocated from IANA officially?
Does the words "we conveniently reuse the next-header value 59" in the document imply this work ?

Thanks
Jingrong