About how many extension headers after basic headers.

[verybigstrong]

2. IPv6 Basic Technology - Extension headers and options:"As explained in 2. Packet Format, every IPv6 packet includes one or more extension headers, of which the last one is the transport layer payload (UDP, TCP, etc.)."

RFC8200: "As illustrated in these examples, an IPv6 packet may carry zero, one, or more extension headers, each identified by the Next Header field of the preceding header"

I think here should be "one or more additional headers" or " zero or more extension headers" ?

[becarpenter]

Yes, I will correct this, thanks. Actually the phrasing in RFC8220 is not very good. It doesn't, I think, say that there MUST be an upper layer header or state that a packet where the initial "Next Header" value is "No Next Header" is invalid. So the zero, one, or more extension headers phrase is a little ambiguous.

[cron2]

Hi,

On Tue, Jan 10, 2023 at 11:44:32AM -0800, Brian E Carpenter wrote:

Yes, I will correct this, thanks, although the value of a packet with no extension headers escapes me :-).

This really depends on whether you call a TCP or UDP header "an extension header". It's clearly a "next header", but is not really an extension.

(IOW, all those things that make ISPs drop packets are EHs, not the normal stuff :-) )

gert

-- "If was one thing all people took for granted, was conviction that if you feed honest figures into a computer, honest figures come out. Never doubted it myself till I met a computer with a sense of humor." Robert A. Heinlein, The Moon is a Harsh Mistress

Gert Doering - Munich, Germany @.***

[becarpenter]

Oops, I just updated my comment for that very reason. Never saw github comments cross in the post before!

[becarpenter]

I think the updated text is correct: "every IPv6 packet may include one or more extension headers before the transport layer payload". I also added a note in Packet Format. Closing the issue for now.