Re: [Tsv-art] [tram] Tsvart last call review of draft-ietf-tram-turnbis-25

Joe Touch <touch@xxxxxxxxxxxxxx> · Wed, 19 Jun 2019 17:29:34 -0700

Tiru,
This sort of patch isn’t sufficient. It doesn’t address the confusion throughout section 15 as to what’s actually happening.

Sec 15 shouldn’t talk about “setting” IP header values at all; it should refer to “configuring transport sessions” in the desired ways. Otherwise you’re implying direct packet-level conversion. Even the title of that section is a problem in this regard.

Tthe sections themselves should be revised to similarly refer to transport-level actions, not packet level, e.g.:
15.1 TCP to UDP
	- because DSCP should not vary within a TCP session, there is no packet-level tracking of copying DSCP from TCP to UDP; instead, DSCP would be a property of the TCP session that would be used to configure the UDP socket pair.
	- IP fragmentation control needs to be explained in terms of UDP interactions
	- IPv6 fragmentation has nothing to do with the received packet (which is TCP
	- IP options are *as default*; it’ isn’t correct that you never use IP options (or are you actively disabling them?)
		NOTE: that goes for the direct IPv4 to IPv6 translation in section 4 (which is similarly problematic)

15.2 UDP to TCP
	- the last sentence of the second paragraph seems at odds with the first; the first says “set these once per connection”, it is sufficient IMO.
	-TCP DSCP should be based on the *first* UDP value seen (it could vary)
	- same issue with IP extension headers and options (presumably you use the default

Joe

On Jun 19, 2019, at 8:14 AM, Konda, Tirumaleswar Reddy <TirumaleswarReddy_Konda@xxxxxxxxxx> wrote:

Hi Joe,

The IPv4 and IPv6 fragmentation description is specific to TCP-to-UDP relaying between the client and the peer (only for TCP-to-UDP relay, the DF attribute in the TURN message will be used to set the DF bit in the outgoing UDP packet to the peer). To avoid confusion, I have added two new sub-sections:
15.1.  IP Header Fields for TCP-to-UDP relaying and 15.2 IP Header Fields for UDP-to-TCP relaying

Please see the attached updated draft.

Cheers,
-Tiru