Hesham Soliman wrote :
On 6/05/08 6:38 PM, "Rémi Després" <remi.despres@free.fr> wrote:
Following the discusion, this is IMHO the right logic: TURN nodes may freely support or not support RFC 3697 flow labels, as sources on their outgoing interfaces,. Independently, they may freely ignore received flow labels, or process them to optimize their transport flow recognition, on thir incoming interfaces.
=> I don't understand two points: - Why is the IPv6 address/header being re-written? - If there is a good answer for the above question then why would you ignore the flow label and not copy it across?
The destination address of a packet received by a TURN relay is the address of the relay. That of the packet it forwards, with the same data field, is the address of the next IP layer destination node (the destination host or an itermediate NAT).
RFC 3697 has a rule that non zero flow labels that leave a node MUST be all different for current flows having the same source-destination pair.
If flow labels received by a TURN relay from two different sources happen to be the same while the next IP destination happens to be the same NAT, copying flow labels will infringe the rule.
Therefore, IMU, flow labels *MUST NOT* be copied from upstream flows to downstream flows.
Rémi