-----Original Message----- From: ipv6-boun...@ietf.org [mailto:ipv6-boun...@ietf.org] On Behalf Of Tina TSOU Sent: Wednesday, July 28, 2010 11:57 AM To: Aleksi Suhonen Cc: ipv6@ietf.org Subject: Re: Flow Label: 12 bits mutable and 8 bits immutable
On Jul 28, 2010, at 5:01 PM, Aleksi Suhonen wrote: > Some earlier discussion has suggested that if the label is "0", then > it's mutable and otherwise it's immutable. It's also fine, if people could agree on it. I'm fine with both proposals, as long as both mutable and immutable are possible. > And if an operator does change it, they should reset it on egress, > and maybe hijack some other bit in the header (e.g. from DSCP?) to > signal that the flow label has been fiddled with. This bit should of > course also be reset at the same time as the label is reset. [[WEG]] I refer you to Bert Manfredi's message http://www.ietf.org/mail-archive/web/ipv6/current/msg12042.html. The lack of a checksum is why I'm generally resistant to the idea of preserving immutability of this field in all or in part - while the RFC says it must be, in practical application, a single bit error ruins that assumption. There's no way to be sure that it's immutable within an AS, let alone across multiple ASes, so any implementation that relies on the intermediate networks not touching it (or worse, an implementation that "fiddles" with it and then somehow resets it to the original value on egress) is doomed to failure. Wes George This e-mail may contain Sprint Nextel Company proprietary information intended for the sole use of the recipient(s). Any use by others is prohibited. If you are not the intended recipient, please contact the sender and delete all copies of the message. -------------------------------------------------------------------- IETF IPv6 working group mailing list ipv6@ietf.org Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
