> -----Original Message----- > From: [email protected] [mailto:[email protected]] On
> My understanding is that it labels a flow. If the right way > to carry a flow is distributed across two network paths, so > be it. BTW, a "flow" has many definitions; the type of flow > that Tony was mentioning this morning is a single application > session; to an ISP, a flow is a stream of traffic from an > ingress to an egress, or perhaps the stream of traffic from > an ingress to an egress via a path. This means that the IPv6 > Working Group wants the flow label to be a hash that helps > the network find status for a specific session's or set of > sessions' shared' state, while to an ISP it wants to be > independent of the source address - associated with the > ingress router. > > > RFC 1710, the original specification for what later because > IPv6, said of the flow label: > > The Flow Label field in the SIPP header may be used by a host to > label those packets for which it requests special handling by SIPP > routers, such as non-default quality of service or "real-time" > service. This labeling is important in order to support > applications > which require some degree of consistent throughput, delay, and/or > jitter. The Flow Label is a 28-bit field, internally > structured into > three subfields as follows: > > RFC 1752 agreed: > > * Flow Label - This field may be used by a host to label those > packets for which it is requesting special handling by routers > within a network, such as non-default quality of service > or "real- > time" service. (28-bit field) > > RFC 2460 reads: > > o Flow Labeling Capability > > A new capability is added to enable the labeling of packets > belonging to particular traffic "flows" for which the sender > requests special handling, such as non-default quality of > service or "real-time" service. But didn't we determine in a long thread that such uses by routers were not very robust, because there is no header checksum to protect that flow label? If I want to use flow label end-to-end, any rule that says that flow label is immutable unless set to zero becomes ambiguous. At the destination host, I would have no idea whether the source host set the label, or whether a router along the path set the label. But I understand that is how they ARE being used now, so I guess the point becomes moot. Bert -------------------------------------------------------------------- IETF IPv6 working group mailing list [email protected] Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6 --------------------------------------------------------------------
