One point in line: On 22-Aug-21 10:43, Michael Richardson wrote: > > Brian E Carpenter <[email protected]> wrote: > > (1) Flooding (M_FLOOD) messages. These are UDP multicasts, so in effect > > all nodes must agree on the same maximum size. To send messages above > > the present limit, the maximum flood message size would have to be > > increased everywhere in the autonomic network. That is trivial if we > > allow operator configuration, but since an AN should be self-creating, > > we want to avoid operator configuration. Therefore, we need GRASP to be > > able to self-configure this. > > For the flooded messages over UDP, it seems unwise to ever assume we can > reliably get more than 1280 through. In production, this goes over IPsec ESP > tunnels.
Why would that break IPv6 fragmentation? We can assume a well-defined MTU within an autonomic network, I think. These are all link-local addressed packets, so there is no PMTUD problem. Brian > > At some point, we probably should specify use of > IP-TFS: Aggregation and Fragmentation Mode for ESP and its Use for IP > Traffic Flow Security > draft-ietf-ipsecme-iptfs-09 > > This would provide a better fragmentation regime than what we do now, and > there maybe some traffic analysis and predictability advantages here. > (If ACP traffic *always* takes 1% of bandwidth, it becomes more predictable, > but also there may be congestion advantages to having "reserved" that > bandwidth) > > > (2) Unicast messages (discovery responses, synchronization, > > negotiation). On investigation, it is very easy to allow such messages > > over TCP to be of any reasonable length, with no protocol change and > > without all nodes necessarily agreeing on what a "reasonable length" > > is. I discovered that my demo implementation of GRASP would already > > handle messages up to 4096 bytes, and tweaked the code to remove that > > limitation. I tested it with a GRASP objective exceeding 5000 bytes. > > For the messages over TCP, which in response to a UDP flooded or discovery > message, the discovering node can announce it's ability to receive bigger > messages (and the size). > > In the Discovery Response Message, the discovered node could initiate it's > maximum too. > > How to fit this into the messages, I don't know yet. > > It's not clear me that we need to do this network-wide, but we could do that. > > -- > Michael Richardson <[email protected]> . o O ( IPv6 IøT consulting ) > Sandelman Software Works Inc, Ottawa and Worldwide > _______________________________________________ Anima mailing list [email protected] https://www.ietf.org/mailman/listinfo/anima
