Hi again Mark >> - The issue of fragmentation. Applying RFC 4944 over a multihop radio >> mesh exposes the network to congestion collapse, as described in >> http://www.tools.ietf.org/html/draft-thubert-6lowpan-simple-fragment-rec >> overy . I think that the WG should dedicate some bandwitdth to provide >> additional functions that would improve the LoWPAN operation WRT flow >> control and recovery of fragments. >> >Fragmentation, OK, but why is flow control a network layer issue rather >than a transport layer issue?
[Pascal] I'm talking about flow control on the fragments themselves; this is either a LLC (the likes of 802.2 or LAPB) or a shim layer above LLC problem (that would be us). The 802.15.4 MAC/PHY was not design to cope with IPv6 MTU and when the IPv6 stack sends a NLPDU of 1280 bytes minimum, it causes a burst of fragments that should be paced and windowed. I suggest we do it in 6LoWPAN and handle the consequences of our own fragmentation rather than rely on a LLC mechanism that might not be there or adapted. Pascal _______________________________________________ 6lowpan mailing list [email protected] https://www.ietf.org/mailman/listinfo/6lowpan
