Repository : ssh://git@diktynna/doc

On branches: backup-redmine/2023-01-14,main

commit 1919e9e4e33292a21379a0f9c18281d355d4892b Author: Linus L��ssing linus.luessing@c0d3.blue Date: Mon Dec 26 15:04:00 2022 +0000

doc: batman-adv/Multicast-Packet-Type

1919e9e4e33292a21379a0f9c18281d355d4892b batman-adv/Multicast-Packet-Type.textile | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/batman-adv/Multicast-Packet-Type.textile b/batman-adv/Multicast-Packet-Type.textile index 43c9defa..d48136c7 100644 --- a/batman-adv/Multicast-Packet-Type.textile +++ b/batman-adv/Multicast-Packet-Type.textile @@ -122,17 +122,21 @@ h3. -Non ideal splits-

-> Going for just one multicast packet instead of up to mcast_fanout to start with, for simplicity.

-h3. Fragmentation / MTUs: +h3. -Fragmentation / MTUs:-

-On transit a forwarding node might have an interface with a smaller MTU than the node which originated the packet. A node could try to split a packet into multiple packets with less destinations. However if the payload data is larger than the interface MTU already then it would still not fit. And the batman-adv fragmentation code won't be able to look into and split within a multicast packet type header. +-On transit a forwarding node might have an interface with a smaller MTU than the node which originated the packet. A node could try to split a packet into multiple packets with less destinations. However if the payload data is larger than the interface MTU already then it would still not fit. And the batman-adv fragmentation code won't be able to look into and split within a multicast packet type header.-

-Workaround A): +-Workaround A):-

-By default only apply multicast packet type if resulting packet is smaller than 1280 (minimum IPv6 packet size) or even 576 (minimum accepeted IPv4 datagram size?). Maybe add a configuration option, which defaults to 576 bytes? While in practice configuring it to 1280 should usually be fine these days with IPv6 capable networks. +-By default only apply multicast packet type if resulting packet is smaller than 1280 (minimum IPv6 packet size) or even 576 (minimum accepeted IPv4 datagram size?). Maybe add a configuration option, which defaults to 576 bytes? While in practice configuring it to 1280 should usually be fine these days with IPv6 capable networks.-

-Solution B) +-Solution B)-

-Later ideally the fragmentation code would be able to split the payload within a multicast packet type, while leaving multicast packet type headers in tact. A node should still forward packets if due to this splitting the mcast-fanout limit were violated, to avoid packet loss. +-Later ideally the fragmentation code would be able to split the payload within a multicast packet type, while leaving multicast packet type headers in tact. A node should still forward packets if due to this splitting the mcast-fanout limit were violated, to avoid packet loss.- + +--- + +-> Workaround C): We require a 1280 bytes MTU on all hard interfaces and only then set the multicast packet type capability flag.

h3. Adding a sequence number? / How to avoid loops with tracker marking later?