AW: [OLSR-users] udp packet groesse

[Thomas Lopatic]

Hi Christian,

> when the packet size is limited, how can we ensure to spread all link information over the network?
> something must be cut?

We have some sort of "application-level fragmentation" in place. OLSR
thinks in terms of messages (HELLO messages, TC messages, etc.). These
messages are packed into UDP packets. To save transmissions, more than
one message can go into a single UDP packet. If a message does not fit
completely into the remaining space of a UDP packet, it is split into
two messages. The first message is used to fill the first UDP packet and
the second message is used to start a new UDP packet. Message handling
is "additive," so that the message in the second packet complements the
message in the first packet and together the two messages have the same
effect as the original single message.

If you see fragmented IP packets, this indicates that our
"application-level fragmentation" does not work as expected. Interesting.

-Thomas