Sergey Safarov writes:
That because to bind link local address need to define
used NIC like
sipp -sn uas -i fe80::b951:ef1f:76c8:e5a2%eth0
Yes, this kind of syntax worked:
$ sipp fe80::6e29:95ff:fe7d:37e6%wlp1s0 -p 5050 -m 1 -sf register.sipp -t t1 -i
fe80::6e29:95ff:fe7d:37e6%wlp1s0 -p 5050 -m 1
and K reported successful registration.
-- Juha