sysctl net.link.ether.bridge.ipfw not working

Hello,

Os: FreeBSD border2.bader.loc 13.2-RELEASE-p9 FreeBSD 13.2-RELEASE-p9 
releng/13.2-n254652-c78c31d2ef40 GENERIC amd64

i'm trying to setup a 'filtering-bridge' 
(https://docs.freebsd.org/en/articles/filtering-bridges/) but the mentioned

systctl does not exist:

root@border2:~ # sysctl net.link.ether.bridge.ipfw=1
sysctl: unknown oid 'net.link.ether.bridge.ipfw'


trying to compile the 'options bridge' results in


--------------------------------------------------------------
>>> stage 1: configuring the kernel
--------------------------------------------------------------
/usr/src/sys/amd64/conf/MYKERNEL: unknown option "BRIDGE"
--- buildkernel ---


any ideas?


best

richard