>> Then i recompiled the kernel source.
>> After a reboot i inserted static entries in the arp table.
>> This resulted in that new entries couldn't be learned anymore.
>
>Doesn't "ifconfig xxx -arp" do the same?

didn't work for me.  :-/

in one window:

	# ifconfig ex0 -arp
	# ifconfig ex0
	ex0: flags=88e3<UP,BROADCAST,NOTRAILERS,RUNNING,NOARP,SIMPLEX,\
			MULTICAST> mtu 1500
		capabilities=7<IP4CSUM,TCP4CSUM,UDP4CSUM>
		enabled=0
		address: 00:00:39:bd:96:19
		...
	# arp -d is
	# ping is
	PING is (192.168.7.141): 56 data bytes
	64 bytes from 192.168.7.141: icmp_seq=0 ttl=255 time=0.860 ms
	64 bytes from 192.168.7.141: icmp_seq=1 ttl=255 time=0.534 ms
	...
	^C
	this# arp -a
	is (192.168.7.132) at 00:50:04:68:c6:10 on ex0
	this (192.168.7.141) at 00:48:54:1f:ce:aa on ex0


in another window:

	# tcpdump -ens0
	13:41:40.889180 00:00:39:bd:96:19 ff:ff:ff:ff:ff:ff 0806 42: \
		arp who-has 192.168.7.141 tell 192.168.7.134
	13:41:40.889464 00:48:54:1f:ce:aa 00:00:39:bd:96:19 0806 60: \
		arp reply 192.168.7.141 is-at 00:48:54:1f:ce:aa
	13:41:40.889491 00:00:39:bd:96:19 00:48:54:1f:ce:aa 0800 98: \
		IP 192.168.7.134 > 192.168.7.141: icmp 64: echo request seq 0
	13:41:40.889878 00:48:54:1f:ce:aa 00:00:39:bd:96:19 0800 98: \
		IP 192.168.7.141 > 192.168.7.134: icmp 64: echo reply seq 0
	13:41:41.900111 00:00:39:bd:96:19 00:48:54:1f:ce:aa 0800 98: \
		IP 192.168.7.134 > 192.168.7.141: icmp 64: echo request seq 1
	13:41:41.900507 00:48:54:1f:ce:aa 00:00:39:bd:96:19 0800 98: \
		IP 192.168.7.141 > 192.168.7.134: icmp 64: echo reply seq 1
	...

-- 
|-----< "CODE WARRIOR" >-----|
codewarrior@daemon.org             * "ah!  i see you have the internet
twofsonet@graffiti.com (Andrew Brown)                that goes *ping*!"
werdna@squooshy.com       * "information is power -- share the wealth."