www.GymRatZ.co.uk wrote on 12/09/2011 :
> On 12/09/2011 07:14, Jono wrote:
>
>>> Otherwise try Draytek UK support there're usually quite helpful...
>>
>> I fired off a support "contact us" form to them.
>
> I'd be interested in any news on this.
> When I had 2 x 2910 I could ring over vpn no problem but having changed
> one end to 2920 (previous one died) I can call via private IP add. but
> also no audio on connection.
>
> 8¬O
Got to the bottom of it, after numerous back & forth emails with
Draytek.
This particular PBX (NEC SV8100) has a physical Ethernet port for VoIP.
Within the VoIP card, there are VoIP "Resources". For each resource (2
in this case), there is an additional IP address required on the LAN. I
found I couldn't ping these IPs from the router, or from the remote
end...but could from a local machine.
So, with SYSLOG running, I could see bucket loads of firewall errors
like this:
134 2011-09-12 17:56:37 Sep 12 17:56:33 HO Arp address mismatch -
Ethernet source address doesn't match ARP sender address
So, the suggestion from Draytek was, from a telnet prompt logged in to
the router, issue the following:
> ip arp accept 1
This will return: Accept illegal ARP REPLY packets.
Subsequently issuing the following should return an indication that the
status is now enabled:
> ip arp accept status
current status: enable
Without doing this, neither router will be able to ping the IP
addresses on the VoIP resources card, nor will any remote machines be
able to ping these two addresses over the VPN...and one-way audio WILL
be experienced, although each router WILL be able to ping the Physical
card itself.
Incidentally, in the 2820 model, this is set to ENABLED by default. In
the 2830, it is DISABLED by default.
One-way audio - Draytek 2830 L2L VPN 
Linear Mode
