IP-PBX on RV042 DMZ - Blocking SIP

Discussion in 'Cisco Small Business Routers and VPN Solutions' started by Sleeman, Mar 31, 2007.

  1. Sleeman

    Sleeman LI Guru Member

    Has anyone else found the RV042 DMZ is getting firewalled even if you have the firewall rules wide open or even off?

    I've done packet traces on both sides of the router, and SIP Invites are _definitely_ getting blocked.

    This is not the case for all VoIP stuff - I can use Linksys PAP devices no problem, but not my IP PBX.


  2. aviegas

    aviegas Network Guru Member

    I use both a PAP2 and Asterisk (connected to 2 VoIP providers) behind a RV082 and it works as a charm. I do not even place them on the DMZ or set it as the DMZ host.

    Just some forwarding and making sure that the RTP ranges (UPD ports for the actual data traffic) do not overlap, or the router will be confused.

    For your problem, check if the ports are not being forwarded. If forwarding is set, then it will take precedence over the DMZ setting. If you previously had a PAP on your network, the forwarding may be a leftover (the PAP manual suggests adding these port forwarding)
  3. eric_stewart

    eric_stewart Super Moderator Staff Member Member

    The Linksys firmware development guys told me about 1.5 months ago that VoIP (SIP actually) is broken across the RV042 and that there would be a firmware upgrade for this issue. I couldn't get my Sipura SPA2000 VoIP adapter to connect across the RV042 to my VoIP provider...not even a dialtone, but it works immediately (well close to immediately...) when I connect it in behind my Cisco ASA5505 firewall.

  4. aviegas

    aviegas Network Guru Member

    Well, it works for me..... I can get 3 different SIP connections at the same time thru a RV042. I have one PAP2 connected to Vonage and a Linux box running asterisk connected to Vonage and another VoIP provider.

    One thing that I do: I use protocol binding to route all traffic (UDP and TCP) to/from my PAP2 and Asterisk PBX to WAN1. Without a protocol binding it does not work reliable.

    Also there is another point that I've noticed and I want others to confirm: I was never able to bind traffic reliably to WAN2, only to WAN1...?????
  5. Sleeman

    Sleeman LI Guru Member

    Linksys admits issue?

    Hi Eric,

    Any word from your contact @ Linksys? Very interesting that they actually admit this is an issue - I'm a partner (soon to be 'Elite'), and couldn't make much headway. I've since stopped using the RV042, but if they fixed this issue, I'd be all over it.


  6. Toxic

    Toxic Administrator Staff Member

    i'll chase this up :)
  7. Sleeman

    Sleeman LI Guru Member


    Anything you can find out would be great. I honestly haven't had the time to dig further into it, or I would have. After doing Ethereal traces on both sides of my router last year and essentially proving there was an issue (SIP Invites happening on the outside but never show up on the inside & outbound calls working, but inbound calls didn't), my VAR technical contact at Linksys never responded. Disappointing. The Canadian Linksys rep has asked me to follow up again and let him know if I made any headway, but I _really_ don't have time to go through all the motions again.

    I notice there hasn't been any firmware updates since February, and I'm skeptical they're even interested in fixing the issue, but if anyone has heard otherwise, my curiousity is piqued.

    I have also been successful in using 'other' VoIP products through the RV042 DMZ interface (like the PAP2), but my IP-PBX hasn't worked since a firmware upgrade a long time ago. I think something that may have changed on the IP-PBX side was they added a function that constantly ARP's for it's own IP addresses (it uses 2), for reasons related to clustering multiple IP-PBX units (admittedly a poor design). This may be confusing the RV042 thinking something like a SYN flood is happening.

    What confuses me though, is this is on the DMZ which shouldn't have ANY firewall, when it obviously does.

    Trying to explain this to the Linksys tech support folks (even at the VAR level) was painful. I did provide the traces, but it was obvious he just wanted to blow me off, as I'm sure there's not may of us with this specific issue.

    Anyway, any help you can lend getting this issue moved forward would be great. I really _could_ use the RV042 in as a client router for many, many installs if it actually worked as it should. Based on my experience, I'm not sure I'd want to, even if they did fix it, as what's to say it doesn't break again?

    Perhaps a Cisco/Linksys conspiracy - i.e. the Cisco folks don't actually want it to work as it should ??


  8. russwmc

    russwmc Network Guru Member

    It's interesting to hear that Vonage works. I could never get Packet8 to work a year ago and gave up.
  9. Sleeman

    Sleeman LI Guru Member

    Any luck?

    Any luck getting some insight on this?


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