WRT120n dropping incoming fragmented IP packets

[TAB120]

Hi

I am trying to use my WRT120n as access device  for an IP Centrex service using SIP protocol. My SIP phone is located right behind the router.

My problem is sometimes the router is dropping incoming calls because signalling packets are fragmented at IP level. So I cannot receive those calls.

Is there a way to enable the router to accept these packets?

Thanks.

[gv]

Did you adjust the MTU?

[TAB120]

It is set to Auto/1500. 

Thx

[gv]

What MTU does it show on the status page?

Did you determine whether it's the optimal MTU?

Check http://www6.nohold.net/Cisco2/ukp.aspx?vw=1&docid=fbf8e8564632422eaa8ea80bf9dcba64_386.xml&pid=96&sl...

[TAB120]

Hi

Status page shows MTU is 1500

When pinging my destination with 1472 I get a normal reply, so 1500 should be fine.

My problem in fact is not reaching my destination, but being reached by them.

Let me explain a bit better. I am registered to a SIP service. Outgoing calls work fine, but sometimes incoming calls do not reach me. After debugging with my service provider it turned out that whenever the SIP message was conveyed using fragmented IP packets, my router ignored them and the call was lost. I have no problems for incoming calls in other circumstances, so I have no NAT pinhole issues or the like.

So my question is, does WRT120n support incoming fragmented IP packets and if yes  how can I enable it?

Hope you can help me!

[scrooge]

# Login to your router’s web interface using the IP address 192.168.1.1.

# Click on the Security tab and disable the SPI Firewall Protection.

# Then Save Settings.

Then check the status of the incoming calls.

[gv]

Never ever disable the firewall of the router. It protects the router!

[TAB120]

Tried, does not help.

Thanks for suggestion.

[TAB120]

Yep, you are right. Firewall should be on.

Now I know it is not the Firewall who stops the packets.

Thx

[scrooge]

What you can try doing for the sake is assign a static IP to the Centrex Device something in range of your router's IP and then use that IP to enable the DMZ feature on your router for that very IP address....