I have a CUCM sitting in my test lab behind a 2851 on the Main site. I have an ASA on this network on the side, handing out DHCP to the Phones. Both 2851's are pointed at each other with default routes connected directly together with serial cables. The only thing using the ASA as a default gateway is the IP phones receiving DHCP on the main site.
My ASA Firewall is handing out DHCP 192.168.5.x. I have a PSTN Simulator sitting between the two 2851 routers. The Branch H323 gateway 2851 is handing out DHCP in the range of 10.0.30.x on the branch site.
Note: Both routers are looking at each other as the default route 0.0.0.0 and I even specifically added 1.1.1.1 so all 1.1.1.1 traffic is passed between the two. The H323 source IP it is using is a loopback of 1.1.1.1.
Here's the part that's interesting/confusing. The calls connect and the Branch audio reaches the Main Site, but the Main Site audio never reaches the Branch site UNLESS I add into my ASA firewall "route inside 1.1.1.1 255.255.255.255 192.168.5.245" (.245 is the 2851 Router on the Main site).
So I have an idea that the IP Phones receiving DHCP are using the ASA as a default gateway and the ASA is only seeing half of the traffic packets since they are returning across the routers only and dropping the packets. So I tried to set up TCP Bypass to allow all TCP traffic, but it still doesn't work unless I add the specific route in. Is this an Asymmetric Routing issue or something else? Why can't I see the packets?
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access-list capin extended permit tcp host 192.168.5.11 any4
access-list capin extended permit udp host 192.168.5.11 any4
access-list capin extended permit ip any4 host 192.168.5.11
access-list capin extended permit tcp any4 host 192.168.5.11
access-list capin extended permit udp any4 host 192.168.5.11
access-list capin extended permit ip host 192.168.5.11 any4
capture capin access-list capin
! Placed phone calls between the phones.
show capture capin
0 packet captured
0 packet shown
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The capture results show zero packets. The 192.168.5.11 is the phone that is using the ASA as a default gateway. Why can I not see any traffic coming from this phone or to this phone when it is using the ASA as a default gateway? If this was an Asymmetric routing issue, why did TCP Bypass not get the audio to work goin both ways? ONLY the route command does (or changing the default gateway of the IP phone).
Is there another capture method that will pick up these ghost packets that the capture command is not? I know the phone is using the ASA as a default gateway, so when its trying to go to 1.1.1.1, I should see SOMETHING in the packet capture. Right? Or is this some other Firewall rule?
