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Phones loose connection to CCM when edge router reboots???

Here is my problem. My phones are on a private subnet 192.168.1.x... My callmanagers are on my real subnet. I have a 6509 MSFC card doing inter vlan routing. I have a default route for 192.168.1.x pointing to the MSFC card on my edge router. Everything works great except if I reboot my edge router all my phones loose their connection to the callmanagers... I think the callmanagers are loosing their route, but I dont see why they would do that just if the edge router rebooted... I have the edge router set as the default gw in callmanagers so it can get out... What am I doing wrong... Should I point my ccm's to the MSFC card instead? If I do that will they still be able to get out beyond the edge router?


Does any one think adding a persistent route using -p will work??

Daniel Baum
Cisco Employee

Jeff, I'm assuming a /24 subnet mask is being used at the remote and "real subnet".

What are the IP address's and subnet mask the CallManagers are using? What is their default gateway? If anything other than 192.168.1.x /24 a router is needed to route between the "real subnet" and the edge router.

Is this the case?

Ok the plot thickens...

The CCMs are using the real subnet and the edge router as their default gateway. Remember the edge router has the route to the MSFC card that can route the two vlans...

However... I ran some traces from the callmanagers to the 192.168 network and they were going through the edge router to the MSFC card!!! I added the static persistent route and did the same trace now they trace directly through the MSFC card...

Now to make issues a bit murkier my Unity box is setup the exact same way, and its trace went right through the MSFC card... The unity box does NOT have a static route... For some reason the callmanager servers were not picking up the route from the default edge router… So now the question is why? I think the problem is now fixed with the static route… but why would the Unity box pick up the route and not the callmanagers… Could it be some setting or just a windows snafu…

On an encouraging note my Voice gateway add a static route to the 192.168 network so called to the PSTN were not lost…

ICMP Redirect. ICMP Redirect. ICMP Redirect

The reason that you're Unity box traces through the MSFC cards is because your Unity box listens to ICMP Redirect messages, while your CallManager boxes do not.

When a router forwards a packet to a next-hop address that is on the same subnet as the source, the router also issues an ICMP Redirect message back to the source. This message basically tells the source host to route future packets to that address to the next-hop address directly, so the router need not be bothered.

It is definitely a good thing that you added the static routes to all three boxes. I would not recommend relying on ICMP Redirect. It will also take some unnecessarily load off of the router.

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