I am in the process of setting up a hypothetical CME system and I have most things out but I need some help with regard to getting internet access. Here is the equipment that I want to use and how I want to use it
Cisco 2811 router with ES module
Linksys WRT54G router (that will handle NAT)
Linksys Cable Modem to Comcast Cable Internet (DHCP)
Here is the scenario I have so far:
On the 2811 there are two DHCP pools created (that correspond to the two VLANS used in the network):
DHCP Pool DATA
with addresses 10.1.10.x
where default router is 10.1.10.1
DHCP Pool VOICE
with addresses 10.1.20.x
where default router is 10.1.20.1
and option 150 is 10.1.20.1 (cisco CME tftp)
Likewise, the telephony-service source ip is configured as 10.1.20.1
The virtual gigabit ethernet interface on the router that connects to the ES module is configured with two subinterfaces that correspond to the two VLANs used:
So Gi1/0 (or whatever its number is)
has two subinterfaces:
Gi1/0.10 for DATA
where the dot1q is for VLAN 10
the interface ip is 10.1.10.1
Gi1/0.20 for VOICE
where the dot1q is for VLAN 20
the interface ip is 10.1.20.1
On the ES switch, the virtual gigabit port (Gi1/0/2 lets call it) is set up for trunking with dot1q and is setup to allow all VLANs across the trunk.
the individual switchports on the ES module are configured as follows:
switchport access vlan 10
switchport trunk encapsulation dot1q
switchport mode access
switchport voice vlan 20
First off, I would like to use the Linksys router for web access and have it connected to one of my switchports on the ES module. The DHCP server on the Linksys would of course be off and lets say the linksys will have a static ip of 10.1.10.2 and would thus reside in the DATA vlan (the linksys would of course still get the comcast internet outside IP via DHCP from the connected cable modem).
So far, if I look at this setup as it would operate it seems to me that most everything would work fine. Inter-vlan routing should be ok thanks to the subinterfaces on the router and trunk on the switch, so computers connected to the switch that are placed in vlan 10 DATA will be able to ping phones that are in the VOICE vlan. Likewise, computers will be able to access to CME as well at its address 10.1.20.1.
Likewise, thanks to the DHCP computers connected to the switch will have a default router address of 10.1.10.1 (the 2811).
So, as far as I understand it, all of the above inter-vlan routing from the DATA to the VOICE vlan will work because of the fact that the computers know to "ask" the router 10.1.10.1 where to route packets that are not in their subnet.
Here's where the problem comes in, supposing I want internet access through the linksys router (on the DATA vlan, but that doesn't really matter, does it?) how do I let a computer know how to route internet traffic to that router without changing the default router command in the DHCP pool for the DATA Vlan?
the reason I ask this is because I thought about this for a while and at one point I figured I could just set the default router for the DATA DHCP pool to point directly to the static ip of the Linksys, however while this should give the computers internet access wouldn't it isolate the DATA vlan from the VOICE vlan altogether? After all, in this scenario supposing a computer tries to ping 10.1.20.1 (the CME) and since its in a different subnet it would query the default router which is the Linksys and the ping would fail since the linksys has no way of routing the traffic between subnets?
Is one possible solution to have the following line in my 2811 config
ip route 0.0.0.0 0.0.0.0 10.1.10.2
I unfortunately do not have the equipment on hand to test this but would such a setup work?
Any and all help is of course appreciated!!