All,
I'm planning to buy my first Cisco router, an 877w. Could anyone take a quick look at my ideas below and let me know if this can be achieved with an Advanced IP Services image please?
I have 2x Cisco 7941 phones (old phones from work), a static /29 block from my ISP (PPPoA connection) and a few PCs on the local network.
I would like to give the 7941's an address from the static ISP- allocated range. Any traffic from the phones should be routed without NAT, directly to the ISP's gateway. PCs plugged into the spare port on the back of the phones should receive a 192.168.0.x address and be NAT'ed on their way to the internet. PCs attached to wireless would act in the same way as the PC's hooked up to the back of the phones.
I think this can be achieved using 802.1Q VLAN trunking and layer 3 VLAN interfaces on the router, but I'm only a newbie. Could anyone confirm please?
- There would be two VLANS trunked through fa0/0-3. The PCs would be in the Native VLAN, the phones in a trunked VLAN .
- The Wireless interface would have only the Native VLAN, since there is no possibility to attach phones.
- Each VLAN would have it's own VLAN interface with a seperate DHCP pool.
- One DHCP pool would contain the /29 from the ISP (minus one address, used by the ATM0 interface) to be allocated to the phones, the other DHCP pool would contain the 192.168.0.x/24 range, for allocation to the PCs.
- The VLAN interface for the PCs would have an "IP nat inside source" statement
- The VLAN interface for the Phones would not require this statement
- The ATM0 interface would have an "IP nat outside" statement and an associated dialer interface.
Does the above sound plausible on this entry-level router?
One question I don't know the answer to is, how will the phones know to use the trunked VLAN rather than the native? Do they need some kind of special setting to ask them to only send traffic along the trunk, while leaving the native for an attached PC?
Sorry this has been such a long explanation and thank you to anyone who responds.
All the best
James.