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VoIP, Qos, Loopback Interface, OSPF

Hi Guys,

I'm new to VoIP, so far I have just configured a simple setup.

Right now, I have this:

- 2 Sites

- 2 Leased Line

- 1 Cisco Router per site (any model that support VoIP). Each router have two Serial Interface and of course the VoIP Module and IOS.

and I have this in mind for the configuration:

- 2 Leased Line connect to each router.

- Use OSPF to Load Balance the 2 lines

- Use Loopback Interface for VoIP

- Use QoS to make sure the VoIP traffic gets priority and always have available bandwidth

I was thinking of this to make sure that the link is always up between two sites and there is link redundancy and load balanced for both Voice and Data

Do you guys think it will work? Any comments?


Re: VoIP, Qos, Loopback Interface, OSPF


If i read your post properly you are putting loopback interface in place for the reachability of the device independent of any of the links is up and carrying the traffic.

one more approach for the same would be having multilink bundle configured over the physical links without running OSPF in your network.

you can have LFI too if you want that in place but if you want them to be independent better go with the static routes and CEF with per destination load sharing instead of per packet load sharing.

Per packet load sharing may affect your voice traffic coz of the rearranging of the packets in both the ends.

since you have got only 2 locations thats the reason i suggest static routes here in the first place..

if you are ok with OSPF then pls go ahead and implement the same in your network :-)

if you ask about QOS -- you can go for LLQ for Voice and normal assured forwarding for the different traffic patterns available or being passed out in the network.

also key in aboutthe kinda voip equipment planned in your network ? is it gonna be a fxo or fxs or any other external equipment ?

so that you can plan the qos policies accordingly which has to be configured in the router based on the marking capability of the voip equipment and to the equipment to which its connected.


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