How can QoS be handled for large IP networks and what are some of the implementation challenges?
I keep hearing that VoIP is not a proven solution for large networks mainly due to lack of QoS in IP. Some of the vendors suggest throwing bandwidth to overcome the QoS issues. How can QoS be handled for large IP networks and what are some of the implementation challenges?
IP has standard QoS mechanisms such as Differentiated Services (DiffServ) which can be enabled throughout an IP network. Proper implementation of QoS requires planning and the amount of planning is directly proportional to the size and complexity of the network. One of the more significant implementation challenges is designing to handle failures within a network where voice traffic will be routed along alternate paths. If the implementation is not well thought out, it is possible that voice traffic routed along alternate paths could cause the available bandwidth to be exceeded. The VoIP equipment that is chosen for deployment in a large network should have the ability to limit the number of calls set up between locations along the various pathways. With those limitations set, proper bandwidth calculations can be made to handle the various failure mode scenarios.
This was first published in July 2004