VLAN Design for IPTV/Multiplay Networks: Understanding the Alternatives

VLANs limit the broadcast domain, ensuring that subscribers cannot see each other's information and also reducing network traffic. They are a fundamental part of how broadband access networks deliver information to subscribers. There are two ways that VLANs are used in this role. A service VLAN (S-VLAN) delivers a single service to all subscribers, while a customer VLAN (C-VLAN) delivers multiple services to a single subscriber. These are often combined by using a single S-VLAN to carry multicast traffic to all subscribers, but using dedicated C-VLANs to carry all unicast traffic to each subscriber. Each of these scenarios differs from the others in manageability, bandwidth requirements and deployability.