AVVID stands for Architecture for Voice, Video and Integrated Data. It's goal is to merge all data, video and voice networks into a single, IP-based network. This includes all telephones migrating to VOIP, all legacy video and audio being streamed across a high-speed network, and the eventual elimination of any other form of data transport. AVVID is a conceptual framework more than an actual product. Depending on the needs of the business, the actual implementation may vary greaty from one installation to another.

The following network solutions are available:

IP telephony	VoiP allows the integration of the phone and IP networks. This allows additional redundancy and increased savings due to no long distance fees.
IP Video conferencing	H.323 video conferencing allows cheap, quick, and administrively easy video conferencing. Significantly superior to non-IP videoconferencing.
Wireless LAN	Wlan allows an easy-to-access network with no cabling headaches.
AVVID Security	Network security products to secure and analyze network traffic.
Virtual Private Network	VPN allows secure remote access to networks from home or elsewhere.
Contact Networking	Video, audio and graphics network for high-speed and reliable distribution of media.
IP Contact Center	IP-based call center to include ACD and IVR in order to quickly set up a distributed call center.
Storage Networking	IP-based storage, network attached storage (NAS), storage over MAN optical, and storage over WAN solutions.

Important points to remember with AVVID is that for a network to handle simultaneous voice, video and data transmissions, it needs to be able to rapidly adapt to changing network conditions. Voice, for instance, has a very low threshold for latency. Video is not nearly as sensitive, while data is virtually insensitive. As such, Quality of Service is an important concept.

Security is also important. With all aspects of communication integrated into a single network, security becomes paramount. Security is broken up into three policy areas:

Internal Network Security	This is tracking the security internal to the network, including physical, enpoint, application, and layer 2.
External Network Security	This involves locking down external access to the internal network.
Network Identity	A need to implement identity-based network access controls and policy enforcement, down to individuals and network ports.

Availability is also of great importance in an AVVID framework. This basically requires a reliable, fault-tolerant network. The following points should be considered:

• Hardware redundancy - Quick failover in case of hardware failures, such as power supplies and redundant supervisor modules.
• Protocol Resliency - Quick failover for protocol or link issues, such as using HSRP and OSPF.
• Network Capacity - The ability to handle sudden load increases, such as when a load-shared link goes down.
• Management - Easy management of ACLs, VPN connections, port assignments, etc.
• Multicasting - Proper use of multicasting to conserve network bandwidth.

The migration of legacy voice and video networks is also possible through the use of various Cisco integration technologies. For instance, a legacy call switch could be used with a Cisco VOIP call manager. The two can be integrated seamlessy from a client perspective, thereby hastening an eventual migration while minimizing immediate costs. Similarly, a Cisco Video Gateway or Video Terminal Adapter can be used to integrate legacy H.320 networks to a digital H.323 video network.

Multicast uses the class D network addresses to send a single packet to a range of destinations. That way, rather than 100 clients having 100 simulataneous connections to a single video server, and thus causing every packet to be duplicated 100 times, all the clients can use the same packet stream. As such, only a single packet would need to be sent onto the wire from the actual video server, conserving a great deal of bandwidth and processor overhead.



It is important that multicast be implemented properly, however. Default settings have multicast flooded out of every switch port. Multicast is a group broadcast type, and therefore is never the originator of a message. As such, a switch never has a multicast address in its bridge table, forcing it to flood all ports.

Internet Group Messaging Protocol (IGMP) is a protocol specifically designed to allow hosts to join a specific multicast group address. However, alot of switches are unable to understand IGMP. As a result, two protocols can be used to managed switch behaviour in a multicast environment. Cisco Group Management Protocol (Cisco proprietary) was created so that a router could inform a switch which hosts subsribed to a specific multicast group. That way, no multicast traffic is sent to hosts that don't want it, conserving bandwidth on those links.

Newer switches can directly read IGMP and don't need to speak with a router to manage which hosts should receive multicast traffic. These switches employ IGMP snooping to dynamically add or remove switch ports as IGMP join or leave messages are received.

Additionally, routers must be configured to forward multicast traffic. Distance Vector Multicast Routing Protocol (DVMRP) and Protocol Independent Multicast (PIM) are multicast routing protocols.

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