User's Manual

General Information Guide - Release 3.1
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LAN/WAN Network Configuration
Network Guidelines
To maintain optimum voice quality, voice and data traffic should be separated as much as possible.
To separate voice and data traffic, you can
• Run Voice and Data on separate Virtual LANs (VLAN)
• Use a separate subnet for voice traffic
• Use Ethernet switches instead of hubs (voice and data should not use the same shared ethernet
hub
• Use Full Duplex Fast Ethernet to the 3300 Controller ports
• Use Full Duplex Fast Ethernet and Ethernet Trunks between switches.
When IP telephones are being placed across routed links, the routers should be configured to
prioritize voice traffic by using techniques such as Weighted Fair Queuing (WFQ) with multiple
queues configured (for example, high priority for voice and low priority for data). Where the routed
connection is across a Wide Area Network (WAN), set the Maximum Transmittable Unit (MTU)
appropriately for the speed of the WAN link to minimize delay on slow WAN links.
3300 ICP as a Backup WAN
Many sites have PRI (Primary Rate Interface) access to their telephone system and a separate WAN
link for their data. The majority of routers allow for a backup link as well. Instead of renting another
BRI or PRI link from the telephone company, you can use the system’s existing ISDN access. Using
the remote LAN access option on ISDN, configure the card as if it was the interface from the public
network; as a result, information can be sent and received from another ISDN-compatible device
(such as a router).