LAN assessment

A Local Area Network assessment determines whether the current network infrastructure and bandwidth will support G700 Media Gateway telephony with adequate voice quality or whether network upgrades are necessary. A LAN assessment gathers information in a number of categories described below.

Network topology

In most cases, LAN infrastructure follows the standard distribution and core configuration. In smaller network environments, standard layers may be collapsed. A complete network topology map indicates the layers, devices, media, and port speeds, as well as servers, firewalls, and gateways.

Figure 4. Sample LAN Topology Map

Figure 5. Sample LAN Topology Map

LAN infrastructure requires assessment in terms of the following:

• Network availability
• Network scalability
• Available average bandwidth
• Available peak or burst bandwidth
• QoS implementations
• Desktop/phone QoS
• Layer 2 and 3 convergence

Servers and existing gateways

LAN assessment identifies and locates all TFTP servers, DNS servers, DHCP servers, NAT gateways, firewalls, and existing gateways within the network, including any existing communication control servers. Server assessment includes level of availability, scalability, and available bandwidth.

Network devices

An inventory of network devices by type, number deployed, software installed, and services supported can help identify potential bottlenecks in VoIP data flow. Such an inventory identifies switched and shared media, bandwidth usage, users per link, and devices per subnet.

Baseline performance

Baseline network performance measurements include the following:

• Device average and peak CPU utilization
• Device average and peak memory utilization
• Peak backplane utilization
• Average link utilization (prefer peak hour average for capacity planning)
• Peak link utilization (prefer five minute average or smaller interval)
• Peak queue depth
• Buffer failure rates
• Average and peak voice call response times

Addressing plan

LAN assessment includes a review of the IP addressing plan and takes into consideration core routes and subnets, route and DHCP server plans, as well as any DNS conventions in effect. The IP addressing plan review should check for duplicate IP addressing and for subnet overlap. The addressing plan must be adequate to include the new addressing required when G700 Media Gateways are introduced.

Protocol implementation

LAN assessment catalogues the current network protocols to determine whether they match or can coexist with the protocols supported by G700 Media Gateways. Protocol analysis covers IP routing protocols, summarization methods, and routing protocol safeguards. It also takes into account HSRP configuration, VTP and VLAN configuration, and IPX, DLSW, or other required protocol services.

LAN assessment form

Table 22 shows a sample LAN assessment form.