Scaling Considerations, DNC-316 | Cisco Systems DNC-305 specification

Telco and ISP Dial Scenarios and Configurations

Large-Scale POPs

This section describes how to set up a stack of access servers for a large-scale dial solution in the following sections:

•Scaling Considerations

•How Stacking Works

•Stack Group of Access Servers Using MMP with an Offload Processor Examples

Scaling Considerations

Because of the significant increase in demand for Internet access, large POPs are required by many Telcos and ISPs. Internet access configurations can be set up to enable users dialing in with individual computers to make mixed ISDN multilink or modem connections using a stack of Cisco AS5200 universal access servers running Multichassis Multilink PPP (MMP).

You must consider scalability and call density issues when designing a large-scale dial-in POP. Because access servers have physical limitations, such as how many dial-in users can be supported on one device, you should consider the conditions and recommendations described in Table 24.

Table 24 Recommended Configurations for Different Remote Access Needs

Dial-in Demand You Need to Support	Recommended Configuration

PCs dialing in, 75 to 90 percent modem calls,	Two Cisco AS5200 access servers configured
10 to 25 percent ISDN calls (terminal	for IP, basic security, MMP, L2F, and no
adapters or routers), and support for fewer	offload server.
than 96 (T1) to 116 (E1) simultaneous dial-in
connections.

PCs dialing in, less than 50 percent modem	Three or more Cisco AS5200 access servers
calls, more than 50 percent ISDN calls	configured for IP, remote security, MMP, and
(terminal adapters or routers), dial-in only,	L2F. Each Cisco AS5200 access server is
and 250 or more simultaneous links into the	configured to offload its segmentation and
offload server.	reassembly of the multilink sessions onto an
	offload server, such as a Cisco 7202 or
	Cisco 4700 router.

Note Depending on the size of your POP requirement, you can replace the Cisco AS5200 access server with a Cisco AS5300, Cisco AS5800, or Cisco AccessPath. This hardware exchange provides higher call density performance and increases the number of ISDN PRI ports, channelized ports, and modem ports on each chassis.

Cisco IOS Dial Services Configuration Guide: Network Services