Telco and ISP Dial Scenarios and Configurations
How Stacking Works
Before you install and configure a stack of access servers, you should understand the basic concepts described in the following sections, and how they work together in a
•A Typical Multilink PPP Session
•Using Multichassis Multilink PPP
•Setting Up an Offload Server
•Using the Stack Group Bidding Protocol
•Using L2F
A Typical Multilink PPP Session
A basic multilink session is an ISDN connection between two routing devices, such as a Cisco 766 router and a Cisco AS5200 access server. Figure 54 shows a remote PC connecting to a Cisco 766 ISDN router, which in turn opens two
Figure 54 A Typical Multilink PPP Session
PC running
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S6752
Using Multichassis Multilink PPP
The dial solution becomes more complex when the scenario is scaled to include multiple multilink calls connecting across multiple chassis. Figure 55 shows a terminal adapter making a call in to the
Cisco AS5200, labeled #1. However, only one of the access server’s 48 B channels is available to accept the call. The other channels are busy with calls. As a result, one of the terminal adapter’s two B channels is redirected to device #2. At this point, a multilink multichassis session is shared between two Cisco AS5200s that belong to the same stack group. Packet fragments A and C go to device #1. Packet fragments B and D go to device #2.
Cisco IOS Dial Services Configuration Guide: Network Services