it as close as possible to the source.
them as true Token Ring traffic to the mainframe, as shown in Figure 13-11. Router A
terminates LLC2 on the Token Ring interface and terminates SDLC on the SDLC interface.
This has the potential to save money if there are many serial SDLC links in the network. By
using a Cisco router and adding a high-speed Token Ring, you can consolidate expensive links
into a Frame Relay network, as illustrated in Figure 13-12. Performance would be increased if
you used the DLSw+ protocol (see the next section) and the local acknowledgment feature of
Cisco IOS. LLC2 frames travel across the WAN links via IP packets and terminate on Routers
B, C, and D. The hub router, Router A, must possess enough CPU horsepower to be able to
withstand the stress of terminating multiple DLSw+ tunnels. This would be a slight trade-off
from converting the LLC2 frames to SDLC frames on Router A.
would be an LLC2 session between the mainframe and Router A. Router A would acknowledge
the LLC2 frames, which would provide for less overhead over the WAN medium.
Routers B, C, and D. Routers B, C, and D acknowledge the SDLC frames toward the cluster
controllers. Again, you should monitor CPU utilization very closely.