Best Practice: Fault Tolerance in Second-Tier Networks
Border Router: Fault Tolerance illustrates fault tolerance in a second-tier network that crosses a WAN link. Notice that this topology addresses two aspects of fault-tolerance:
| • | Redundant border routers—BR1 and BR2 |
| • | Redundant routing across WAN communications—the X pattern spanning the first-tier routers L1, L2, M1 and M2 within zone B |
Figure 84: Border Router: Fault Tolerance
