- Physical Network Topology and Availability
- Layer 2 Availability: Trunking —802.3ad—Link Aggregation
- Layer 2 Trunking Availability Strategies using SMLT and DMLT
- Layer 2 Availability: Spanning Tree Protocol
- Layer 3—VRRP Router Redundancy
- Layer 3—IPMP—Host Network Interface Redundancy
- Layer 3—Integrated VRRP and IPMP
- Layer 3—OSPF Network Redundancy— Rapid Convergence
- Layer 3—RIP Network Redundancy
- About the Authors
We presented several approaches for increased availability for network designs by evaluating fault detection and recovery times and the adverse impact on computing and memory resources. In comparing these networking designs, we drew the following conclusions:
Link aggregaton is suitable for increasing the bandwidth capacity and availability on point-to-point links only.
Spanning Tree Protocol is not suitable because failure detection and recovery are slow. A recent improvement, IEEE 802.3w, Rapid Spanning Tree, designed to improve these limitations may be worth considering in the future
The VRRP and IPMP is one of the most popular availability strategy combinations for server-to-network connection and a recommended approach. This approach provides rapid failure detection and recovery, is scalable, and economically feasible when considering the increased MTBF calculations.
OSPF provides a much better failure detection and recovery than RIPv2 and is recommended for interswitch availablity. However, OSPF is not recommended to run a routing protocol on a server because of potential security issues, scalability, and performance. The calculation of route tables from Link State Database in OSPF, for example, can impact server performance, depending on the number of routes in the autonomous system; the rate of changes in routing state; and the size of the server.