Issue link: https://epubs.iltanet.org/i/58400
www.iltanet.org "People will notice any outage that lasts more than 200 milliseconds." failures, but its failover times are too slow for today's traffic. Rapid Spanning Tree (or a comparable feature) offers a significant improvement in failover times. There are also techniques using features of port aggregation, virtual switching and/or layer 3 techniques that can dramatically improve failover times of switches. WAN Resiliency: WAN resiliency also significantly improves the perception of an invisible network. This is especially vital in environments with centralized resources. Whereas a WAN is a large component of the operational network budget, it is also the network element most prone to failure, even in a well-designed network. Having two WAN circuits from separate carriers will offer the best protection from WAN failures. Dual WAN connections can come in the form of two MPLS/ VPLS circuits or as an MPLS primary with an Internet VPN backup. Having two routers per office will improve the resiliency even more. WAN failover times are as important as LAN failover times. With the WAN, it is all about routing protocol convergence. A good internal dynamic routing protocol like OSPF, IS-IS or EIGRP is a good start. But this should be layered with newer technologies like route dampening, fast reroute, NSF and incremental SPF. In some cases, it might make sense to have multiple route instances in the routing table by using either floating static routes or technologies like EIGRP's variance command, making the importance of convergence times less significant. 8 ILTA White Paper Internet Resiliency: To today's lawyer, data on the Internet and data on the internal network are equally important. It is important that the Internet be just as invisible to the lawyer as the network. To maintain an always-on Internet, every office needs at least two exit points to the Internet. This could be the local office and data center, or possibly two different data centers. Use well-tuned routing protocols to distribute the default route, allowing for dynamic and quick failover of Internet access. Allow the Internet edge routers to detect Internet upstream failures using features like tracking to ensure the default route gets removed from a nonfunctioning Internet path. Load Balancing/Content Switching There are a number of products that can provide server resiliency via network elements. Load balancers can exist in the data center to switch content between local servers, as well as between data centers using smart DNS servers. The key with all load-balancing techniques is the detection of failure and then routing packets to the surviving servers. Wireless: It is important to keep the network without wires just as invisible as the one with wires. Lawyers are rarely stationary and will move from floor to floor and office to office. It is important to maintain a consistent wireless experience throughout the organization, no