Technical White Papers are designed to introduce Symantec partners and end users to key technologies and technical concepts that are associated with the Symantec Backup and Recovery product family. The information within a Technical White Paper will assist partners and end users as they design and implement data protection solutions based on Symantec Backup and Recovery products.
This document outlines the WAN Optimization feature enhancements introduced on the NetBackup 5220 and NetBackup 5020 and applies to:
In a world of ever increasing data flow as well as globalization of data centers the effectiveness and utilization of the networks connecting sites is of the highest importance to end users. Even with network enhancement and improvement, the ability of the infrastructure to keep pace with the flow of data has proved not to be in lockstep. To optimize the flow of data verses increasing the pipe that is flows along is seen as critical to keeping operations running and costs minimal. This paper discusses the new WAN Optimization technology that has been introduced in the NetBackup 5220 and 5020 appliances.
Local Area Networks and Wide Area Networks
Modern TCP/IP based networks are segregated into one of two forms. Internal and local to a customer data center is the Local Area Network (LAN). External to the data center and leveraged to enable scale and resiliency is a Wide Are Network (WAN). Both networks have three primary characteristics being bandwidth, latency and loss. Corporate networks usually are comprised of LAN’s that interact with WAN’s to ensure that data is available to a level that allows the business to sustain operations.
The bandwidth of a network, be it LAN or WAN gives a measurement of the total amount of data that could pass through the network from one point to another. Generally, the network could be a combination of different networking technologies based of Ethernet (100Mbs, 1Gbs, 10Gbs, Infiniband) or other transports (ASL) with various capacities for data transportation - bandwidth. The bandwidth of most corporate networks in the US is general segmented at the 100Mb (megabits) per second range with a WAN performing up to this level. A LAN should be capable of sustaining 100Mb/s up to the theoretical maximums of the leading edge technologies available today.
The latency of the network gives a measurement of how long a packet would take to be transmitted and returned from one system to another (commonly referred to as Round Trip Latency). Latency is measured using tools like ‘ping’, which mitigates a lot of processing at the receiving end and therefore skewing the results of the network testing. Another element that plays into latency is that most networks are not a direct connection. The common network environments in the data center is constructed of many devices (switches, routers, gateways, firewalls) which all add some overhead to the packets that are passing through them. The loss is amplified as the network is expanded over a geographical expanse, which is common to a WAN. Typically the latency is measured in milliseconds (msecs) and can range from nearly 0 through to more than 150msecs. The two tables below show the general constraints of a LAN or a WAN as well as some examples of what to expect as the transportation expands across continents and around the world.
Network loss is a concept that explains the degradation of network connectivity and the resulting performance forfeiture. Even the best networks can encounter network loss but generally speaking the more dispersed a network is the higher the rate of network loss. Network loss is amplified in a geographically dispersed network due to the fact that most networks are TCP controlled verses UDP and this results in the need to retransmit packets that were received in error or not received at all – the further the distance these retransmitted packets need to travel the more exposure to network degradation. A UDP network doesn’t require this but the application that uses this type of network management needs to be capable of handling data loss – media streaming for example. A well performing network would loose or have to have packets retransmitted every 1 in 10000 (0.01%) packet transmissions. A poorly configured or slow WAN this number would be seen as being 50 in 10000 (0.5%).
You can download the full White Paper below.