Switching technologies are crucial to network design, as they allow traffic to be sent only where it is needed in most cases, using fast, hardware-based methods.
A multilayer switch can prioritize packets by the 6 bit differentiated services code point (DSCP).
The following 4 mappings are normally available in an MLS:[citation needed] MLSs are also able to route IP traffic between VLANs like a common router.
Layer-2 switching uses the MAC addresses of the hosts’ network interface controllers (NICs) to decide where to forward frames.
Broadcast and multicasts, along with the slow convergence of spanning tree, can cause major problems as the network grows.
Bridges are good if a network is designed by the 80/20 rule: users spend 80 percent of their time on their local segment.
Because many layer-3 switches offer the same functionality as conventional routers they can be used as cheaper, lower latency replacements in some networks.
Load balancing often involves destination network address translation so that the client of the load-balanced service is not fully aware of which server is handling its requests.
Content switches can often be used to perform standard operations such as SSL encryption and decryption to reduce the load on the servers receiving the traffic, or to centralize the management of digital certificates.
Since the client isn't generally aware of which server it spoke to earlier, content switches define a notion of stickiness.
Stickiness can also be based on SSL IDs, and some content switches can use cookies to provide this functionality.
Modern load balancing routers can use different rules to make decisions on where to route traffic.
This can be based on least load, or fastest response times, or simply balancing requests out to multiple destinations providing the same services.
Layer-7 switches may distribute the load based on uniform resource locators (URLs), or by using some installation-specific technique to recognize application-level transactions.