Computer Hardware Terms, Glossary and Dictionary

Layer 4 switch, based on the OSI "transport" layer, allows for policy-based switching such as limiting different types of traffic on specific end-user switch ports, or for prioritizing certain packet types, such as database or application server traffic. Layer 4 switches also offer a powerful combination of Network Address Translation (NAT) with higher-layer address screening. Actually, layer 4 switch may make forwarding decisions based upon information at any OSI layer from 4 through 7, depending upon the particular product. In fact, some of the so-called "Layer 4 Switches" even monitor the state of individual sessions from beginning to end, just as firewalls do, in which case they're referred to as "session switches." Therefore, it is called Layer 4 - 7 switch.

Related Terms

layer 4 switch