The Conversion Link Protocol (ISL) is the Cisco Private Protocol, which is mainly used to maintain VLAN information such as communication traffic between switches and routers.
The ISL tag can perform the same task with 802.1q trunk, but the frame format used is different. The ISL trunk (TRUNKS) is a Cisco private, that is, a point-to-point connection line that refers to two devices (such as switches). This layer mean is included in the Switching Link Protocol name. The ISL frame label uses a low-latency mechanism to provide multiple VLANS traffic on a single physical path. ISL is mainly used to implement connections between switches, routers, and nodes (such as network interface cards used by the server). To support ISL feature, each connection device must use ISL configuration. The router configured by ISL supports communication services in VLANs. Non-ISL configurations are configured to receive Ethernet frames in the ISL package, usually, non-ISL configurations of devices to be attributed to protocol errors. For more information, please visit the following page: 中文 版: http://www.networkDictionary.com/chinese/protocols/isl.php English version: http://www.networkDictionary.com/protocols/isl.php
