ISL Inter-Switch Link Protocol – Trunking or Frame Tagging protocol
September 19, 2012
Data link layer
Inter-Switch Link (ISL) is specifically used for tagging information of VLAN onto an Ethernet frame. This tagging information permits multiplexing of VLANs over a trunk link and this takes place through an external covering procedure or method, as a result of which the switch can easily determine/identify the membership of VLAN frame over the trunked link. When you run ISL, then it is easy to interconnect number of switches and it is also possible to maintain the information of VLAN while the traffic is passing on trunk links between switches.