Transmitting frames between, possibly different, local VLANs by encapsulating frames for global VLAN tunnel

摘要

A source host 110 transmits a frame including a VLAN tag (eg. IEEE 802.1q tag) addressed to a destination host 120. A switch ToR1 receives the frame and determines that the frame should be forwarded over a global VLAN (eg. on L3 network). The switch encapsulates the VLAN frame (eg. into an IP packet) and forwards it over the global VLAN to a further switch ToR2. ToR2 de-encapsulates the frame from the packet and determines the global VLAN from the frame header. Based on the global VLAN ID switch ToR2 determines a local VLAN ID 002 which may be different from the source VLAN ID 001. If the ID is different the VLAN tag is modified appropriately and then forwarded to the destination host. Determination of local/global VLANs may utilise a directory server DS. A system for broadcast frames is also disclosed (see Fig. 5b). The system decouples source, destination and global VLAN IDs to assist efficient use of the ID space.