Control channel implementation in a packet switched communications network
A system and method for implementing a control channel in a packet switched communications network. In a computer network, such as a local area network (LAN) it is known to utilize the Ethernet for distributing communications between stations. The Ethernet employs a standard frame format that includes header frames and, in particular a preamble frame which may be used to provide synchronization information between switching devices or nodes. The preamble frame is not required in a Gigabit Ethernet implementation and the present invention employs a portion of the preamble frame to implement a control channel between switching devices.
1. A method of implementing a control channel for exchanging information between switching devices in a packet switched Gigabit Ethernet network, comprising:
selecting an unused portion of an 8 octet preamble frame of a packet format used for communicating between switching devices, wherein a third octet of said preamble frame containing a special code to signify that following frames contain control information; and
embedding the control information in the unused portion.
2. The method as defined in claim 1 , wherein said control information is embedded in three octets following said third octet.
3. The method as defined in claim 2 , wherein said three octets having embedded control information have a distinctive high order bit.
4. The method as defined in claim 1 wherein said switching devices are managed as a group of switches in a clustered arrangement.
5. The method as defined in claim 4 wherein said control information relates to disable and enable flow control.
6. The method as defined in claim 4 wherein said control information relates to transmission of priority packets between switching devices.
7. The method as defined in claim 4 wherein said control information relates to results of a hash algorithm implemented as between ports within said cluster.
8. The method as defined in claim 4 wherein said control information relates to ports making up a mirrored pair involving a switch cluster.
9. The method as defined in claim 4 wherein said control information relates to multicast packet protocols distributed to cluster switches within said network.
10. A system for implementing a control channel for use in exchanging information between switching devices in a packet switched Gigabit Ethernet network comprising:
means to select an unused portion of a packet format used to carry communication between switching devices, the unused portion being an 8 octet preamble frame, a octet of the preamble contains a special code to signify that following frames contain control information; and
means to embed control information in the unused portion.