Method and apparatus for controlling congestion in packet switching networks
First Claim
1. A method of controlling congestion in a packet transmission system comprising formatting information to be transmitted into blocks according to whether it is core information or enhancement information, transmitting the blocks of core information in core packets and transmitting at least some of the blocks of enhancement information in enhancement packets which are separate from the core packets and which are each marked with a discard marker, and discarding said enhancement packets under congestion conditions by reference to said discard marker only, so as to relieve congestion.
1 Assignment
0 Petitions
Accused Products
Abstract
A system in which core information, for example in the form of a core block or blocks (C), is transmitted in a core packet (PC), and at least some enhancement information, for example, in the form of enhancement blocks (E), is transmitted in an enhancement packet (PE) which is separate from the core packet (PC) and is discardable to relieve congestion. Preferably, the core and enhancement packets have headers (H) which include a discard eligible marker (DE) to indicate whether or not the associated packet can be discarded. The enhancement blocks (E) may be distributed between the core packet and enhancement packet in accordance with congestion conditions, or the enhancement blocks may be incorporated only in the enhancement packet, and the actual number of enhancement blocks included are varied depending on congestion conditions. Preferably, the packets are transmitted in frame relay format and congestion forward (CF) and congestion backwards (CB) markers are used to feed back information of congestion conditions within a network to the packet assembler (7) forming the core and enhancement packets.
-
Citations
12 Claims
- 1. A method of controlling congestion in a packet transmission system comprising formatting information to be transmitted into blocks according to whether it is core information or enhancement information, transmitting the blocks of core information in core packets and transmitting at least some of the blocks of enhancement information in enhancement packets which are separate from the core packets and which are each marked with a discard marker, and discarding said enhancement packets under congestion conditions by reference to said discard marker only, so as to relieve congestion.
- 9. Apparatus for controlling congestion in a packet transmission system comprising encoder means for formatting information to be transmitted into blocks according to whether it is core information or enhancement information, packet assembler means for assembling the blocks of core information into core packets and at least some of the blocks of enhancement information into enhancement packets, said enhancement packets being separate from the core packets and being each marked with discard marker, congestion monitor means for monitoring congestion conditions in the system, and discard means for discarding said enhancement packets under congestion conditions by reference to said discard marker only.
Specification