Single-anchored soft bandwidth allocation system with deflection routing for optical burst switching

Abstract

In optical burst-switched (OBS) networks, the most important problem is the collision problem, which occurs when burst packets contend for the same outgoing interface. TCP-based retransmission is a poor solution since it complicates the ingress edge router due to sequencing, and requires excessive amount of memory. We propose a single-anchored soft bandwidth allocation system for OBS networks to provide 100 percent reliability without retransmissions. The anchor node, which is the OBS node that blocks the burst, stores the burst, and informs the ingress router by a negative acknowledgment message. The anchor also provides a bandwidth reservation between itself and the egress OBS node using probe-probe-ACK handshake. This handshake provides soft allocation state along the path. The LSPs may be in "anchor mode" or "non-anchor mode". Soft allocation does not allow other "anchor mode" LSPs to use the allocated bandwidth, but "non-anchor mode" LSPs may use with low priority. The high priority is reserved for the "anchor mode" LSP. A soft bandwidth allocation system provides reliability. Another advantage is that no retransmission is needed in this mechanism.