Signaling protocol extensions for converter-saving wavelength assignment in GMPLS optical networks

GMPLS architecture specifies signaling protocol extensions, such as the label set, to support dynamic connection setup in the optical domain. However, current extensions do not carry information to minimize converter utilization in wavelength routed optical networks. Converter waste increases the network cost and negatively impacts the blocking probability if the available converters are limited. With the aim of reducing wavelength converter utilization, in this paper we propose to use standard (suggested label) and novel (suggested vector) extensions to collect information on the label (i.e., wavelength) preference from the nodes along the connection path. Two advanced label preference schemes are proposed exploiting these extensions: SL scheme supports the label set with the suggested label, carrying one preferred wavelength; SV scheme supports the label set with the suggested vector, indicating the preference level for each wavelength. They are compared against two currently used schemes: NP (no preference) scheme uses no extension; LS scheme uses just the label set to notify the acceptable wavelengths. In all schemes, network nodes adopt either first-fit or random tie-breaking policies to select a wavelength from a pool with equal preference. Simulations with unlimited and limited amount of wavelength converters show that both the suggested label and the suggested vector extensions significantly improve network performance. SL and SV schemes allow to decrease wavelength converter utilization compared to NP and LS schemes. When the converter count is limited, SL and SV also reduce blocking probability. SV with first-fit policy outperforms all the other schemes in terms of both converter utilization and blocking, while SL obtains very good performance without requiring any protocol modification