A novel OSPF extension including node architectural constraints for GMPLS networks

Next generation IP over WDM networks are expected to be characterized by the presence of both IP routers and transparent network elements (NE), e.g. optical cross connects (OXC). All-optical NEs, however, typically introduce some architectural routing limitations, e.g. partial or no wavelength conversion capability. Current OSPF routing protocol with GMPLS extensions does not consider architectural routing constraints introduced by the node. In fact, only the signaling protocol is responsible to verify the availability of paths calculated by the routing algorithm. As a consequence, several set up attempts may be necessary by the signaling protocol before the successful creation of all-optical paths. We introduce a novel extension into the OSPF routing protocol taking into account the limitation of a class of architectural routing constraints (i.e. partial or no wavelength conversion capability). Furthermore, we give evidence by simulation of the benefits of the proposed extension. Specifically, a significant blocking probability reduction, referred to path set up at the first signaling attempt can be achieved, maintaining the additional overhead negligible. A prototypical OSPF extension implementation is then proposed to formally include the novel information into current routing protocol version.