Kyung Gyu Chun

Review on the operation, administration, and maintenance (OAM) of BcN

This paper briefly reviews ITU-T recommendations associated with multi protocol label switch (MPLS) and Ethernet operation, administration, and maintenance (OAM). The broadband convergence network (BcN) architecture with a centralized network controller is introduced. An aggregation structure employing Ethernet, MPLS, and time division multiplexing (TDM) signal is presented for the BcN. A physical link failure scenario is examined to investigate how the maintenance signal is propagated between different layers.

Tandem connection monitoring in the MPLS network

A method to monitor the quality of a MPLS LSP at the user, the service provider and the network providers aspect is suggested. The CV packet of the MPLS OAM packets is modified, and one bit for checking the incoming error is defined, the BIP-8 byte is added to evaluate the signal quality at the service provider and the network provider level respectively. By performing the tandem connection monitoring like the above the possible conflict between network providers can be avoided as the error location will be clearly identified.

Blocking of unauthorized multicast frame intake into layer 2 network for IPTV

A simple and effective method to protect the layer 2 network from the forged multicast frames is proposed. Forged multicast frame is a potential threat to the network. The proposed method is based on the assumption the IPTV servers do not reside in the same subnet as that of the users. It assures the legal multicast traffic flows into the network from a specific interface. By blocking the multicast frames for IPTV except this interface, unauthorized multicast traffic intake can be prevented.

Review on the Operation, Administration and Maintenance (OAM) of BcN

The BcN architecture of VPWS is introduced as a service model. The network elements forming the BcN data plane and a centralized controller forming the BcN control plane functionality are briefly described. A mapping architecture which transports the VPWS signal is presented. We examine the propagation of the maintenance signal under the network failure condition. The main purpose of this architecture is to find out the relationship between the maintenance signals in each layer. Finally, we briefly review the MPLS OAM ITU-T Rec. Y.1711 and Ethernet OAM being recommended in ITU-T Rec. Y.1731.

A Simulation Study on Clock Recovery of a Minimum Bandwidth Signal

Jitter and BER performance of non-linear clock recovery circuits are evaluated for a minimum bandwidth signal. To investigate the effect of bandwidth in optical transmission, BER performance of MB810 and NRZ signals with various types of timing recovery circuits are compared for a 40 Gbit/s optical link. Among the systems adopting non-linear timing recovery circuits, the MB810 signal employing an absolute value rectifier shows superior performance. We show that timing recovery without a non-linear circuit is also possible, and compare its BER performance with that of the others. Jitter performance of the fourth-law rectifier and that of the absolute-value rectifier is made for a minimum bandwidth signal. The mathematical derivation of the timing wave is also carried out for the clock recovery of the fourth-law rectifier. The result shows that the derived timing wave is expressed as a function of a pulse shape entering the timing path and the band-pass filter tuned to the pulse repetition rate.