i) Functions of Switch, Bridge and Router:

Functions of Switch:

• They are intelligent, supports full duplex, divides the network into smaller less congested sections. It supports high bandwidth and can be used instead of a router.
• The basic function that any switch is supposed to perform is to receive information from any source connected to it and dispatch that information to the appropriate destination only. This differentiates switches from hubs. Hub gets the information and forwards that to every other device in the network.
• It has address learning: Layer 2 switches and bridges remember the source hardware address of each frame received on an interface, and they enter this information into a MAC database called a forward/filter table.
• It performs forward / filter decisions: When a frame is received on an interface, the switch looks at the destination hardware address and finds the exit interface in the MAC database. The frame is only forwarded out the specified destination port.
• It can avoid loop: If multiple connections between switches are created for redundancy purposes, network loops can occur. Spanning Tree Protocol (STP) is used to stop network loops while still permitting redundancy.

Functions Bridge: 

• It is a device that connects 2 segments of a network and sends data to one or the other based on a set of criteria.
• It used to divide the network into smaller segments.
• It reduces traffic bottlenecks. It does not differ between one protocol and another. It is simple and inexpensive.
• It links different physical media and network segments. It works at Data link layer of OSI model. It does broadcast storms.

Functions of Router: 

• It is a device that forwards the packet from one physical network to another.
• It does not broadcast storms, they resolve storms.
• It is an interconnect device to connect 2 topologically similar or dissimlar LANs.
• It is an intelligent device and uses a algorittm to determine the best route to send a packet to any given network.
• It operate at Network Layer of the OSI model. It is used to divide large, busy LANs into smaller segments.
• It is used to connect LAN to WAN. There are 2 types of router: Static and Dynamic routers. Static routers do not determine paths but you have to specify them. Dynamic routers have the capacity to determine paths.
• It connects networks that have different protocols or dissimilar networks. It performs protocol conversion at Application layer. It allows PCs to communicate with a mainframe system.

ii) OAM&P:

• OAM&P stands for Operations, Administration, Maintenance & Provisioning.
• Using synchronous network technology has several benefits, it has more bandwidth available by using optical fibers, but SONET and SDH have been designed with extensive maintenance and error control features, these features are referred to as OAM&P.
• OAM&P allows the service providers to detetct, collect and correct network error conditions.
• The frames of both SONET and SDH provide a lot of bandwidth forerror detection and communication channels between equipments. This facilities the ability to manage the network from a central location. A good portion of the overhead assignments in each STS or STL level is used for the OAM&P functions.
• OAM refers to managing and maintaining a network device. The Provisioning has been added for the telecommunications industry as a term for setting up services creating the acronym OAM&P.
• Its components allow Service Providers and Enterprises alike to manage, maintain and provision their services and network devices from a centralized browser based environment.
• OAM&P handle the important daily tasks that leads to a successful deployment and effectively aids decision making teams in assessing key performance indicators to make the most accurate businesses decisions.
• In addition to providing the right information to decision makers, the requirement for a powerful OAM&P component is to also provide service managers with a powerful and easy to use Service Creation Environment for developing and deploying applications.
• The OAM&P Module functionality is broken down into the following key areas Configuration Management, Network Management, Service Creation, Fault Management and Performance Management.