A service is a type of communication connection from one place to another. These communication connections have particular attributes and characteristics that are needed to provide a specific communications link through which an information flow or exchange can occur. The 7705 SAR-Hm series of routers support the following services:
Layer 2 Virtual Leased Line (VLL) and BGP virtual private wire services (VPWS)
Layer 2 virtual private LAN services (VPLS) and BGP VPLS services
Layer 3 IP VPN services (VPRN)
serial transport using raw socket and IP transport services
transporting WLAN interface traffic over a service
The service model uses (logical) service entities to construct a service. These logical entities provide a uniform, service-centric configuration and management model for service provisioning (see Nokia service model for more information). Different services can be created on the same node at the same time, and each service is uniquely identified by a service ID.
The supported services provide connectivity between a service access point (SAP) on one node and a SAP on a remote node. A SAP is a logical point where data traffic enters and exits a service. SAPs on the node are associated with Ethernet ports, VLANs, access router interfaces, serial ports, or the WLAN interface.
A connection between two SAPs on the same router is known as a local service. A connection between SAPs on a local and a remote router is known as a distributed service. SAP-to-SAP local services are supported for Ethernet and WLAN-based services. SAP-to-SAP local services are not supported for serial port and raw socket IP transport services.
Distributed services use service destination points (SDPs) to direct traffic from a local router to a remote router through a service tunnel. An SDP is created on the local router and identifies the endpoint of a logical unidirectional service tunnel. Traffic enters the tunnel at the SDP on the local router and exits the tunnel at the remote router. Hence, a service tunnel provides a path from one service router to another. Because an SDP is unidirectional, two service tunnels are needed for bidirectional communication between two service routers (one SDP on each router). The only supported SDP tunnel type is GRE-MPLS tunnels.
SDPs are configured on each participating service router or are auto-bound to the far-end router depending on the requirements and type of service. When configuring SDPs on the source router, the address of the destination router must be specified. When using the auto-bind function for SDPs, configuring individual SDPs between service routers is not required. The node uses BGP advertised information to perform the auto-bind SDP function to the far-end routers. For more information about auto-bind, see SDP binding.
After SDPs are created, they are bound to a specific service, or the service is enabled with auto-bind SDPs, to create a binding to the transport tunnels. In both cases, the SAPs that are part of the service use the bound SDPs as the transport for data traffic between nodes. The binding process is needed to associate the far-end devices to the service; otherwise, far-end devices are not able to participate in the service.