Topics in this section include:
A service access point (SAP) is the point at which a service begins (ingress) or ends (egress) and represents the access point associated with a service. A SAP may be a physical port or a logical entity within a physical port. For example, a SAP may be an Ethernet port or a VLAN that is identified by an Ethernet port and a VLAN tag. Each application service connection is configured to use only one SAP.
A SAP identifies the application interface point for a service on a service router. Figure: Service Access Point (SAP) shows two applications connected to the same service via two different SAPs. The SAP identifiers are 1/2/5 and 1/2/6, which represent the physical ports associated with these SAPs. The physical port information should be configured before provisioning a service. See the 7705 SAR-Hm and SAR-Hmc Interface Configuration Guide for more information about configuring a port.
The 7705 SAR-Hm series supports VLL, VPWS, VPLS, and VPRN services. For each service type, the SAP has slightly different parameters; see Layer 2 and Layer 3 services for information.
In general, SAPs are logical endpoints that are local to the node and are uniquely identified by:
the physical Ethernet port
the physical serial port
the encapsulation type for the service
the encapsulation identifier (ID), which is the optional VLAN ID for Epipes
Depending on the encapsulation, a physical port can have more than one SAP associated with it (for example, a port may have several VLANs, where each VLAN has an associated SAP). SAPs can only be created on ports designated as "access" in the physical port configuration.
SAPs cannot be created on ports designated as core-facing "network" ports because these ports have a different set of features enabled in software.
