Service Entities
Page 30 7210 SAS M Services Guide
Figure 3: Multiple SAPs in a service using QinQ uplinks in access-uplink mode
SAP Encapsulation Types and Identifiers
The encapsulation type is an access property of a service Ethernet port. The appropriate
encapsulation type for the port depends on the requirements to support multiple services on a
single port on the associated SAP and the capabilities of the downstream equipment connected to
the port. For example, a port can be tagged with IEEE 802.1Q (referred to as dot1q) encapsulation
in which each individual tag can be identified with a service. A SAP is created on a given port by
identifying the service with a specific encapsulation ID.
Ethernet Encapsulations
The following lists encapsulation service options on Ethernet ports:
• Null — Supports a single service on the port. For example, where a single customer with a
single service customer edge (CE) device is attached to the port. The encapsulation ID is
always 0 (zero).
• Dot1q — Supports multiple services for one customer or services for multiple customers
(Figure 4).. The encapsulation ID used to distinguish an individual service is the VLAN
ID in the IEEE 802.1Q header. For example, the port is connected to a Ethernet switch
(for example, a 7210 SAS E) with multiple downstream customers.
• QinQ — The QinQ encapsulation type adds a IEEE 802.1Q tag to the 802.1Q tagged
packets entering the network to expand the VLAN space by tagging tagged packets,
producing a double tagged frame. 7210 SAS M OS supports QinQ encapsulation for
OSSG002A
Customer
27
IP/MPLS Network
SAP
1/1/6
dot1q
SAP
1/1/3
dot1q
Service
Cust-27
DPSAP
ALA-A
Customer
27
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