VLL Service Considerations
Page 146 7750 SR OS Services Guide
PWE3 AAL5 SDU Mode
The endpoints of an AAL5 SDU mode VLL must be ATM VCs specified by port/vpi/vci. VPI/
VCI translation is supported. The endpoint can also be a FR VC, specified by port/dlci. In this case
FRF.5 FR-ATM network interworking is performed between the ATM VC SAP or the SDP and the
FR VC SAP.
In SDU mode, the mandatory PWE3 control word is supported. This allows the ATM VLL to
transport OAM cells along with SDU frames, using the âTâ bit to distinguish between them, to
recover the original SDU length, and to carry CLP, EFCI and UU information.
QoS Policies
When applied to 7750 SR Epipe, Apipe, and Fpipe services, service ingress QoS policies only
create the unicast queues defined in the policy. The multipoint queues are not created on the
service.
With Epipe, Apipe, and Fpipe services, egress QoS policies function as with other services where
the class-based queues are created as defined in the policy.
Note that both Layer 2 or Layer 3 criteria can be used in the QoS policies for traffic classification
in a service. QoS policies on Apipes cannot perform any classification and on Fpipes Layer 3 (IP)
classification is performed.
Filter Policies
7750 SR Epipe, Fpipe, and Ipipe services can have a single filter policy associated on both ingress
and egress. Both MAC and IP filter policies can be used on Epipe services.
Filters cannot be configured on 7750 SR Apipe service SAPs.
MAC Resources
Epipe services are point-to-point layer 2 VPNs capable of carrying any Ethernet payloads.
Although an Epipe is a layer 2 service, the 7750 SR Epipe implementation does not perform any
MAC learning on the service, so Epipe services do not consume any MAC hardware resources.
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