•
Facility loopback (external)
—
Traffic loopback occurs at the Ingress interface. Traffic does not flow into
the router for loopback.
•
Terminal loopback (internal)
—
Traffic loopback occurs at the Egress interface. Traffic loopback occurs
after the traffic flows into the router to the other interface.
QoS Support for Ethernet Data Plane Loopback
•
Ingress QoS is bypassed in external loopback on service instances.
•
Internal loopback sequence is as follows:
◦
Ingress QoS
◦
Egress QoS (egress port) (both, shaper and policer are supported).
•
All port-level and EFP-level QoS is applicable for internal Ethernet data plane loopback.
•
For external Ethernet data plane loopback:
◦
All port-level and EFP-level QoS is bypassed except for shaper.
◦
Port-level shaper cannot be bypassed.
How to Configure Ethernet Data Plane Loopback
Enabling Ethernet Data Plane Loopback
enable
configure terminal
interface gigabitethernet 0/2/1
service instance 1 ethernet
encapsulation dot1q 100
bridge-domain 120
ethernet loopback permit external
end
Starting an Ethernet Data Plane Loopback Session
To start a loopback for untagged and default EFPs, dot1q and second-dot1q are not needed.
Note
By default the session would be running for 300 seconds unless you explicitly specify and automatically
stops after the session time expiry.
Note
enable
configure terminal
ethernet loopback start local interface gigabitEthernet 0/4/1 service instance 10 external
Layer 2 Configuration Guide for Cisco NCS 4200 Series
3
Configuring Ethernet Dataplane Loopback
QoS Support for Ethernet Data Plane Loopback