The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
Ethernet data plane loopback provides a means for remotely testing the throughput of an Ethernet port.
The Ethernet data plane loopback feature provides a means for remotely testing the throughput of an Ethernet port. You can verify the maximum rate of frame transmission with no frame loss. This feature allows for bidirectional or unidirectional throughput measurement, and on-demand/out-of-service (intrusive) operation during service turn-up. This feature supports two types of Ethernet loopback.
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.
Ingress QoS is bypassed in external loopback on service instances.
Internal loopback sequence is as follows:
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.
Data plane loopback on routed port infrastructure is not supported.
Etype, src-mac, and llc-oui based loopback traffic filtering is not supported.
Port-level QoS is not bypassed.
Port shaper cannot be bypassed in facility loopback.
Facility and terminal Ethernet data plane loopback (ELB) are not supported on dot1ad nni interface.
Internal loopback sessions configured must be within the 1 GB reserved bandwidth for Cisco ASR 900 Series RSP2 Module.
A maximum number of 20 facility loopback sessions can be created per system, provided 16 sessions are with Dot1Q and 4 sessions are with Dot1Q and destination MAC address. This scale reduces if SPAN or RSPAN is configured. This scale is supported on the Cisco ASR 900 Series RSP2 module.
A maximum number of 12 terminal loopback sessions can be created per system, provided 8 sessions are with Dot1Q and 4 sessions are with Dot1Q and destination MAC address. This scale reduces if RSPAN or SADT is configured. This scale is supported on the Cisco ASR 900 Series RSP2 module.
Only one Ethernet loopback (terminal or facility) session can be active on an EFP at any instance.
Local SPAN and ELB cannot be enabled on a physical interface at the same time.
Loopback sessions cannot be initiated on a port configured with SPAN or RSPAN.
Ethernet loopback is not supported on a range of dot1q tags.
Ethernet Data Plane Loopback is affected on STP enabled interface.
Dynamic addition of rewrite ingress tags with default EFP is not supported.
Dynamic changes at EFP and interface level are not supported when Ethernet Data Plane Loopback is active.
Egress EFP is not updated for external Ethernet data plane loopback statistics.
For internal Ethernet data plane loopback ingress and egress interface statistics are not updated on interface, where internal ELB is enabled.
Etype, VLAN, COS, src-mac, and llc-oui based loopback traffic filtering is not supported.
Port-based ELB is not supported.
Internal ELB is not supported when the physical interface port state is down.
Data filtering of loopback is not enforced for the traffic coming in the opposite direction.
Filtering based on specific VLAN is not supported.
Dot1Q filter is not supported.
Internal loopback sessions configured must be within the 100 GB reserved recycle bandwidth.
MAC-ACL cannot be bypassed in with facility loopback.
A maximum number of 20 facility loopback and 12 terminal loopback sessions are supported.
enable configure terminal interface gigabitethernet 0/2/1 service instance 1 ethernet encapsulation dot1q 100 bridge-domain 120 ethernet loopback permit external end
Note | 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. |
enable configure terminal ethernet loopback start local interface gigabitEthernet 0/4/1 service instance 10 external dot1q 10 cos 1 destination mac-address 0000.0000.0001 timeout none end This is an intrusive loopback and the packets matched with the service will not be able to pass through. Continue? (yes/[no]): yes
Use the ethernet loopback stop command to stop an active session on an interface or to stop all sessions based on the session id.
Router# ethernet loopback stop local interface gigabitEthernet 0/4/1 id 1
This example shows how to configure external (facility) loopback.
Router(config)# interface gigabitEthernet 0/4/1 Router(config-if)# service instance 1 ethernet Router(config-if-srv)# encapsulation dot1q 120 Router(config-if-srv)# bridge-domain 120 Router(config-if-srv)# ethernet loopback permit external
This example shows external (facility) loopback on the Gigabit Ethernet 0/4/1 interface:
interface GigabitEthernet0/4/1 no ip address negotiation auto service instance 10 ethernet encapsulation dot1q 10 rewrite ingress tag pop 1 symmetric bridge-domain 10 ethernet loopback permit external ===? For facility loopback ! end
This example below shows how to start external (facility) loopback on the router. A warning message is displayed. Type yes to continue.
Router# ethernet loopback start local interface gigabitEthernet 0/4/1 service instance 10 external dot1q 10 cos 1 destination mac-address 0000.0000.0001 timeout none This is an intrusive loopback and the packets matched with the service will not be able to pass through. Continue? (yes/[no]): yes
This example shows how to configure internal (terminal) loopback.
Router(config)# interface gigabitEthernet 0/0/0 Router(config-if)# service instance 1 ethernet Router(config-if-srv)# encapsulation dot1q 120 Router(config-if-srv)# bridge-domain 120 Router(config-if-srv)# ethernet loopback permit internal
This example shows internal (terminal) loopback on Gigabit Ethernet 0/0/0 interface:
interface TenGigabitEthernet0/0/0 no ip address service instance 10 ethernet encapsulation dot1q 10 rewrite ingress tag pop 1 symmetric bridge-domain 10 ethernet loopback permit internal ! end
Use the show ethernet loopback {active | permitted} [interface interface number] command.
Router# show ethernet loopback permitted -------------------------------------------------------------------------------- Interface SrvcInst Direction Dot1q/Dot1ad(s) Second-Dot1q(s) -------------------------------------------------------------------------------- Te0/0/0 10 Internal 10 Gi0/4/1 10 External 10
Router# show ethernet loopback active ============================================================ Loopback Session ID : 1 Interface : GigabitEthernet0/4/1 Service Instance :10 Direction : External Time out(sec) : none Status : on Start time : 10:31:09.539 IST Mon Aug 26 2013 Time left : N/A Dot1q/Dot1ad(s) : 10 Second-dot1q(s) : Source Mac Address : Any Destination Mac Address : 0000.0000.0001 Ether Type : Any Class of service : 1 Llc-oui : Any Total Active Session(s) : 1 Total Internal Session(s) : 0 Total External Session(s) : 1
This example shows how to stop the sessions on the router.
Router# ethernet loopback stop local interface GigabitEthernet 0/4/1 id 1