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Ethernet data plane loopback provides a means for remotely testing the throughput of an Ethernet port.
Ethernet loopback sessions are supported only of EFPs (service instances, Ethernet flow points, EVCs).
Dot1q tags are not configured for default and untagged EFPs.
Ethernet loopback sessions are supported on dot1q or QinQ or untagged and default EFPs.
Internal loopback sessions configured must be within the 1 GB reserved bandwidth.
Internal loopback can be launched even when the physical interface port state is down.
Data plane loopback on routed port infrastructure is not supported.
Etype, src-mac, or llc-oui based loopback traffic filtering is not supported.
Port-level QoS is not bypassed. The egress port shaper cannot be bypassed.
Port shaper on the ingress port in both external and internal loopback cannot be bypassed.
Ethernet loopback is not supported on a range of dot1q tags.
Default EFP loopback is not supported in the shutdown state.
Loopback sessions cannot be initiated on a port configured with SPAN or RSPAN.
During Internal loopback, MAC swap is not supported for multicast or broadcast traffic.
Only one Ethernet loopback (terminal or facility) session can be active on an EFP at any instance.
Egress span on the port and internal loopback on an EFP on the same port cannot be configured at the same time.
Egress ACL is not supported on the EFP.
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.
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 .
Internal Ethernet Data Plane Loopback session can also be launched when the interface or port is in down state.
It is recommended to avoid performing any dynamic changes to the interface state when the Ethernet Data Plane Loopback is configured on a port that is in the down state.
Ethernet Data Plane Loopback is not supported with the XConnect service when the physical interface port state is down.
Ethernet Data Plane Loopback will be 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.
dot1q tag inclusion in the configuration for default and untagged EFP disables the Ethernet Data Plane Loopback.
When loopback is configure for a default EFP on the the interface, then all the traffic (ingressing) in this interface will get looped back.
BFD flaps on enabling internal loopback and traffic looped back with line rate as both the traffic passes through the HPCT queue.
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. Two types of Ethernet loopback is supported:
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. Internal loopback can be launched even when the physical interface port state is down.
![]() Note |
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 is not needed. |
![]() Note | By default the session would be running for 300 seconds unless explicitly specified by the user and automatically stopped 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 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
In the following scenario, ELB is supported using a MAC filter for UP-MEP session. If you starting ELB with out MAC filter, the UP-MEP session will go DOWN.
enable configure terminal service instance 800 ethernet 800 encapsulation dot1q 800 service-policy input <NAME> xconnect 2.2.2.2 880 encapsulation mpls cfm mep domain <NAME> mpid 200 cos 7 ethernet loopback permit external ethernet loopback permit internal Router#ethernet loopback start local interface gi0/0/0 service instance 800 internal dot1q 800 destination mac-address f078.1685.313f 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
Router#show ethernet cfm maintenance-points remote -------------------------------------------------------------------------------- MPID Domain Name MacAddress IfSt PtSt Lvl Domain ID Ingress RDI MA Name Type Id SrvcInst EVC Name Age Local MEP Info -------------------------------------------------------------------------------- 220 CCI f078.1685.313f Up Up 0 CCI Gi0/0/0:(2.2.2.2, 880) - 800 XCON N/A 800 800 0s MPID: 200 Domain: CCI MA: 800 Total Remote MEPs: 1
Related Topic | Document Title |
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Cisco IOS commands |
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mcl/allreleasemcl/all-book.html |
Standard/RFC | Title |
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No specific Standards and RFCs are supported by the features in this document. |
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MIB | MIBs Link |
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To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
Description | Link |
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The Cisco Support website provides extensive online resources, including documentation and tools for troubleshooting and resolving technical issues with Cisco products and technologies. To receive security and technical information about your products, you can subscribe to various services, such as the Product Alert Tool (accessed from Field Notices), the Cisco Technical Services Newsletter, and Really Simple Syndication (RSS) Feeds. Access to most tools on the Cisco Support website requires a Cisco.com user ID and password. |
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Feature Name |
Releases |
Feature Information |
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Ethernet Dataplane Loopback |
Cisco IOS XE Release 3.14.0S |
This feature was introduced on the Cisco ASR 920 Series Aggregation Services Router (ASR-920-12CZ-A, ASR-920-12CZ-D, ASR-920-4SZ-A, ASR-920-4SZ-D, ASR-920-10SZ-PD, ASR-920-24SZ-IM, ASR-920-24SZ-M, ASR-920-24TZ-M) . |