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Updated:June 25, 2013
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This document describes the solution to an issue in which port-channel group members flap after Ethernet Virtual Connections (EVC) are configured on Cisco ASR 903 Series Aggregation Services Routers.
There are no specific requirements for this document.
The information in this document is based on Cisco ASR 903 Series Aggregation Services Routers configured as a Provider Edge device with port-channel towards the Customer Edge device.
The information in this document was created from the devices in a specific lab environment. All of the devices used in this document started with a cleared (default) configuration. If your network is live, make sure that you understand the potential impact of any command.
The port-channel group members start to flap after you configure Ethernet Virtual Connections (EVC); when you remove the EVC configuration, the port-channel group members no longer flap.
The logs display output similar to this:
GigabitEthernet0/0/4 taken out of port-channel1 GigabitEthernet0/0/4 added as member-2 to port-channel1 GigabitEthernet0/0/5 taken out of port-channel1 GigabitEthernet0/0/5 added as member-2 to port-channel1
This issue is specific to the ASR 903 port channels with EVC and is seen in this sample configuration:
! interface Port-channel1 mtu 1604 no ip address no negotiation auto service instance 999 ethernet encapsulation dot1q 999 rewrite ingress tag pop 1 symmetric bridge-domain 999 ! service instance 1700 ethernet encapsulation dot1q 1700 rewrite ingress tag pop 1 symmetric xconnect 172.26.225.1 1700 encapsulation mpls pw-class TE101 ! service instance 1820 ethernet encapsulation dot1q 1820 rewrite ingress tag pop 1 symmetric xconnect 172.26.225.15 1820 encapsulation mpls pw-class TE305 ! interface GigabitEthernet0/0/4 mtu 1604 no ip address negotiation auto service-policy input Core-In service-policy output Core-Out channel-group 1 mode active ! interface GigabitEthernet0/0/5 mtu 1604 no ip address negotiation auto cdp enable service-policy input Core-In service-policy output Core-Out channel-group 1 mode active
When you configure port channels with EVC on the ASR 903, you must configure 1 EVC with untagged encapsulation and L2 protocol. For example: