Possible causes for failures to forward Layer 3 traffic between directly connected interfaces on CE series switches

2

In V100R002 and later versions, the interface can be switched to the Layer 3 mode through the undo portswitch command. The possible causes for a Layer 3 traffic forwarding failure between interfaces are as follows:
- The interface is connected incorrectly.
- The physical layer status of the interface is Down.
- The interface is not assigned an IP address.
- The IP addresses of interfaces are on different network segments.
You can run the display interface command to check the physical layer status and IP address of an interface.
display
interface 10ge
1/0/1

10GE1/0/1 current state : UP (ifindex:
16)

Line protocol current state :
UP

Last line protocol up time : 2013-12-26
03:20:13

Description:

Route Port,The Maximum Frame Length is
9216

Internet Address is 10.1.1.1/24

IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is
0025-9e01-0205

Port Mode: COMMON FIBER, Port Split:
-

Speed :
10000, Loopback: NONE

Duplex:
FULL, Negotiation:
DISABLE

Mdi
:
-

Last physical up time : 2013-12-26
03:20:13

Last physical down time : 2013-12-26
03:20:02

Current system time: 2013-12-27
01:58:44

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Other related questions:
Do Ethernet interfaces on CE series switches support switching between Layer 2 and Layer 3 modes
Ethernet interfaces on all CE series switches, except the CE6810LI, support switching between Layer 2 and Layer 3 modes. By default, Ethernet interfaces on CE series switches work in Layer 2 mode. 1. Switching Layer 2 interface to Layer 3 mode: Run the undo portswitch command in the interface view to switch a Layer 2 interface to Layer 3 mode. Before switching, delete all non-default configurations from the interface. 2. Switching Layer 3 interface to Layer 2 mode: Run the portswitch command in the interface view to switch a Layer 3 interface to Layer 2 mode. Before switching, delete all Layer 3 service configurations from the interface.

The reason why a device directly connected to an AR router cannot be pinged or the IP address of the device that is obtained over DHCP is returned slowly
In Layer 2 networks, STP can solve network loop problems. By default, this function is enabled on an AR router. If the AR router is used as a user access device (the WAN interface of the router is connected to the Internet, and the LAN interface is connected to an intranet), there is no risk of loop generally. In this case, you are advised to run the stp disable command to disable STP and avoid interface blockage due to the enabled STP function or network flapping due to STP convergence. For example, a device directly connected to an AR router cannot be pinged or the IP address of the device that is obtained over DHCP is returned slowly.

What are causes for QinQ traffic forwarding failures
Traffic forwarding on an interface configured with selective QinQ fails in the following situations: The outer VLAN specified for selective QinQ is not created. The interface is not added to the outer VLAN specified for selective QinQ in untagged mode.

How to change an interface on a CE series switch to Layer 3 mode
The procedure for changing an interface on a CE series switch to Layer 3 mode is described on the right.

Possible causes for an IPv6 address conflict on an interface
In V100R002 and later versions, an IPv6 address conflict on an interface may be caused by the following - The peer interface directly connected to this interface has been configured with the same IPv6 address as that of the interface. - After the internal loopback detection function is enabled on an Ethernet interface, the IPv6 link-local address status of the interface is DUPLICATE, and the IPv6 global unicast address status of the interface is TENTATIVE (the address is a tentative address and have not passed the duplicate address detection). You can run the undo loopback command in the Ethernet interface view to disable the loopback detection mode on the interface. - There is a loop on the network. Note: By default, a switch performs duplicate address detection after an IPv6 address is configured for an interface on the switch. You can run the display ipv6 interface interface-type interface-number command in any view to check whether the IPv6 address of an interface conflicts with another IPv6 address.

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