Why does a user on an AR slowly obtain an IP address

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The cause is that the interface is enabled with STP. By default, all interfaces of an AR are configured with STP.
When the interface changes from Down to Up, STP convergence is performed (the process takes about 30s). During STP convergence, an interface on an AR directly discards received packets. That is, DHCP Request messages are all discarded during the STP convergence period. IP addresses are obtained slowly in this case.
Use either of the following methods to solve this problem:
- Run the stp edged-port enable command on the AR interface connected to a user terminal to configure the interface as an edge interface.
If the AR is configured with the stp bpdu-protection command, the edge interface of the AR becomes Down when there are malicious attacks of BPDUs. To enable the edge interface to automatically go Up, run the error-down auto-recovery cause bpdu-protection interval interval-value command.
- If there is no physical loop, run the stp disable command on the AR in the system view or the AR interface connected to a user terminal.

Other related questions:
IP addresses are obtained slowly on the AR
The cause is that the interface is enabled with STP. By default, all interfaces on an AR are configured with STP. When the interface changes from Down to Up, STP convergence is performed (the process takes about 30s). During STP convergence, an interface on an AR directly discards received packets. That is, DHCP Request messages are all discarded during the STP convergence period. IP addresses are obtained slowly in this case. Use either of the following methods to solve this problem: Run the stp edged-port enable command on the AR interface connected to a user terminal to configure the interface as an edge interface. If the AR is configured with the stp bpdu-protection command, the edge interface of the AR becomes Down when there are malicious attacks of BPDUs. To enable the edge interface to automatically go Up, run the error-down auto-recovery cause bpdu-protection interval interval-value command. If there is no physical loop, run the stp disable command on the AR in the system view or the view of the AR interface connected to a user terminal to disable the STP function.
For details about client's failure to obtain and IP address, see the Revelations of Troublesolving on the right page.

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.

A user on an AR waits for a long time to obtain an IP address through DHCP
When the AR is used as the user access device (the WAN uplink interface connects to the Internet and the LAN downlink interface connects to the intranet), STP is enabled by default. After a user connects to an AR, the interface is in Discarding state in the first 30s. DHCP Request messages are discarded. After 30s, DHCP messages can be exchanged. You are advised to enable STP to prevent network flapping caused by STP convergence.

Wireless users cannot obtain IP addresses and the device displays a message indicating that the connection is restricted or needs to be reestablished
1. The dhcp enable command is not configured in the system view. 2. The dhcp select interface command is not configured in the interface view.

An AP fails to obtain an IP address
If the management address pool for APs is created on an AC, run the display ip pool name ip-pool-name used command on the AC. If the command output displays an AP's MAC address and a corresponding IP address, the AP has obtained an IP address. You can also run the following command to check whether an AP has obtained an IP address: - For V200R005 or earlier version: display ap-run-info id ap-id - For V200R006 or a later version: display ap all

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