When the device functions as the access device, it takes a long time for users to obtain IP addresses through DHCP

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By default, STP is enabled on the device used as the user access device (WAN-side interface connects to the Internet and LAN-side interface connects to the internal network). The device interface is in Discard state 30s after users connect to the device. DHCP Request packets are discarded. DHCP packets are processed after 30s.

It is recommended that STP be disabled to prevent network flapping caused by slow STP convergence.

Other related questions:
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.

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.

Long time to obtain IP addresses from S series switch
Users on S series switches except S1700 switches obtain IP addresses slowly because the STP function is enabled on interfaces of the switches. (By default, STP is enabled on all interfaces of a switch.) When an interface of a switch goes Up, STP convergence is performed for about 30 seconds. During STP convergence, the switch discards all received packets including DHCP request packets sent from users. As a result, the users obtain IP addresses slowly. You can resolve the problem using either of the following methods: - Run the stp edged-port enable command to configure the switch interface connected to users as an edge interface. If the stp bpdu-protection command has been configured on the switch, the edge interface of the switch goes Down when the switch receives attack BPDUs. To enable the edge interface to automatically go Up, run the error-down auto-recovery cause bpdu-protection interval interval-value command. - If no physical ring topology exists on the network, you can run the stp disable command on the switch globally or on the switch interface connected to users. Additionally, when the switch functions as a DHCP server and after you remove and reinstall the network cable, the PC obtains an IP address after 1 minute. The problem may be caused by a software bug. When you remove and reinstall the network cable, the PC sends DHCP Request messages to the DHCP server. In earlier versions of a switch, software cannot properly process this event.

What can I do if it takes a long time to log in to the ViewPoint 9000 endpoint using SSH
This issue is caused by the non-standardized connection setup process between the endpoint and an SSH client (such as PuTTY). To accelerate the login, use SecureCRT or XShell.

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