Unsuccessful authentication after client roaming across ACs

DHCP Server —— H3C AC —— AP

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Vendor A AC

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AP 

The client first connects to AC of vendor A, obtains IP address a, and can access the Internet normally. It cannot access the Internet normally after roaming from vendor A to our wireless AC device.

1. At the beginning, the client connects to vendor A's equipment, obtains address a normally, and can also pass the authentication of vendor A's server, and can access the Internet normally. 

2. From vendor A roaming to our device, the client has also re-acquired IP address b, but the iMC server to see the client authentication still belongs to the appearance of IP address a, resulting in network failure. 

3, After analyzing the principle, iMC on the client's IP is AC through the billing message to bring up, here the client has been through the DHCP to obtain a new address b but AC is still with the old address. There are two ways for the AC to learn the client's IP address, one is the DHCP message and the other is the ARP message. The client may send an ARP with the old address before DHCP acquires the new address, and this old ARP message is recognized by the AC and learns the client's address. So the AC uses the old client IP address to send the billing message.

Disable the feature of ARP learning client ip, and keep only DHCP learning client IP address. 

Command: undo client ipv4-snooping arp-learning enable