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I've got an embedded system running hostapd and dnsmasq acting as a wifi access point. Very repeatably it will take 11s between the time clients (Macbook pros, Dell laptops, iphones, android tablets) associate/authenticate with the AP and the time they get an IP address.

It appears that multipe dhcpdiscover/offers go through at nearly the same time, followed by a dhcprequest and dhcpack:

Apr  5 23:27:01 AP daemon.info hostapd: wlan0-ap: STA b8:e8:56:2d:45:ae IEEE 802.11: authenticated
Apr  5 23:27:01 AP daemon.info hostapd: wlan0-ap: STA b8:e8:56:2d:45:ae IEEE 802.11: associated (aid 2)
Apr  5 23:27:01 AP daemon.info hostapd: wlan0-ap: STA b8:e8:56:2d:45:ae RADIUS: starting accounting session 5521BC1F-00000007
Apr  5 23:27:01 AP daemon.info hostapd: wlan0-ap: STA b8:e8:56:2d:45:ae WPA: pairwise key handshake completed (RSN)
Apr  5 23:27:13 AP daemon.info dnsmasq-dhcp[734]: DHCPDISCOVER(wlan0-ap) b8:e8:56:2d:45:ae 
Apr  5 23:27:13 AP daemon.info dnsmasq-dhcp[734]: DHCPOFFER(wlan0-ap) 10.1.1.166 b8:e8:56:2d:45:ae 
Apr  5 23:27:13 AP daemon.info dnsmasq-dhcp[734]: DHCPDISCOVER(wlan0-ap) b8:e8:56:2d:45:ae 
Apr  5 23:27:13 AP daemon.info dnsmasq-dhcp[734]: DHCPOFFER(wlan0-ap) 10.1.1.166 b8:e8:56:2d:45:ae 
Apr  5 23:27:14 AP daemon.info dnsmasq-dhcp[734]: DHCPREQUEST(wlan0-ap) 10.1.1.166 b8:e8:56:2d:45:ae 
Apr  5 23:27:14 AP daemon.info dnsmasq-dhcp[734]: DHCPACK(wlan0-ap) 10.1.1.166 b8:e8:56:2d:45:ae Allans-MBP

How can I speed up the time it takes to get an IP address on clients?

Allan
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  • Have you tried sniffing the air interface? When do the clients actually send the `DHCPDISCOVER` message? Does it occur immediately upon successful association or about 10 seconds later as inferred from the enclosed `hostapd` log? – Yoel Apr 10 '15 at 22:17

0 Answers0