Thursday, September 3, 2020

Unifi AP and Juniper EX2200 ARP Loop after DHCP Offer

I'm trying to deploy a Unifi AP and have it reach my controller but I can't seem to get the AP to accept a DHCP address. I can see in my DHCP server that an address is offered and it can see the mac address and my switch updates it's ARP table to show the address for the MAC address attached to the correct port. However, I can never ping the AP and it can't be adopted by the controller. I decided to packet capture the interface to see what exactly was happening and it looks like after a DHCP Offer is sent the AP starts sending out ARP requests for the default gateway and it never resolves this. My switch continually replies back to the AP with the MAC address for the gateway but it just continues. The packet capture is below:

14:01:24.258194 Out IP 0.0.0.0 > 224.0.0.1: igmp query v2 14:01:24.260177 Out IP 0.0.0.0 > 224.0.0.1: igmp query v2 14:01:24.940126 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:26.259176 Out IP 0.0.0.0 > 224.0.0.1: igmp query v2 14:01:26.260903 Out IP 0.0.0.0 > 224.0.0.1: igmp query v2 14:01:26.879076 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:27.125544 In IP6 fe80::822a:a8ff:fe19:995b > ff02::2: ICMP6, router solicitation , length 16 14:01:28.847581 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:30.743371 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:31.134914 In IP6 fe80::822a:a8ff:fe19:995b > ff02::2: ICMP6, router solicitation , length 16 14:01:32.572936 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:34.448114 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:36.350146 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:36.735177 In IP truncated-ip - 321 bytes missing! 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request [|bootp] 14:01:36.757313 Out IP truncated-ip - 292 bytes missing! 10.4.51.1.bootps > 10.4.51.3.bootpc: BOOTP/DHCP, Reply, length 320 14:01:36.760229 In IP truncated-ip - 333 bytes missing! 0.0.0.0.bootpc > 255.255.255.255.bootps: BOOTP/DHCP, Request [|bootp] 14:01:36.778264 Out IP truncated-ip - 292 bytes missing! 10.4.51.1.bootps > 10.4.51.3.bootpc: BOOTP/DHCP, Reply, length 320 14:01:36.890499 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:36.890852 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:36.950167 In arp who-has 10.4.51.1 (Broadcast) tell 10.4.51.3 14:01:36.950485 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:37.885160 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:37.885480 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:37.956955 In arp who-has 10.4.51.1 (Broadcast) tell 10.4.51.3 14:01:37.957273 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:38.334141 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:38.885160 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:38.885479 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:39.086180 In arp who-has 10.4.51.1 (Broadcast) tell 10.4.51.3 14:01:39.086494 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:40.094871 In arp who-has 10.4.51.1 (Broadcast) tell 10.4.51.3 14:01:40.095189 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:40.154973 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:41.895235 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:41.895549 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:42.143391 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:42.895251 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:42.895565 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:43.895267 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:43.895579 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:43.950828 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:45.758998 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:46.901051 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:46.901367 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:47.708213 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 14:01:47.895276 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:47.895590 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:48.896285 In arp who-has 10.4.51.1 tell 10.4.51.3 14:01:48.896597 Out arp reply 10.4.51.1 is-at 5c:5e:ab:70:e1:01 14:01:49.645686 Out STP 802.1w, Rapid STP, Flags [Proposal], bridge-id 8000.5c:5e:ab:70:e1:01.822d, length 36 

I also am using dhcp-relay because my DHCP server is on a different VLAN.

Is there something else I have to configure on this switch for the AP to properly receive a DHCP address.



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