Re: 2802 series AP not coming online when connected to 3750X switch.

Mogwai · ‎08-07-2023

Hey guys, hoping that I can get another set of eyes on this that might be able to see where I'm going wrong?

I've got a new Cisco 2802 series Ap which I know is good as I've connected it to the network & configured it at my desk. When configuring it, the AP was connected to a 3850 switch & the port settings are as below:

When I connected it to the new location the AP just repeatedly flashes Red/Green & never comes online. At the new location the Ap is connected to a 3750X & the port settings are below:

show running-config int fa1/0/10
Building configuration...

Current configuration : 444 bytes
!
interface FastEthernet1/0/10
 description Data-Voice Port
 switchport access vlan 40
 switchport mode access
 switchport voice vlan 232
 switchport port-security maximum 50
 switchport port-security
 switchport port-security aging time 1
 switchport port-security aging type inactivity
 speed 100
 storm-control action shutdown
 storm-control action trap
 spanning-tree portfast
 spanning-tree bpduguard enable
 spanning-tree guard root
end

I know the speed settings are not the best on the older 3750X, but I don't see anything else that would prevent the AP from coming online. The 3750X trunk should also be allowing all VLANs from the uplink.

show running-config int gi1/0/1 
Building configuration...

Current configuration : 123 bytes
!
interface GigabitEthernet1/0/1
 switchport trunk encapsulation dot1q
 switchport mode trunk
 switchport nonegotiate
end

Any ideas?

Flavio Miranda · ‎08-07-2023

Hi @Mogwai

I would remove any port-securty and make sure the AP joins to the WLC. Actually, I would keep on the minimum and add the Native vlan also.

interface FastEthernet1/0/10
description Data-Voice Port
switchport access vlan 40
switchport mode access

Mogwai · ‎08-07-2023

No luck. I've defaulted int fa1/0/10 & configured it as an access port for VLAN 40.

interface FastEthernet1/0/10
 description AP MSN-3315-2802
 switchport access vlan 40
 switchport mode access
end

Please correct me if I'm mistaken, but wouldn't I have to configure the port as a trunk in order to add the native VLAN.

Flavio Miranda · ‎08-07-2023

"

Please correct me if I'm mistaken, but wouldn't I have to configure the port as a trunk in order to add the native VLAN. "

You are right. In access is not necessary.

Does the AP at least get an IP address?

Show cdp neigh int Fa0/0 details

Show what?

Mogwai · ‎08-07-2023

No IP from the AP that I can tell. It doesn't appear on the controller when connected to the 3750X. When it is connected to the 3850 it does get an IP.

That command you provided doesn't match the syntax of the 3750X.

MSN-IDF9-3750X#show cdp neigh int fa0/0 details
                              ^
% Invalid input detected at '^' marker.

MSN-IDF9-3750X#show cdp neigh ?                
  Async              Async interface
  Auto-Template      Auto-Template interface
  BVI                Bridge-Group Virtual Interface
  CTunnel            CTunnel interface
  Dialer             Dialer interface
  FastEthernet       FastEthernet IEEE 802.3
  Filter             Filter interface
  Filtergroup        Filter Group interface
  GigabitEthernet    GigabitEthernet IEEE 802.3z
  GroupVI            Group Virtual interface
  Lex                Lex interface
  Port-channel       Ethernet Channel of interfaces
  Portgroup          Portgroup interface
  Pos-channel        POS Channel of interfaces
  Tunnel             Tunnel interface
  Vif                PGM Multicast Host interface
  Virtual-Template   Virtual Template interface
  Virtual-TokenRing  Virtual TokenRing
  Vlan               Catalyst Vlans
  detail             Show detailed information
  fcpa               Fiber Channel
  |                  Output modifiers
  <cr>

Flavio Miranda · ‎08-07-2023

The commamd is

show cdp neighbors [interface-id] [detail]

show cdp nei fa1/0/10 detail

Mogwai · ‎08-08-2023

Sorry about that!

MSN-IDF9-3750X#show cdp neighbors fa1/0/10 detail
-------------------------
Device ID: MSN-3315-2802
Entry address(es): 
  IPv6 address: FE80::EE01:D5FF:FE6A:D538  (link-local)
Platform: cisco AIR-AP2802I-B-K9,  Capabilities: Router Trans-Bridge 
Interface: FastEthernet1/0/10,  Port ID (outgoing port): GigabitEthernet0
Holdtime : 112 sec

Version :
Cisco AP Software, ap3g3-k9w8 Version: 8.5.151.0
Technical Support: http://www.cisco.com/techsupport
Copyright (c) 2014-2015 by Cisco Systems, Inc.

advertisement version: 2
Power drawn: 15.400 Watts
Management address(es):

Flavio Miranda · ‎08-08-2023

No worries. The problem is that the AP is not receiving IP address, as we can see here:

Device ID: MSN-3315-2802
Entry address(es):

The AP only joins to a WLC when it gets an IP address. You need to check why the Vlan 40 is not providing IP address. You can connect a PC on this port to check.

Mogwai · ‎08-08-2023

Since the VLAN's are being trunked from a 3850 in the same closet & the VLAN does appear in the 3750X I'm not quite sure why that wouldn't be getting an IP? I did connect my laptop to the port, but still wasn't able to grab the IP.

Flavio Miranda · ‎08-08-2023

Interesting. Is that the only Vlan on this switch?

If you set static IP on the PC, can you ping the gateway?

Mogwai · ‎08-08-2023

No, there are multiple VLAN's on this switch.

MSN-IDF9-3750X#   sho vlan brief

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa1/0/1, Fa1/0/20, Gi1/0/2, Gi1/0/3, Gi1/0/4
8    Security                         active    Fa1/0/3, Fa1/0/4, Fa1/0/5, Fa1/0/6, Fa1/0/7, Fa1/0/8, Fa1/0/9, Fa1/0/11, Fa1/0/12, Fa1/0/13, Fa1/0/14, Fa1/0/15, Fa1/0/16, Fa1/0/17, Fa1/0/18, Fa1/0/19, Fa1/0/21, Fa1/0/22, Fa1/0/23, Fa1/0/24
                                                Fa1/0/25, Fa1/0/26, Fa1/0/27, Fa1/0/28, Fa1/0/29, Fa1/0/30, Fa1/0/31, Fa1/0/32, Fa1/0/33, Fa1/0/34, Fa1/0/35, Fa1/0/36, Fa1/0/37, Fa1/0/38, Fa1/0/39, Fa1/0/40, Fa1/0/41, Fa1/0/42, Fa1/0/43
                                                Fa1/0/44, Fa1/0/45, Fa1/0/46, Fa1/0/47, Fa1/0/48
16   MS_DATA                          active    
32   CO_Data                          active    
40   MS_Data_3                        active    Fa1/0/2, Fa1/0/10
64   Campus_Mgmt                      active    
216  MS_Voice                         active    Fa1/0/2
232  CO_Voice                         active    Fa1/0/3, Fa1/0/4, Fa1/0/5, Fa1/0/6, Fa1/0/7, Fa1/0/8, Fa1/0/9, Fa1/0/11, Fa1/0/12, Fa1/0/13, Fa1/0/14, Fa1/0/15, Fa1/0/16, Fa1/0/17, Fa1/0/18, Fa1/0/19, Fa1/0/21, Fa1/0/22, Fa1/0/23, Fa1/0/24
                                                Fa1/0/25, Fa1/0/26, Fa1/0/27, Fa1/0/28, Fa1/0/29, Fa1/0/30, Fa1/0/31, Fa1/0/32, Fa1/0/33, Fa1/0/34, Fa1/0/35, Fa1/0/36, Fa1/0/37, Fa1/0/38, Fa1/0/39, Fa1/0/40, Fa1/0/41, Fa1/0/42, Fa1/0/43
                                                Fa1/0/44, Fa1/0/45, Fa1/0/46, Fa1/0/47, Fa1/0/48
1002 fddi-default                     act/unsup 
1003 token-ring-default               act/unsup 
1004 fddinet-default                  act/unsup 
1005 trnet-default                    act/unsup

If you set static IP on the PC, can you ping the gateway? > No

Flavio Miranda · ‎08-08-2023

Can you please share the "show run int <interface> on the other switch?

Also, can you share the command "show spanning-tree vlan 40" on both switches?

Mogwai · ‎08-08-2023

Thanks for all the help Favio, found the initial issue. It was due to DHCP snooping being enabled on the 3850 & not on the 3750!

Leo Laohoo · ‎08-07-2023

@Mogwai wrote:

When I connected it to the new location the AP just repeatedly flashes Red/Green & never comes online.

Post the complete output to the command "sh interface <PORT>".

Mogwai · ‎08-08-2023

Sure thing! Anything look out of the ordinary?

MSN-IDF9-3750X#sh int fa1/0/10
FastEthernet1/0/10 is up, line protocol is up (connected) 
  Hardware is Fast Ethernet, address is 08d0.9f1c.268c (bia 08d0.9f1c.268c)
  Description: AP MSN-3315-2802
  MTU 1500 bytes, BW 100000 Kbit, DLY 100 usec, 
     reliability 255/255, txload 1/255, rxload 1/255
  Encapsulation ARPA, loopback not set
  Keepalive set (10 sec)
  Full-duplex, 100Mb/s, media type is 10/100BaseTX
  input flow-control is off, output flow-control is unsupported 
  ARP type: ARPA, ARP Timeout 04:00:00
  Last input 00:00:02, output 00:00:00, output hang never
  Last clearing of "show interface" counters never
  Input queue: 0/75/0/0 (size/max/drops/flushes); Total output drops: 0
  Queueing strategy: fifo
  Output queue: 0/0 (size/max)
  5 minute input rate 2000 bits/sec, 1 packets/sec
  5 minute output rate 1000 bits/sec, 2 packets/sec
     93800 packets input, 22779950 bytes, 0 no buffer
     Received 93800 broadcasts (89623 multicasts)
     0 runts, 0 giants, 0 throttles
     0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored
     0 watchdog, 89623 multicast, 0 pause input
     0 input packets with dribble condition detected
     426963 packets output, 34987997 bytes, 0 underruns
     0 output errors, 0 collisions, 5 interface resets
     0 babbles, 0 late collision, 0 deferred
     0 lost carrier, 0 no carrier, 0 PAUSE output
     0 output buffer failures, 0 output buffers swapped out