Multiple IP address on single Access point

[zeljkosan]

Hello team, I have some weird problem on few access points connected to L3 switch.

This is situation:

L3 switch is DHCP for few access points connected directly to it.

ip dhcp pool VLAN75_WIFI_MGMT
network 10.2.75.0 255.255.255.0
default-router 10.2.75.1
option 43 hex f104.0a00.680a
dns-server 10.0.66.10 10.0.66.11
domain-name wr

with exlude on : ip dhcp excluded-address 10.2.75.1 10.2.75.30

And on port there are MAC address (they are connected):

switch#show mac ad int Gi0/41
75 f44e.0581.027c DYNAMIC Gi0/41

But for that MAC address

switch#show arp | inc f44e.0581.027c
Internet 10.2.75.99 229 f44e.0581.027c ARPA Vlan75
Internet 10.2.75.96 239 f44e.0581.027c ARPA Vlan75
Internet 10.2.75.102 219 f44e.0581.027c ARPA Vlan75
+ at least 15 lines of different IP with same MAC

there are large number of IP address. I have pinged broadcast address to find ''alive'' addresses in subnet, and found 

Reply to request 0 from 10.2.75.171, 1 ms
Reply to request 0 from 10.2.75.169, 1 ms
Reply to request 0 from 10.2.75.170, 1 ms
Reply to request 0 from 10.2.75.31, 1 ms

So practically there are only 4 address (and there should be 4 addresses, not more)

But in other iteration of pinging broadcast address, I get different

Reply to request 0 from 10.2.75.174, 1 ms
Reply to request 0 from 10.2.75.173, 1 ms
Reply to request 0 from 10.2.75.172, 1 ms
Reply to request 0 from 10.2.75.31, 1 ms

Switch: WS-C3560G-48TS , Version/Image : 12.2(25)SEB4                C3560-IPBASE-M

AP: cisco AIR-CAP1702I-E-K9, Version : Cisco IOS Software, C1700 Software (AP3G2-K9W8-M), Version 15.3(3)JD17

What could cause problem, because in ''show logging'' there are no info about ports with AP.

[MHM Cisco World]

Multi IP to same MAC 

This MAC is for interface?

MHM

[zeljkosan]

Hello, yes this MAC is on active port with AP.

We have controller (but in different network), and I just read that these AP have problems regarding lost of power, which happened here.

So only solution is to add manually AP on wireless controller

[MHM Cisco World]

This AP work as ME ? 

If yes what you see normal' wifi connect to AP is get IP from dhcp and SW add mac of AP to IP assign to wifi client.

MHM

[Saikat Nandy]

@MHM Cisco World AP model is 1700 - so ME is out of equation.
@zeljkosan how frequently are you seeing APs to change the IP address? do you have wireless clients as well on the same vlan 75 where your APs are?These APs are configured with static ip or DHCP?anything on this VLAN configured with static IP?

[MHM Cisco World]

It two case 

If AP reboot then it ask IP' so it have multi IP' but his ping test is eliminate this.

He ping IPs and get reply' so IP is assign to active host and it not AP reboot issue.

Other case is host connect to AP

He can by take laptop and connect to AP and check if laptop get IP same as what he see in arp.

Thanks 

MHM

[MHM Cisco World]

@zeljkosan if you ping and get reply from IP to same Mac ? Or you get reply from IP other than that?

switch#show arp | inc f44e.0581.027c
Internet 10.2.75.99 229 f44e.0581.027c ARPA Vlan75
Internet 10.2.75.96 239 f44e.0581.027c ARPA Vlan75
Internet 10.2.75.102 219 f44e.0581.027c ARPA Vlan75
+ at least 15 lines of different IP with same MAC

If not same IP then your AP reboot

Remember ping and reply meaning IP from active host 

Ping and not get reply for IP (only one) then you have AP reboot

MHM

[zeljkosan]

Hello guys, thanks for tips.

For example, there is AP connected to port 0/43, and this is MAC:

switch#show mac ad int Gi0/43

Vlan Mac Address     Type Ports
---- ----------- -------- -----
75 f07f.06c0.3da0     DYNAMIC Gi0/43

show arp | inc f07f.06c0.3da0

Internet 10.2.75.194 71 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.197 61 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.203 42 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.200 51 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.206 32 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.209 23 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.215 3 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.212 13 f07f.06c0.3da0 ARPA Vlan75

+ many more lines with different IP but same MAC address

As there are many IPs, I ping broadcast address to check live address from that subnet:

KBC-N020#ping 10.2.75.255

Reply to request 0 from 10.2.75.215, 1 ms
Reply to request 0 from 10.2.75.217, 1 ms
Reply to request 0 from 10.2.75.216, 1 ms
Reply to request 0 from 10.2.75.31, 1 ms

switch#show arp | inc f07f.06c0.3da0
Internet 10.2.75.194 74 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.155 199 f07f.06c0.3da0 ARPA Vlan75
Internet 10.2.75.215 7 f07f.06c0.3da0 ARPA Vlan75

switch#
switch#ping 10.2.75.215
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.2.75.215, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/1 ms
switch#
switch#ping 10.2.75.194

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.2.75.194, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
switch#ping 10.2.75.155
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 10.2.75.155, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
switch#

So, I also agree with MHM, I think they are rebooting all the time, and I would like to add them manually on wlc controler, cause I think that could prevent reboot, if I add it to WLC

[MHM Cisco World]

Yes friend 

Since only one IP reply then AP reboot and this make it ask IP each time.

I dont recommend connect it to wlc.

Try check why it reboot always maybe it PoE issue or cable.

MHM

[zeljkosan]

Hello, thanks for help, will check tips you mentioned.

Switch is not PoE, APs have ''normal'' power supply