MAC Flaps on Cisco Switch

[Ranjit]

Dear All,

I have access point connected to cisco switch and i am seeing lots of MAC flaps on my switch where meraki AP are connected and i suspect because of which the WIFI connectivity is not stable and i have drops in the network for wifi users and slow browsing speed can you guys check the same

*Mar 12 16:30:57.643 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 2816.ad52.567f in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/45
*Mar 12 16:31:01.823 IST: %SW_MATM-4-MACFLAP_NOTIF: Host f0d5.bfa1.4e0b in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:02.267 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 7c2a.3123.eb32 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:03.347 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 0e59.11e2.433d in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:04.307 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 4845.2028.4808 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:09.234 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 2816.ad54.4011 in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/46
*Mar 12 16:31:09.450 IST: %SW_MATM-4-MACFLAP_NOTIF: Host e4a4.7133.f784 in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/45
*Mar 12 16:31:09.645 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 74e5.f956.4019 in vlan 211 is flapping between port Gi1/0/45 and port Gi1/0/47
*Mar 12 16:31:09.882 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a0c5.89d7.6a13 in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/46
*Mar 12 16:31:11.351 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a86d.aaab.bab2 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:12.107 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 58a0.238c.b842 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:12.778 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 4403.2c82.e448 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:13.066 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a86d.aaab.bafd in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:13.175 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 0e59.11e2.433d in vlan 211 is flapping between port Gi1/0/45 and port Gi1/0/47
*Mar 12 16:31:14.067 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 2816.ad52.567f in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:14.090 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 7c2a.3123.eb32 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:14.653 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 58a0.238c.6ca7 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:15.499 IST: %SW_MATM-4-MACFLAP_NOTIF: Host e442.a6b2.9ada in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/46
*Mar 12 16:31:16.438 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 4c1d.961f.066c in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:17.375 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 4c1d.9621.9cb0 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:19.490 IST: %SW_MATM-4-MACFLAP_NOTIF: Host f0d5.bfa1.4e0b in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:19.503 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a86d.aaab.baa8 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:20.309 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 7c2a.3124.b0e4 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:24.319 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a86d.aaab.bafd in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/45
*Mar 12 16:31:24.379 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a0c5.89d7.6a13 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:24.702 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 74e5.f956.4019 in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/46
*Mar 12 16:31:24.919 IST: %SW_MATM-4-MACFLAP_NOTIF: Host e4a4.7133.f784 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:24.931 IST: %SW_MATM-4-MACFLAP_NOTIF: Host b88a.608f.c6e0 in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/46
*Mar 12 16:31:26.194 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a86d.aaab.baa8 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:26.290 IST: %SW_MATM-4-MACFLAP_NOTIF: Host a86d.aaab.bab2 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:26.542 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 2816.ad52.567f in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:27.315 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 74e5.f956.4087 in vlan 211 is flapping between port Gi1/0/45 and port Gi1/0/46
*Mar 12 16:31:27.519 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 58a0.238c.b842 in vlan 211 is flapping between port Gi1/0/45 and port Gi1/0/47
*Mar 12 16:31:27.578 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 4485.0099.5881 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:28.592 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 58a0.238c.6ca7 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/47
*Mar 12 16:31:28.931 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 0e59.11e2.433d in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/45
*Mar 12 16:31:30.099 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 4403.2c82.e448 in vlan 211 is flapping between port Gi1/0/46 and port Gi1/0/45
*Mar 12 16:31:31.207 IST: %SW_MATM-4-MACFLAP_NOTIF: Host 7c2a.3123.eb32 in vlan 211 is flapping between port Gi1/0/47 and port Gi1/0/46
INBIN02ASW1#

config on cisco switch..

interface GigabitEthernet <>
description "Meraki Access-Points"
switchport trunk allowed vlan <>
switchport mode trunk
switchport nonegotiate

[PhilipDAth]

What is plugged into ports 45, 46 and 47?

[Ranjit]

To port 45 , 46 & 47 Meraki AP MR 53 is connected and only WIFI clients MAC connected to it are fallping..

[PhilipDAth · Accepted solution]

The most likely thing I can think of is clients roaming between the APs.

[NolanHerring]

That would be clients roaming between access points, and this is normal, not related to Meraki per say but really any wireless vendor. It's also annoying so I came up with the following, you can thank me later =P

logging discriminator WIFI-MAC msg-body drops flapping
logging buffered discriminator WIFI-MAC
logging console discriminator WIFI-MAC
logging monitor discriminator WIFI-MAC
logging host <Your syslog IP here if used> discriminator WIFI-MAC

[phelpsa06]

I too have this issue, and I wish there was a better fix rather than ignoring or discriminating the logs.  Like others have said, its due to roaming and the MAC address aging time for clients.  I've engaged Meraki TAC and a few others.  The default aging time for Meraki switches is 10 seconds (according to TAC, which to me is crazy) and for Cisco its 300 seconds.  TAC and the others I've engaged say they have not seen this on MS switches....

I've experimented with lowering my switchport configs with Meraki AP's to 1 minute.  It helps, but doesn't 100% solve the issue.  I wish there was a better fix. 

[phelpsa06]

Nolan,

Do you apply this to all your switches?  If I have Meraki AP's on several downstream switches, from our core switch, and I can see the MAC flap traverse all the way up.  Depending on If they roam from one building to another before the MAC address times out.

So I'm guessing you make this part of your default config for your switches?

Thanks,

[NolanHerring]

It is for my 2960 stacks yes

[randhall]

OH! I wish I was at the office right now!