MAC flapping issue - Packet Life

amitabha

18 posts

16 Aug 2010 at 8:22 a.m. UTC

Can any one give me idea about MAC Flapping? I have searched and didn't found any good details about this issue.

%SW_MATM-4-MACFLAP_NOTIF:

Please share.

fgabut

14 posts

16 Aug 2010 at 9:25 a.m. UTC

Hello,

Spanning tree loop ? a misconfigured LAG (etherchannel configured only on the other side for example) ?

Fred

soonsing

2 posts

17 Aug 2010 at 2:41 a.m. UTC

maybe u can share more details about ur network ?

the flapping might be caused from STP loop, wireless client moving from one location to another and etc..

and also how frequent u getting this kind of message ? =)

amitabha

18 posts

17 Aug 2010 at 7:24 a.m. UTC

Actually I need basic information/tutorial about this issue. I hope somebody can post blog about the general advance information about this issue.

abulanov

15 posts

17 Aug 2010 at 10:25 a.m. UTC

I met such behavoir. The basics were following. We use a several core/distribution switches (Cisco) and cheaper access swithes connected to core. A core switch sees certain mac address on another port than previously ( I think before mac address table record expire). In my case it couldn't be explained by migrating user, because of distance between access switches. Finally I found one of access switches which was faulty. It either replayed back or generated frames with src mac known/taken from its mac address table. Trobleshooting of this situation was complicated and time consuming. So please try to avoid of using cheap china switches.

amitabha

18 posts

19 Aug 2010 at 6:31 a.m. UTC

Thanks for sharing your experience.

loloy

4 posts

21 Aug 2010 at 5:51 a.m. UTC

I had a recent encounter with this issue, there were hubs/switches on an access port and that warning popped up whenever a new host is plugged into it. It stabilized after enabling portfast on the port. My theory was that stp seemed to resync everytime a new host is added, which somehow led to stray frames.

amitabha 18 posts	16 Aug 2010 at 8:22 a.m. UTC Can any one give me idea about MAC Flapping? I have searched and didn't found any good details about this issue. %SW_MATM-4-MACFLAP_NOTIF: Please share.
fgabut 14 posts	16 Aug 2010 at 9:25 a.m. UTC Hello, Spanning tree loop ? a misconfigured LAG (etherchannel configured only on the other side for example) ? Fred
soonsing 2 posts	17 Aug 2010 at 2:41 a.m. UTC maybe u can share more details about ur network ? the flapping might be caused from STP loop, wireless client moving from one location to another and etc.. and also how frequent u getting this kind of message ? =)
amitabha 18 posts	17 Aug 2010 at 7:24 a.m. UTC Actually I need basic information/tutorial about this issue. I hope somebody can post blog about the general advance information about this issue.
abulanov 15 posts	17 Aug 2010 at 10:25 a.m. UTC I met such behavoir. The basics were following. We use a several core/distribution switches (Cisco) and cheaper access swithes connected to core. A core switch sees certain mac address on another port than previously ( I think before mac address table record expire). In my case it couldn't be explained by migrating user, because of distance between access switches. Finally I found one of access switches which was faulty. It either replayed back or generated frames with src mac known/taken from its mac address table. Trobleshooting of this situation was complicated and time consuming. So please try to avoid of using cheap china switches.
amitabha 18 posts	19 Aug 2010 at 6:31 a.m. UTC Thanks for sharing your experience.
loloy 4 posts	21 Aug 2010 at 5:51 a.m. UTC I had a recent encounter with this issue, there were hubs/switches on an access port and that warning popped up whenever a new host is plugged into it. It stabilized after enabling portfast on the port. My theory was that stp seemed to resync everytime a new host is added, which somehow led to stray frames.