[c-nsp] What causes mac table relearning?

[Shaun Dombrosky]

VTP pruning?

Shaun Dombrosky
Data Network Engineer
V: 406-541-5749
Stay connected with Blackfoot:

      



-----Original Message-----
From: cisco-nsp [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of cisco-nsp-request at puck.nether.net
Sent: Thursday, October 18, 2018 10:00 AM
To: cisco-nsp at puck.nether.net
Subject: cisco-nsp Digest, Vol 191, Issue 13

Send cisco-nsp mailing list submissions to
	cisco-nsp at puck.nether.net

To subscribe or unsubscribe via the World Wide Web, visit
	https://puck.nether.net/mailman/listinfo/cisco-nsp
or, via email, send a message with subject or body 'help' to
	cisco-nsp-request at puck.nether.net

You can reach the person managing the list at
	cisco-nsp-owner at puck.nether.net

When replying, please edit your Subject line so it is more specific than "Re: Contents of cisco-nsp digest..."


Today's Topics:

   1. What causes mac table relearning? (Mike)
   2. Re: What causes mac table relearning? (Aaron1)
   3. Re: What causes mac table relearning? (Randy)


----------------------------------------------------------------------

Message: 1
Date: Wed, 17 Oct 2018 14:32:08 -0700
From: Mike <mike-cisconsplist at tiedyenetworks.com>
To: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
Subject: [c-nsp] What causes mac table relearning?
Message-ID: <1e423352-4d48-449d-582b-87bd36831ea6 at tiedyenetworks.com>
Content-Type: text/plain; charset=utf-8; format=flowed

Hi,


 ??? I have a network consisting of 3560g switches and I do not run spanning tree in this network. I have noticed a symptom when a vlan trunk interface goes down/up,? all mac addresses in the vlans carried by that trunk also seem to be cleared at the same time. Im not just talking the mac addresses on the port itself; rather, across the other switches themselves , even for mac addresses that have no connection to the port itself they just happen to be in one of the vlans. If I have missed something fundamental I'd love to know but I am not aware of any lan switching rules that would require this behavior.


Mike-



------------------------------

Message: 2
Date: Wed, 17 Oct 2018 17:27:30 -0500
From: Aaron1 <aaron1 at gvtc.com>
To: Mike <mike-cisconsplist at tiedyenetworks.com>
Cc: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
Subject: Re: [c-nsp] What causes mac table relearning?
Message-ID: <772CDDCB-A385-45D7-AF71-0BBB3C4688DA at gvtc.com>
Content-Type: text/plain;	charset=utf-8

You say you weren?t running spanning tree, but I thought topology change notification bridge PDUs caused a Mac flush, I don?t know For sure

Aaron

> On Oct 17, 2018, at 4:32 PM, Mike <mike-cisconsplist at tiedyenetworks.com> wrote:
> 
> Hi,
> 
> 
>     I have a network consisting of 3560g switches and I do not run spanning tree in this network. I have noticed a symptom when a vlan trunk interface goes down/up,  all mac addresses in the vlans carried by that trunk also seem to be cleared at the same time. Im not just talking the mac addresses on the port itself; rather, across the other switches themselves , even for mac addresses that have no connection to the port itself they just happen to be in one of the vlans. If I have missed something fundamental I'd love to know but I am not aware of any lan switching rules that would require this behavior.
> 
> 
> Mike-
> 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net 
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/



------------------------------

Message: 3
Date: Wed, 17 Oct 2018 23:02:34 +0000 (UTC)
From: Randy <randy_94108 at yahoo.com>
To: Mike <mike-cisconsplist at tiedyenetworks.com>
Cc: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
Subject: Re: [c-nsp] What causes mac table relearning?
Message-ID: <1021359067.571049.1539817354996 at mail.yahoo.com>
Content-Type: text/plain; charset=UTF-8

Hi Mike,

L2 re-learn can happen for a lot of different reasons.
Can you please share your topology where you are seeing this behavior.
-Randy




________________________________
From: Aaron1 <aaron1 at gvtc.com>
To: Mike <mike-cisconsplist at tiedyenetworks.com>
Cc: "cisco-nsp at puck.nether.net" <cisco-nsp at puck.nether.net>
Sent: Wednesday, October 17, 2018 3:28 PM
Subject: Re: [c-nsp] What causes mac table relearning?



You say you weren?t running spanning tree, but I thought topology change notification bridge PDUs caused a Mac flush, I don?t know For sure

Aaron

> On Oct 17, 2018, at 4:32 PM, Mike <mike-cisconsplist at tiedyenetworks.com> wrote:
> 
> Hi,
> 
> 
>     I have a network consisting of 3560g switches and I do not run spanning tree in this network. I have noticed a symptom when a vlan trunk interface goes down/up,  all mac addresses in the vlans carried by that trunk also seem to be cleared at the same time. Im not just talking the mac addresses on the port itself; rather, across the other switches themselves , even for mac addresses that have no connection to the port itself they just happen to be in one of the vlans. If I have missed something fundamental I'd love to know but I am not aware of any lan switching rules that would require this behavior.
> 
> 
> Mike-
> 
> _______________________________________________
> cisco-nsp mailing list  cisco-nsp at puck.nether.net
> https://puck.nether.net/mailman/listinfo/cisco-nsp
> archive at http://puck.nether.net/pipermail/cisco-nsp/


_______________________________________________
cisco-nsp mailing list  cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp
archive at http://puck.nether.net/pipermail/cisco-nsp/


------------------------------

Subject: Digest Footer

_______________________________________________
cisco-nsp mailing list
cisco-nsp at puck.nether.net
https://puck.nether.net/mailman/listinfo/cisco-nsp


------------------------------

End of cisco-nsp Digest, Vol 191, Issue 13
******************************************