Unknown new s-series feature: V8.62 "control-frame-learning disable" ?

[M_Nees]

2 weeks ago a new s-series firmware was going public.

Release Notes tell me the following new feature:

which kind of "control-frames" can be disabled from learning? In what szenario will help me that function?

Unfortunately no manual for V8.62 is available! No KB Article, nothing that will explain that feature.

Regards

[dfroe]

Does this mean that Enterasys (EOS) switches actually learn MAC addresses from STP BPDUs into their CAM table? This will most likely lead to CAM inconsistencies due to the facts you described. Do Extreme (XOS) switches have the same problem? Just to make sure that we are aware of the facts and being able to configure the same behaviour for EOS and XOS gear.

Other vendors describe in their pubilc documentation that they do not learn source MAC addresses from received BPDUs. Most likely because it doesn't really make sense and to avoid such inconsistencies.

Source: http://www.cisco.com/c/en/us/support/docs/lan-switching/spanning-tree-protocol/24063-pvid-inconsiste...
This article is more than a decade old but still contains correct and useful Information.

Quote: "the fact that switches typically do not learn a source’s MAC addresses from BPDU frames."

[Erik_Auerswald]

The 01-80-C2-XX-XX-XX MAC address range comprises more than just the STP destination MAC address, see e.g. http://standards.ieee.org/develop/regauth/grpmac/public.html.

[Alex24]

Hello Matthias,

Being in a blocked state will prevent the switch from transmitting and have it discard any traffic that comes in. The exception to this is control frames such as STP where the frames are received and processed and the source MAC address learned. If the remote switch uses the same MAC address for all its ports then this could cause some issues for traffic destined to that remote switch mac such as SNMP or Telnet. When forwarding the traffic to that remote MAC the most recent entry in the database could be on a blocked port so the traffic would be dropped. By disabling learning the source MAC from control frames then the EOS switch would then rely on other packets to learn the source mac of the remote switch and populate its tables.

-Alex

[M_Nees]

Hi Alex,

normally i think STP blocking state will not update the mac address table. So from that point of view that does not make sense ?!

i think i should wait till the KB Article is fully written. I hope the Article has enough deepness to get a complete understanding of that feature and the szenario this would be helpful.

Regards