June 2007
Intermediate to advanced
600 pages
18h 19m
English
Content preview from Network Warrior
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MAC Address Table Instability
Another problem caused by a looped environment is MAC address tables (CAM tables in CatOS) being constantly updated. Take the network in Figure 8-3, for example. With all of the switches interconnected, and spanning tree disabled, Switch A will come to believe that the MAC address for the PC directly connected to it is sourced from a different switch. This happens very quickly during a broadcast storm, and, in the rare instances when you see this behavior without a broadcast storm, chances are things are about to get very bad very quickly.
Figure 8-3. MAC address table inconsistencies
With this network in place, and spanning tree disabled, I searched for the MAC address
of the PC on Switch A using the show mac-address-table | include
0030.1904.da60 command. I repeated the command as fast as I could and got the
following results:
3550-IOS#sho mac-address-table | include 0030.1904.da601 0030.1904.da60 DYNAMICFa0/103550-IOS#sho mac-address-table | include 0030.1904.da601 0030.1904.da60 DYNAMICFa0/103550-IOS#sho mac-address-table | include 0030.1904.da601 0030.1904.da60 DYNAMICFa0/23550-IOS#sho mac-address-table | include 0030.1904.da601 0030.1904.da60 DYNAMICFa0/33550-IOS#sho mac-address-table | include 0030.1904.da601 0030.1904.da60 DYNAMICFa0/23550-IOS#sho mac-address-table | include 0030.1904.da60
This switch is directly connected to the ...
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.