Info seen on scan of network

Recently, I've noticed an awful amount of information that is coming from our

2950XL switch. The following is the setup: C2821 router connected gigabitethernet port to a linux server (fw), both have gigabit ethernet cards. They are connected using a crossover cable. The 2nd gigabitethernet card on the linux server is connected to the C2950XL 48port switch. I monitor the traffic on both eth0 (incoming and outgoing to the internet) and eth1 (incoming and outgoing traffic to the LAN). I happened to notice the log of STP traffic on the eth1 interface and was wondering if STP is to prevent looping in a switched network this would be valid in a multiple switch environment. Why do I need to worry about it in a single switch environment? Trying to find out which device is 01:80:c2:00:00:00, this is where the packets seemed destined to. But I cannot see any device with this MAC address. Is this a broadcast? If so can it be shut down/off? I ask because it seems to broadcast packets every second or 2. Trying to trim the amount of information the switch is generating. The information is: 6502.781220 00:13:c3:d9:0a:b2 -> 01:80:c2:00:00:00 STP Conf. Root = 32769/00:13:c3:d9:0a:80 Cost = 0 Port = 0x8032 6503.998413 00:13:c3:d9:0a:b2 -> 01:00:0c:cc:cc:cc LLC U, func = UI; SNAP, OUI 0x00000C (Cisco), PID 0x2004 6504.793148 00:13:c3:d9:0a:b2 -> 01:80:c2:00:00:00 STP Conf. Root = 32769/00:13:c3:d9:0a:80 Cost = 0 Port = 0x8032 6506.815214 00:13:c3:d9:0a:b2 -> 01:80:c2:00:00:00 STP Conf. Root = 32769/00:13:c3:d9:0a:80 Cost = 0 Port = 0x8032 6508.829056 00:13:c3:d9:0a:b2 -> 01:80:c2:00:00:00 STP Conf. Root = 32769/00:13:c3:d9:0a:80 Cost = 0 Port = 0x8032

Thanks

Reply to
Jon L. Miller
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Yes, STP is to prevent looping among multiple switches. Switches use it automatically so they'll immediately detect if there's another switch. Cisco has lots of configuration options to control it, see the documentation.

STP uses multicast, so only devices that subscribe to the address (normally just other switches) or run in promiscuous mode should notice it.

Reply to
Barry Margolin

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