I have a network with only 2 2924 connected together so I get 48 ports.
The problem: The network was getting slow and it stopped for a while, then it was OK for a while. Up and down. Then I replaced the 2 2924's with a simple 3com and then it was working fine again! I keep getting messages on the 2924-switches: "Fastethernet x/x relearning xxxx addrs per min". And "Fastethernet x/x experiencing errors". What is wrong?
Seems like the FastEthernet port of yours is being made to learn too many MAC addresses in a min, What is connected to that port? Can you post the running configuration of the port on which you got the error?
The config is this:
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
enable secret xxx
ip address 10.3.0.250 255.255.255.0
no ip directed-broadcast
ip nat outside
no ip route-cache
ip default-gateway 10.3.0.1
snmp-server engineID local xxx
snmp-server community private RW
snmp-server community public RO
line con 0
transport input none
line vty 0 4
line vty 5 15
On these port I have modems with lines to different sites. On those sites I have a hub, a PC and/or some other terminal.
I am using port 24 for the other switch to get up to 48 ports.
I get the errors on Fastethernet 0/1, 0/3, 0/22 and some others.
Mayby there could be something with the modems/lines?
Line speed 64kbit.
It may be a sign of duplex mismatch. Are you forcing the speed/duplex setting on the modem's LAN interface ? Your cisco interface is set to auto/auto and that's the setting the modems should have.
The cisco switch has more advanced error detection techniques than a unmanaged 3COM switch.
Can you please post the SH LOG where it contains the error verbatim ?
This is a little piece of the log file.
Log Buffer (4096 bytes):
1-ADDR_FLAP: FastEthernet0/3 relearning 31 addrs per min
03:06:19: %LINK-3-UPDOWN: Interface FastEthernet0/24, changed state to down
03:06:20: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/24, changed state to down
03:06:25: %LINK-3-UPDOWN: Interface FastEthernet0/24, changed state to up
03:06:26: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet0/24, changed state to up
03:07:10: %RTD-1-ADDR_FLAP: FastEthernet0/5 relearning 19 addrs per min
03:08:10: %RTD-1-ADDR_FLAP: FastEthernet0/3 relearning 6 addrs per min
03:11:30: %RTD-1-ADDR_FLAP: FastEthernet0/24 relearning 7 addrs per min
03:12:30: %RTD-1-ADDR_FLAP: FastEthernet0/7 relearning 65 addrs per min
Please check below link :
It explained :
ADDR_FLAP, RTD, LOG_ALERT, 0, "%s relearning %d addrs per min
Normally, MAC addresses are learned once on a port. Occasionally, when a switched network reconfigures, due to either manual or STP reconfiguration, addresses learned on one port are relearned on a different port. However, if there is a port anywhere in the switched domain that is looped back to itself, addresses jump back and forth between the real port and the port that is in the path to the looped back port.
Determine the real path (port) to the MAC address. Use the debug ethernet-controller addr privileged EXEC command to see the alternate path-port on which the address is being learned. Go to the switch attached to that port. Note that the show cdp neighbors privileged EXEC command is useful in determining the next switch. Repeat this procedure until you find the port that is receiving what it is transmitting, and remove that port from the network.
Please follow the action and try to find out the device which create the problem.
Hope this helps.
not sure if that makes a difference, but since you seem to have only one uplink between the switches, try and disable spanning tree alltogether on both switches:
no spanning-tree vlan 1
You could try and configure the ports connecting both switches as trunk ports, e.g.:
switchport mode trunk
switchport trunk encapsulation isl
It seems like I have found the problem!
In the modem on the other side, the ethernetport there, seems to have problems. I know nothing is connected there...
So after disconnecting the 3-4 modem, it got up&running nice again!
But I need help to debug trafic going in/out the fastethernet ports.
I think there still are som suspicious trafic...
Fast Ethernet 0/7 relearning 21 addrs per min
These error message signify that a MAC address moves consistently between different ports. These error messages are only applicable on the Catalyst 2900XL and 3500XL switches. The messages can indicate that two or more HSRP routers have become active. The messages can indicate the source of an STP loop, duplicated frames, or reflected packets.
use debug ethernet-controller address
The ports that the debug command references are off by one. For example, port 0 is Fast Ethernet 0/1. The error messages indicate the flap of a MAC address between ports 5 and 34 on the respective switch.
Note: The message RTD-1-ADDR_FLAP can be incorrect. Refer to these Cisco bug IDs in order to rule out this possibility:
CSCdp81680 ( registered customers only) ?Incorrect RTD-1-ADDR_FLAP message
CSCds27100 ( registered customers only) and CSCdr30113 ( registered customers only) ?Fast EtherChannel issues cause RTD-1-ADDR_FLAP
The most common causes for the move of MAC addresses are spanning tree problems or physical layer problems. When you troubleshoot this error message, complete these steps:
Note: Also complete the steps in the HSRP Troubleshooting Modules for CatOS Switches section of this document.
Determine the correct source (port) of the host MAC address.
Disconnect the port that should not source the host MAC address.
Document the STP topology on a per-VLAN basis and check for STP failure.
Verify the port channeling configuration.
An incorrect port channel configuration can result in the flap of error messages by the host MAC address. This is because of the load-balancing nature of port channeling.
check the following link for more info