Cisco Switch Problem: %rtd-1-addr_flap:?

Question

Hi all,

I am having weird problem on my cisco switches. Let me explain the situation. I have got 3 switches those are interconnected to each other and there is NO redundant link in between.
I am not getting any error message when they are on live. But as soon as I connect my laptop (with a static IP which is not been used anywhere in the network) in any port of my switches, it starts getting the following message. As soon as I unplugged my connect and these error message stops.

[B]Dec 21 09:52:39.216 GMT: %RTD-1-ADDR_FLAP: FastEthernet0/23 relearning 48 addrs per min
Dec 21 09:53:39.215 GMT: %RTD-1-ADDR_FLAP: FastEthernet0/23 relearning 16 addrs per min
Dec 21 09:54:39.223 GMT: %RTD-1-ADDR_FLAP: FastEthernet0/23 relearning 18 addrs per min
Dec 21 09:55:39.214 GMT: %RTD-1-ADDR_FLAP: FastEthernet0/23 relearning 21 addrs per min
Dec 21 09:56:39.214 GMT: %RTD-1-ADDR_FLAP: FastEthernet0/23 relearning 14 addrs per min
Dec 21 09:57:39.213 GMT: %RTD-1-ADDR_FLAP: FastEthernet0/23 relearning 19 addrs per min
Dec 21 09:58:39.215 GMT: %RTD-1-ADDR_FLAP: FastEthernet0/23 relearning 14 addrs per min[/B]

I have checked with ' debug ethernet-controller addresses' and the mac address which was causing the issue was my laptop's mac address.

Any Idea, where am I missing the point?????

Regards

Mohammad

Answer 1

You say that the three switches are interconnected, and that there are no redundant connections... Just so I understand this, is the topology a triangle between the switches or is it a daisy chain from switch 1, to switch 2, to switch 3?



If it's a triangle, double-check your STP configuration. Do a "show spanning vlan x" where "x" is whatever vlan that laptop is in. Make sure that at least one trunk port on one of the non-root switches is in the blocking state for that vlan. If STP is turned off, or if there's some other kind of STP problem (ie: links between switches are access ports with portfast configured), that could be causing this.



There's no one answer to this, except that it really looks like you're dealing with a switching loop on your network or a duplicate MAC address. I would zero in on your STP deployment.



Edit: Disregard Funkie... There are a few major problems with his advise, not the least of which being that he's referring to STP and VTP as if they were interchangeable terms (ie: transparent and server switches are part of a VTP domain, which has nothing to do with STP. Also, making a single VTP server with two transparent switches would completely defeat the purpose of VTP since there would be no vlan information forwarded in any useful way). Making the 'main' switch the STP root bridge is a good design best-practice, but the placement of the root with that topology shouldn't allow for a loop to be forming either way. I don't mean to be rude but that answer is just totally wrong. The last part is right, in that pulling a cable would work, but that is not an optimal solution.

Answer 2

Error Message RTD-1-ADDR_FLAP [chars] relearning [dec] addrs per min



Explanation 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 will jump back and forth between the real port and the port that is in the path to the looped back port. In this message, [chars] is the interface, and [dec] is the number of addresses being learnt.



Recommended Action 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 command is useful in determining the next switch. Repeat this procedure until the port is found that is receiving what it is transmitting, and remove that port from the network.



Error Message RTD-1-LINK_FLAP [chars] link down/up [dec] times per min



Explanation This message means that an excessive number of link down-up events has been noticed on this interface: [chars] is the interface, and [dec] is the number of times the link goes up and down. This might be the result of reconfiguring the port, or it might mean a faulty device at the other end of the connection.



Recommended Action If someone is reconfiguring the interface or device at the other side of the interface, ignore this message. However, if no one is manipulating the interface or device at the other end of the interface, it is likely that the Ethernet transceiver at one end of the link is faulty and should be replaced.







This could be a unicast flooding issue, which is quite common in Layer-2 networks with multiple switches:



http://www.cisco.com/en/US/products/hw/switches/ps700/products_tech_note09186a00801d0808.shtml



If it is this then you can tweak the ARP & CAM timers to try to compensate but really the network should be designed and implemented correctly to avoid these issues.



If this isn't your problem it could be a server or appliance clustering issue where an application (or server etc) shares a common MAC address across multiple hosts and/or NICs?









I have put in the "debug ethernet-controller addr" command. Shouldn't I recieve some output? Sorry, I'm not very Cisco "savvy".



.





ADB100 (TechnicalUser) 11 May 05 13:53

Are you on the console or telnet? If the console check the fisrt bit of the output of the 'show log' command and make sure logging to the console is enabled. If you are telnet'd in then type 'terminal monitor' to enable the debug commands to be sent to the telnet sesssion.

Answer 3

Rtd-1-addr_flap

Answer 4

Well, I wouldn't switch in the middle of a chapter, but alot of authors switch between narratives by chapters example: chapter1: 1st chap2: 3rd chap 3 1st chap 4 1st you dont have to go comepletely alternative on this like 1st 3rd 1st 3rd 1st, but for it to make sense you cant have just 1 chapter that is 3rd otherwise it will just confuse the readers, so try to even it up a bit

Answer 5

Looks like you have a loop on your network.



If your network is a triangle then you need to make sure STP is configured correctly.



Check that your "main" switch is set to the STP server and the rest are transparent.



OR if the switches can talk through one other switch.. Maybe pull the plug on one of your links ( to temp fix the problem )

Answer 6

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It's the same command as what you use to enter name servers, just with the word "no" in front of it. So: no ip name-server 192.168.10.1 no ip name-server 154.32.72.43 And I would love to debate with you sometime on Cisco's cost-effectiveness. :P