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Case Study #4: HSRP State Changes and Switch Reports SYS-4-P2_WARN: 1/Host <mac_address> Is Flapping Between Port <port_1> and Port <port_2> in Syslog
These error messages can appear:
2001 Jan 03 14:18:43 %SYS-4-P2_WARN: 1/Host 00:00:0c:14:9d:08
is flapping between port 2/4 and port 2/3In software version 5.5.2 and later for the Catalyst 4500/4000 and 2948G, the switch reports a host MAC address that moves if the host MAC address moves twice within 15 seconds. A common cause is an STP loop. The switch discards packets from this host for about 15 seconds in an effort to minimize the impact of an STP loop. If the MAC address move between two ports that is reported is the HSRP virtual MAC address, the problem is most likely an issue in which both HSRP routers go into the active state.
If the MAC address that is reported is not the HSRP virtual MAC address, the issue can indicate the loop, duplication, or reflection of packets in the network. These types of conditions can contribute to HSRP problems. 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 MAC address that the error message reports.
Disconnect the port that must not source the host MAC address and check for HSRP stability.
Document the STP topology on each VLAN and check for STP failure.
Verify the port channel 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.
以上是官方处理方法 |
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发表于 2011-02-23 09:02
发表于 2011-02-23 19:48