Networking Knowledge Base

Core issueThe Catalyst fixed configuration switch will not power on.ResolutionTo resolve this issue, perform these steps: If all LEDs (including the system LED) are off, make sure the power switch is on and that all the connections to and from the po...

Core issueWhen Quality of Service (QoS) is disabled, unicast traffic is assigned to queue 1. Broadcast, multicast, and unknown traffic is assigned to queue 2. If QoS is enabled, but the Class of Service (CoS)-to-transmit queue mappings are not modifi...

Core issueThe %C4K_CHASSIS-3-UNKNOWNLINECARD error message indicates that the module serial EEPROM has been read, and that the Field-Replaceable Unit (FRU) minor type is unknown. The current software image does not recognize this kind of module.Resol...

Core issueThe default error message is:%FABRIC-6-TIMEOUT_ERR: Fabric in slot [dec] reported timeout error for channel [dec] (Module [dec], fabric connection [dec])This message indicates that the firmware code on the fabric detected that the input or ...

Core issueAn incorrect channel mode configuration on a switch connected to a Catalyst 2900XL or 3500XL switch results in the inability to bring up an EtherChannel.ResolutionThe Catalyst 2900XL and 3500XL switches do not support Port Aggregation Proto...

Core issueIf the Cisco Catalyst 4500 switch reboots suddenly and reports NFL parity errors, the system displays this log message every time it sees a non-fatal error:Non fatal NFL Error [NFL] [FDT1] [FDT2] [FLD]The system resets itself right after th...

Core issueThe %ILPOWER-3-CONTROLLER_ERR: Controller error, Controller number [chars]: accessing failed error message means that an error reported or caused by the inline power controller was detected.When a Cisco Catalyst 3550-24 PWR interface receiv...

Core issueThis issue is due to the CatOS that does not support the internal 512 MB compact Flash adapter, referred to as bootdisk, on the Supervisor 720. It is not possible to migrate from native Cisco IOS  to hybrid with the use of only this interna...

ResolutionSmart multicast is a new level of efficiency for converged networks.The Cisco Catalyst 3750 series supports smart multicast, which has only one copy of the multicast in the stack interconnect, thereby conserving bandwidth. With Cisco StackW...

Core issue:Description:Resolution:Related Information: Core issue: Having portfast enabled on a port connected to a device generating Bridge Protocol Data Units (BPDUs) causes the port to go to errdisable status when BPDU guard is enabled on the swit...

Core issueThe error message is received when the archive copy-sw  or archive download-sw privileged EXEC command is issued on the stack master to copy the running image from the Flash memory on one stack member to the Flash memory on other stack memb...

Core IssueThe inside global address must be advertised into the routing protocol for remote subnets to communicate with Network Address Translated (NATed) hosts.ResolutionTo resolve this issue, choose one of these options:Configure the loopback inter...

Core IssueThe voice module is not recognized by the router during a new install, or after a Cisco IOS  Software change.ResolutionTo ensure that the module is supported on your platform, refer to the Voice Hardware Compatibility Matrix (Cisco 175x, 17...

Core IssueThe router may get stuck in a continuous loop, which may be due to a hardware issue. A continuous loop never lets you gain access to the router. The router continues to scroll error messages until it is powered off.  These symptoms may be o...

Core issueAfter a traffic class has been defined with the Access Control List (ACL), a policy can be attached to it. A policy can contain multiple classes with actions specified for each. A policy can include commands to classify the class as a parti...