Networking Knowledge Base

Core issueThe %IP-4-DUPADDR: Duplicate address [IP_address] on [chars], sourced by [enet]error message means another system is using your IP address.When you run Cisco IOS  SLB with client NATPOOLs, the NATPOOLS on redundant devices must not overlap....

ResolutionTo support new software versions and new hardware like the ATA FlashDisk device, a ROMmon (boot ROM) upgrade may be required on Supervisor Engine 2.To resolve this issue, perform these steps:Verify the current ROMmon version by issuing the ...

Core IssueBus error exceptions can be caused in these instances: Loaded Cisco IOS  Software does not support installed hardwareSoftware failureMis-seated hardwareHardware failureResolutionUsually, a boot loop caused by a bus error exception is hardwa...

Core issueThis message indicates that a fabric channel error has been detected. [chars] is the type of channel error, the first [dec] is the channel number, and the second [dec] is the module number. ResolutionThe system attempts to recover by re-syn...

Core IssueThe boot image is a subset of the Cisco IOS  Software that is used to download main Cisco IOS Software images to the router using TFTP in recovery situations. The user can interact with this image through a command line interface signified ...

Core IssueThe established keyword indicates that packets belong to an existing connection if the Transmission Control Protocol (TCP) datagram has the Acknowledgment (ACK) or Reset (RST) bit set.ResolutionTo resolve this issue, perform these steps:Per...

Core IssueThis issue is due to a Cisco IOS  Software bug. This is usually a cosmetic issue. However, a great number of these errors can result in high CPU utilization.ResolutionTo resolve this issue, perform these options:To stop the error messages, ...

Core issueIf the port costs of the switch ports are calculated and assigned, it is possible to ensure that the shortest   lowest cost   distance to the root switch is used to transmit data. In order to calculate and assign lower path cost values, or ...

Core IssueTroubleshoot your Policy-Based Routing (PBR) issues without including any IP routing protocol information. This is also true for Hot Standby Router Protocol (HSRP) and Network Address Translation (NAT) issues.ResolutionPBR gives you a flexi...

ResolutionThe Cisco Catalyst 6500 Series Wireless LAN Services Module (WLSM) builds Fast Secure Roaming Tunnels (FSRT) to provide fast secure roaming across subnets. FSRTs provide a logical Layer 3 (L3) network over the existing network infrastructur...

Core IssueWhen the image decompresses into memory and hits a bad spot in the memory, the checksum is thrown off and the error is produced. This may occur after a Cisco IOS upgrade to a larger Cisco IOS image than was previously running on the router....

Core issueThe CiscoWorks process sometimes consumes a great deal of resources.This is normal behavior. During the initial discovery, ANI queries the devices sequentially starting at the seed device.ResolutionTo resolve this issue, take note of the "P...

Core IssueA Virtual Private Network (VPN) is a network where connectivity between multiple customer sites is deployed on a shared infrastructure. This provides the same access or security policies as a private network. The Multiprotocol Label Switchi...

Core IssueThe problem occurs when issuing a write memory or copy running-config startup-config command. Compressing the configuration may resolve this issue.ResolutionTo resolve this problem, issue theservice compress-config global configuration comm...

Core issueExtended-range VLANs cannot be created in the 1006 to 4094 range from the VLAN database mode. But, the Cisco Catalyst switch allows the creation of extended-range VLANs from the config-vlan mode. VLAN Trunking Protocol (VTP)only learns norm...