Networking Knowledge Base

Core IssueIf a Cisco IOS  Software upgrade is performed using the tftpdnld command from ROM Monitor (ROMmon), and the router boots successfully but no image is in Flash, then the -r switch was used when the tftpdnld command was issued. The -r option ...

ResolutionThe Cisco IOS  Server Load Balancing (SLB) feature allows the user to define a virtual server that represents a cluster of real servers, known as a server farm. When a client initiates a connection to the virtual server, the Cisco IOS SLB l...

Core issueThis message means that, due to a software error, a VLAN timer is detected as active when it should have been inactive, or was detected inactive when it should have been active.These tracebacks can be seen sometimes when these conditions oc...

Core issueThis issue is documented in Cisco bug ID CSCsc90277.On a Supervisor 720, if you have unicast Reverse Path Forwarding (uRPF) configured on multiple VLANs and one of those VLANs is shut down, Layer 2 traffic to the Supervisor 720 and within a...

Core issueIn Cisco Access Point (AP) devices that run Cisco IOS  release 12.3(2) and earlier, the beacons sent to Wireless LAN Solutions Engine (WLSE) are corrupted randomly.ResolutionUpgrade the software of Cisco Access Point devices to Cisco IOS re...

ResolutionThe NVRAM cannot be increased and is not upgradeable. This insufficient NVRAM issue is normal in switches with large configuration files.The workaround is to save the configuration file as a text file. To do this, issue the set config mode ...

Core issueThis message indicates that the private host port cannot be configured with the trunk, private promiscuous, and Switched Port Analyzer (SPAN) destination port on the same coil.While configuring private VLAN, these guidelines and restriction...

Core IssueOn Cisco 2600, 3600, and 3700 series routers, the size of I/O memory is by default dynamically allocated during the boot, based on the size of the Cisco IOS  Software image after decompression. The size of I/O memory is then checked against...

Core IssueHow to configure default routing so different default routes are used based on the source of the packet, such as based on which devices or users are originating the packets. The default route is already configured on the router, and you wan...

Core issueThe Cisco GBIC is a hot-swappable input/output device that plugs into a Gigabit Ethernet port or slot, linking the port with the network. Cisco GBICs can be interchanged on a wide variety of Cisco products and can be intermixed in combinati...

Core issueThis problem occurs in switches that run Cisco IOS  Software Release 12.2(18)SXF2 when Multicast is enabled. There are some instances when the created Reverse Path Forwarding (RPF) information does not get freed, for example, it causes a me...

Core issueFast Ethernet and Gigabit Ethernet trunk ports support five different trunk modes. Some Fast Ethernet and Gigabit Ethernet ports also allow the encapsulation type to be specified. These are the encapsulation types that the trunk can use:Int...

Core issueCluster Management Suite (CMS) is used for the management of switch clusters and individual switches from web browsers such as Netscape Communicator or Microsoft Internet Explorer. It is also referred to as Device Manager (DM).It is seen th...

Core issueCisco StackWise technology unites up to nine individual Cisco Catalyst 3750 switches into a single, logical unit. For this, Cisco StackWise uses special stack interconnect cables and stacking software. The stack behaves as a single switchin...

Core issueThis error message is displayed in the show version output of your switch. In some cases, the show test 1 command output possibly shows the NVRAM:F.The global checksum error means that the next time the box is reloaded, the nvram most likel...