Networking Knowledge Base

ResolutionIf you have a Catalyst 6500 switch with different input voltages connected, for example, power supplies (3000W) with 110V/20A inputs, and want to migrate to 220V/20A inputs, then one power supply can be connected to 220 Volts and the other ...

ResolutionTo resolve CNS NetFlow Collection Engine application failures, refer to the Solving CNS NetFlow Collection Engine Problems section of Troubleshooting CNS NetFlow Collection Engine.

Core issueThis is a normal behavior.ResolutionTechnologies such as ATM, frame relay and VLANs introduced a different type of interface, the virtual interface, or sub-interface. On an ATM interface, for example, you can have several permanent virtual ...

Core issueThe %SYS-5-MOD_NOSCPPINGRESPONSE: Module [dec] not responding... resetting module error message indicates that a module does not respond to the Supervisor Engine after three attempts to poll the module. [dec] represents the module number.Th...

Core IssueBuffer tuning allows you to modify the way a router allocates buffers from its available memory, and helps prevent packet drops during a temporary burst of traffic.ResolutionTo see if you might benefit from buffer tuning, use the show  inte...

Core issueOccasionally, unknown unicast or multicast traffic is flooded to a switch port because a MAC address has timed out or has not been learned by the switch. This condition is especially undesirable for a private VLAN isolated port.By default, ...

Core issueThe media type does not appear, or is blank in the output of the show interface status command. However, the interface works fine and there are no connectivity issues.These are some of the reasons for this problem:A non-Cisco Gigabit Interf...

Core IssueThe most common reason an internal Border Gateway Protocol (iBGP) route is not advertised is enabled synchronization. The outbound filter policies can also prevent the BGP from sending updates.ResolutionTo resolve this issue, perform these ...

ResolutionIf the router displays the system bootstrap version and hangs or falls into a booting loop, repeating the same information, the memory may not be well-seated. To address this issue, perform these steps:Re-seat by removing and then re-insert...

ResolutionRedundancy for multicast traffic requires these two things:A unicast routing protocol, for example, Open Shortest Path First (OSPF) or Enhanced Interior Gateway Routing Protocol (EIGRP)Configuration of Protocol Independent Multicast (PIM) o...

Core IssueThis occurs when the router is reloaded, and is caused by echoing being enabled on the modem.ResolutionIf a Cisco 2600 or 3600 series router goes into ROM Monitor (ROMmon) mode after a reload when a modem is connected to the console port, p...

Core issueDevices connected to a Catalyst 4000 switch may experience partial or full loss of network connectivity. The loss of connectivity may affect only a portion of the switch ports and may include the uplink ports. The problem is due to an SRAM ...

Core issueThis error message indicates that the system is self-correcting a transient DRAM error.ResolutionNo action is needed if this error occurs only once. However, if the error message occurs again within 24 hours, perform these steps:Schedule a ...

Core issueA Catalyst 6K running the K9 software image may crash when an SSH client tries to connect. This problem is first found in Catalyst OS (CatOS) version 8.3(2).The switch may crash while establishing an SSH connection to the client. The chance...

Core issueAfter Policy-based Routing (PBR) is configured and applied in the source VLAN, the traffic flows according to the configured PBR but the switch debug does not show any output.The show ip route-map counter does not increase for the PBR switc...