Networking Knowledge Base

Core issueEtherChannel configuration errors usually occur because of mismatched parameters on the ports involved. This includes different speeds, different duplexes, and different Spanning Tree Protocol (STP) port values. It is possible that no error...

Core IssueBorder Gateway Protocol (BGP) is an interdomain routing protocol used to exchange network reachability information with configured peers known as BGP neighbors. Unlike other Interior Gateway Protocols (IGPs) used for routing, BGP sends pack...

Core issueThe loadprog: error - on file open error message occurs when the software image is corrupted during an upgrade, or when the software image is not appropriate for the switch. This issue can also be caused by incorrect software handling of un...

ResolutionA basic and required task for configuring IP is to assign IP addresses to network interfaces. Doing so enables the interfaces and allows communication with hosts on those interfaces using IP. Associated with this task are decisions about su...

Core IssueThis issue occurs on a Cisco 7500 series router with two Route Switch Processors (RSPs). This may be due to the slave RSP being in a halted state, a communication issue between the master and slave RSP on the Inter-Process Communication (IP...

Core issueThe Catalyst 6500 Switch that runs Cisco IOS  software uses Maintenance Operations Protocol (MOP) packets in order to advertize its existence to Digital Equipment Corporation machines that use the MOP protocol. A switch periodically broadca...

ResolutionIf the cable between the devices is known to be good and is the correct type, yet the link does not light up, one of these commands may need to be issued on the Cisco Gigabit interface: On a CatOS-based switch, the set port negotiation mod#...

ResolutionTo enable the Inter-Switch Link (ISL) trunking on a Catalyst OS (CatOS) and integrated Cisco IOS  Software (native mode) switch, issue these commands: In the CatOS switch:     cat5000>set trunk mod_num/port_num [on|desirable|auto|nonegotiat...

Core IssueIf a router receives an outdated, corrupted, or missing link, state advertisement Open Shortest Path First Protocol (OSPF) stays in loading state and generates the OSPF-4-BADLSA error message.ResolutionCapture the output from the show tech-...

Core issueThe %IP-3-LOOPPAK: LOOPING PACKET DETECTED AND DROPPED error message indicates that a looping packet is detected. A common cause is the incorrect configuration of the ip helper-address command. The helper address must be the same address as...

Core IssueThis error message occurs when incorrect command syntax is used to access a Flash device by issuing the show [device:] command. The command syntax depends on the Flash media type. For example, if the device is an Advanced Technology Attachm...

Core IssueAdministrative distance is a parameter used by the router to choose a route learned through a specific  routing protocol, if the same route is learned through more than one protocol. In other words, it indicates the believability of a certa...

Core IssueThe jumper position on the mainboard must be changed for the memory to be recognized correctly.ResolutionIf after upgrading the total DRAM memory on a AS5300 series access server to 128MB, the router  only recognizes 32MB, follow the steps ...

Core issueAn Access Point (AP) is discovered only if these options are met:AP is entered as a seed device.AP is directly connected to a seed switch.ResolutionTo resolve this issue, perform one of these options:Enter the AP as a seed device in the Wir...

Core issueHot Standby Router Protocol (HSRP) changes its state when it fails to receive three consecutive HSRP hello packets from its peer, indicating the hello packets are getting dropped.These are the most common issues:Physical layer problems or e...