Networking Knowledge Base

ResolutionA Permanent Virtual Circuit (PVC) is a circuit that a network operator manually provisions over an Asynchronous Transfer Mode (ATM) switched network between a specific source and a specific destination.Multipoint bridging (MPB) enables poin...

ResolutionFast EtherChannel (FEC) and Gigabit EtherChannel (GEC) port groups act as single, logical ports for high-bandwidth connections between switches, or between switches and servers. There are two different types of port groups:source-based forw...

Core issueThe error message format can also look like this:%SYS-5-SPAN_CFGSTATECHG: [chars] session [chars]active for [chars].This message indicates whether a session is active or inactive. The first [chars] specifies a local or remote Switched Port ...

Core IssueWhen Hot Standby Router Protocol (HSRP) is running on a device, the %HSRP-4-DUPADDR:Duplicate address [IP_address] on [chars], sourced by [enet] error message can appear on the console if the IP address in an HSRP message received on the sp...

Core IssueA Cisco 7500 series router may display log messages similar to these: %CI-4-ENVWARN: 2.5 Reference measured at 1.99  %CI-2-ENVCRIT: +12 Voltage measured at 9.78   %CI-2-ENVCRIT: +5 Voltage measured at 4.12  %CI-2-ENVCRIT: -12 Voltage measur...

Core IssueOn routers running Enhanced Interior Gateway Routing Protocol (EIGRP), an error message indicating that the neighbor is down due to K-value mismatch might appear for these reasons: Different settings for metric calculation on the EIGRP neig...

Core issueThe error message looks similar to this:%C4K_PKTPROCESSING-4-ERRORPACKET: Warning - Unexpected packet hitting input acl%C4K_HWACLMAN-4-WARNINGSTRING: Entry: 48 PacketCount: 7The software is unable to process a packet. Instead, the packets a...

Core IssueOnline Insertion and Removal (OIR) of network modules is not supported on Cisco 3620 and 3640 series routers. A drop in output voltage from the power supply is reported as an OIR event. Such events on the 3620 and 3640 series routers typica...

Core issueDifferent software versions running on the two Multilayer Switch Feature Cards (MSFCs) in the same chassis may produce this message.ResolutionBecause the %IPC-5-NULL: Registering Control Port Id=0x2210003 message  may be displayed when two ...

ResolutionThere are basically three types of versions which shows up when you issue the show module command:Hardware version (Hw)Software version (Sw)Firmware version (Fw)    HW and FW versions are codes that the manufacturer handles on some chips of...

Core issueThe error message similar to this appears in the logs:%MCAST-2-IGMP_SNOOP_DISABLE:IGMP Snooping disabled due to excessive events/packets, 0/19820; auto reenable in about 2 minsThe error message indicates that you receive too many IGMP packe...

ResolutionWhen a line card or module is removed from the slot, any previous commands or configurations are removed from the running-config. When the card is installed in a different slot, it must be reconfigured. Before the line card is moved to anot...

ResolutionThe Simple Gateway Monitoring Protocol (SNMP) Object Identifier (OID) is used to query the in use and available Digital Service Zero (DS0) channels.The MIB you need to look at is CISCO-POP-MGMT-MIB.This is the OID in question:.1.3.6.1.4.1.9...

Core IssueOn Cisco 2600/3600/3700 series routers with an installed Advanced Integration Module (AIM), encryption may still be performed by the main processor instead of the AIM. The reason for this may be a hardware and software incompatibility issue...

Core IssueThis issue occurs when the boot ROM version on the 2600 series router is not properly comparing the checksum.ResolutionIf the tftpdnld command fails with the TFTP copy: operation terminated due to bad checksum comparison error message, perf...