Troubleshooting guide

11-21
ATM and Layer 3 Switch Router Troubleshooting Guide
OL-1969-01
Chapter 11 Troubleshooting Layer 3 Network Connections
Troubleshooting Half- or Full-Duplex Negotiation
• HSRP hellos
• DHCP helper
• Invalid next hop
IPX Packet Traffic on the Control Plane
IPX packets are sent to the route processor in the following situations:
• Packets matching the switch router IPX address
• GNS packets
• Certain broadcast packets (for example, RIP/EIGRP/SAP route updates).
• Destination node broadcast
• Invalid next hop
Miscellaneous Packet Traffic on the Control Plane
The following packets are sent to the route processor on the control plane:
• SNMP Queries
• BPDUs
• Layer 2 Learning
• CAM Entry Overflows
Troubleshooting Half- or Full-Duplex Negotiation
Autonegotiation converges to using the minimum capability of the local interface and the peer interface.
For example, if the local interface is capable of full-duplex transmission and the peer interface is only
capable of half-duplex transmission, after the local interface performs autonegotiation the interface
changes to operate in half-duplex mode.
If the peer interface does not have transmission mode autonegotiation capability, but the local interface
has transmission mode autonegotiation capability and the local interface receives no response to its
negotiation requests, the local interface changes to operate in half-duplex mode.
To Support half-duplex and full-duplex autonegotiation, your interface must confirm to the following:
• media type must be UTP
• Ethernet processor interface version must be C1 (Slicer Register EVER 0x1704)
Other interfaces (10/100Mbps Ethernet processor interface versions less than C1) have a default speed
of 100Mbps, full duplex, and are not capable of autonegotiation.
To determine the installed interface version, use the show controllers {fastethernet | gigabitethernet}
slot/subslot/port command and find the EVER field under the Slicer registers. The Ever field should be
EVER 0x1704 (C1); or if it is not, your interface is not capable of autonegotiation.