Teaming of Network Interface Cards
Teaming of Network Interface Cards, or NIC Teaming, can cause instability in the networks. Such setups can introduce disruptions to the Spanning tree and can make it undergo frequent recomputations. If intermittent loss of connectivity to NIC teamed servers occurs for devices or hosts in the same VLAN, try to disable NIC teaming. If the connectivity stabilizes, refer to the NIC vendor documentation in order to tune the NIC teaming configuration.
Additional Troubleshooting for 1000BASE−X NICs
Gigabit Autonegotiation (No Link to Connected Device)
Gigabit Ethernet has an autonegotiation procedure that is more extensive than what is used for 10/100 Mbps Ethernet (Gigabit autonegotiation specification IEEE 802.3z−1998). The Gigabit autonegotiation negotiates flow control, duplex mode, and remote fault information. You must either enable or disable link negotiation on both ends of the link. Both ends of the link must be set to the same value or the link does not connect.
If either device does not support Gigabit autonegotiation, disable Gigabit autonegotiation in order to force the link up. The default configuration of all Cisco switches is autonegotiation−enabled. If you disable autonegotiation, it hides link drops and other physical layer problems. Only disable autonegotiation to end−devices, such as older Gigabit NICs that do not support Gigabit autonegotiation. Do not disable autonegotiation between switches unless absolutely required, as physical layer problems can go undetected and result in spanning tree loops. Rather than disable autonegotiation, you can contact the vendor for a software or hardware upgrade for IEEE 802.3z Gigabit autonegotiation support.
Table 6Gigabit Autonegotiation Configuration Table
Autonegotiation | NIC Gigabit |
|
|
| Alternate |
|
Setting |
| Switch Port |
|
| ||
Autonegotiation |
|
| Switch |
| ||
|
| Gigabit Link |
|
| ||
| Setting |
|
| Link/NIC Link |
| |
|
|
|
|
| ||
Enabled | Enabled |
| Up |
| Up |
|
|
|
|
| |||
Disabled | Disabled |
| Up |
| Up |
|
|
|
|
| |||
Enabled | Disabled |
| Down |
| Up |
|
|
|
|
| |||
Disabled | Enabled |
| Up |
| Down |
|
|
|
|
|
Issue these commands for Gigabit autonegotiation configuration:
∙CatOS command:
set port negotiation mod/port enable disable
∙Cisco IOS Software command:
negotiation auto no negotiation auto
Verifying GBIC
When you troubleshoot link issues on Gigabit Ethernet, it is also important to verify the use of the correct Gigabit Interface Converter (GBIC) adapter with the correct cable distance. Refer to Gigabit Interface Converter Installation Note for information on distances and cable specifications required for different versions of GBIC adapters.
