A P P E N D I X Technical Information

I keep getting an intermittent loss of link (or data is not being transmitted). Why?

You may be using the wrong grade of cable. The wrong cable can cause erratic performance and you may eventually lose the connection between the port and the attached device. For more information on cabling, see “Connection Guidelines” in Chapter 1.

Check the duplex setting for the device connected to the port. You may need to use Local Management or Web Device Manager to force the port to half- or full-duplex (470T only).

A cable segment somewhere in your collision domain may be too long. Make sure your UTP cabling is no longer than 100 meters and your mulitmode fiber cable is no longer than 550 meters.

I created a tag-based VLAN, and I have tag-capable LAN adapters in my PCs, but I can still communicate with devices outside the VLAN. Why?

There are two areas to check in this situation. This can occur if ingress filtering is disabled. Enable ingress filtering so that the switch drops incoming packets if the packet’s VID is not a member of the port.

The PC’s NIC may not be enabled for tagging. If the NIC is not enabled for tagging, the PC sends and receives untagged traffic, and the switch classifies the traffic using the PVID. Ensure that the NIC is enabled for tagging.

Locating MIB files

If you use a MIB browser, you can configure or view statistics for the switch. You can find these switch MIB files at the Intel Support Web site at http://support.intel.com/support

intel.mib

intel_gen.mib

int_s470.mib

int_pbrd.mib

int_qprd.mib

When compiling the MIBs into an SNMP-compliant management application, compile the intel.mib first then compile the intel_gen.mib, int_s470.mib, int_pbrd.mib, and int_qprb.mib files.

Appendix

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Intel 470 manual Locating MIB files