Interoperability with Older Hubs

BLADEOS 6.3 Application Guide

The command-line interface might display link up and link down messages continuously for an external port that is connected to certain older hub models configured for 100 Mbps half-duplex. The display might show link up erroneously. This behavior has been observed when connecting the GbESM with the following devices:

NETGEAR FE104 100 hub

SBS 1000Base-T NIC

3Com Linkbuilder FMS100 Hub 3C250 TX/I

3Com SuperStack II 100TX 3C250C-TX-24/12

Nortel Baystack 204 Hub

If the GbESM is connected to an Alteon Application Switch which requires a link speed of 100 Mbps half-duplex, then enable auto negotiation on the GbESM port with port speed=any, mode=any, fctl=both, and auto=on.

Link Aggregation Control Protocol

If a static trunk on a GbESM is connected to another GbESM with LACP configured (but no active LACP trunk), the /info/l2/trunk command might erroneously report the static trunk as forwarding.

Since LACP trunks use LACPDU packet to maintain trunking with the partner, there is a possibility for those packets to be dropped from an extremely busy trunk. If this happens, some links in the LACP trunk might be removed, then aggregated back to the trunk if an LACPDU is received. To avoid this unstable LACP trunk link, you can add more links to the trunk to increase the bandwidth, or use regular static trunk if there are no more links available.

Linking at 10/100Mb

When the link speed for an external connection is forced (i.e. no Auto-Negotiation) to 100 Mbps and then changed to 10 Mbps, if the external device is changed first, the external device may erroneously report the link as DOWN even after the GbESM is changed to 10 Mbps.

Solution: At the external device, disconnect and reconnect the cable.

28	BMD00178, April 2010