Connected and Running with half duplex speed

UNIX AIX
1

VIO Server connected to switch port and running with half duplex speed on one of the shared ethernet adapter. We have verified at switch end and everythings looks good.
Other ethernet adapter in the VIO server are connected and running in Full duplex speed.

Please help me find why this shared ethernet adapter is having half duplex speed and how to fix this back to full duplex.

Sometime back it was running as full duplex and recently there were no changes/upgrades on both switch and VIO server level.

 
$ ioslevel
2.1.2.10-FP-22
 
# lsdev -Cc adapter | grep -i ent14
ent14    Available       Shared Ethernet Adapter
 
# entstat -d ent14 | grep -i media
Media Speed Selected: Auto negotiation
Media Speed Running: 10 Mbps Half Duplex
 
# lsattr -El ent14 | grep -i real
real_adapter  ent4     Physical adapter associated with the SEA                           True
  • Mugunth
2

Proper fix is to get rid of "Auto negotiation" at both the Server and the Switch Port and positively set the line speed. Then cold start the Switch and then the Computer.

This problem arises from re-plugging network ports with the power on. Very bad practice. The same net-effect happens by power-cycling the Switch.

The quick fix is to power-down the server, power-cycle the Switch, power-up the server. In that strict order.

1 Like
3

Also, check to see if you have the latest microcode on your card. Sometimes when we get replacement hardware, the microcode is way behind. I can't think of a good reason to not be on the latest microcode level released by IBM.

4

Why is this bad practice? Negotiation can happen at any time, yes?

5

I have no opinion about this being bad practice or not - IMHO you are right and negotiation can happen at any time. On the other hand, since the times of the 10/100-Adapters Auto Negotiation in IBM Adapters has created far more problems than it solved (if it solved any, that is). I.e. CISCO Switches were for a long time famous for not being able to cope with IBMs adapters in Auto-Negotiation mode and consistently one ended with a port set to 100-Full and a NIC set to 100-Half Duplex (resulting in a bandwidth of ~1kbit/min).

In my experience switching off Auto Negotiation first thing a connection problem arised solved an awful lot of cases - even ones where Auto Negotiation worked for some time, because every microcode update or firmware upgrade might introduce this damn incompatibility again even if it was already solved.

I hope this helps.

bakunin

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