IBM BladeCenter S Problem Determination And Service Manual page 70

Problem
A blade server is unable to communicate through a CPM.
Investigation
The Copper Pass-thru module (CPM) is a gigabit-only device; connections to
10/100 switches will not work. All blade server-to-blade server connectivity
requires the CPM to be connected to a properly configured external switch. The
external switch ports must be copper gigabit ports configured for autonegotiation.
All other configurations are unsupported and can result in errors that make it
appear that the CPM is not functioning correctly.
The CPM does not have switch functionality, which requires that you be able to
see the configuration of the external switch when troubleshooting CPM
connectivity problems. In addition, Serial over LAN (SoL) will not work if there is
a CPM in I/O-bay 1.
The following link indications are available for isolating a connection problem:
v The external (upstream) switch likely provides a link indication. It indicates a
v The advanced management module provides internal and external link status
v The operating system on the blade server provides link indication from the
v The LEDs on the CPM are equivalent to the advanced management module
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BladeCenter S Type 7779/8886: Problem Determination and Service Guide
link in the conventional networking sense of layer 1 link being up between the
CPM and the upstream switch. Even with all blade servers removed from the
BladeCenter S chassis, the upstream (external) switch link light will be on if the
external cables are properly connected.
(from the CPM perspective). If the external link indicates up, it means that both
sides of the connection (external switch to CPM and CPM to blade server) have
successfully negotiated the speed and duplex mode and that carrier is detected
from the blade for that connection. If no internal signal is detected, the external
indication will not provide an indication (it will not indicate a connection
whether one exists or not).
The internal link indication does not indicate a successful negotiation of speed
and duplex. It only tells you that a blade server is in the slot, and some electrical
current has been detected. For example, if you boot a blade server into BIOS and
disable the NIC, the link still shows up, even though speed and duplex have
obviously not be successfully negotiated. (The one exception to this is that if the
system is booting Linux, and the NIC driver module is removed, the link will
show down after about 15 minutes).
Unlike the advanced management module external link status, the internal link
status, as seen from the advanced management module Web interface, is
independent of the external link and is accurate with and without an external
connection. Link up indicates that the Ethernet port, Ethernet driver, cable, and
upstream port and blades are configured correctly for layer 1 of the OSI model.
Ethernet port.
viewable external link status. Only one physical CPM LED is associated with
each blade connection. When that CPM link LED lights, both the internal (CPM
to blade) and external (CPM to switch) connections recognize electrical signals
are connected.