CX3-20 controller network port settings

Hi Thomas,

Welcome to the EMC support forums - hope you find this useful, helpful and worth participating regularly.

Coming to your question, the Storage Processors Ethernet ports are by default set to auto-negotiate and it is not recommended to change that unless absolutely required. In fact, you 'll not be able to change it - only support personnel can do so if absolutely required or instructed by higher level of EMC CLARiiON Support team.

I suggest, if you can not set the Ethernet switch ports as auto-negotiate - set them as 100mbps / Full Duplex (or whaever settings supported) and SPs will negotiate to that settings.

However, it may be worth referring to the EMC primus solutions emc59461, emc79617 and emc158513 for your specific requirement.

Hope this helps. You may also take a look at the follwoing old threads in this forum -

http://forums.emc.com/forums/thread.jspa?tstart=0&threadID=95134

http://forums.emc.com/forums/thread.jspa?tstart=0&threadID=65767


Thanks,
Sandip

Unfortunately the CX3-20 SP Management port is fixed at autonegotiate. If the network switch ports must be set to a fixed speed 100Mb fixed or some other fixed setting the SP port will negotiate to the correct speed but the connection will be running at half duplex which may result in slower management performance, results vary. The only fix for this is to set the network switch port at autonegotiate. CX4 series systems allow you to set the desired management port speed and reports out the current speed settings

You have 2 options for network communications with a CX3-20 for correct communication between SP which is auto and the switch.
1. Set switch port to auto-negotiate
2. Set switch port to 100/half-duplex

NOTE - test the response time using navicli getagent command.

See primus emc79617 which outlines the issue with hardcoding the switch port to 100 full duplex...

Here's an excerpt from the primus.

This is expected behavior and is not related to how a CLARiiON array works. Instead, the issue is explained exactly by how auto-negotiation works. When both ends of a link support auto-negotiation, they exchange data in the form of Fast Link Pulses (FLPs) by which each end is informed of the capabilities of the other. Both speed and duplex setting are negotiated. However if only one end supports auto-negotiation, the fixed side does not send any information about what it supports. The auto-negotiating side is forced to determine what the fixed side supports. It can figure out speed based on the way the fixed side initializes but it is impossible to figure out its duplex setting. Because of that, the auto-negotiating side MUST set itself to half-duplex. If the fixed side is set to full-duplex, this will lead to a duplex mismatch and errors such as those described above.

According to a Cisco "Application Note 10/100 Mbps Auto-Negotiation:"

"If auto-negotiation only exists on one device on the link, the protocol is designed to detect the condition and respond correctly using a mechanism called parallel detection. Parallel detection allows detection of link partners that support 100BaseTX, 100BaseT4, and/or 10BaseT, but do not support auto-negotiation.

For example, if a Catalyst 5000 10/100 Mbps switching module is set to auto negotiate and it is connected to a 10BaseT NIC that does not support auto negotiation, the 10/100 switching module port will configure itself to 10 Mbps half duplex, because it will detect only 10 Mbps NLPs. The switch will then configure itself to 10 Mbps half-duplex. If the NIC were 100 Mbps, then it would be generating a carrier. The 10/100 Mbps switching module will recognize this and configure itself to 100 Mbps. If the NIC or the switch does not support auto negotiation then duplex cannot be negotiated. The 10/100 Mbps switching module will always configure to half duplex in the absence of FLPs defining full duplex. This implies that if a NIC is set to full duplex but does not advertise this capability in FLPs, a mismatch will occur because the auto-negotiation side assumes half duplex even though the speed is correctly identified ..."