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Asset ID: 1-72-1009287.1
Update Date:2009-09-22
Keywords:

Solution Type  Problem Resolution Sure

Solution  1009287.1 :   Disabling Auto-negotiation on the Sun [TM] B1600 Up-link Ports Causes the Link to go Down  


Related Items
  • Sun Fire B1600 Blade System Chassis
  •  
Related Categories
  • GCS>Sun Microsystems>Servers>Blade Servers
  •  

PreviouslyPublishedAs
212857


Symptoms
After disabling auto-negotiation on a Sun Fire[TM] B1600 Intelligent Shelf up-link port which is connected to an external switch or hub using a "straight-through" cable the link goes down.
For example, after disabling auto-negotiation on up-link port NETP4 the following may be seen.
Console#show interfaces status ethernet NETP4
Information of NETP4
Basic information:
Port type: 1000T
Mac address: 00-03-BA-1A-8D-0E
Configuration:
Name: External RJ-45 connector NETP4
Port admin: Up
Speed-duplex: 100full
Capabilities: 10half, 10full, 100half, 100full, 1000full,
Broadcast storm: Enabled
Broadcast storm limit: 256 packets/second
Flow control: Disabled
Port security: Disabled
Lacp: Disabled
Current status:
Link status: 
Down

Operation speed-duplex: 100full
Flow control type: None


Resolution
In the following discussion we continue to use NETP4 as our example port but the statements apply equally to all of the up-link ports, NETP0 to NETP7.


Auto-negotiation is enabled on the up-link ports by default, i.e.,
Console#show interfaces status ethernet NETP4
Information of NETP4
Basic information:
Port type: 1000T
Mac address: 00-03-BA-1A-8D-0E
Configuration:
Name: External RJ-45 connector NETP4
Port admin: Up
Speed-duplex: 
Auto

Capabilities: 10half, 10full, 100half, 100full, 1000full,
Broadcast storm: Enabled
Broadcast storm limit: 256 packets/second
Flow control: Disabled
Port security: Disabled
Lacp: Disabled
Current status:
Link status: Up
Port operation status: Up
Operation speed-duplex: 100half
Flow control type: None

Here the port is connected to a hub using a "straight-through" cable and we see Speed-duplex shown as "Auto" indicating that auto-negotiation is enabled.

Auto-negotiation may be disabled by running the following commands.

Console#config
Console(config)#interface ethernet NETP4
Console(config-if)#no negotiation
Console(config-if)#end

Note : When auto-negotiation is disabled you can set the up-link ports to operate at 10 Mbit/s or 100 Mbit/s but not 1000 Mbit/s full duplex, i.e.,

Console#config
Console(config)#interface ethernet NETP4
Console(config-if)#speed-duplex
10full    Force 10full Mbps operation
10half    Force 10half Mbps operation
100full   Force 100full Mbps operation
100half   Force 100half Mbps operation
1000full  Force 1000full Mbps operation
Console(config-if)#speed-duplex 1000full
Failed to set speed-duplex on ethernet NETP4

The default setting will be 100 Mbit/s full duplex which is confirmed by checking the port status again as follows.

Console#show interfaces status ethernet NETP4
Information of NETP4
Basic information:
Port type: 1000T
Mac address: 00-03-BA-1A-8D-0E
Configuration:
Name: External RJ-45 connector NETP4
Port admin: Up
Speed-duplex: 
100full

Capabilities: 10half, 10full, 100half, 100full, 1000full,
Broadcast storm: Enabled
Broadcast storm limit: 256 packets/second
Flow control: Disabled
Port security: Disabled
Lacp: Disabled
Current status:
Link status: 
Down

Operation speed-duplex: 100full
Flow control type: None

Notice that the Speed-duplex now shows "100full" indicating that the port has been forced to operate at 100 Mbit/s full duplex but the Link status is reported as "Down".

We could have run the following to achieve the same result.

Console#config
Console(config)#interface ethernet NETP4
Console(config-if)#speed-duplex 100full
Console(config-if)#end

The Medium Dependent Interface (MDI) is the name for the connector used to make the physical and electrical connection between a transceiver and a media segment. A port on a switch which has the transmit and receive signals crossed over is known as an MDI-X port.

The B1600 up-link ports have an auto-switching capability which is enabled by default and allows them to detect the type of cable connected and automatically switch between MDI and MDI-X as necessary. This means that by default you can connect an up-link port to another device using either a "straight-through" or "crossover" cable. This functionality is known as "auto MDI/MDI-X".

However, when auto-negotiation is disabled on the up-link ports the auto-switching capability is also disabled. Therefore you will need to use a crossover cable to connect the port to another similar device. In reality this means using a crossover cable to connect to another piece of Data Communications Equipment (DCE), e.g, another switch or hub. However, you may still be able to use a "straight-through" cable to connect to a piece of Data Terminal Equipment (DTE), e.g. another host system.

So, if another switch has been successfully attached to NETP4 and the link is auto-negotiating then either a crossover or straight-through UTP cable will work but if the link is forced then you must use a  crossover cable.

Referring back to our example, where we had forced the operating mode, the link comes back up after connecting a crossover cable between NETP4 and the hub, i.e.,

Console#show interfaces status ethernet NETP4
Information of NETP4
Basic information:
Port type: 1000T
Mac address: 00-03-BA-1A-8D-0E
Configuration:
Name: External RJ-45 connector NETP4
Port admin: Up
Speed-duplex: 100full
Capabilities: 10half, 10full, 100half, 100full, 1000full,
Broadcast storm: Enabled
Broadcast storm limit: 256 packets/second
Flow control: Disabled
Port security: Disabled
  Lacp: Disabled
Current status:
Link status: 
Up

Port operation status: Up
Operation speed-duplex: 100full
Flow control type: None

Notice that enabling auto-negotiation does not cause the link to go down with the crossover cable connected as auto-switching is then re-enabled,

i.e.,

Console#config
Console(config)#interface ethernet NETP4
Console(config-if)#negotiation
Console(config-if)#end
Console#show interfaces status ethernet NETP4
Information of NETP4
Basic information:
Port type: 1000T
Mac address: 00-03-BA-1A-8D-0E
Configuration:
Name: External RJ-45 connector NETP4
Port admin: Up
Speed-duplex: Auto
Capabilities: 10half, 10full, 100half, 100full, 1000full,
Broadcast storm: Enabled
  Broadcast storm limit: 256 packets/second
Flow control: Disabled
Port security: Disabled
Lacp: Disabled
Current status:
Link status: 
Up

Port operation status: Up
Operation speed-duplex: 100half
Flow control type: None

It is important to realise that auto-negotiation and auto MDI/MDX-X switching are not related technologies. The functionality described in this document is a design feature of the switch.



Product
Sun Fire B1600 Blade System Chassis

Internal Comments
For internal Sun use only.

The Sun Fire B1600 Intelligent Shelf's internally managed
network switch(es) are manufactured by Accton.




Author: Neil Cheney




September 2004


Sun, Fire, B1600, Intelligent, Shelf, duplex, up-link, force, Ethernet, interface, MDI, switch, port, link, auto-negotiation
Previously Published As
78326

Change History
Date: 2005-01-07
User Name: 31620
Action: Approved
Comment: Verified Metadata
Verified still correct for audience - contract
Checked review date 2006-09-24
Checked for TM - added Sun[TM] for B1600
Publishing
Version: 5
Date: 2005-01-07
User Name: 121361
Action: Approved
Comment: Andy,
Added my name as original author in the internal section as discussed on the telephone.
Neil.
Version: 0
Date: 2005-01-07
User Name: 31620
Action: Reassign
Comment: reassigned at users request
Version: 0
Product_uuid
10bec5e4-5865-11d6-9ffc-c65b6cd3fd7d|Sun Fire B1600 Blade System Chassis

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