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What is the recommended Fillword setting for using 8GBps Brocade switches?

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Applies to

  • Brocade 8GBps Switches 
  • Brocade 300
  • Brocade 5100

Question(s) and Answer(s)

What are Fillwords in a fibre channel environment and what does NetApp recommend they be set at?

What is the recommended Fillword setting for using 8GBps Brocade switches?

Fillwords are 4-byte words without a special task. A port sends them when it does not have to send something else. They are used to maintain the synchronization of the link.

The recommended Fillword setting is 3.

E ports and ISL ports may require different settings depending on xWDM vendors. Contact the vendors in both of these situations. 

The available Fillword values are as follows:

0 | -idle-idle Sets IDLE mode in the Link Init and IDLE as the fill word (default).
1 | -arbff-arbff Sets ARB(ff) in the Link Init and ARB(ff) as the fill word.
2 | -idlef-arbff Sets IDLE mode in the Link Init and ARB(ff) as the fill word.
3 | -aa-then-ia Attempts hardware arbff-arbff (mode 1) first. If the attempt fails to go into active state, this command executes software idle-arb (mode 2). Mode 3 is the preferable to modes 1 and 2 as it captures more cases.

The difference is that '3' attempts '1' and then '2'.

Note:

  • Changing fillword is a disruptive event as the port will bounce when this change is made.
  • Some third-party storage vendors might require different Fillwords for their storage than
  • E ports and ISL ports may require different settings depending on xWDM vendors. Contact the vendors in both of these situations.