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What is port fillword
What is port fillword
What does “fillword” in SAN switch documents mean?
Detailed Information
The word “fillword” is commonly used for Brocade switches such as 300, 5100, 5300, DCX-S, and DCX-4S. Fillword is OrderdSet that is sent between data frames. In a simple term, it is the minimum-size frame that fills space between data frames or fills space when there is no data to send. IDLE was used as fillword when the max link speed was 4Gb. When 8Gb switch was introduced, ARBff was adopted instead of IDLE mostly because it could contribute to lower bit error. IDLE that used for initialization was also changed to ARBff, along with the fillword change.
Brocade switches that support 8Gbcan configure the fillword setting by portCfgFillword command. Below is an output of “portcfgfillword --help” .
admin> portcfgfillword --help
Usage: portCfgFillWord [SlotNumber/]PortNumber Mode [Passive]
Mode: 0/-idle-idle - IDLE in Link Init, IDLE as fill word (default)
1/-arbff-arbff - ARBFF in Link Init, ARBFF as fill word
2/-idle-arbff - IDLE inLink Init, ARBFF as fill word (SW)
3/-aa-then-ia - If ARBFF/ARBFF failed, then do IDLE/ARBFF
Passive: 0/1
admin>
0: Use IDLE for initialization as 4Gb switches do.
1: Always use ARBff.
2: Use IDLE for initialization and use ARBff for between data frames.
3: Use ARBff for initialization first. If it fails, use IDLE. Use ARBff for between data frames.
When we use 8Gb switches, “1” basically works. However, since sometimes some switches do not work with ARBff, if you are not confident, it is safe to use “3”. Despite the circumstances, strangely the default setting has value “0” (use IDLE for initialization).
You can check the current status by “portCfgShow”. (Below output shows the setting is “3”)
Ports of Slot 7 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
----------------------+---+---+---+---+-----+---+---+---+-----+---+---+---+-----+---+---+---
Speed AN AN AN AN AN AN AN AN AN AN AN AN AN AN AN AN
Fill Word(On Active) 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
Fill Word(Current) 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3 3
AL_PA Offset 13 .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
Trunk Port ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON ON
Long Distance .. .. .. .. .. .. .. .. .. .. .. .. .. .. .. ..
Please keep in mind that if your switch is 16Gb model such as 6510, 6520, and DCX-8510, there is no such settings and they use ARBff for both initialization and between-frames.
As for MDS switches, they use ARBffas default if the switches support 8Gb/16Gb. So, we usually do not have to change the settings but, if needed, we can change it through switchport fill-pattern command.
The original content is https://community.emc.com/thread/201938 (written in Japanese)
Author: Yutaro
