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Fibre Channel (SAN)

New Contributor
Posts: 4
Registered: ‎02-03-2010
Accepted Solution

How can I determine the compatibility of 6505 and 1620

I've been asked to assess the impact of replacing old Brocade 4100 switches FOS v5.2.0a with new 6505's. I've since discovered that each fabric is connected with McData 1620 SAN routers. I'm pretty sure that these routers are ancient, as I can't find any info on them. The 6505 replacements will only run FOS 7, so I need to confirm if they'll work with these old routers. Can anyone point me in a direction to get more info. 

Many thanks


External Moderator
Posts: 5,620
Registered: ‎02-23-2004

Re: How can I determine the compatibility of 6505 and 1620

Old Brocade M-Series aka McDATA platforms, are no compatible with 16G Platforms.


here is NO WAY to connect 1620 to 6505


for details, refer FOS 7.x  Release Notes

Broadcom Moderator
Posts: 108
Registered: ‎03-29-2010

Re: How can I determine the compatibility of 6505 and 1620

[ Edited ]

1) The 6505 switch will not form an E-port with the 1620 McData router. It has formed an E-port with the 4100, which serves your local fabric on each end of the 1620 route.

2) The 6505 switch will negotiate down to 2Gbps and form an E-port with the 4100. Then your local fabrics will be able to connect to devices which require 8 or 16Gbps via the 6505. This will be a 'cascaded' solution, retaining the routing capability of the 1620. It will have MASSIVE latency and bottleneck problems trying to move data from one fabric, over the route to the other fabric for local devices operating at 8 or 16Gbps..

3) The proper design would be to eliminate both the 4100 and the 1620 and use the 6505 to go native FC across the existing route, in place of the 1620 solution.

3a) The 6505 supports modes for extended fabrics using the LE, LD, and LS distance capability modes to solve the buffer credit problems associated with long distance native FC. I believe the limits are 7000Km(?) between switches.

3b) If the 1620 is transmitting over a third party DWDM multiplexer(a common aggregation scheme) the 6505 switch supports a new 10Gbps speed which is typically compatible with most DWDM and CWDM existing infrastructures.


I believe eliminating the 1620 is your best bet unless this is a very long route with super high latency(Chicago to NYC, etc) where no synchroinzation is possible, or required. If that is the case, Brocade will provide you with it's extended fabrics solution which implements FCIP to encapsulate the FC frame like the existing 1620 McData product.


An important aspect of the buffers required is knowing the size of the frame typically sent over the line. Don't quote me on this, and I'm not going to look it up, but try checking to see if the ave frame size output is present on the 4100 command; portstats64show. Use this and the calculator in this reference to determine your buffer credit. Or - simply set it at LD mode and let the magic happen!


Going native FC over distance is like corn through a goose compared to the tin cans and string you now have. You can also implement both compression and encryption on the fly with the 6505. Someone there knew what they were doing getting the 6505 in place of the existing routed stuff.


Best of luck.


Any and all information provided by me is for entertainment value and should not be relied upon as a guaranteed solution or warranty of mechantability. All systems and all networks are different and unique. If you have a concern about data loss, or network disconnection, please open a TAC service request for service through Brocade, or through your OEM equipment provider. If this provided you with a solution to this issue, Please mark it with the button at the bottom "Accept as solution".

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