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10064
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10
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Slow FTP transfer

ITSS Network
Level 1
Level 1

Hi,

We have a network between two locations. WAN is 100 Mbps MPLS provided by service provider. There is a FWSM module on core switches.

Problem we are facing is FTP file transfer between two servers across WAN link never crosses 20 Mbps. Link is 100 Mbps. However if we do parallel file tranfers each transfer is 20 Mbps . But we dont get transfer rate above 20 Mbps in a single FTP session. Is there any bottle neck where traffic is getting restricted.

Traffic between two mservers passes through 100Mbps MPLS WAn link , 6500 core switch and FWSM module in switch.

Thanks

KP

17 Replies 17

"With all due respect, are you part of presales department?"

Laugh - hardly!

". . . this is not the point of this discussion, the problem is slow FTP transfer . . ."

Indeed, although the OP, I don't believe, considered such as specific to a Cisco switch as the host, but between a pair of servers using a WAN, implying the problem was not seen on the LAN.

In your OP, you noted also finding slow FTP transfers to Cisco switches due to their slow flash write speeds.  However you also noted this as an (implied) poor design by Cisco to allow usage of inexpensive flash.

All possibly true, but my first response noted if flash was slow, it most likely because Cisco (unlike you) didn't/doesn't see a (market) need for a faster flash.  Further, I noted, some of poor FTP performance you found might not be just due to flash write speeds but also due to default RWIN and non-PMTUD settings.  Which although I didn't mention that in that post, can also apply to high speed links on LANs, too.

Then in your next post you note how HP does it better and how Cisco's flash choice " is really a wrong way to go ".

You're certainly allowed such an opinion, and in my next post, I tried to describe how you have a market choice.  Basically, again, if you consider this an important feature, chose a vendor who provides what you want.  But, if Cisco's choice was really wrong, they should suffer market loss.

Personally, I don't recall ever seeing a RFP with specifications for FTP speeds to a network device (laugh - nor have a seen one asking for the chassis to be painted in a certain color - certainly also another "wrong way to go" - if I cannot obtain devices that match my decor).

Again you have a right to your opinion that Cisco's design choice "literally sucks" regarding their flash write speeds, and can also suggest they should provide better.  But, also again, I hope you're free to make your choice of network vendor.  Heck, if you feel this is such a key feature, with others, not being provided by any vendor, feel empowered to start your own network hardware company.

I suspect, if you do (start your own company), then you might find it's not easy having no one believe you're doing it wrong or what you're doing sucks.

BTW, for the record, my experience pre-dates Cisco.  I mention that because I've seen Cisco grow from a "Cisco who?", to the 800 pound gorilla.

I believe Cisco has grown, as it has, for two reasons.  First, their equipment usually does what it's documented to do.  Second, if their equipment doesn't work as documented, they usually fix it.  My experience with other vendors has been, on those two points, finding them more hit or miss.

Wow , how does it help?

Btw same story

https://community.cisco.com/t5/switching/3850-flash-slow-file-transfer-rates/td-p/2286056/page/2

Just out of curiosity I tried with a different Cisco switch 9.5k - lightning fast

"Wow , how does it help?"

Sorry, but what is "it"?

"Btw same story"

Not exactly.  That transfer was using tftp, which uses UDP, and I believe (?) does not window data transfer, like FTP.  By Luke increasing the block size (i.e. a reconfiguration change), number of packets that needed to be ACKed was much reduced.  Effectively, data transfer rate increased.

Further, copying from USB was noted as much faster, so this case appeared to be network related, not flash related (solution was also network related).

"Just out of curiosity I tried with a different Cisco switch 9.5k - lightning fast "

Interesting.  Is it running an IOS-XE?  If so, you know those use a Linus kernel?  (Note, other IOS variants, i.e. IOS-XR and NX-OS.)  Such devices might have a completely revamped network host stack and/or different default parameters for the host stack.

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