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New Member

Flowcontrol - Throughput issues

This is one example, I have a NAS 10GbE connected to a 4507 10GbE interface. When I copy a large CIFS file, the resource reports are telling us we are getting 20-30MBs, OS tells us 7MBs? Apart from the obvious reported throughput differences, thats slow!

Devices IPs are in the same subnet, Interface config

interface TenGigabitEthernet5/10

description QNAP 10GbE

switchport access vlan 10

switchport mode access

spanning-tree portfast

I'm not so familiar with flowcontrol (Just yet ) could this be affecting our system throughput negatively? The show flowcontrol output is not consistant, I have listed the 10GbE line cards stats below.

Some explanation as to why some Flowcontrol operations are 'on' 'off' 'disagree' and why Recieve Admin is set to 'desired' and 'on' - is this automatically generated by the system, I certainly did not specify these configurations.

Port       Send FlowControl  Receive FlowControl  RxPause TxPause

           admin    oper     admin    oper

---------  -------- -------- -------- --------    ------- -------

Te5/1      on       on       desired  on          325168  3773725

Te5/2      on       on       desired  on          166494  3847509

Te5/3      on       on       on       on          43476   65887

Te5/4      on       on       on       on          489200  1649744

Te5/5      on       on       desired  on          595828  1607934

Te5/6      on       on       on       on          11910638 6504

Te5/7      on       off      on       off         1974    26

Te5/8      on       off      desired  off         14      0

Te5/9      on       off      on       off         4470    4

Te5/10     on       on       on       on          25704   0

Te5/11     on       off      desired  off         0       0

Te5/12     on       on       desired  on          11915312 0

Thanks in advance

Brendan

  • LAN Switching and Routing
3 REPLIES
VIP Super Bronze

Flowcontrol - Throughput issues

It is common to have jumbo frames enabled on the device where storage connect to.  Is jumbo frame enabled?

HTH

New Member

Flowcontrol - Throughput issues

I've tried a MTU 9000 and the throughput still performs like a 10MB link.

Thanks

Super Bronze

Re: Flowcontrol - Throughput issues

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Posting

This is one example, I have a NAS 10GbE connected to a 4507 10GbE interface. When I copy a large CIFS file, the resource reports are telling us we are getting 20-30MBs, OS tells us 7MBs? Apart from the obvious reported throughput differences, thats slow!

Are both your resource reports and OS measuring in bits per second or bytes per second?  Networks often report in the former and OSs in the later.  Also, sometimes network stuff also accounts for bandwidth being used by L2, often OSs do not.

With CIFS, older versions of SMB weren't too optimal for high speed links. Additionally, if running over TCP, older Windows devices (pre-NextGen) didn't allocate very large TCP RWINs.  However, from your very low rate, which is lower than I would expect even with older SMB and/or pre-NextGen TCP, your NAS is 10g, but what about the host?  I'm wondering whether you NAS sends bursts that are being dropped if bandwidth to the host is less than 10g.  If your NAS keeps cycling through slow start - that might account for your slow overall transmission rate.

Of course, there are many other possible issues to.  For example, your (?) 4712 line card is, by design, oversubscribed 2.5:1.

BTW, "ordinary" Ethernet flow-control often "hurts" performance.

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