[CentOS] Jumbo frames problem with Realtek NICs?

[Ljubomir Ljubojevic]

Tim Nelson wrote:
> ----- Original Message -----
>> I was trying to do some performance testing between using iSCSI on the
>> host as a diskfile to a guest vs the VM guest using the iSCSI device
>> directly.
>>
>> However, in the process of trying to establish a baseline performance
>> figure, I started increasing the MTU settings on the PCI-express NICs
>> with RTL8168B chips.
>>
>> First bottleneck was discovering the max MTU allowed on these is 7K
>> instead of 9K but googling seems to indicate that the RTL8168B is only
>> capable of 4K frames.
>>
>> I assumed 4K would still be better than nothing but unfortunately
>> bumping up the MTU to anything else but 1.5K caused the file transfers
>> (using NFS for easy testing), to hang at random points or more
>> accurate slow to a crawl.
>>
>> Checking the syslog, I discovered warnings that increasing MTU with
>> this adapter may cause problems.
>>
>> Searching around, it seems to be a common problem but there doesn't
>> appear to be any clear cut fix, including some suggestions to use a
>> third party driver.
>>
>> Does anybody know of a proven solution or is the Realtek chip itself
>> irrevocably broken/bugged that anything above the default 1500 will
>> simply not work?
> 
> Realtek NICs are known to be some of the poorest interfaces available. A quality Intel or Broadcom NIC will set you back very little in terms of cost. Just replace it and be done. :)
> 
> --Tim
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> 
I can not say I had any problems with Realtek NIC's. I operate a small 
WISP and I am active in StarOS wireless network reouter community. Most 
of us there agree that when you have problems with NICS like 3Com or 
even Intel, you can always use Realtek NIC's for X86-PC routers.

Try ElRepo driver and please report if that helps. I would like to know 
your experience with ElRepo driver.

Ljubomir