[dpdk-dev] Fwd: dpdk ixgbe PMD lro limits

[Lu, Wenzhuo]

Hi Asim,


> -----Original Message-----
> From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Asim Jamshed
> Sent: Tuesday, June 28, 2016 2:41 PM
> To: dev at dpdk.org
> Subject: [dpdk-dev] Fwd: dpdk ixgbe PMD lro limits
> 
> Hi,
> 
> Apologies in advance if this question has been asked in the past.
> 
> I have been performing mTCP-related tests on dpdk-16.04 with ixgbe PMD. I am
> using 82599ES 10-Gigabit adapters for my experiments. I have a few queries
> regarding LRO.
> 
> 1) What is the theoretical maximum size of the Ethernet frame I can get from
> the driver once LRO is enabled? In my experiments, I was seeing packet size as
> high as 16KB. Can it be as high as ~2^16 bytes (iph->tot_len)?
I'm not sure about if I understand your question correctly. Assume you're talking about the TCP segment after LRO. So, it's said there are no limitations on the maximum packet length.

> 
> 2) Since the NIC is reassembling payloads (of one flow) into a single packet,
> what does the Ethernet controller do with the tcp checksum field in the TCP
> header? I am observing that each LRO packet has checksum value as zero? Is
> that normal? I could not find any relevant documentation on the Web.
That's expected. 
You can search 82599 datasheet. I think that's what you're looking for.

> 
> Thanks in advance,
> --Asim