[dpdk-users] dpdk ixgbe PMD lro limits

Asim Jamshed asim.jamshed at gmail.com
Fri Jun 24 16:49:55 CEST 2016


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)?

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

Thanks in advance,

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