[ovs-discuss] gso packet is failing with af_packet socket with packet_vnet_hdr

Flavio Leitner fbl at sysclose.org
Thu Nov 7 12:25:48 UTC 2019

On Wed, 6 Nov 2019 01:59:41 +0530
Ramana Reddy <gtvrreddy at gmail.com> wrote:

> Hi Flavio,
> As per your inputs, I modified the gso_size, and now
> skb_gso_validate_mtu(skb, mtu) is returning true, and
> ip_finish_output2(sk, skb)  and dst_neigh_output(dst, neigh, skb); are
> getting called. But still, I am seeing the large packets getting
> dropped somewhere in the kernel
> down the line and retransmission happening.

The gso_size is the size of the data payload, so it doesn't account the
headers. Usually this depends on the iface MTU like I pointed before and
that MTU should account for the encapsulation later on. For example:

veth0(1450)----veth1(1450) -- VXLAN(64k) --- eth0(1500)

Perhaps you can use ``dropwatch´´ to find out where the packet is


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