From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Ananyev, Konstantin" <konstantin.ananyev@intel.com>
Subject: Re: [PATCH 2/5] gso/lib: add TCP/IPv4 GSO support
Date: Mon, 11 Sep 2017 13:04:07 +0000
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Cc: "dev@dpdk.org" <dev@dpdk.org>, "Kavanagh, Mark B"
 <mark.b.kavanagh@intel.com>, "Tan, Jianfeng" <jianfeng.tan@intel.com>
To: "Hu, Jiayu" <jiayu.hu@intel.com>
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Hi Jiayu,

> > > Linux supports two kinds of IP identifier: fixed identifier and incre=
mental
> > identifier, and
> > > which one to use depends on upper protocol modules. Specifically, if =
the
> > protocol module
> > > wants fixed identifiers, it will set SKB_GSO_TCP_FIXEDID to skb->gso_=
type,
> > and then
> > > inet_gso_segment() will keep identifiers the same. Otherwise, all seg=
ments
> > will have
> > > incremental identifiers. The reason for this design is that some prot=
ocols
> > may choose fixed
> > > IP identifiers, like TCP (from RFC791). This design also shows that l=
inux
> > ignores the issue
> > > of repeated IP identifiers.
> > >
> > > From the perspective of DPDK, we need to solve two problems. One is i=
f
> > ignore the issue of
> > > repeated IP identifiers. The other is if the GSO library provides an =
interface
> > to upper
> > > applications to enable them to choose fixed or incremental identifier=
s, or
> > simply uses
> > > incremental IP identifiers.
> > >
> > > Do you have any suggestions?
> >
> >
> > Do the same as Linux?
> > I.E. add some flag RRE_GSO_IPID_FIXED (or so) into gso_ctx?
>=20
> OK, I see. We can do that.
>=20
> In the GRO library, we check if the IP identifiers are incremental compul=
sorily. If we
> enable fixed IP identifier in GSO, it seems we also need to change the GR=
O library.
> I mean ignore IP identifier when merge packets, and don't update the IP i=
dentifier
> for the merged packet. What do you think of it?

I suppose we can, if there is a use-case for it.
Konstantin
>=20