On Tue, Dec 6, 2022 at 12:10 PM David Ahern <dsahern@xxxxxxxxx> wrote:
>
> On 12/6/22 9:43 AM, team lnx wrote:
> > Hello,
> >
> > I am a beginner for xdp and following is the setup
> >
> > 3rd party Board - (64 bit arch): This has 2 ethernet interfaces
> > supporting XDP (v0 and v1)
> > Host machine: Ubuntu
> >
> > step 1: 3rd party Board <-----connected over ethernet (v0) ------> Host - Ubuntu
> > step 2: echo "1" > /proc/sys/net/ipv4/ip_forward
> > step 3: Assign static ip address for v0 and v1
> > step 4: run: xdp_fwd -D v0 v1 on 3rd party Board
> > step 5: start ping from host to v0 of 3rd party Board with expectation
> > of forwarding from v0 to v1
> >
> > Observation : In the above experiment I see xdp_fwd has a return code
> > always set to XDP_PASS and when I traced it found that below
> > conditions is the reason
> > in net/core/filter.c
> > if (res.type != RTN_UNICAST) {
> > return BPF_FIB_LKUP_RET_NOT_FWDED;
> > }
> >
> > 1. Could you please help in understanding the reason behind this ?
>
> RTN_LOCAL means delivery to a local process -- ie., nothing to forward
> to another device / host.
>
> RTN_MULTICAST and RTN_BROADCAST: broadcast is not supported. Multicast
> ... I forget how to use that. The fib lookup and xdp_fwd test predates
> multicast support
>
>
> > 2. Once #1 is resolved, do we need to add manually arp table/neighbor
> > information as well ?
> >
>
> the xdp_fwd app is a demo. In a production deployment, you will need to
> have something manage the neighbor entries for hosts. e.g., look at `ip
> neigh ... managed` if you have a new enough kernel.
>
Thanks for the response,
Understood #2, but for #1
I have initiated ping from Host (ubuntu) -> V0 (ethernet) of 3rd party
board with intention of forwarding/redirecting to V1 on the same board
But I see XDP_PASS being returned instead of XDP_REDIRECT, anything
missing/wrong in steps ?
Thanks !
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