netdev - Re: [Query]: DSA Understanding

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Date:   Thu, 9 Aug 2018 12:31:31 +0100
From:   "Lad, Prabhakar" <prabhakar.csengg@...il.com>
To:     Andrew Lunn <andrew@...n.ch>
Cc:     netdev <netdev@...r.kernel.org>
Subject: Re: [Query]: DSA Understanding

Hi Andrew,

On Thu, Aug 2, 2018 at 5:05 PM Andrew Lunn <andrew@...n.ch> wrote:
>
> > I dont see any Reply's on the PC with tcpdump on PC
>
> So try ethool -S on the PC. Any packets dropped because of errors?
>
I dont see any drops/errors on the PC, following is the dump from PC:

sudo ethtool -S enx00e04c68c229
[sudo] password for prabhakar:
NIC statistics:
     tx_packets: 1659
     rx_packets: 485
     tx_errors: 0
     rx_errors: 0
     rx_missed: 0
     align_errors: 0
     tx_single_collisions: 0
     tx_multi_collisions: 0
     rx_unicast: 18
     rx_broadcast: 295
     rx_multicast: 172
     tx_aborted: 0
     tx_underrun: 0

> Try turning off hardware checksums on the switch. ethtool -K.
>
Following is the dump from the switch, the checksums are off

~$ ethtool -k eth1
Features for eth1:
Cannot get device udp-fragmentation-offload settings: Operation not supported
rx-checksumming: off [fixed]
tx-checksumming: off
        tx-checksum-ipv4: off [fixed]
        tx-checksum-ip-generic: off [fixed]
        tx-checksum-ipv6: off [fixed]
        tx-checksum-fcoe-crc: off [fixed]
        tx-checksum-sctp: off [fixed]
scatter-gather: off
        tx-scatter-gather: off [fixed]
        tx-scatter-gather-fraglist: off [fixed]
tcp-segmentation-offload: off
        tx-tcp-segmentation: off [fixed]
        tx-tcp-ecn-segmentation: off [fixed]
        tx-tcp-mangleid-segmentation: off [fixed]
        tx-tcp6-segmentation: off [fixed]
udp-fragmentation-offload: off
generic-segmentation-offload: off [requested on]
generic-receive-offload: on
large-receive-offload: off [fixed]
rx-vlan-offload: off [fixed]
tx-vlan-offload: off [fixed]
ntuple-filters: off [fixed]
receive-hashing: off [fixed]
highdma: off [fixed]
rx-vlan-filter: on [fixed]
vlan-challenged: off [fixed]
tx-lockless: off [fixed]
netns-local: off [fixed]
tx-gso-robust: off [fixed]
tx-fcoe-segmentation: off [fixed]
tx-gre-segmentation: off [fixed]
tx-gre-csum-segmentation: off [fixed]
tx-ipxip4-segmentation: off [fixed]
tx-ipxip6-segmentation: off [fixed]
tx-udp_tnl-segmentation: off [fixed]
tx-udp_tnl-csum-segmentation: off [fixed]
tx-gso-partial: off [fixed]
tx-sctp-segmentation: off [fixed]
tx-esp-segmentation: off [fixed]
fcoe-mtu: off [fixed]
tx-nocache-copy: off
loopback: off [fixed]
rx-fcs: off [fixed]
rx-all: off [fixed]
tx-vlan-stag-hw-insert: off [fixed]
rx-vlan-stag-hw-parse: off [fixed]
rx-vlan-stag-filter: off [fixed]
l2-fwd-offload: off [fixed]
hw-tc-offload: off [fixed]
esp-hw-offload: off [fixed]
esp-tx-csum-hw-offload: off [fixed]
rx-udp_tunnel-port-offload: off [fixed]

Tshark dump on the switch:

~$ tshark -i lan4
Running as user "root" and group "root". This could be dangerous.
Capturing on 'lan4'
[ 1482.987520] device lan4 entered promiscuous mode
[ 1482.992169] device eth1 entered promiscuous mode
    1 0.000000000 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
    2 0.000062952 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
    3 0.997115432 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
    4 0.997142272 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
    5 1.997036539 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
    6 1.997063379 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
    7 3.014232032 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
    8 3.014252528 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
    9 4.013008290 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
   10 4.013031064 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
   11 5.012951194 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
   12 5.012970552 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
   13 6.030173853 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
   14 6.030192234 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
   15 7.028911559 RealtekS_68:c2:29 ��→ Broadcast    ARP 60 Who has
169.254.126.126? Tell 169.254.78.251
   16 7.028947183 c4:f3:12:08:fe:7f ��→ RealtekS_68:c2:29 ARP 42
169.254.126.126 is at c4:f3:12:08:fe:7f
^C[ 1494.020087] device lan4 left promiscuous mode
[ 1494.024475] device eth1 left promiscuous mode
16 packets captured

Seems like the packet is not being transmitted from the switch at all
? (as ping from switch lan4 to PC fails)

~$ ping -I lan4 169.254.78.251
PING 169.254.78.251 (169.254.78.251): 56 data bytes
^C
--- 169.254.78.251 ping statistics ---
24 packets transmitted, 0 packets received, 100% packet loss

Cheers,
--Prabhakar