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Hi, all,

I created a lb whose vip is 10.0.1.4. When requesting the vip, i cannot
receive the responses. Hence, I console in the amphora and trace packets
handled by eth0 in the amphora-haproxy network namespace. The detailed info
is as follows.

ubuntu at amphora-a0621f0e-d27f-4f22-a4ee-05b695e2b71f:~$ sudo ip netns exec
amphora-haproxy tcpdump -i eth1 -nn
sudo: unable to resolve host amphora-a0621f0e-d27f-4f22-a4ee-05b695e2b71f
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), capture size 262144 bytes
^C07:25:24.225614 IP 10.0.1.2.55294 > 10.0.1.4.80: Flags [S], seq
1637781601, win 28200, options [mss 1410,sackOK,TS val 30692602 ecr
0,nop,wscale 7], length 0
07:25:24.237854 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:25.224801 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:25.228610 IP 10.0.1.2.55294 > 10.0.1.4.80: Flags [S], seq 1637781601,
win 28200, options [mss 1410,sackOK,TS val 30692853 ecr 0,nop,wscale 7],
length 0
07:25:26.224533 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:27.230911 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:27.250858 IP 10.0.1.2.55294 > 10.0.1.4.80: Flags [S], seq 1637781601,
win 28200, options [mss 1410,sackOK,TS val 30693359 ecr 0,nop,wscale 7],
length 0
07:25:28.228796 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:29.228697 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:29.290551 ARP, Request who-has 10.0.1.4 tell 10.0.1.2, length 28
07:25:29.290985 ARP, Reply 10.0.1.4 is-at fa:16:3e:be:5a:d5, length 28
07:25:31.251122 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:32.248737 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28
07:25:33.250309 ARP, Request who-has 10.0.1.1 tell 10.0.1.4, length 28

14 packets captured
14 packets received by filter
0 packets dropped by kernel

As shown above, the amphora can receive the requests comes from outside but
it fails to find 10.0.1.1. As a result, amphora cannot send the request to
its load balancing member.

To further demonstrate my environment, the route table and arp cache are
listed as follows.

ubuntu at amphora-a0621f0e-d27f-4f22-a4ee-05b695e2b71f:~$ sudo ip netns exec
amphora-haproxy route
sudo: unable to resolve host amphora-a0621f0e-d27f-4f22-a4ee-05b695e2b71f
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use
Iface
default         10.0.1.1        0.0.0.0         UG    0      0        0 eth1
10.0.1.0        *               255.255.255.0   U     0      0        0 eth1

ubuntu at amphora-a0621f0e-d27f-4f22-a4ee-05b695e2b71f:~$ sudo ip netns exec
amphora-haproxy arp
sudo: unable to resolve host amphora-a0621f0e-d27f-4f22-a4ee-05b695e2b71f
Address                  HWtype  HWaddress           Flags Mask
Iface
10.0.1.2                 ether   fa:16:3e:62:68:a8   C
 eth1
10.0.1.1                         (incomplete)
eth1

What do you think? Look forward to your comments. Thank you.

Best regards,
Yipei
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