neutron netns arp issue

Satish Patel satish.txt at gmail.com
Tue Jul 9 02:42:45 UTC 2019


Hello,

I am deploying openstack-ansible with octavia and i can see neutron
created network for lb-mgmt-net which also created dhcp namespace for
that network which is in vlan27 so far everything good so for testing
i have created vm and it didn't get IP address so i have started
troubleshooting and i found my namespace sending arp request but not
getting reply back.

[root at ostack-infra-2-2 ~]# ip netns exec
qdhcp-2b94d9df-dd49-45b5-a992-63fee27bfa77 ip a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN
group default qlen 1000
    link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
    inet 127.0.0.1/8 scope host lo
       valid_lft forever preferred_lft forever
    inet6 ::1/128 scope host
       valid_lft forever preferred_lft forever
2: ns-5604eec1-20 at if132: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500
qdisc noqueue state UP group default qlen 1000
    link/ether fa:16:3e:c2:b3:4d brd ff:ff:ff:ff:ff:ff link-netnsid 0
    inet 172.27.12.3/21 brd 172.27.15.255 scope global ns-5604eec1-20
       valid_lft forever preferred_lft forever
    inet 169.254.169.254/16 brd 169.254.255.255 scope global ns-5604eec1-20
       valid_lft forever preferred_lft forever
    inet6 fe80::f816:3eff:fec2:b34d/64 scope link
       valid_lft forever preferred_lft forever



This is my linuxbridge

[root at ostack-infra-2-2 ~]# brctl show brq2b94d9df-dd
bridge name             bridge    id            STP
enabled        interfaces
brq2b94d9df-dd                   8000.16d25dbea2cc           no
        br-vlan.27

                                     tap5604eec1-20


on same controller node "ostack-infra-2-2"  i have br-lbaas network
which has same VLAN 27 subnet IP.

now when i ping from dhcp-namespace to outside host on same vlan 27, i
can see ARP going out and remote host replying back but my reply
coming on br-lbaas interface.

[root at ostack-infra-2-2 ~]# ip netns exec
qdhcp-2b94d9df-dd49-45b5-a992-63fee27bfa77 ping 172.27.8.4
PING 172.27.8.4 (172.27.8.4) 56(84) bytes of data.
>From 172.27.12.3 icmp_seq=1 Destination Host Unreachable
>From 172.27.12.3 icmp_seq=2 Destination Host Unreachable


on other terminal i am running tcpdump on br-lbaas and i am seeing
remote host ARP reply coming on that interface but not going to
br-vlan.27 which neutron created.

[root at ostack-infra-2-2 network-scripts]# tcpdump -i br-lbaas -nn
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on br-lbaas, link-type EN10MB (Ethernet), capture size 262144 bytes
22:41:38.920858 ARP, Reply 172.27.8.4 is-at 32:7c:a1:91:79:7c, length 46
22:41:39.922167 ARP, Reply 172.27.8.4 is-at 32:7c:a1:91:79:7c, length 46
22:41:40.924052 ARP, Reply 172.27.8.4 is-at 32:7c:a1:91:79:7c, length 46


Do you think i can't create two same subnet bridge on same host?



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