[EVPN VXLAN]: TSN not responding to ARP query for DNS server from BMS

[chhandak]

When BMS is trying to reach VM using VM name, Arp query is coming for DNS server address to TSN. I don’t see any response from TSN. So in BMS DNS arp is unresolved and further communication is broken.

In vrouter table, proxy flag is set for DNS server address. Also as per agent introspect it getting trapped to agent and agent is responding. But the response is never leaving the compute.

root@5b11s14:~# rt --dump 1 --family inet | grep -w 1.1.1.2| more
1.1.1.2/32 32 PT - 8 -

root@5b11s14:~# vif --get 2
Vrouter Interface Table

Flags: P=Policy, X=Cross Connect, S=Service Chain, Mr=Receive Mirror
       Mt=Transmit Mirror, Tc=Transmit Checksum Offload, L3=Layer 3, L2=Layer 2
       D=DHCP, Vp=Vhost Physical, Pr=Promiscuous, Vnt=Native Vlan Tagged
       Mnp=No MAC Proxy, Dpdk=DPDK PMD Interface, Rfl=Receive Filtering Offload, Mon=Interface is Monitored
       Uuf=Unknown Unicast Flood, Vof=VLAN insert/strip offload, Df=Drop New Flows, L=MAC Learning Enabled
       Proxy=MAC Requests Proxied Always, Er=Etree Root

vif0/2 OS: pkt0
            Type:Agent HWaddr:00:00:5e:00:01:00 IPaddr:0.0.0.0
            Vrf:65535 Flags:L3Er QOS:-1 Ref:3
            RX packets:486 bytes:44596 errors:0
            TX packets:1787 bytes:190197 errors:0
            Drops:0

BMS Entry programmed by DHCP response from
----------------------------------------------------------------
root@5b11s16:~# cat /etc/resolv.conf
# Dynamic resolv.conf(5) file for glibc resolver(3) generated by resolvconf(8)
# DO NOT EDIT THIS FILE BY HAND -- YOUR CHANGES WILL BE OVERWRITTEN
nameserver 1.1.1.2 >>>>>>> DNS Server
nameserver 10.84.5.100
nameserver 172.21.200.60
search contrail.juniper.net juniper.net jnpr.net
root@5b11s16:~#

root@5b11s16:~# arp -n
Address HWtype HWaddress Flags Mask Iface
1.1.1.2 (incomplete) p2p1.6
1.1.1.5 ether 80:71:1f:c3:e9:f0 C p2p1.6
10.87.69.126 ether 30:7c:5e:0f:8f:c0 C p4p1
1.1.1.6 ether 02:15:69:8e:17:78 C p2p1.6

Arp Query from BMS to TSN for DNS server address
------------------------------------------------

root@5b11s14:~# tcpdump -nei p514p2 udp port 4789
tcpdump: WARNING: p514p2: no IPv4 address assigned
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on p514p2, link-type EN10MB (Ethernet), capture size 65535 bytes
15:41:27.618309 9c:cc:83:e4:83:32 > 90:e2:ba:a7:30:cd, ethertype IPv4 (0x0800), length 106: 172.16.2.1.13507 > 172.16.180.101.4789: VXLAN, flags [I] (0x08), vni 4
90:e2:ba:c4:2e:6c > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 56: Request who-has 1.1.1.2 tell 1.1.1.4, length 42
15:41:28.617914 9c:cc:83:e4:83:32 > 90:e2:ba:a7:30:cd, ethertype IPv4 (0x0800), length 106: 172.16.2.1.13507 > 172.16.180.101.4789: VXLAN, flags [I] (0x08), vni 4
90:e2:ba:c4:2e:6c > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 56: Request who-has 1.1.1.2 tell 1.1.1.4, length 42
15:41:29.617913 9c:cc:83:e4:83:32 > 90:e2:ba:a7:30:cd, ethertype IPv4 (0x0800), length 106: 172.16.2.1.13507 > 172.16.180.101.4789: VXLAN, flags [I] (0x08), vni 4
90:e2:ba:c4:2e:6c > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 56: Request who-has 1.1.1.2 tell 1.1.1.4, length 42

[Hari Prasad Killi (haripk)]

commits are being done as part of https://bugs.launchpad.net/juniperopenstack/+bug/1713314.