Hi vpp-dev team, I use vpp17.10 in vagrant VM for a vcpe test，and use dnsmasq as dhcp and dns server。 dnsmasq is binded interface lstack，which is created by： sudo vppctl tap connect lstack address 192.168.1.1/24 A namespace lan1 is a virtual lan network。When an interface in lan1 send a dhcp discover request， it can get a ip address assigned by dnsmasq，and I can see the packets flow by vppctl show trace。 When I send a dns query request，the interface lstack/tap-0 received the request,but the dnsmasq has no response。 The interface tap-0/lstack doesn't forward dns query to dnsmasq is bad udp cksum. I failed to turn off the checksumming, and don't know why it happened.
The following is some logs, and maybe be helpful. vagrant@localhost:~$sudo ip netns exec lan1 ping -c1 www.baidu.com vagrant@localhost:~$ sudo vppctl show trace Packet 1 21:04:07:489032: af-packet-input af_packet: hw_if_index 2 next-index 4 tpacket2_hdr: status 0x9 len 123 snaplen 123 mac 66 net 80 sec 0x5a4f3fc3 nsec 0x69f47a6 vlan 0 vlan_tpid 0 21:04:07:489045: ethernet-input IP4: 92:5d:c3:e1:15:86 -> 02:fe:11:e7:4c:c7 21:04:07:489059: ip4-input UDP: 192.168.10.10 -> 192.168.10.9 tos 0x00, ttl 64, length 109, checksum 0x0ce6 fragment id 0xd836 UDP: 60440 -> 4789 length 89, checksum 0x0000 21:04:07:489070: ip4-lookup fib 0 dpo-idx 7 flow hash: 0x00000000 UDP: 192.168.10.10 -> 192.168.10.9 tos 0x00, ttl 64, length 109, checksum 0x0ce6 fragment id 0xd836 UDP: 60440 -> 4789 length 89, checksum 0x0000 21:04:07:489080: ip4-local UDP: 192.168.10.10 -> 192.168.10.9 tos 0x00, ttl 64, length 109, checksum 0x0ce6 fragment id 0xd836 UDP: 60440 -> 4789 length 89, checksum 0x0000 21:04:07:489090: ip4-udp-lookup UDP: src-port 60440 dst-port 4789 21:04:07:489093: vxlan4-input VXLAN decap from vxlan_tunnel0 vni 101 next 1 error 0 21:04:07:489097: l2-input l2-input: sw_if_index 4 dst 92:61:a3:de:b0:ca src b2:72:a6:93:be:f5 21:04:07:489107: l2-learn l2-learn: sw_if_index 4 dst 92:61:a3:de:b0:ca src b2:72:a6:93:be:f5 bd_index 1 21:04:07:489112: l2-fwd l2-fwd: sw_if_index 4 dst 92:61:a3:de:b0:ca src b2:72:a6:93:be:f5 bd_index 1 21:04:07:489114: l2-output l2-output: sw_if_index 5 dst 92:61:a3:de:b0:ca src b2:72:a6:93:be:f5 data 08 00 45 00 00 3b c2 8d 40 00 40 11 21:04:07:489117: tap-0-output tap-0 IP4: b2:72:a6:93:be:f5 -> 92:61:a3:de:b0:ca UDP: 192.168.1.10 -> 192.168.1.1 tos 0x00, ttl 64, length 59, checksum 0xf4c8 fragment id 0xc28d, flags DONT_FRAGMENT UDP: 35083 -> 53 length 39, checksum 0x8394 vagrant@localhost:~$ sudo tcpdump -vvv -i lstack 01:05:07.114638 IP (tos 0x0, ttl 64, id 49805, offset 0, flags [DF], proto UDP (17), length 59) 192.168.1.10.35083 > 192.168.1.1.domain: [bad udp cksum 0x8394 -> 0x192f!] 7636+ A? www.baidu.com. (31) vagrant@localhost:~$ sudo ethtool -K lstack tx off rx off Cannot change rx-checksumming Best Regards jzhchen www.fiberhome.com
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