tcpdump to verify 802.1q traffic exists on a trunk

If you are setting up OpenShift Virt you oftent want to confirm the customer is actually sending VLAN tags to the node before troubleshooting deeper. Here is a tcpdump that can be used.

Log into the node and run toolbox to gain access to tcpdump.

prove 802.1q trunking is coming from the switch

[root@rhel-node-1 ~]# tcpdump -enni eth1 ether proto 0x8100 # 802.1q
dropped privs to tcpdump
tcpdump: verbose output suppressed, use -v[v]... for full protocol decode
listening on eth1, link-type EN10MB (Ethernet), snapshot length 262144 bytes
15:13:15.268363 02:a8:3f:00:00:04 > 33:33:00:00:00:02, ethertype 802.1Q (0x8100), length 66: vlan 1924, p 0, ethertype IPv6 (0x86dd), fe80::4d5d:a931:b476:63a5 > ff02::2: ICMP6, router solicitation, length 8
15:13:18.309588 02:a8:3f:00:00:04 > ff:ff:ff:ff:ff:ff, ethertype 802.1Q (0x8100), length 335: vlan 1924, p 0, ethertype IPv4 (0x0800), 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 02:a8:3f:00:00:04, length 289
15:13:31.256173 02:a8:3f:00:00:04 > ff:ff:ff:ff:ff:ff, ethertype 802.1Q (0x8100), length 335: vlan 1924, p 0, ethertype IPv4 (0x0800), 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 02:a8:3f:00:00:04, length 289
15:13:31.261943 02:a8:3f:00:00:04 > 33:33:00:00:00:16, ethertype 802.1Q (0x8100), length 94: vlan 1924, p 0, ethertype IPv6 (0x86dd), :: > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
15:13:31.656030 02:a8:3f:00:00:04 > 33:33:ff:76:63:a5, ethertype 802.1Q (0x8100), length 90: vlan 1924, p 0, ethertype IPv6 (0x86dd), :: > ff02::1:ff76:63a5: ICMP6, neighbor solicitation, who has fe80::4d5d:a931:b476:63a5, length 32
15:13:32.152367 02:a8:3f:00:00:04 > 33:33:00:00:00:16, ethertype 802.1Q (0x8100), length 94: vlan 1924, p 0, ethertype IPv6 (0x86dd), :: > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
15:13:32.664377 02:a8:3f:00:00:04 > 33:33:00:00:00:16, ethertype 802.1Q (0x8100), length 94: vlan 1924, p 0, ethertype IPv6 (0x86dd), fe80::4d5d:a931:b476:63a5 > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
15:13:32.878015 02:a8:3f:00:00:04 > 33:33:00:00:00:02, ethertype 802.1Q (0x8100), length 66: vlan 1924, p 0, ethertype IPv6 (0x86dd), fe80::4d5d:a931:b476:63a5 > ff02::2: ICMP6, router solicitation, length 8
15:13:33.304143 02:a8:3f:00:00:04 > 33:33:00:00:00:16, ethertype 802.1Q (0x8100), length 94: vlan 1924, p 0, ethertype IPv6 (0x86dd), fe80::4d5d:a931:b476:63a5 > ff02::16: HBH ICMP6, multicast listener report v2, 1 group record(s), length 28
15:13:34.098182 02:a8:3f:00:00:04 > ff:ff:ff:ff:ff:ff, ethertype 802.1Q (0x8100), length 335: vlan 1924, p 0, ethertype IPv4 (0x0800), 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 02:a8:3f:00:00:04, length 289
15:13:37.196983 02:a8:3f:00:00:04 > 33:33:00:00:00:02, ethertype 802.1Q (0x8100), length 66: vlan 1924, p 0, ethertype IPv6 (0x86dd), fe80::4d5d:a931:b476:63a5 > ff02::2: ICMP6, router solicitation, length 8
15:13:38.213081 02:a8:3f:00:00:04 > ff:ff:ff:ff:ff:ff, ethertype 802.1Q (0x8100), length 335: vlan 1924, p 0, ethertype IPv4 (0x0800), 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP, Request from 02:a8:3f:00:00:04, length 289

prove LACP is setup on the switch

tcpdump -ni eth0 ether proto 0x8809 # LACP

dlbewley/tcpdump to verify 802.1q traffic exists on a trunk.md