我在eth0上添加了一个标记的VLAN：

#ip link add link eth0 name eth0.20 type vlan id 20

这导致：

#ip link

2: eth0: mtu 1500 qdisc pfifo_fast state UP qlen 1000

link/ether 9c:c7:a6:95:65:1c brd ff:ff:ff:ff:ff:ff

....

12: eth0.20@eth0: mtu 1500 qdisc noqueue state UP

link/ether 9c:c7:a6:95:65:1c brd ff:ff:ff:ff:ff:ff

#ip -d link show eth0.20

70: eth0.20@eth0: mtu 1500 qdisc noqueue state UP

link/ether 9c:c7:a6:95:65:1c brd ff:ff:ff:ff:ff:ff

vlan id 20

#cat /proc/net/vlan/config

VLAN Dev name | VLAN ID

Name-Type: VLAN_NAME_TYPE_RAW_PLUS_VID_NO_PAD

eth0.234 | 234 | eth0

eth0.20 | 20 | eth0

现在我开始dhclient：

#dhclient -d -v -1 eth0.20

我在tcpdump中看到的是一个未标记的DHCP发现帧：

#tcpdump -i eth0 -XX

0x0000: ffff ffff ffff 9cc7 a695 651c 0800 4500

^^^^

为什么没有标记？

似乎使用802.1q模块：

#lsmod | grep 8021q

8021q 28324 0

garp 14311 1 8021q

(OS：SLES11SP2内核3.0.13-0.27-默认)

BTW其他流量也没有标记(至少tcpdump没有显示)…

10月16日更新

# tcpdump -Uw - | tcpdump -i eth0 -en -r - &

[1] 7310

# tcpdump: WARNING: eth0: no IPv4 address assigned

tcpdump: listening on eth0,link-type EN10MB (Ethernet),capture size 96 bytes

# dhclient -d -v -1 eth0.20

Internet Systems Consortium DHCP Client 4.2.3-P2

Copyright 2004-2012 Internet Systems Consortium.

All rights reserved.

For info,please visit https://www.isc.org/software/dhcp/

Listening on LPF/eth0.20/9c:c7:a6:95:65:1c

Sending on LPF/eth0.20/9c:c7:a6:95:65:1c

Sending on Socket/fallback

DHCPDISCOVER on eth0.20 to 255.255.255.255 port 67 interval 3

reading from file -,link-type EN10MB (Ethernet)

18:49:14.437882 9c:c7:a6:95:65:1c > ff:ff:ff:ff:ff:ff,ethertype IPv4 (0x0800),length 347: 0.0.0.0.68 > 255.255.255.255.67: BOOTP/DHCP,Request from 9c:c7:a6:95:65:1c,length 305

^^^^^^

所以,这里仍然没有显示标签.

但实际上,在运行dhclient时,/ proc / net / dev中eth0.20的传输计数器确实会增加…