DHCP:一个网卡和多个子网

Question

我正在建立一个Debian，作为一个小型办公网络的网关。我需要有三个子网络在公司内部的不同领域，我将定义哪些PC将得到什么IP基于他们的MAC地址。

我的问题是:是否可以用一个NIC来处理3个子网的DHCP？怎么做？

我尝试为每个网络设置虚拟接口，如下所示：

# ip addr show dev eth2
4: eth2: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000
    link/ether 6c:f0:49:a4:47:38 brd ff:ff:ff:ff:ff:ff
    inet 192.168.1.10/24 brd 192.168.1.255 scope global eth2
    inet 10.1.2.1/24 brd 10.1.2.255 scope global eth2:1
    inet 10.1.3.1/24 brd 10.1.3.255 scope global eth2:2
    inet 10.1.1.1/24 brd 10.1.1.255 scope global eth2:0
    inet6 fe80::6ef0:49ff:fea4:4738/64 scope link 
       valid_lft forever preferred_lft forever

注意: eth2使用的是192.168.1.10，因为盒子目前不是网络网关。这只是暂时的。

然后我把我的dhcpd.conf设置成这样：

ddns-update-style interim;
option domain-name "mydomain.com";
option domain-name-servers ns1.mydomain.com;
default-lease-time 86400;
max-lease-time 86400;
authoritative;
log-facility local7;

subnet 10.1.1.0 netmask 255.255.255.0 {
        range 10.1.1.100 10.1.1.254;
        default-lease-time 86400;
        max-lease-time 86400;
        option routers 10.1.1.1;
        option ip-forwarding off;
        option broadcast-address 10.1.1.255;
        option subnet-mask 255.255.255.0;
        option ntp-servers 10.1.1.1;
        option domain-name-servers 10.1.1.1;
}

subnet 10.1.2.0 netmask 255.255.255.0 {
        range 10.1.2.100 10.1.2.254;
        default-lease-time 86400;
        max-lease-time 86400;
        option routers 10.1.2.1;
        option ip-forwarding off;
        option broadcast-address 10.1.2.255;
        option subnet-mask 255.255.255.0;
        option ntp-servers 10.1.2.1;
        option domain-name-servers 10.1.2.1;
}

subnet 10.1.3.0 netmask 255.255.255.0 {
        range 10.1.3.100 10.1.3.254;
        default-lease-time 86400;
        max-lease-time 86400;
        option routers 10.1.3.1;
        option ip-forwarding off;
        option broadcast-address 10.1.3.255;
        option subnet-mask 255.255.255.0;
        option ntp-servers 10.1.3.1;
        option domain-name-servers 10.1.3.1;
}

但是，当我试图启动dhcpd时，我得到了这样的信息：

# dhcpd -4 eth2:0 eth2:1 eth2:2
Internet Systems Consortium DHCP Server 4.1.1-P1
Copyright 2004-2010 Internet Systems Consortium.
All rights reserved.
For info, please visit https://www.isc.org/software/dhcp/
Wrote 0 leases to leases file.

No subnet declaration for eth2:2 (no IPv4 addresses).
** Ignoring requests on eth2:2.  If this is not what
   you want, please write a subnet declaration
   in your dhcpd.conf file for the network segment
   to which interface eth2:2 is attached. **


No subnet declaration for eth2:1 (no IPv4 addresses).
** Ignoring requests on eth2:1.  If this is not what
   you want, please write a subnet declaration
   in your dhcpd.conf file for the network segment
   to which interface eth2:1 is attached. **


No subnet declaration for eth2:0 (no IPv4 addresses).
** Ignoring requests on eth2:0.  If this is not what
   you want, please write a subnet declaration
   in your dhcpd.conf file for the network segment
   to which interface eth2:0 is attached. **


Not configured to listen on any interfaces!

我对DHCP很陌生，所以我可能遗漏了一些显而易见的东西。我已经搜索了一段时间了，但我找不到我需要的答案，或者我没有找到正确的答案。

Answer 1

由于这三个子网共享相同的介质(eth2)，它们应该在同一个shared-network中声明：

shared-network my-net {
  subnet 10.1.1.0 netmask 255.255.255.0 {
    ...
  }

  subnet 10.1.2.0 netmask 255.255.255.0 {
    ...
  }

  subnet 10.1.3.0 netmask 255.255.255.0 {
    ...
  }
}

Answer 2

实际上只有两种方法可以做到这一点；

1. 将DHCP服务器的IP设置为每个VLAN的L3交换机上的“DHCP地址”，然后为服务器上的服务器定义作用域。
2. 将交换机上DHCP服务器的NIC端口设置为包含所有适当VLAN的.1q主干，然后在服务器上设置单独的vNIC，为每个VLAN设置相应的IP，然后从那里开始。

无论哪种方式，不要只使用单一的网卡，你应该有两个恢复力，然后只是联系他们。