DHCP 子網路選取選項DHCP Subnet Selection Options

適用於:Windows Server(以每年次管道)、Windows Server 2016Applies To: Windows Server (Semi-Annual Channel), Windows Server 2016

您可以使用本主題的新 DHCP 子網路選取選項的相關資訊。You can use this topic for information about new DHCP subnet selection options.

DHCP 現在支援 (sub-option 5) 118 與 82 選項。DHCP now supports options 118 and 82 (sub-option 5). 您可以使用這些選項來讓您要求的 IP 位址特定子網路,以及從指定 IP 位址和範圍 DHCP proxy 戶端及轉送代理程式。You can use these options to allow DHCP proxy clients and relay agents to request an IP address for a specific subnet, and from a specific IP address range and scope.

如果您使用 DHCP proxy client 設定 DHCP 選項 118,例如執行 Windows Server 2016 和遠端存取伺服器角色 virtual 私人網路 (VPN) 伺服器、VPN 伺服器可以要求 IP 位址租用 VPN 戶端的特定的 IP 位址。If you are using a DHCP proxy client that is configured with DHCP option 118, such as a virtual private network (VPN) server that is running Windows Server 2016 and the Remote Access server role, the VPN server can request IP address leases for VPN clients from a specific IP address range.

如果您使用 DHCP 轉送代理設定 DHCP 選項 82,子選項 5 轉接可以要求 IP 位址租用 DHCP 戶端的特定的 IP 位址。If you are using a DHCP relay agent that is configured with DHCP option 82, sub-option 5, the relay agent can request an IP address lease for DHCP clients from a specific IP address range.

以下是的意見主題這些選項要求的連結。Following are links to Request for Comments topics for these options.

DHCP 子網路選取選項提供機制 DHCP proxy,若要指定 IP 子網路,DHCP 伺服器應該指定 IP 位址和選項。The DHCP subnet selection option provides a mechanism for DHCP proxies to specify an IP subnet from which the DHCP server should assign IP addresses and options.

使用案例Use case scenario

在本案例中,virtual 私人網路 (VPN) 伺服器以 VPN 戶端配置的 IP 位址。In this scenario, a virtual private network (VPN) server allocates IP addresses to VPN clients.

在這個情況,VPN 伺服器已連接兩個內部 DHCP 伺服器安裝所在的網路和網際網路,以便 VPN 戶端可以連接的 VPN 伺服器從遠端位置。In this circumstance, the VPN server is connected to both the intranet where the DHCP server is installed and to the Internet, so that VPN clients can connect to the VPN server from remote locations.

VPN 伺服器 VPN 戶端可以提供 IP 位址租用之前,請伺服器連絡人內部子網路上的 DHCP 伺服器,並保留封鎖的 IP 位址。Before the VPN server can provide IP address leases to VPN clients, the server contacts the DHCP server on an internal subnet and reserves a block of IP addresses. VPN 伺服器然後管理它取得從 DHCP 伺服器的 IP 位址。The VPN server then manages the IP addresses it obtained from the DHCP server. 如果 VPN 伺服器提供所有的期保留 IP 位址 VPN 戶端,VPN 伺服器再從 DHCP 伺服器取得額外的 IP 位址。If the VPN server provides all of the reserved IP addresses in leases to VPN clients, the VPN server then obtains additional IP addresses from the DHCP server.

藉由設定 VPN 伺服器 DHCP 選項 118,您可以指定 IP 位址範圍及您想要使用的 VPN 戶端範圍。By configuring the VPN server with DHCP option 118, you can specify the IP address range and scope that you want to use for VPN clients. 設定選項 118 之後,VPN 伺服器會要求特定 IP 位址,範圍從 DHCP 伺服器的 IP 位址。After you configure option 118, the VPN server requests IP addresses from a specific IP address range and scope from the DHCP server.

[DHCP 子網路選擇選項] 欄位The DHCP subnet selection option field

[DHCP 子網路選擇選項] 欄位包含單一 IPv4 位址用來表示 DHCP 租賃要求的原始子網路位址。The DHCP subnet selection option field contains a single IPv4 address used to represent the originating subnet address for a DHCP lease request. 設定此選項回應 DHCP 伺服器會從配置地址:A DHCP server that is configured to respond to this option allocates the address from either:

  1. 子網路選取選項中指定子網路。The subnet that is specified in the subnet selection option.
  2. 上相同的網路區段子網路中子網路選取選項指定作為子網路。A subnet that is on the same network segment as the subnet that is specified in the subnet selection option.

轉送代理連結選取項目子選項可讓 DHCP 轉送代理指定 IP 子網路,DHCP 伺服器應該指定 IP 位址和選項。The Relay Agent Link Selection sub-option allows a DHCP Relay Agent to specify an IP subnet from which the DHCP server should assign IP addresses and options.

通常 DHCP 轉送代理程式需依賴 (GIADDR) 閘道 IP 位址] 欄位來與 DHCP 伺服器通訊。Typically, DHCP relay agents rely on the Gateway IP Address (GIADDR) field to communicate with DHCP servers. 不過,GIADDR 受到其兩個操作功能:However, GIADDR is limited by its two operational functions:

  1. 若要 DHCP 伺服器的 IP 位址租用要求 DHCP client 位於子網路通知。To inform the DHCP server about the subnet upon which the DHCP client that is requesting the IP address lease resides.
  2. 通知 DHCP 伺服器的 IP 位址,以用來與轉接通訊。To inform the DHCP server of the IP address to use to communicate with the relay agent.

有時候,可能會不同的 IP 位址範圍需要配置 DHCP client IP 位址,轉接用來與 DHCP 伺服器的 IP 位址。In some cases, the IP address that the relay agent uses to communicate with the DHCP server might be different than the IP address range from which the DHCP client IP address needs to be allocated.

使用功能有限現狀選項 118,並可以僅限 GIADDR 欄位或轉送代理程式資訊選項 (option 82) 寫入不能 DHCP 轉送代理程式。DHCP relay agents cannot make use of option 118, as their functionality is limited and can only write to the GIADDR field or the Relay Agent Information Option (option 82).

選項 82 連結選擇子選項適用於這種情形,允許轉接明確陳述子的網路,它想要的 IP 位址 DHCP v4 選項的形式 82 子選項 5 配置。The Link Selection Sub option of option 82 is useful in this situation, allowing the relay agent to explicitly state the subnet from which it wants the IP address allocated in the form of DHCP v4 option 82 sub option 5.

使用案例Use case scenario

在本案例中,組織網路包括 DHCP 伺服器和無線存取點的訪客使用者 (AP)。In this scenario, an organization network includes both a DHCP server and a Wireless Access Point (AP) for the guest users. 從組織 DHCP 伺服器-不過,因為防火牆原則限制指派來賓 client IP 位址、DHCP 伺服器無法存取來賓 wireless 網路或 wireless 戶端 broadcase 訊息。Guests client IP addresses are assigned from the organization DHCP server - however, due to firewall policy restrictions, the DHCP server cannot access the guest wireless network or wireless clients with broadcase messages.

若要透過這項限制身分查驗,AP 設定是連結選擇子選項 5 指定子網路它想要從中來賓戶端,在也指定內部介面,導致公司網路的 IP 位址 GIADDR 中的配置的 IP 位址。To resolve this restriction, the AP is configured with the Link Selection Sub Option 5 to specify the subnet from which it wants the IP address allocated for guest clients, while in the GIADDR also specifying the IP address of the internal interface that leads to the corporate network.