TCP and IP TCP與IP << Previous Next >> IPv4 Addressing IPv4 位址

IPv4 and IPv6 Addresses IPv4 與 IPv6 位址

Network devices require a logical address — either an IPv4 or IPv6 address (see the network layer in the diagram above) — when moving data from one network segment to another. As we discussed in previous modules, switches make their intelligent switching decisions (see the data link layer in the diagram above based on media access control (MAC) addresses. The MAC address, also known as the physical address, is the unique identifier hard coded on a network interface card by the manufacturer. Switches use these MAC addresses to identify which devices are on which switch ports, and forward traffic within the network segment to the correct ports based on these addresses. When data traffic needs to cross the boundaries of the network, it requires a logical address that the router can use to make intelligent routing decisions. In most modern networks, this is done by using TCP/IP addressing. Historically, other protocols existed, such as internetwork packet exchange/sequenced packet exchange (IPX/SPX) for Novell networks, AppleTalk, and NetBEUI for Microsoft networks. TCP/IP replaced these protocols almost exclusively due to its robust nature, reliability, and availability.

將數據從一個網段移動到另一個網段時，網絡設備需要邏輯地址-IPv4或IPv6地址（請參見上圖中的網
絡層）。正如我們在之前的模塊中討論的那樣，交換機做出明智的交換決策（請參見上圖中的數據鏈路
層，基於媒體訪問控制（MAC）地址。MAC地址，也稱為物理地址，是唯一的硬編碼標識符）交換機使用這
些MAC地址來識別哪些設備在哪個交換機端口上，然後根據這些地址將網段內的流量轉發到正確的端口。
網絡中，它需要路由器可以用來做出智能路由決策的邏輯地址。在大多數現代網絡中，這是通過使用
TCP / IP尋址來完成的。 / SPX）（用於Novell網絡，AppleTalk和用於Microsoft網絡的NetBEUI）
，TCP / IP幾乎完全由於其魯棒性，可靠性和可用性而取代了這些協議。不可靠。

While the majority of our networks today still use IPv4, many networks are migrating to the newer IPv6 addressing standards. Additionally, many networks are offering dual support to both IPv4 and IPv6 during the transition. The reason for this transition is that we were running out of valid IPv4 addresses. IPv4 uses a 32-bit addressing scheme, providing only 4.2 billion available addresses, but IPv6 uses a 128-bit addressing scheme. IPv6 allows for 2¹²⁸addresses, or 340,282,366,920,938,000,000,000,000,000,000,000,000 (3.4 x 10³⁸) unique IP addresses. IPv6 allows for more IP addresses than humanity could ever utilize. At least that is what we think right now.

儘管當今我們的大多數網絡仍使用IPv4，但許多網絡正在遷移到更新的IPv6尋址標準。此外，在過渡期間
，許多網絡都對IPv4和IPv6提供雙重支持。進行此轉換的原因是我們用盡了有效的IPv4地址。 IPv4使用
32位尋址方案，僅提供42億個可用地址，而IPv6使用128位尋址方案。 IPv6允許2128個地址或340,282,
366,920,938,000,000,000,000,000,000,000,000,000,000（3.4 x 1038）個唯一IP地址。 IPv6所
允許的IP地址比人類所能利用的更多。至少這就是我們現在的想法。

TCP and IP TCP與IP << Previous Next >> IPv4 Addressing IPv4 位址