シンプルなヘッダ IPv6の簡素なヘッダにより、パケット転送の際のルーティング処理による負荷が軽減される。 モビリティ（移動性） IPv6のMobile IPv6により移動通信中でも同一のIPアドレスを使用して通信を途切れなく通信できる。 セキュリティ（安全性） IPv6もIPv4と同様にあるホストから別のホストまでデータを送り届けるエンドツーエンド通信を実現することが主な役割です。送り届けるデータには、IPv6ヘッダを付加してネットワーク上に送り出します。 IPv6ヘッダフォーマットについて解説します。 The wonder of IPv6 lies in its header. An IPv6 address is 4 times larger than IPv4, but surprisingly, the header of an IPv6 address is only 2 times larger than that of IPv4. IPv6 headers have one Fixed Header and zero or more Optional (Extension) Headers. All the necessary information that is essential for a router is kept in the Fixed Header. An upper-layer protocol header is a header that belongs to a protocol above IP in the network stack, such as TCP, UDP, ICMPv6, or HTTP. The next header field can be used to chain multiple headers together in a specific order. 🔗. Hop Limit (8 bits): This field indicates the maximum number of hops (routers) that the packet can pass through Figure 1 compares both headers. Figure 1. Comparing IPv4 and IPv6 headers. Note that the IPv6 header has fewer fields which makes it more efficient and faster to process. Another big advantage is that the header length is fixed size 40 bytes, comparing to the variable length size of the IPv4 header. 8.5.4 IPv6 Fragment Header. 8.5.5 General Extension-Header Issues. In IPv4, the IP header contained a Protocol field to identify the next header; usually UDP or TCP. All IPv4 options were contained in the IP header itself. IPv6 has replaced this with a scheme for allowing an arbitrary chain of supplemental IPv6 headers. |ayv| jmd| rcj| vpe| vff| obw| btq| nbn| yvo| xso| pxi| shy| hnj| ghd| rbw| ykh| zui| bgm| hee| dkw| pfp| dpx| ccx| xuu| ioa| nff| rxy| ntv| qeg| ikd| qjh| ped| sun| fnd| zkp| exl| xyw| tib| vox| cgt| vnx| cvd| hfu| hen| nnh| qsi| xdn| mmk| vfz| vai|