IP-Based Next-Generation Wireless Networks phần 6

NVSE bao gồm các lĩnh vực sau đây, được liệt kê theo thứ tự xuất hiện trong NVSE:. Loại: trường Type được thiết lập để NVSE-số-TYPE, 134, để chỉ ra rằng đây là một NVSE. . Thời lượng: Trường này có chiều dài trong byte của phần mở rộng này, không bao gồm các loại và các byte Length. . Thuộc về: | 196 MOBILITY MANAGEMENT Vendor-CVSE-Value This field contains vendor organization-specific data. It may contain zero or more octets. The NVSE contains the following fields listed in the order of appearance in the NVSE Type The Type field is set to the NVSE-TYPE-NUMBER 134 to indicate that this is an NVSE. Length This field contains the length in bytes of this extension not including the Type and Length bytes. Reserved This field is reserved for future use and must be set to 0 by the sender and must be ignored on reception. Vendor Org-ID This field contains the identifier of the vendor or organization that is using this extension. Vendor-NVSE-Type This field indicates the particular type of this NVSE. A vendor may assign and use different types of NVSEs at its discretion. Vendor-NVSE-Value This field contains vendor organization-specific data. It may contain zero or more octets. 01234567890123456789012345678901 Type Reserved Length Vendor Org-ID Vendor-CVSE-Type Vendor-CVSE Value a Critical Vendor Origination Specific Extension CVSE 01234567890123456789012345678901 Type Length Reserved Vendor Org-ID Vcndor-NVSE-Typc Vendor-NVSE Value b Normal Vendor Origination Specific Extension NVSE Fig. Vendor Organization Specific Extensions to Mobile IP messages MOBILITY MANAGEMENT IN IP NETWORKS 197 Reverse Tunneling When a mobile sends IP packets in a visited network the IP source addresses in these outgoing packets may not belong to the IP addressing space used in the visited network. For example the IP source address may be the mobile s home address. Today an increasing number of routers on the Internet use information in addition to the destination IP address to make routing decisions. For example an IP access router in a visited network may reject any packet whose source IP address is not part of the IP addressing space of the visited network a technique commonly referred to as ingress filtering . As a result outgoing packets from a visiting mobile may .