帧格式
图1 Ethernet Ⅱ帧格式
| 字段 | 长度 | 含义 |
|---|---|---|
| DMAC | 6字节 | 目的MAC地址，IPV4为6字节，该字段确定帧的接收者。 |
| SMAC | 6字节 | 源MAC地址，IPV4为6字节，该字段标识发送帧的工作站。 |
| Type | 2字节 | 协议类型。下表列出了链路直接封装的协议。 |
| Data | 变长 | 数据字段的最小长度必须为46字节以保证帧长至少为64字节，这意味着传输一字节信息也必须使用46字节的数据字段。 如果填入该字段的信息少于46字节，该字段的其余部分也必须进行填充。数据字段的最大长度为1500字节。 |
| CRC | 4字节 | 用于帧内后续字节差错的循环冗余检验（也称为FCS或帧检验序列）。 |
| 值 | 协议 |
|---|---|
| 0x0800 | Internet Protocol (IP) [RFC894] |
| 0x0801 | X.75 Internet |
| 0x0805 | X.25 Level 3 |
| 0x0806 | Address Resolution Protocol (ARP)[RFC7042] |
| 0x0808 | Frame Relay ARP [RFC1701] |
| 0x8000 | IS-IS |
| 0x8035 | Reverse Address Resolution Protocol (RARP) [RFC903] |
| 0x8137 | Novell NetWare IPX/SPX (old) |
| 0x8138 | Novell, Inc. |
| 0x8100 | IEEE Std 802.1Q - Customer VLAN Tag Type |
| 0x814C | SNMP over Ethernet [RFC1089] |
| 0x86DD | IP Protocol version 6 (IPv6) [RFC7042] |
| 0x8808 | IEEE Std 802.3 - Ethernet Passive Optical Network (EPON) [RFC7042] |
| 0x880B | Point-to-Point Protocol (PPP) [RFC7042] |
| 0x880C | General Switch Management Protocol (GSMP) |
| 0x8847 | MPLS (multiprotocol label switching) label stack - unicast [RFC 3032] |
| 0x8848 | MPLS (multiprotocol label switching) label stack - multicast [RFC 3032] |
| 0x8863 | PPP over Ethernet (PPPoE) Discovery Stage [RFC2516] |
| 0x8864 | PPP over Ethernet (PPPoE) Session Stage [RFC2516] |
| 0x888E | IEEE Std 802.1X - Port-based network access control |
| 0x88A8 | IEEE Std 802.1Q - Service VLAN tag identifier (S-Tag) |
| 0x88B7 | IEEE Std 802 - OUI Extended Ethertype |
| 0x88C7 | IEEE Std 802.11 - Pre-Authentication (802.11i) |
| 0x88CC | IEEE Std 802.1AB - Link Layer Discovery Protocol (LLDP) |
| 0x88E5 | IEEE Std 802.1AE - Media Access Control Security |
| 0x88F5 | IEEE Std 802.1Q - Multiple VLAN Registration Protocol (MVRP) |
| 0x88F6 | IEEE Std 802.1Q - Multiple Multicast Registration Protocol (MMRP) |
帧示例
参考标准
| 标准 | 描述 |
|---|---|
| IEEE 802.3 | Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications |
| IEEE 802.3ae | Media Access Control (MAC) Parameters, Physical Layers, and Management parameters for 10Gb/s Operation |
| RFC 894 | A Standard for the Transmission of IP Datagrams over Ethernet Networks |
| RFC 1042 | A Standard for the Transmission of IP Datagrams over IEEE 802 Networks |