1# New IP Kernel Protocol Stack 2 3 4## Basic Concepts 5 6On basis of the traditional IP, New IP employs lightweight packet headers and variable-length, multi-semantic addresses and integrates Layer 2 and Layer 3 protocols to simplify protocols, reduce redundant bytes, and improve the energy efficiency ratio (EER), net throughput, and communication efficiency. New IP strives to implement end-to-end interconnection between heterogeneous networks to support ultimate experience of Super Device via efficient communication between devices. 7 8The Wi-Fi protocol packets cause low transmission efficiency due to high overheads in Layer 3 packet headers and addressing. 9 10 11 12``` 13An IPv4 address has a fixed length of 4 bytes, and an IPv6 address has a fixed length of 16 bytes. 14The network layer header ranges from 20 to 60 bytes for an IPv4 packet and is 40 bytes for an IPv6 packet. 15``` 16 17New IP supports variable-length multi-semantic addresses (min. 1 byte) and customized header encapsulation (min. 5 bytes). Simplified packet headers reduce overheads and improve transmission efficiency. 18 19New IP provides 25.9% less packet header overheads than IPv4 and 44.9% less than IPv6. 20 21New IP provides at least 1% higher payload transmission efficiency than IPv4 and 2.33% higher than IPv6. 22 23| Scenario | Header Overhead (Bytes) | Payload Transmission Efficiency<br>(Wi-Fi MTU = 1500 Bytes, BT MTU = 255 Bytes)| 24| --------------- | ------------ | ------------------------------------------- | 25| IPv4 for Wi-Fi | 30 + 8 + 20 = 58 | (1500 - 58)/1500 = 96.13% | 26| IPv6 for Wi-Fi | 30 + 8 + 40 = 78 | (1500 - 78)/1500 = 94.8% | 27| New IP for Wi-Fi | 30 + 8 + 5 = 43 | (1500 - 43)/1500 = 97.13% | 28 29## Variable-Length Header Format 30 31The following figure shows a New IP Wi-Fi packet header. "EtherType = 0xEADD" in the LLC header identifies the New IP packet. A bitmap is a binary sequence. The value of each binary bit indicates whether a field is carried in the New IP header. That is, the New IP header can be customized based on service requirements. 32 33 34 35- **Dispatch** indicates the encapsulation type. The value **0b0** indicates the New IP encapsulation child class, which is 1 bit long (**0b** indicates that the following values are binary). 36- **Bitmap** is of variable length. By default, it is seven bits following the **Dispatch** valid bit. The length of **Bitmap** can be extended contiguously. If the last bit of **Bitmap** is **0**, it indicates the end of **Bitmap**. If the last bit is **1**, it means one more byte until the last bit **0**. 37- **Value** indicates the field value. The length is an integer multiple of 1 byte. The value type and length are determined by the semantic table of the header field. 38 39The **Bitmap** field is defined as follows: 40 41| Bitmap Identifier | Bitops | Length of the Field Carried (Byte) | Setting | Remarks | 42| ---------------------------- | ------ | ---------------- | -------------- | --------------------------------------- | 43| Bitmap first byte | - | - | - | The eight bits are from the most significant bit to the least significant bit. | 44| Dispatch | 0 | - | Set to **0**. | **0**: indicates a New IP packet; **1**: indicates a non-New-IP packet. | 45| Whether the packet header carries the TTL | 1 | 1 | Set to **1**. | Indicates the number of remaining hops. | 46| Whether the packet header carries the total length | 2 | 2 | Set to **0** for UDP and **1** for TCP.| Total length of the new IP packet (including the header) | 47| Whether the packet header carries the Next Header | 3 | 1 | Set to **1**. | Protocol type. | 48| Reserve | 4 | Reserved | Set to **0**. | Reserved. | 49| Whether the packet header carries the destination address | 5 | Variable length (1 to 8 bytes)| Set to **1**. | Destination address. | 50| Whether the packet header carries the source address| 6 | Variable length (1 to 8 bytes)| Determined by the protocol.| Source address. | 51| Flag bit, indicating whether there is the second byte | 7 | - | - | **0**: indicates the end of the bitmap. **1**: indicates another 8-bit bitmap.| 52| Bitmap second byte | - | - | - | The eight bits are from the most significant bit to the least significant bit. | 53| Whether the packet header carries the header Length | 0 | 1 | - | New IP header length. | 54| Reserve | 1 | Reserved | Set to **0**. | - | 55| Reserve | 2 | Reserved | Set to **0**. | - | 56| Reserve | 3 | Reserved | Set to **0**. | - | 57| Reserve | 4 | Reserved | Set to **0**. | - | 58| Reserve | 5 | Reserved | Set to **0**. | - | 59| Reserve | 6 | Reserved | Set to **0**. | - | 60| Flag bit, indicating whether there is the third byte | 7 | - | - | **0**: indicates the end of the bitmap. **1**: indicates another 8-bit bitmap.| 61 62The New IP header is parsed as follows: 63 64Only the bitmap fields defined in New IP are parsed. All the bitmap fields with unknown semantics are skipped. The start position of the packet is located for parsing based on the header length. If the packet header contains bitmap fields with unknown semantics and does not contain the header length, the packet will be discarded. 65 66## Variable-Length Address Format 67 68Different from IPv4 and IPv6, which use fixed-length addresses, New IP supports variable-length addresses and parse of the address length. The packet header may not carry the address length field. The encoding format of new IP addresses is as follows: 69 70| First Byte | Semantics | Valid Range of Address | 71| ---------- | ------------------------------------------------------------ | ------------------------------------------------------------ | 72| 0x00 | Address is 0 | [1 byte] 0 to 220 (0x00 to 0xDC) | 73| 0x01 | Address is 1 | - | 74| 0x02 | Address is 2 | - | 75| ... | ... | - | 76| 0xDC | Address is 220 | - | 77| 0xDD | An 16-bit address, which is 0 + 256 * (0xDD - 0xDD) + the last byte value | [2 bytes] 221 to 255 (0x**DD**DD to 0x**DD**FF) | 78| 0xDE | An 16-bit address, which is 0 + 256 * (0xDE - 0xDD) + the last byte value | [2 bytes] 256 to 511 (0x**DE**00 to 0x**DE**FF) | 79| 0xDF | An 16-bit address, which is 0 + 256 * (0xDF - 0xDD) + the last byte value | [2 bytes] 512 to 767 (0x**DF**00 to 0x**DF**FF) | 80| ... | ... | - | 81| 0xF0 | An 16-bit address, which is 0 + 256 * (0xF0 - 0xDD) + the last byte value | [2 bytes] 4864 to 5119 (0x**F0**00 to 0x**F0**FF) | 82| 0xF1 | An 16-bit address is followed | [3 bytes] 5120 to 65535 (0x**F1** 1400 to 0x**F1** FFFF) | 83| 0xF2 | An 32-bit address is followed | [5 bytes] 65536 to 4,294,967,295 (0x**F2** 0001 0000 to 0x**F2** FFFF FFFF)| 84| 0xF3 | An 48-bit address is followed | [7 bytes] 4,294,967,296 to 281,474,976,710,655 (0x**F3** 0001 0000 0000 to 0x**F3** FFFF FFFF FFFF)| 85| 0xFE | An 56-bit address is followed | [8 bytes] 0 to 72,057,594,037,927,935 (0x**FE**00 0000 0000 0000 to 0x**FE**FF FFFF FFFF FFFF)| 86 87 88 89## New IP Configuration 90 91### Enabling New IP 92 93Only the Linux 5.10 kernel of the RK3568 development board supports the New IP kernel protocol stack. To enable New IP, search for "NEWIP" in the kernel module configuration file of the RK3568 development board and set related parameters as follows: 94 95``` 96# kernel/linux/config/linux-5.10/arch/arm64/configs/rk3568_standard_defconfig 97CONFIG_NEWIP=y // Enable the New IP kernel protocol stack. 98CONFIG_NEWIP_HOOKS=y // Enable New IP stub functions to be dynamically registered non-disruptively. This feature must be enabled when New IP is enabled. 99VENDOR_HOOKS=y // Enable the basic kernel instrumentation framework. New IP depends on this setting. It is enabled by default for the RK3568 development board. 100``` 101 102Run the following command to check whether the New IP protocol stack is successfully enabled: 103 104``` 105find out/ -name *nip*.o 106... 107out/kernel/OBJ/linux-5.10/net/newip/nip_addrconf_core.o 108out/kernel/OBJ/linux-5.10/net/newip/nip_hdr_decap.o 109out/kernel/OBJ/linux-5.10/net/newip/nip_addr.o 110out/kernel/OBJ/linux-5.10/net/newip/nip_checksum.o 111out/kernel/OBJ/linux-5.10/net/newip/tcp_nip_output.o 112... 113``` 114 115> **NOTE** 116> 117> All native kernel code must be non-disruptively modified into stub functions. For example, when New IP is added to the common process of IPv4/IPv6 stacks, you need to break into New IP stubs instead of calling New IP functions directly. After New IP is enabled, register the New IP functions with the function pointers during module initialization. Then, the New IP functions can be called in the common IPv4/IPv6 process through the function pointers. 118 119```c 120/* Register the New IP ehash function with the kernel. */ 121register_trace_ninet_ehashfn_hook(&ninet_ehashfn_hook, NULL); 122 123 124/* Add the New IP stack processing to the general entry function of IPv4/IPv6 stacks. */ 125static u32 sk_ehashfn(const struct sock *sk) 126{ 127 /* IPv6 */ 128#if IS_ENABLED(CONFIG_IPV6) 129 if (sk->sk_family == AF_INET6 && 130 !ipv6_addr_v4mapped(&sk->sk_v6_daddr)) 131 return inet6_ehashfn(sock_net(sk), 132 &sk->sk_v6_rcv_saddr, sk->sk_num, 133 &sk->sk_v6_daddr, sk->sk_dport); 134#endif 135 136#if IS_ENABLED(CONFIG_NEWIP_HOOKS) 137 if (sk->sk_family == AF_NINET) { 138 u32 ret = 0; 139 140 /* Register the New IP ehash function. */ 141 trace_ninet_ehashfn_hook(sock_net(sk), &sk->sk_nip_rcv_saddr, sk->sk_num, 142 &sk->sk_nip_daddr, sk->sk_dport, &ret); 143 return ret; 144 } 145#endif 146 147 /* IPv4 */ 148 return inet_ehashfn(sock_net(sk), 149 sk->sk_rcv_saddr, sk->sk_num, 150 sk->sk_daddr, sk->sk_dport); 151} 152``` 153 154### Disabling New IP 155 156To disable New IP, search for "NEWIP" in the kernel module configuration file of the RK3568 development board and delete or comment out "CONFIG_NEWIP=y" and "CONFIG_NEWIP_HOOKS=y". 157 158``` 159# kernel/linux/config/linux-5.10/arch/arm64/configs/rk3568_standard_defconfig 160# CONFIG_NEWIP is not set 161# CONFIG_NEWIP_HOOKS is not set 162``` 163 164## New IP APIs 165 166The user-mode application calls **socket()** to create a New IP socket and uses the New IP frame header encapsulation to send and receive packets. The following table lists the socket APIs for New IP. 167 168| API | Input | Output | Return Value | Description | 169| -------- | ------------------------------------------------------------ | ---------------------------------------------- | ---------------- | ------------------------------------------------------------ | 170| socket | int **domain**, int type, int **protocol** | NA | Socket handle **sockfd**.| Creates a New IP socket. <br>**domain** must be **AF_NINET**, which indicates a New IP socket.<br>**protocol** can be **IPPROTO_TCP** or **IPPROTO_UDP**.<br>This API returns the handle of the **socket** instance created.| 171| bind | int sockfd, const **struct sockaddr_nin** *myaddr, socklen_t addrlen | NA | Error code, which is an integer. | Binds the **socket** instance to the specified IP address and port.<br> **myaddr->sin_family** must be **AF_NINET**.| 172| listen | int socket, int backlog | NA | Error code, which is an integer. | Listens for the New IP address and port from the server. | 173| connect | int sockfd, const **struct sockaddr_nin** *addr, aocklen_t addrlen | NA | Error code, which is an integer. | Sets up a connection between the client and the server. | 174| accept | int sockfd, **struct sockaddr_nin** *address, socklen_t *address_len | NA | **sockfd**. | Accepts the connection request from the client. | 175| send | int sockfd, const void *msg, int len, unsigned int flags, const **struct sockaddr_nin** *dst_addr, int addrlen | NA | Error code, which is an integer. | Sends New IP packets via the socket using TCP. | 176| recv | int sockfd, size_t len, int flags, **struct sockaddr_nin** *src_addr, | void **buf, int* *fromlen | Error code, which is an integer. | Receives New IP packets via the socket using TCP. | 177| close | int sockfd | NA | Error code, which is an integer. | Closes the socket to release resources. | 178| ioctl | int sockfd, unsigned long cmd, ... | NA | Error code, which is an integer. | Queries or modifies information about the New IP protocol stack. | 179| sendto | int sockfd, const void *msg, int len, unsigned int flags, const **struct sockaddr** *dst_addr, int addrlen | NA | Error code, which is an integer. | Sends New IP packets via the socket using UDP. | 180| recvfrom | int sockfd, size_t len, int flags, | void *buf, struct sockaddr *from, int *fromlen | Error code, which is an integer. | Receives New IP packets via the socket using UDP. | 181 182The structure of the New IP short address is as follows: 183 184```c 185enum nip_8bit_addr_index { 186 NIP_8BIT_ADDR_INDEX_0 = 0, 187 NIP_8BIT_ADDR_INDEX_1 = 1, 188 NIP_8BIT_ADDR_INDEX_2 = 2, 189 NIP_8BIT_ADDR_INDEX_3 = 3, 190 NIP_8BIT_ADDR_INDEX_4 = 4, 191 NIP_8BIT_ADDR_INDEX_5 = 5, 192 NIP_8BIT_ADDR_INDEX_6 = 6, 193 NIP_8BIT_ADDR_INDEX_7 = 7, 194 NIP_8BIT_ADDR_INDEX_MAX, 195}; 196 197enum nip_16bit_addr_index { 198 NIP_16BIT_ADDR_INDEX_0 = 0, 199 NIP_16BIT_ADDR_INDEX_1 = 1, 200 NIP_16BIT_ADDR_INDEX_2 = 2, 201 NIP_16BIT_ADDR_INDEX_3 = 3, 202 NIP_16BIT_ADDR_INDEX_MAX, 203}; 204 205enum nip_32bit_addr_index { 206 NIP_32BIT_ADDR_INDEX_0 = 0, 207 NIP_32BIT_ADDR_INDEX_1 = 1, 208 NIP_32BIT_ADDR_INDEX_MAX, 209}; 210 211#define nip_addr_field8 v.u.field8 212#define nip_addr_field16 v.u.field16 213#define nip_addr_field32 v.u.field32 214 215#pragma pack(1) 216struct nip_addr_field { 217 union { 218 unsigned char field8[NIP_8BIT_ADDR_INDEX_MAX]; 219 unsigned short field16[NIP_16BIT_ADDR_INDEX_MAX]; /* Big-endian */ 220 unsigned int field32[NIP_32BIT_ADDR_INDEX_MAX]; /* Big-endian */ 221 } u; 222}; 223 224struct nip_addr { 225 unsigned char bitlen; /* The address length is in bit (not byte). */ 226 struct nip_addr_field v; 227}; 228#pragma pack() 229 230/* The following structure must be larger than V4. System calls use V4. 231 * If the definition is smaller than V4, the read process will have memory overruns 232 * v4: include\linux\socket.h --> sockaddr (16Byte) 233 */ 234#define POD_SOCKADDR_SIZE 3 235struct sockaddr_nin { 236 unsigned short sin_family; /* [2 bytes] AF_NINET */ 237 unsigned short sin_port; /* [2 bytes] Transport layer port, big-endian */ 238 struct nip_addr sin_addr; /* [9 bytes] New IP address */ 239 240 unsigned char sin_zero[POD_SOCKADDR_SIZE]; /* [3 bytes] Byte alignment */ 241}; 242``` 243 244## New IP Development 245 246Only the OpenHarmony Linux-5.10 kernel supports New IP kernel protocol stack. You must manually configure IP address and route data for New IP in user mode, and connect the two devices through the router Wi-Fi. If you want to automatically switch to the new IP kernel protocol stack after configuring the new IP address and route, see the description in the blue box in the following figure. 247 248 249 250For details about the address and route configuration, see [examples](https://gitee.com/openharmony/kernel_common_modules_newip/tree/master/examples). Modify the CC definition in Makefile based on the CPU you use, compile the CC definition into a binary file, and push the file to the development board. Refer to the figure above to configure the address and route data for New IP. 251 252| File | Description | 253| ------------------ | -------------------------------------------------------- | 254| nip_addr.c | Sample code for configuring variable-length New IP addresses (any valid New IP address can be configured). | 255| nip_route.c | Sample code for configuring New IP route information (any valid New IP address can be configured). | 256| check_nip_enable.c | Code for obtaining the New IP capabilities of the local host. | 257 258Check the New IP address and route information on device 1. 259 260```sh 261# cat /proc/net/nip_addr 26201 wlan0 263# cat /proc/net/nip_route 26402 ff09 1 wlan0 # Route to device 2. 26501 01 2149580801 wlan0 # Route for sending packets to itself and receiving the packets. 266``` 267 268Check the New IP address and route information on device 2. 269 270```sh 271# cat /proc/net/nip_addr 27202 wlan0 273# cat /proc/net/nip_route 27401 ff09 1 wlan0 # Route to device 1. 27502 02 2149580801 wlan0 # Route for sending packets to itself and receiving the packets. 276``` 277 278## Sample Code for Receiving and Sending New IP Packets 279 280The following table lists the related sample code. For details about how to use the user-mode APIs of the New IP stack, see [examples](https://gitee.com/openharmony/kernel_common_modules_newip/tree/master/examples). Fixed addresses and routes are configured in the demo code. You do not need to manually specify the addresses and routes when executing the binary program. 281 282| File | Description | 283| --------------------- | ------------------------------ | 284| nip_addr_cfg_demo.c | Sample code for configuring variable-length IP addresses. | 285| nip_route_cfg_demo.c | Sample code for configuring NEW IP routes. | 286| nip_udp_server_demo.c | Sample code for the server to send and receive New IP packets using UDP.| 287| nip_udp_client_demo.c | Sample code for the client to send and receive New IP packets using UDP.| 288| nip_tcp_server_demo.c | Sample code for the server to send and receive New IP packets using TCP.| 289| nip_tcp_client_demo.c | Sample code for the client to send and receive New IP packets using TCP.| 290| nip_lib.c | API demo code, for example, obtaining the interface index. | 291 292**Basic Procedure** 293 294 295 2961. Copy the demo code to the Linux compiler, and run **make clean** and **make all** to compile the demo code. 297 2982. Upload the generated binary files to device 1 and device 2. 299 3003. Run the **ifconfig wlan0 up** command to start the network adapter. 301 3024. Run the **./nip_addr_cfg_demo server** command on shell of device 1 to configure a variable-length address **0xDE00** (2 bytes) for the server. Run the **./nip_addr_cfg_demo client** command on shell of device 2 to configure a variable-length address **0x50** (1 byte) for the client. Run **cat /proc/net/nip_addr** to view the configuration result. 303 3045. Run the **./nip_route_cfg_demo server** command on shell of device 1 to configure the server route data. Run the **./nip_route_cfg_demo client** command on shell of device 2 to configure the client route data. Then, run the **cat /proc/net/nip_route** command to check the kernel route configuration. 305 306Now, you can send and receive packets over UDP/TCP. By default, the addresses and routes configured are used for sending and receiving packets. 307 308 309 310**Sending and Receiving Packets over UDP** 311 312Run the **./nip_udp_server_demo** command on the server and then the **./nip_udp_client_demo** command on the client. The client sends 10 New IP packets. After receiving the packets, the server sends them to the client. 313 314``` 315The following information is displayed in the shell window on the server: 316Received -- 1661826989 498038 NIP_UDP # 0 -- from 0x50:57605 317Sending -- 1661826989 498038 NIP_UDP # 0 -- to 0x50:57605 318Received -- 1661826990 14641 NIP_UDP # 1 -- from 0x50:57605 319Sending -- 1661826990 14641 NIP_UDP # 1 -- to 0x50:57605 320Received -- 1661826990 518388 NIP_UDP # 2 -- from 0x50:57605 321Sending -- 1661826990 518388 NIP_UDP # 2 -- to 0x50:57605 322... 323Received -- 1661827011 590576 NIP_UDP # 9 -- from 0x50:37758 324Sending -- 1661827011 590576 NIP_UDP # 9 -- to 0x50:37758 325 326The following information is displayed in the shell window on the client: 327Received --1661827007 55221 NIP_UDP # 0 sock 3 success: 1/ 1/no= 0 328Received --1661827007 557926 NIP_UDP # 1 sock 3 success: 2/ 2/no= 1 329Received --1661827008 62653 NIP_UDP # 2 sock 3 success: 3/ 3/no= 2 330... 331Received --1661827011 590576 NIP_UDP # 9 sock 3 success: 10/ 10/no= 9 332``` 333 334 335 336**Sending and Receiving Packets over TCP** 337 338Run the **./nip_tcp_server_demo** command on the server and then the **./nip_tcp_client_demo** command on the client. The client sends 10 New IP packets. After receiving the packets, the server sends them to the client. 339 340``` 341The following information is displayed in the shell window on the server: 342Received -- 1661760202 560605 NIP_TCP # 0 --:1024 343Sending -- 1661760202 560605 NIP_TCP # 0 --:1024 344Received -- 1661760203 69254 NIP_TCP # 1 --:1024 345Sending -- 1661760203 69254 NIP_TCP # 1 --:1024 346Received -- 1661760203 571604 NIP_TCP # 2 --:1024 347Sending -- 1661760203 571604 NIP_TCP # 2 --:1024 348... 349Received -- 1661760207 86544 NIP_TCP # 9 --:1024 350Sending -- 1661760207 86544 NIP_TCP # 9 --:1024 351 352The following information is displayed in the shell window on the client: 353Received --1661760202 560605 NIP_TCP # 0 sock 3 success: 1/ 1/no= 0 354Received --1661760203 69254 NIP_TCP # 1 sock 3 success: 2/ 2/no= 1 355... 356Received --1661760207 86544 NIP_TCP # 9 sock 3 success: 10/ 10/no= 9 357``` 358 359## SELinux Policy 360 361The SELinux policy must be added for the user-mode process to use New IP sockets. Otherwise, the operation will be intercepted. 362 363```sh 364# base\security\selinux\sepolicy\ohos_policy\xxx\xxx.te 365# socket operation 366# avc: denied { create } for pid=540 comm="thread_xxx" scontext=u:r:thread_xxx:s0 tcontext=u:r:thread_xxx:s0 tclass=socket permissive=0 367allow thread_xxx thread_xxx:socket { create bind connect listen accept read write shutdown setopt getopt }; 368 369# ioctl operation 370# The operation code is defined in linux-xxx\include\uapi\linux\sockios.h. 371# 0x8933 : name -> if_index mapping 372# 0x8916 : set PA address 373# 0x890B : add routing table entry 374allowxperm thread_xxx thread_xxx:socket ioctl { 0x8933 0x8916 0x890B }; 375``` 376 377## WireShark Packet Parsing Template 378 379The default packet parsing rules of Wireshark cannot parse New IP packets. You can add a New IP packet parsing template to Wireshark to parse New IP packets. For details about the template, see [New IP packet parsing template](https://gitee.com/openharmony/kernel_common_modules_newip/blob/master/tools/wireshark_cfg_for_newip.lua). 380 381The procedure is as follows: 382 3831. Choose **Help** > **About Wireshark** > **Folders**, and open the **init.lua** file in the **Global Configuration** directory. 3842. Add **dofile (DATA_DIR.."newip.lua")** to the end of the file. *DATA_DIR* is the path of the **newip.lua** file. 385 386 387 388Example: 389 390``` 391Path of the New IP packet parsing template: 392D:\tools\WireShark\wireshark_cfg_for_newip.lua 393 394Path of the WireShark configuration file: 395C:\Program Files\Wireshark\init.lua 396 397Add the following to the end of the **init.lua** file (Windows 11, for example): 398dofile("D:\\tools\\WireShark\\wireshark_cfg_for_newip.lua") 399``` 400 401### Packet Parsing Example 402 403#### ND Request 404 405The following figure shows the format of a New IP Neighbor Discovery (ND) request packet. The header contains a 1-byte bitmap (**0x76**), which is followed by the TTL, total length of the packet, upper-layer protocol type, destination address, and source address. The New IP ND request packet contains the packet type, operation code, checksum, and request address. 406 407> **NOTE** 408> 409> New IP supports variable-length addresses (1 to 8 bytes). The 1-byte address in Bitmap 1 indicates that the address carried in the current packet header is of 1 byte. 410 411 412 413 414 415#### ND Response 416 417The following figure shows the format of a New IP ND response packet. The New IP header contains two bitmaps (**0x77** and **0x00**). Bitmap1 is followed by the TTL, total packet length, upper-layer protocol type, destination address, and source address. Bitmap2 is used for byte alignment and does not carry any data. (For the rk3568 development board, the data transmitted in the link layer must be of an even number of bytes.) A New IP ND response packet contains the packet type, operation code, checksum, neighbor MAC address length, and neighbor MAC address. 418 419> **NOTE** 420> 421> New IP supports variable-length addresses (1 to 8 bytes). The 1-byte address in Bitmap 1 indicates that the address carried in the current packet header is of 1 byte. 422 423 424 425 426 427#### TCP Handshake 428 429The figure below shows the format of a TCP three-way handshake SYN packet. The New IP packet header contains two bitmaps (**0x77** and **0x00**). Bitmap1 is followed by the TTL, total packet length, upper-layer protocol type, destination address, and source address. Bitmap2 is used for byte alignment and does not carry any data. (For the rk3568 development board, the data transmitted in the link layer must be of an even number of bytes.) 430 431> **NOTE** 432> 433> New IP supports variable-length addresses (1 to 8 bytes). The 1-byte address in Bitmap 1 indicates that the address carried in the current packet header is of 1 byte. 434 435 436 437 438 439#### TCP Data Packet 440 441The figure below shows the TCP data format. The New IP header contains two bitmaps (**0x77** and **0x00**). Bitmap 1 is followed by the TTL, total packet length, upper-layer protocol type, destination address, and source address. Bitmap2 is used for byte alignment and does not carry any data. (For the rk3568 development board, the data transmitted in the link layer must be of an even number of bytes.) 442 443> **NOTE** 444> 445> New IP supports variable-length addresses (1 to 8 bytes). The 1-byte address in Bitmap 1 indicates that the address carried in the current packet header is of 1 byte. 446 447 448 449 450
