FPGA生成的IPv4/UDP数据包被PC丢弃的问题排查求助

各位前辈好，我最近在做FPGA生成IPv4/UDP数据包的项目，遇到了一个卡壳的问题，想请大家帮忙分析下。

目前遇到的现象 #

• 我生成的数据包，只有在执行sudo ethtool -K enp2s0 rx-all on开启网卡全接收模式时，Wireshark才能抓到；
• 关闭rx-all（也就是网卡正常工作模式）时，这些数据包会被PC在Wireshark之前就丢弃，并且被标记为帧错误；
• 但如果我去掉IPv4头，只发原始以太网帧的话，即使rx-all关闭，PC也能正常接收，这说明MII接口和以太网帧的封装应该是没问题的。

已经排查过的内容 #

• Wireshark检查数据包无错误：UDP校验码设为0x0000（IPv4规范允许这么做），MAC/IP目标地址和我的PC完全匹配，FCS和IPv4校验码也都是正确的；
• 反复核对了目标MAC和IP地址，确认和PC的enp2s0网卡信息一致；
• 用sudo ethtool -S enp2s0查看网卡统计信息，没找到能指向问题的错误提示；
• 裸以太网帧能正常接收，排除了链路层的基础问题。

我的PC网卡配置 #

$ sudo ifconfig enp2s0
enp2s0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
inet 192.168.1.100  netmask 255.255.255.0  broadcast 192.168.1.255
ether 74:d4:35:aa:9d:1a  txqueuelen 1000  (Ethernet)
RX packets 26372  bytes 13819100 (13.1 MiB)
RX errors 177  dropped 0  overruns 0  frame 177
TX packets 1613  bytes 137389 (134.1 KiB)
TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

网卡统计信息 #

$ sudo ethtool -S enp2s0
NIC statistics:
tx_packets: 1597
rx_packets: 26372
tx_errors: 0
rx_errors: 0
rx_missed: 0
align_errors: 0
tx_single_collisions: 0
tx_multi_collisions: 0
unicast: 26372
broadcast: 0
multicast: 0
tx_aborted: 0
tx_underrun: 0

Wireshark抓包详情（rx-all开启时抓到的数据包） #

Frame 1257: 54 bytes on wire (432 bits), 54 bytes captured (432 bits) on interface enp2s0, id 0
Section number: 1
Interface id: 0 (enp2s0)
Encapsulation type: Ethernet (1)
Arrival Time: Nov 24, 2023 15:24:18.467278031 SAST
[Time shift for this packet: 0.000000000 seconds]
Epoch Time: 1700832258.467278031 seconds
[Time delta from previous captured frame: 0.127289169 seconds]
[Time delta from previous displayed frame: 0.127289169 seconds]
[Time since reference or first frame: 4627.139850121 seconds]
Frame Number: 1257
Frame Length: 54 bytes (432 bits)
Capture Length: 54 bytes (432 bits)
[Frame is marked: False]
[Frame is ignored: False]
[Protocols in frame: eth:ethertype:ip:udp:data]
[Coloring Rule Name: UDP]
[Coloring Rule String: udp]

Ethernet II, Src: PcsCompu_fb:dd:66 (08:00:27:fb:dd:66), Dst: Giga-Byt_aa:9d:1a (74:d4:35:aa:9d:1a)
Destination: Giga-Byt_aa:9d:1a (74:d4:35:aa:9d:1a)
Source: PcsCompu_fb:dd:66 (08:00:27:fb:dd:66)
Type: IPv4 (0x0800)

Internet Protocol Version 4, Src: 192.168.1.101, Dst: 192.168.1.100
0100 .... = Version: 4
.... 0101 = Header Length: 20 bytes (5)
Differentiated Services Field: 0x00 (DSCP: CS0, ECN: Not-ECT)
0000 00.. = Differentiated Services Codepoint: Default (0)
.... ..00 = Explicit Congestion Notification: Not ECN-Capable Transport (0)
Total Length: 40
Identification: 0x0000 (0)
000. .... = Flags: 0x0
...0 0000 0000 0000 = Fragment Offset: 0
Time to Live: 64
Protocol: UDP (17)
Header Checksum: 0xf6ab [correct]
[Header checksum status: Good]
[Calculated Checksum: 0xf6ab]
Source Address: 192.168.1.101
Destination Address: 192.168.1.100

User Datagram Protocol, Src Port: 65535, Dst Port: 65535
Source Port: 65535
Destination Port: 65535
Length: 20
Checksum: 0x0000 [zero-value ignored]
[Checksum Status: Not present]
[Stream index: 43]
[Timestamps]
[Time since first frame: 43.780741653 seconds]
[Time since previous frame: 40.026103244 seconds]

UDP payload (12 bytes)
Data (12 bytes)
Data: 53574954434845533a2087e0
[Length: 12]

我已经把能想到的点都查了一遍，但还是找不到问题根源。我的最终目标是生成能在正常网络环境（比如经过交换机）中传输的UDP数据包，想请教大家：

• 有没有什么我遗漏的检查点？
• 是否需要先发送ARP数据包来完成地址解析？
• 是不是必须要启用UDP校验码，即使IPv4允许设为0？

备注：内容来源于stack exchange，提问作者stanri