busybox - In BusyBox why the maximum packet size is limited to 32768 while maximum IP packet size can be 65535

Question

There is a check in busybox,the packet size should be in between 38 to 32768(32 * 1024). If the size is greater than 32768 traceroute will not be triggered. Why this kind of limitation exists in busybox? The maximum IP Packet size can be 65535. Could you please clarify the reason for this limitation? Do we face any issues if the packet size is increased beyond 32768?

Answer 1

根据设计，BusyBox 是为资源有限（RAM、CPU）的设备/系统开发的，例如家用路由器、嵌入式控制器。

对于较旧的嵌入式系统，32k 是相当多的 RAM。

编辑：

通过查看 RFC1191 第 3.1 节，TCP MSS 选项描述包括一个注释，即某些 IP 实现可能存在符号位错误，可能会因不必要地使用如此大的 MSS 而引起问题。