Mbed-os: LPC1768 DHCP

[chrissnow]

• Type: Bug
• Priority: Major

---

Bug

Target
LPC1768

Toolchain:
ARM

Toolchain version:

mbed-cli version:
1.0.0

Since mbed-os 5.4.0 DHCP appears to be broken.
I can see DHCP request and offers with wireshark but no IP is assigned to the interface
Statically assigned IP works fine.

[toyowata]

Related this issue:
https://github.com/ARMmbed/mbed-os-example-sockets/issues/17

[geky]

I'm having a difficult time reproducing this issue. The LPC1768 and ARCH_PRO both seem to work on the two networks I have available.

Could you attach the wireshark dump of the DHCP request/offer? I can probably fake the traffic to reproduce it here.

Also what does your ethernet hardware setup look like? If you are using an Arch Pro, did you compile with mbed compile -m ARCH_PRO?

[chrissnow]

I will get you a wireshark capture tomorrow, I may try a Ublox C027 I have at home tonight which is basically the same hardware.
I'm using the EA LPC1769 board and a magjack.
https://www.embeddedartists.com/products/lpcxpresso/lpc1769_cmsis_xpr.php
mbed compile -t arm -m lpc1768

since going to static IP I haven't had any issues so it's unlikely to be hardware.

[chrissnow]

@geky here is a capture
dhcp.zip

[geky]

Thanks! that will help a bunch.

Starting to dig my teeth in, it looks like the difference between our DHCP servers is that yours is responding with broadcast packets. This is likely an issue with a recent change to add broadcast support (https://github.com/ARMmbed/mbed-os/pull/3482?)

[geky]

@chrissnow, I think I found the issue in https://github.com/ARMmbed/mbed-os/pull/4060, let us know if there is still an issue.