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Re: [lwip-users] broken DHCP/ARP interaction
From: |
Sergio R. Caprile |
Subject: |
Re: [lwip-users] broken DHCP/ARP interaction |
Date: |
Wed, 14 May 2014 15:10:36 -0300 |
User-agent: |
Mozilla/5.0 (Windows NT 5.1; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
Hi,
Quick&dirty workaround: disable ARP checking by defining
DHCP_DOES_ARP_CHECK to 0
Analysis:
I'm no expert in DHCP nor ARP, but I don't see anything similar to what
you are experiencing.
I've setup three scenarios:
1- different IP (static) prior to DHCP
2- same IP (static) prior to DHCP
3- 0.0.0.0
In scenarios 1 and 3, everything works "as expected"
In scenario 2, I see a "gratuitous ARP", but the address is accepted
anyway. Here is my capture:
No. Time Source Destination
Protocol Length Info
1 0.000000000 192.168.1.42 255.255.255.255
DHCP 350 DHCP Discover - Transaction ID 0xabcd0001
2 0.001705000 192.168.1.1 192.168.1.42
DHCP 342 DHCP Offer - Transaction ID 0xabcd0001
3 0.002564000 192.168.1.42 255.255.255.255
DHCP 350 DHCP Request - Transaction ID 0xabcd0002
4 0.040420000 192.168.1.1 192.168.1.42
DHCP 342 DHCP ACK - Transaction ID 0xabcd0002
5 0.040841000 3com_03:04:05 Broadcast
ARP 60 Gratuitous ARP for 192.168.1.42 (Request)
Frame 5: 60 bytes on wire (480 bits), 60 bytes captured (480 bits) on
interface 0
Ethernet II, Src: 3com_03:04:05 (00:01:02:03:04:05), Dst: Broadcast
(ff:ff:ff:ff:ff:ff)
Address Resolution Protocol (request/gratuitous ARP)
Hardware type: Ethernet (1)
Protocol type: IP (0x0800)
Hardware size: 6
Protocol size: 4
Opcode: request (1)
[Is gratuitous: True]
Sender MAC address: 3com_03:04:05 (00:01:02:03:04:05)
Sender IP address: 192.168.1.42 (192.168.1.42)
Target MAC address: 00:00:00_00:00:00 (00:00:00:00:00:00)
Target IP address: 192.168.1.42 (192.168.1.42)
6 0.499760000 3com_03:04:05 Broadcast
ARP 60 Gratuitous ARP for 192.168.1.42 (Request)
I suggest you check your options and step the code to see where this
rejection takes place
--
- Re: [lwip-users] broken DHCP/ARP interaction,
Sergio R. Caprile <=