[SOLVED] DHCP client, problem in DHCP-Request phase

RouterOS General
1

Hi there,
I’m trying to assign static IPs via DHCP to mikrotik devices.
In the tests I’m doing, I need to give IP to a SXT (with DHCP-CLIENT) via a RB450 (with DHCP proxy).


SXT ---------- DHCP RELAY ----------- DHCP SERVER

this should be so:
→ discover
← offer
→ request
← ack

The SXT performs correctly “discover” request and this arrives at the server, the server answers the request with a “offer”, and this return to SXT correctly. But the SXT does not perform the “request” phase, but rather continues repeating a discovery again and again.

00:57:21 dhcp,debug,packet dhcp-client on wlan1-gateway sending discover with id 3670985585 to 255.255.255.255 
00:57:21 dhcp,debug,packet     secs = 4 
00:57:21 dhcp,debug,packet     flags = broadcast 
00:57:21 dhcp,debug,packet     ciaddr = 0.0.0.0 
00:57:21 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
00:57:21 dhcp,debug,packet     Msg-Type = discover 
00:57:21 dhcp,debug,packet     Parameter-List = Subnet-Mask,Classless-Route,Router,Static-Route,Domain-Server,NTP-Server,CAPWAP-Server 
00:57:21 dhcp,debug,packet     Host-Name = "SXT STATION" 
00:57:21 dhcp,debug,packet     Client-Id = 01-D4-CA-6D-C0-41-D7 
00:57:22 dhcp,debug,packet dhcp-client on wlan1-gateway received offer with id 3670985585 from 172.28.1.1 
00:57:22 dhcp,debug,packet     hops = 1 
00:57:22 dhcp,debug,packet     flags = broadcast 
00:57:22 dhcp,debug,packet     ciaddr = 0.0.0.0 
00:57:22 dhcp,debug,packet     yiaddr = 172.28.1.12 
00:57:22 dhcp,debug,packet     siaddr = 10.1.2.10 
00:57:22 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
00:57:22 dhcp,debug,packet     Msg-Type = offer 
00:57:22 dhcp,debug,packet     Subnet-Mask = 255.255.0.0 
00:57:22 dhcp,debug,packet     Router = 172.28.1.1 
00:57:22 dhcp,debug,packet     Address-Time = 86400 
00:57:22 dhcp,debug,packet     Domain-Server = 8.8.8.8 
00:57:25 dhcp,debug,packet dhcp-client on wlan1-gateway sending discover with id 3670985585 to 255.255.255.255 
00:57:25 dhcp,debug,packet     secs = 7 
00:57:25 dhcp,debug,packet     flags = broadcast 
00:57:25 dhcp,debug,packet     ciaddr = 0.0.0.0 
00:57:25 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
00:57:25 dhcp,debug,packet     Msg-Type = discover 
00:57:25 dhcp,debug,packet     Parameter-List = Subnet-Mask,Classless-Route,Router,Static-Route,Domain-Server,NTP-Server,CAPWAP-Server 
00:57:25 dhcp,debug,packet     Host-Name = "SXT STATION" 
00:57:25 dhcp,debug,packet     Client-Id = 01-D4-CA-6D-C0-41-D7 
00:57:25 dhcp,debug,packet dhcp-client on wlan1-gateway received offer with id 3670985585 from 172.28.1.1 
00:57:25 dhcp,debug,packet     hops = 1 
00:57:25 dhcp,debug,packet     flags = broadcast 
00:57:25 dhcp,debug,packet     ciaddr = 0.0.0.0 
00:57:25 dhcp,debug,packet     yiaddr = 172.28.1.12 
00:57:25 dhcp,debug,packet     siaddr = 10.1.2.10 
00:57:25 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
00:57:25 dhcp,debug,packet     Msg-Type = offer 
00:57:25 dhcp,debug,packet     Subnet-Mask = 255.255.0.0 
00:57:25 dhcp,debug,packet     Router = 172.28.1.1 
00:57:25 dhcp,debug,packet     Address-Time = 86400 
00:57:25 dhcp,debug,packet     Domain-Server = 8.8.8.8

Graphically:

→ discover
← offer
→ discover
← offer
→ discover
← offer
…


Why the SXT does not continue with the next step (“request”) if already received correctly “offer” packet?

Thanks for read.

2

Solved!

It needs the Option 54 “Server identifier”, it was not being provided by my server. I fixed that and all work now.
In logs appear as:

Server-Id = 10.1.2.10

01:54:12 dhcp,debug,packet dhcp-client on wlan1-gateway sending discover with id 2974431265 to 255.255.255.255 
01:54:12 dhcp,debug,packet     secs = 11 
01:54:12 dhcp,debug,packet     flags = broadcast 
01:54:12 dhcp,debug,packet     ciaddr = 0.0.0.0 
01:54:12 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
01:54:12 dhcp,debug,packet     Msg-Type = discover 
01:54:12 dhcp,debug,packet     Parameter-List = Subnet-Mask,Classless-Route,Router,Static-Route,Domain-Server,NTP-Server,CAPWAP-Server 
01:54:12 dhcp,debug,packet     Host-Name = "SXT STATION" 
01:54:12 dhcp,debug,packet     Client-Id = 01-D4-CA-6D-C0-41-D7 
01:54:12 dhcp,debug,packet dhcp-client on wlan1-gateway received offer with id 2974431265 from 172.28.1.1 
01:54:12 dhcp,debug,packet     hops = 1 
01:54:12 dhcp,debug,packet     flags = broadcast 
01:54:12 dhcp,debug,packet     ciaddr = 0.0.0.0 
01:54:12 dhcp,debug,packet     yiaddr = 172.28.1.12 
01:54:12 dhcp,debug,packet     siaddr = 10.1.2.10 
01:54:12 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
01:54:12 dhcp,debug,packet     Msg-Type = offer 
01:54:12 dhcp,debug,packet     Subnet-Mask = 255.255.0.0 
01:54:12 dhcp,debug,packet     Router = 172.28.1.1 
01:54:12 dhcp,debug,packet     Address-Time = 86400 
01:54:12 dhcp,debug,packet     Domain-Server = 8.8.8.8 
01:54:12 dhcp,debug,packet     Server-Id = 10.1.2.10 
01:54:12 dhcp,debug,state dhcp-client on wlan1-gateway entering <requesting...> state 
01:54:12 dhcp,debug,packet dhcp-client on wlan1-gateway sending request with id 2974431265 to 255.255.255.255 
01:54:12 dhcp,debug,packet     secs = 11 
01:54:12 dhcp,debug,packet     flags = broadcast 
01:54:12 dhcp,debug,packet     ciaddr = 0.0.0.0 
01:54:12 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
01:54:12 dhcp,debug,packet     Msg-Type = request 
01:54:12 dhcp,debug,packet     Server-Id = 10.1.2.10 
01:54:12 dhcp,debug,packet     Address-Request = 172.28.1.12 
01:54:12 dhcp,debug,packet     Parameter-List = Subnet-Mask,Classless-Route,Router,Static-Route,Domain-Server,NTP-Server,CAPWAP-Server 
01:54:12 dhcp,debug,packet     Host-Name = "SXT STATION" 
01:54:12 dhcp,debug,packet     Client-Id = 01-D4-CA-6D-C0-41-D7 
01:54:12 dhcp,debug,packet dhcp-client on wlan1-gateway received ack with id 2974431265 from 172.28.1.1 
01:54:12 dhcp,debug,packet     hops = 1 
01:54:12 dhcp,debug,packet     flags = broadcast 
01:54:12 dhcp,debug,packet     ciaddr = 0.0.0.0 
01:54:12 dhcp,debug,packet     yiaddr = 172.28.1.12 
01:54:12 dhcp,debug,packet     chaddr = D4:CA:6D:C0:41:D7 
01:54:12 dhcp,debug,packet     Msg-Type = ack 
01:54:12 dhcp,debug,packet     Subnet-Mask = 255.255.0.0 
01:54:12 dhcp,debug,packet     Router = 172.28.1.1 
01:54:12 dhcp,debug,packet     Address-Time = 86400 
01:54:12 dhcp,info dhcp-client on wlan1-gateway got IP address 172.28.1.12 
01:54:12 dhcp,debug,state dhcp-client on wlan1-gateway entering <bound> state