Junos
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Junos

DHCP Relay issues

‎12-15-2018 07:18 PM

Hi, 

Having an issues with DHCP relay... My client are getting and IP adress, but look like the DHCP handshake isn't completing properly..  I don't see the bound status int he dhcp relay binding status..  

In the traceoption I see the following error message..  

 

Dec 16 01:39:50.694686 [MSTR][DEBUG][default:users][RLY][INET][irb.30][SID=1409] jdhcpd_packet_handle: Dropping ACK due to server-identifier mismatch

 

What would that mean ?  

 

 

 

3 REPLIES 3
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Junos

Re: DHCP Relay issues

‎12-15-2018 09:01 PM

plz attach configuration and traffic dump. This looks like your dhcp server return incorrect server-id to client and when client reply with this server-id - packet is dropped. 

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Junos

Re: DHCP Relay issues

‎12-15-2018 11:41 PM
Every DHCP packet from server contains “DHCP Server Identifier” (PFA), ideally the OFFER packet and ACK packet should have same identifier.
As per your traces it looks like they are not same and that’s why the ACK is getting dropped.

Most possible reason is you have multiple servers sending Offers .
Thanks,
Suraj
Please Mark My Solution Accepted if it Helped, Kudos are Appreciated too
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Junos

Re: DHCP Relay issues

‎12-17-2018 06:51 AM

I acutally have 2 QFX10K configure with JFD running DHCP Relay.  The dhcp relay does point to 2 linux DHCP server.  My relay configuration look as this .. 

set routing-instances users forwarding-options dhcp-relay forward-snooped-clients all-interfaces
set routing-instances users forwarding-options dhcp-relay server-group PROD-DHCP-SERVERS 10.250.52.11
set routing-instances users forwarding-options dhcp-relay server-group PROD-DHCP-SERVERS 10.250.52.12
set routing-instances users forwarding-options dhcp-relay group PROD-DHCP active-server-group PROD-DHCP-SERVERS
set routing-instances users forwarding-options dhcp-relay group PROD-DHCP overrides no-unicast-replies
set routing-instances users forwarding-options dhcp-relay group PROD-DHCP overrides delete-binding-on-renegotiation
set routing-instances users forwarding-options dhcp-relay group PROD-DHCP interface irb.40
set routing-instances users forwarding-options dhcp-relay group PROD-DHCP interface irb.30
set routing-instances users forwarding-options dhcp-relay group PROD-DHCP interface irb.31
set routing-instances users forwarding-options dhcp-relay group PROD-DHCP interface irb.32

 

Actually I just notice that it look like that intead of having replies from my primary dhcp server I am getting replies from my secondary.