Switching

can anyone tell me why you can configure Forwarding Options Helpers Bootp in the EX4550 but not in the EX4600? You can configure the Helpers Bootp but its commented out as a feature that's not supported by EX4600. Any help would be greatly appreciated.

the newer switches that use the ELS syntax all use the new [forwarding-options dhcp-relay] syntax (EX4300, QFX, EX4600, EX9200).

basically define a server group, set it as active, and define which IP interfaces you want to enable DHCP relay on.

Unless they've fixed it, please please please make sure you include the following command:

set forwarding-options dhcp-relay forward-snooped-clients all-interfaces

we saw without this, if transit DHCP traffic passed the switch (ie from a downstream router sending a relay back to a DHCP server), switches configured with this "new style" would eat any transit DHCP packets, because it seems to snoop any and all DHCP messages once you enable DHCP Relay on an interface.  In some versions of code the above command wasn't needed, in others it was, so I just default to configuring it to be safe.

the new method of DHCP relay early on was really buggy, but its been pretty solid as of late.

will

Thanks Will, I will try your suggestion.

Will,

    Can the dhcp relay be defined on a IRB interface?

Chris

yes it can.  you just configure irb.50 or whatever the IRB interface is that you need to enable DHCP Relay on.

I recently installed a VC with 4600-4300 multimode , the below configuration is supported for helper address in the new ELS code. the old code would be taken by the system but it will be show as not supported.

You are putting the DHCP in a group and then calling them , again in ELS code Irb is used instead of Vlan

set forwarding-options dhcp-relay server-group DHCP-RELAY-GP 10.x.x.x #your DHCP
set forwarding-options dhcp-relay server-group DHCP-RELAY-GP 10.X.x.x # your secondary DHCP server if any
set forwarding-options dhcp-relay active-server-group DHCP-RELAY-GP
set forwarding-options dhcp-relay group DHCP-RELAY-GP interface irb.1  # your Vlans 
set forwarding-options dhcp-relay group DHCP-RELAY-GP interface irb.2
set forwarding-options dhcp-relay group DHCP-RELAY-GP interface irb.5

set forwarding-options dhcp-relay group DHCP-RELAY-GP interface irb.x
set forwarding-options dhcp-relay group DHCP-RELAY-GP interface irb.y
set forwarding-options dhcp-relay group DHCP-RELAY-GP interface irb.z

thanks alot this help me out...it working now...

thankx alot these configuration worked out and helped me alot ...

i still have an issue with the bootp .

How to configure the bootp with DHCP relay ..

set forwarding-options dhcp-relay server-group DHCP-RELAY-GP 10.45.1.10 (MyDHCP server )

shoud I add the same command for the Bootp Server (10.45.1.20)

Hi,

I think the answer is on this doc.

 Services Feature Guide for EX4600 Switches

https://www.juniper.net/documentation/en_US/junos/topics/concept/dhcp-bootp-qfx-series.html

Regards,

TP