DHCP relay over MPLS network

[Beaurr]

Hello,

I have several branch connected in MPLS.

Branch A ( main branch, with 2 DHCP servers)

Branch B ( without DHCP server).

I would like to use DHCP servers on branch A to distribute IP adresses on branch B.

I asked to my operator to set up dhcp relay because I can't make modification myself on the ISP router.

But i was still able to obtain the configuration files of the 2 ISP routers ( A and B), and i see that they put the DHCP relays on interface 0/0 on router A ( main branch).

interface GigabitEthernet 0/0
ip address x.x.x.x  255.255.255.0
no negotiation
duplex full
speed 1000
ip helper-address 10.39.1.223  ==>My first DHCP server
ip helper-address 10.39.1.224  ==>Second DHCP server
description *** LAN CLIENT ***

Does the configuration have to be applied on the main router ( A) or on the remote branch router (B) or the two?

[Beaurr]

Ok thank you MHM Cisco Monde

the wiring at this site is being completely replaced ( parallel to production) so as soon as the work has progressed, i can go and test by plugging my L3 switch, instead of the current one, to test the connectivity with the central site and the DHCP.

[emurray]

I have done this in MPLS sites with DHCP servers on different sites. If the difference is that it is a Layer 3 switch instead of a router, the logic does not change at all. You add the ip-helper at the VLAN interface in the L3SW. You create an interface VLAN with the subnet of site B and you put the ip-helper there. You can specify the default router in the access switch