IP Helper-Address Not Forwarding DHCP Requests to a Different Site

[alexellington]

I have 2 sites, one router & one switch per site. There is connectivity between the two sites on the fiber interface. The routing method is EIGRP and is configured correctly. The routes are being updated in the routing table and I can ping any IP address from either side (including the remote DHCP server).

Here is my problem: connecting on the access port of the switch I am unable to get an IP address from the DHCP server on the other site. I have the interface for the VLAN to be using an ip helper-address on the opposite side andddd nothing.

I thought maybe it was because it was sharing the same IP pool, so I created a pool that matched the subnet to hand out leases. Still not working.

I've attached the full devices config with redacted passwords on the site to site setup here with Router1, Switch1, Router2 & Switch2. Mind you, everything else in the configuration works minus the DHCP relay.

If someone could tell me why I cannot get my ip helper-request to forward into a remote site, I would greatly appreciate it and probably owe you a beer.

[M02@rt37]

Hello @alexellington,

Does R1 know the route towards 10.20.30.1 ?

Try a ping from Router 1 towards 10.20.30.1 source with 10.10.30.1 (ip of Gi0/0.30) 

Does R2 kwow the route towards 10.10.30.1? 

Same test and check on Router 2 adjusting IP dest and source for ping.

[balaji.bandi · Accepted solution]

If the VLAN 10 from Local Site not getting from remote side Router DHCP  pool from 10.20.10.0/24

quick fix is  as below  test and let me know.

interface GigabitEthernet0/0.10
encapsulation dot1Q 10
ip address 10.20.10.1 255.255.255.0

no ip helper-address 10.20.10.1

ip helper-address 62.22.247.169  <-- add this and test it

Note : there are other things in DHCP exclude list to be added , i was just only commented based on the issue

[alexellington]

This resolved the problem, thanks!

[MHM Cisco World]

I send you message check it 

[paul driver]

Hello
You don't mention what hardware/software you are running for eigrp, however older ios software by default uses automatic summarization, which your case negates disconnected classful subnets (10.0.0.0/8) if you disable this feature you will be able to advertise the correct classless subnets by specifying "no auto-summary" under the eigrp routing stanza and then append the more specific eigrp interfaces.

example:
dhcp rtr
router eigrp 100
no auto-summary
network  62.22.247.169 0.0.0.0
network 10.100.1.254 0.0.0.0
network 10.10.10.1 0.0.0.0
network 10.10.20.1 0.0.0.0
network 10.10.30.1 0.0.0.0
no network 10.0.0.0
no network 62.22.247.0 0.0.0.255

rtr
router eigrp 100
no auto-summary
network  62.22.247.170 0.0.0.0
network 10.200.1.254 0.0.0.0
network 10.20.10.1 0.0.0.0
network 10.20.20.1 0.0.0.0
network 10.20.30.1 0.0.0.0
no network 10.0.0.0
no network 62.22.247.0 0.0.0.255

interface GigabitEthernet0/0.10
encapsulation dot1Q 10
ip address 10.20.10.1 255.255.255.0
ip helper-address 62.22.247.169

[alexellington]

Thanks for the information!

[MHM Cisco World]

I don't see anything in config wrong so

As other suggestions check the route is known in dhcp local router 

And check if there is FW (or any Acl) drop unicast udp 67 traffic