Tunneling DHCP requests through MPLS 1

[itd17]

We recently upgraded to an MPLS network from Frame and we are unable to contact the DHCP server sitting at the head end.

What is the proper way to tunnel requests through?

Thanks,

Jason

 

[plshlpme]

do you have ip helper address' in your routers?

 

[itd17]

I did, but nothing seemed to pass-through. Right now the router is set a the DHCP server as an interim.

 

[voltron1011]

I'd be interested in the answer to this because we are also talking about implementing MPLS...

 

[plshlpme]

well the mpls should be transparent. and the helpers should do the trick i would think.

are you doign your own mpls backbone or have you gone to a provider for it?

is the address of the dhcp server in your routing table?

 

[itd17]

We're using AT&T as the provider and they state we need to tunnel the requests via GRE. I am able to ping the dhcp server as that subnet is redistributed via eigrp.

 

[leedsit]

Hi,

if you are using a DHCP helper on the L3 device your DHCP requests are heard, then the packet should traverse the MPLS ok. With have 6 Sites which all connect to us via MPLS to get their IP Address`s and that works fine!

Lee.

LEEroy
MCNE6,CCNP,CWNA,CCSA,Project+

 

[leedsit]

Hmm, itd17... after reading your statement a little more.... im not sure AT&T are right.... DHCP requests by Nature are Broadcast... however when you are using IP Helper, it becomes a unicast.... unless their network filter out DHCP packets!!!! ( not sure why, its your Virtual Circuit )... then it should work!!!

LEEroy
MCNE6,CCNP,CWNA,CCSA,Project+

 

[AJ1982]

Why are you not localising DHCP, if you have an on site router,why not just use the DHCP Server on that or a MS Server or whatever you use, rather than relying on your WAN , if it does down, then potentially your clients loose all connectivity...

AJ

===

Fatman Superstar (Andrew James)

CCNA

 

[Belushi]

FatmanSuperstar,

There are all sorts of pros and cons for having a centrally located DHCP server/servers rather than having them locally. Never the less, the answer to this question is based upon the type of MPLS network employed by the provider. Generally, the client side router forms a layer 3 conenction with the Provider edge router via EIGRP, BGP, or OSPF. This is in direct contrast to frame which is layer 2. The other option with MPLS is for the customer to perform layer 3 switching via MPLS labels all the way down to the customer edge. This is rare and most customers don't have the technical know how to do such a thing, but it's possible.

As stated, DHCP broadcasts will most likely need to be converted to unicats via the ip helper command. I'm doing this today with over 150 sites communicating across a provider supplied MPLS network without issue. And you'll never guess who my provider is? I'll give you one hint, the first two letter of the provider are A and T.

Belushi, CCNP