IOS-XR multiple giaddr per helper / smart-relay

[matthew.almen]

Is there any way to allow for multiple giaddr's to be sent sequentially for a set of helper addresses in a dhcp proxy profile?  Something similar to how DHCP smart-relay works in IOS? 

We have VLANs with DHCP clients from multiple DHCP networks/ranges. I am struggling to get a config in IOS-XR that allows for more than a single DHCP network attached to a subinterface using the proxy profile.  I tried putting a secondary ipv4 address on the loopback interface we're unnumbering to but that doesn't work.  The router never changes to using the secondary ipv4 address no matter if I have the subinterface configured for proxy or relay profile.  It only uses the primary loopback ipv4 address.  The proxy profile only allows for two helper-addresses not multiple helper-addresses so I can specify different giaddrs to try.  There must be a work around for this but I'm having trouble finding it.  Thanks, Matt

[joshuacmoore]

Can you provide the corresponding IOS config that you say works? From my experience DHCP relay always uses the first (non-secondary) IP on the interface you are relaying for. Also, please provide a sample config from your IOS-XR that shows "sh run dhcp ipv4" and the interface config for the subinterfaces you are trying to relay for.

[xthuijs]

you could try this sample below, it will set the giaddr based on what you signal in the vendor class.

smart relay, as in what IOS does, that XR doesnt have.

you can suggest multiple giaddr like this below and that does require a secondary address on the access interface too.

if not this, you can also use radius to provide the dhcp info. so we still use dhcp, but we leverage radius to get ip addr and gw info as an alternative?

xander

profile AutoSelectGiaddr proxy

  class MATCHALL

   helper-address vrf default 81.1.1.2 giaddr 10.1.1.254

  !

  class HardPhone1

   helper-address vrf default 81.1.1.2 giaddr 10.1.1.254

  !

  class HardPhone2

   match option 60 hex 4861726450686F6E6532

   helper-address vrf default 81.1.1.2 giaddr 172.28.15.254

  !

  relay information option

  relay information policy replace

  relay information option remote-id testme

  relay information option allow-untrusted

!

[matthew.almen]

We figured this out and the problem was not the router!  My test network was not configured to be in the shared-network with the rest of our production DHCP pools.  When I had just my test gateway on the loopback interface it worked fine since it was it's own pool and the giaddr was correct.  When I changed it to test when another gateway was primary on the loopback (glad I did this before migrating everyone) and my test laptop requested an address it already had from the test DHCP pool the DHCP server gave the error no free leases like it should have.  Once I added my test /24 to the shared network on our DHCP server it works fine. Turns out it was the DHCP shared network allowing this to work all along so I learned something about our network I didn't know before!  Thanks for the information.

[xthuijs]

hey matt, haha, that is awesome! ok glad we firugred it out and you have something running smoothly and nice! :)

cheers

xander