Running DHCPv6 relay without interfaces
glen.neff at emc.com
Thu Mar 14 15:35:28 UTC 2013
> >> Can I able to run DHCPv6 relay with single interface
> > This makes no sense. If you don't have multiple interfaces, then you
> > shouldn't need a relay.
> I think it makes sense for IPv6, which uses multicast instead of the
> traditional broadcast/unicast.
> Clients send to the link-local DHCP address "FF02::1:2". The DHCP
> server listens at the site-wide DHCP address "FF05::1:3". Something has
> to piece the two together.
> Even in an IPv4 world, a DHCP relay does not HAVE to run on the gateway
> so a single interface relay to pick up the broadcasts and unicast them off
> the local network to the server is perfectly valid. The OP said his box had
> a single interface, not that he only had a single broadcast domain.
Since I've become the list whipping-boy for the day. . .
While correct that a DHCPv6-relay does not have to be a router, I do not think it's correct to say a single interface can mean multiple broadcast domains. If there was multiple broadcast domains associated with a single NIC, then surely this would be a trunked interface with sub-interfaces for each broadcast domain.
I've also struggled with both the lack of DHCPv6-relay support on Cisco NXOS devices, and 'dhcrelay -6' and its upper & lower interface designations used for ISC-DHCPv6-relay. I'm not sure how well a config where the same interface is specified as both lower & upper would work.
* Glen R. J. Neff
* USD Lab Operations Infrastructure Team
* glen.neff at emc.com
* EMC^2 == E^2
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