IPv6 - Sending Default Gateway to Client

[Colin_Painter]

Hi All,

I am starting an IPv6 journey -- Learning that DHCPv6 doesn't send the unicast global IP default gateway and it is done through 'ra' communication. However I am struggling with this.

I have setup a DHCPv6 to provide the unicast global to a server connected to the VLAN and this works but I cannot seem to get the default gateway passed on through the ra communication, so even though it gets the IP it is not routable.

I assume I must be missing something, any input/thoughts appreciated.

My Config:

ipv6 dhcp pool lan-6
 network xxx.xxx::xx/64
 address range xxx.xxx::xx xxx.xxx::yy
 gateway-list xxx.xxx::y

interface Vlan-interface10
 ipv6 dhcp select server
 ipv6 dhcp server apply pool lan-6 
 ipv6 address xxx.xxx::y/64
 ipv6 nd autoconfig managed-address-flag
 ipv6 nd router-preference high

Thanks

[Ivan_B]

Hello!

As per documentation the 'gateway-list' DHCPv6 pool option is for DHCP relays only for some corner cases:

---------

DHCPv6 clients of the same access type can be classified into different types by their locations. In
this case, the relay interface typically has no IPv6 address configured. You can use the
gateway-list command to specify gateway addresses for clients matching the same DHCPv6
address pool.

---------

In fact IPv6 host uses link-local address of the router in the segment to forward packets outside local network. There is no 1:1 match between features of IPv4 and IPv6, so expectation to have global address as a gateway is understandable, but incorrect To be honest DHCPv6 at this time is needed only for cases when you have a strict requirement to have staticly binded global addresses to each host. Also, until RFC 8106 won't be implemented everywhere you need DHCPv6  for DNS server addresses propagation to IPv6 clients. And since you don't have any DNS info in your pool configured, seems like SLAAC is a better fit for your needs, just something to consider...

Hope it helps!