I'm learning to set up an ipv6 dhcp pool in Packet Tracer. And I'm stomped on what a link-address is as an option in a dhcp server ipv6. I've read this https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6/configuration/15-2mt/ipv6-15-2mt-book/ip6-dhcp.html a couple of times but I do not understand in layman terms the purpose of this option "link-address".

For example: I understand the dns-server, domain-name, address prefix options but not the link-address

 address prefix 2001:DB8:1000::/64 lifetime infinite infinite

 link-address 2001:DB8:1000::1/64

 dns-server 2001:DB8:1000::1

 domain-name cisco.com

Any help on this topc is appreciated and thanks in advance.


The link-address is the address of the DHCPv6 server on the LAN where the DHCPv6 request came in. It is mostly used with DHCPv6 relays.

DHCPv6 messages usually have link-local source and destination addresses. When those are sent to a relay, the DHCPv6 server that receives the relayed message has no idea what link the original message came from. Therefore the relayed message contains the global address of the DHCPv6 relay on the link that the message came in on. That way the server knows which link it is, and it can send an appropriate response.

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