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diff --git a/docs/ch11-services.rst b/docs/ch11-services.rst index 35acb71d..52303b36 100644 --- a/docs/ch11-services.rst +++ b/docs/ch11-services.rst @@ -410,6 +410,175 @@ Commit the changes and show the configuration: DHCP Relay ---------- +If you want your router to forward DHCP requests to an external DHCP server +you can configure the system to act as a DHCP relay agent. The DHCP relay +agent works with IPv4 and IPv6 addresses. + +All interfaces used for the DHCP relay must be configured. See +https://wiki.vyos.net/wiki/Network_address_setup. + +DHCP relay example +^^^^^^^^^^^^^^^^^^ + +.. figure:: images/service_dhcp-relay01.png + :scale: 80 % + :alt: DHCP relay example + + DHCP relay example + +In this example the interfaces used for the DHCP relay are eth1 and eth2. The +router receives DHCP client requests on eth1 and relays them through eth2 to +the DHCP server at 10.0.1.4. + +Configuration +^^^^^^^^^^^^^ + +Enable DHCP relay for eth1 and eth2: + +.. code-block:: sh + + set service dhcp-relay interface eth1 + set service dhcp-relay interface eth2 + +Set the IP address of the DHCP server: + +.. code-block:: sh + + set service dhcp-relay server 10.0.1.4 + +The router should discard DHCP packages already containing relay agent +information to ensure that only requests from DHCP clients are forwarded: + +.. code-block:: sh + + set service dhcp-relay relay-options relay-agents-packets discard + +Commit the changes and show the results: + +.. code-block:: sh + + commit + show service dhcp-relay + interface eth1 + interface eth2 + server 10.0.1.4 + relay-options { + relay-agents-packets discard + } + +The DHCP relay agent can be restarted with: + +.. code-block:: sh + + restart dhcp relay-agent + +DHCPv6 relay example +^^^^^^^^^^^^^^^^^^^^ + +.. figure:: images/service_dhcpv6-relay01.png + :scale: 80 % + :alt: DHCPv6 relay example + + DHCPv6 relay example + +In this example DHCPv6 requests are received by the router on eth1 (`listening +interface`) and forwarded through eth2 (`upstream interface`) to the external +DHCPv6 server at 2001:db8:100::4. + +Configuration +************* + +Set eth1 to be the listening interface for the DHCPv6 relay: + +.. code-block:: sh + + set service dhcpv6-relay listen-interface eth1 + +Set eth2 to be the upstream interface and specify the IPv6 address of the DHCPv6 server: + +.. code-block:: sh + + set service dhcpv6-relay upstream-interface eth2 address 2001:db8:100::4 + +Commit the changes and show results: + +.. code-block:: sh + + commit + show service dhcpv6-relay + listen-interface eth1 { + } + upstream-interface eth2 { + address 2001:db8:100::4 + } + +Show the current status of the DHCPv6 relay agent: + +.. code-block:: sh + + show dhcpv6 relay-agent status + +The DHCPv6 relay agent can be restarted with: + +.. code-block:: sh + + restart dhcpv6 relay-agent + +Additional parameters +^^^^^^^^^^^^^^^^^^^^^ + +DHCP relay agent options +************************ + +Set the maximum hop count before packets are discarded. Range 0...255, +default 10. + +* :code:`set service dhcp-relay relay-options hop-count 'count'` + +Set maximum size of DHCP packets including relay agent information. If a +DHCP packet size surpasses this value it will be forwarded without appending +relay agent information. Range 64...1400, default 576. + +* :code:`set service dhcp-relay relay-options max-size 'size'` + +Set the port used to relay DHCP client messages. Range 1...65535, default 67. +After setting a different port, requests are still accepted on port 67 but +replies are forwarded to 255.255.255.255 port 0 instead of 68. + +* :code:`set service dhcp-relay relay-options port 'port'` + +Four policies for reforwarding DHCP packets exist: + +* **append:** The relay agent is allowed to append its own relay information + to a received DHCP packet, disregarding relay information already present in + the packet. + +* **discard:** Received packets which already contain relay information will + be discarded. + +* **forward:** All packets are forwarded, relay information already present + will be ignored. + +* **replace:** Relay information already present in a packet is stripped and + replaced with the router's own relay information set. + +* :code:`set service dhcp-relay relay-options relay-agents-packet 'policy'` + +DHCPv6 relay agent options +************************** + +Set listening port for DHCPv6 requests. Default: 547. + +* :code:`set service dhcpv6-relay listen-port 'port'` + +Set maximum hop count before packets are discarded. Default: 10. + +* :code:`set service dhcpv6-relay max-hop-count 'count'` + +If this is set the relay agent will insert the interface ID. This option is +set automatically if more than one listening interfaces are in use. + +* :code:`set service dhcpv6-relay use-interface-id-option` DNS Forwarding -------------- diff --git a/docs/images/service_dhcp-relay01.png b/docs/images/service_dhcp-relay01.png Binary files differnew file mode 100644 index 00000000..cd7f30cf --- /dev/null +++ b/docs/images/service_dhcp-relay01.png diff --git a/docs/images/service_dhcpv6-relay01.png b/docs/images/service_dhcpv6-relay01.png Binary files differnew file mode 100644 index 00000000..9a10a10f --- /dev/null +++ b/docs/images/service_dhcpv6-relay01.png |
