DHCP
""""

Schéma de base
''''''''''''''

.. graphviz::

  digraph "arch" {
   subgraph cluster_client {
    label="Client";
    "client_dhcp"[label="Client DHCP"];
   }
   subgraph cluster_client2 {
    label="Client 2";
    "client2_dhcp"[label="Client DHCP"];
   }
   subgraph cluster_client4 {
    label="Client 3";
    "client3_dhcp"[label="Client DHCP"];
   }
   subgraph cluster_client3 {
    label="Client 4";
    "client4_dhcp"[label="Client DHCP"];
   }
   subgraph cluster_chassis {
    label="Chassis Switch";
    "switch_relay"[label="Opt82 Relay to first server"];
   }
   subgraph cluster_chassis2 {
    label="Chassis Switch 2";
    "switch_relay2"[label="Opt82 Relay to second server"];
   }
   subgraph cluster_islet_switch {
     label="Islet Switch"
    "islet_router"[label="Router"];
   }
   subgraph cluster_islet_switch2 {
     label="Islet 2 Switch"
    "islet_router2"[label="Router"];
   }
   subgraph cluster_top_switch {
     label="Top Switch"
    "top_switch"[label="Switch"];
   }
   subgraph cluster_dhcp_server1 {
     label="Server 1"
    "server1_dhcp"[label="dhcpd"];
   }
   subgraph cluster_dhcp_server2 {
     label="Server 2"
    "server2_dhcp"[label="dhcpd"];
   }

    "client_dhcp" -> "switch_relay"[label="brodcast",color=green];
    "client2_dhcp" -> "switch_relay"[label="brodcast",color=green];
    "client3_dhcp" -> "switch_relay2"[label="brodcast",color=red];
    "client4_dhcp" -> "switch_relay2"[label="brodcast",color=red];
    "switch_relay" -> "islet_router"[label="unicast",color=green];
    "switch_relay2" -> "islet_router2"[label="unicast",color=red];
    "islet_router" -> "top_switch"[label="unicast",color=green];
    "islet_router2" -> "top_switch"[label="unicast",color=red];
    "top_switch" -> "server1_dhcp"[label="unicast",color=green];
    "top_switch" -> "server2_dhcp"[label="unicast",color=red];
  }


Description
'''''''''''
We suggest to use N DHCP servers, where the load balancing is done via DHCP relays in a static and predefined manner. Indeed, the current (and probably also the future) generation of supercomputers require the option 82 (`circuit-id` + `remote-id`). This requires to configure all the switches of each chassis with a DHCP relay.


The relays are configured using confiture, and the switches will be able to use different DHPC servers. The N servers will thus all be configured in the same way with the same configuration (generated by confiture), but each one will have a unique service IP address, allowing for static load balancing. 


.. raw:: latex

  \clearpage