License: (CC 3.0) BY-NC-SA

quantum.agent.l3_agent

L3PluginApi(proxy.RpcProxy)

a wrapper of prc call, only support get_routers(…) and get_external_network_id(…)

RouterInfo(object)

• store infomation of whole l3, not for router only
• it seems just hold a single router, the router’s value is stored in self.router
• _snat_action, according to current router info
• iptables_manager

L3NATAgent(manager.Manager)

• cfg: external_network_bridge, interface_driver, metadata_port, send_arp_for_ha, use_namespaces, router_id, handle_internal_only_routers, gateway_external_network_id, enable_metadata_proxy
• l3 will destroy all namespaces when init, unless router_id is set
• the destroy work is done by self.driver.unplug(device.name)
• _router_added(id, router) will cache it, and _create_router_namespace(ri) if needed, then ri.ip_tables_managedr.apply(), metadata_proxy will be spawned if needed
• process_router(ri) first scan all internal_ports of ri, append new ports, remove unactive ports, and do internal_network_{added,remove} respectively. if ex_gw_port is added, then invoke external_gateway_added(…) or if is removed, invoke external_gateway_removed(…). finally, update snat rules via ri.perform_snat_action(), update dnat via process_router_floating_ips() and update routes via routes.updated()
• it seems ex_gw_port can have many fixed_ips and _handle_router_snat_rules(…) will just use the first one
• process_router_floating_ips(ri, ex_gw_port) will scan all floating ips, if floating ip is new then floating_ip_added(…), if floating ip does not exist, floating_ip_removed(…), if floating ip -> fixed_ip has been changed, remapping it, floating_ip_removed() old and floating_ip_added new. ri cache is updated also.
• external_gateway_added(…) firstly ensure device exists via self.driver.plug(…), then self.driver.init_l3(…), then _send_gratuitous_arp_packet(…), then if ex_gw_port subnet’s gateway_ip exists, set default route gw
• external_gateway_removed(…) directly unplug the device
• external_gateway_nat_rules(…) generate rules, including internal_network_nat_rules(ex_gw_ip, internal_cidr), and POSTROUTING ! -i $if ! -o $if -m conntrack ! --ctstate DNAT -j ACCEPT
• internal_network_added(…) ensure device exist, then driver.init_l3(…) and _send_gratuitous_arp_packet(…)
• internal_network_removed(…) will directly unplug device from driver
• internal_network_nat_rules(ex_gw_ip, internal_cidr) just generate rule snat -s internal_cidr -j SNAT --to-source ex_gw_ip
• floating_ip_added(…) get interface_name via get_external_device_name(ex_gw_port.id), create IPDevice, add floating ip to device.addr and _send_gratuitous_arp_packet, then for floating_forward_rules(floating_ip, fixed_ip) iptables_manager.apply() them
• floating_ip_removed(…) will delete floating ip from device.addr and remove floating_forward_rules(…)
• floating_forward_rules(…) is PREROUTING -d $float -j DNAT --to $fix, OUTPUT -d $float -j DNAT --to $fix, float-snat -s $fix -j SNAT --to $float
• router_deleted -> _router_removed(id) with sync_sem and exception
• routers_updated -> wrapper with sync_sem and exception
• _process_routers(routers) remove routers not meet conditions and process others via process_router(ri)
• routes_update(ri) will replace changed route and delete removed route

why external network cannot use as internal network?

internal_network_added() will get interface name from get_internal_device_name(port_id), however, external network has different device prefix, so it will plug a new device to driver, which can be wrong or fail? and the following driver.init_l3 and gratuitous arp packet may fail too

L3NATAgentWithStateReport(L3NATAgent)

a looping report wrapper of l3NatAgent