----- Original Message ----- > The L3 agent uses ARP and static routes like a normal router would. The L2 > agent is where there might be differences depending on the network type > used. If it's a tunnel overlay, the L2 agent may perform an ARP offload from > information it has learned via the L2 population mechanism. >
To expand on what Kevin is saying, the L3 agent currently does not support any sort of dynamic routing, and a Neutron virtual router may only have access to up to one external network. It can be (Directly) connected to many internal networks and performs static routing. If you connect a router to one external network (8.8.8.0/24) and two internal networks (10.0.1.0/24, 10.0.2.0/24) then you can observe the router's routing table and see that it has three routes to said network, as well as a default gateway (The external network's gateway). > On Sat, Mar 7, 2015 at 4:02 AM, Leo Y < [email protected] > wrote: > > > > Hello, I am looking to learn how neutron agent (probably L3) calculates a new > routing path when VM on compute node wants to communicate with some > destination. Does it use neutron API to learn about network topology or it > uses its internal structures to simulate path resolving like in real > network? If the latter is correct, then what happens when a network topology > is changed in neutron DB (due user intervention for by other actions) and > the "local" data is invalid? When a router is updated (Internal/external interface added/removed, floating IPs added or removed) then an update is sent to the relevant L3 agent which adds or removes the interface or floating IP. > > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: [email protected]?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > > > > > -- > Kevin Benton > > __________________________________________________________________________ > OpenStack Development Mailing List (not for usage questions) > Unsubscribe: [email protected]?subject:unsubscribe > http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev > __________________________________________________________________________ OpenStack Development Mailing List (not for usage questions) Unsubscribe: [email protected]?subject:unsubscribe http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
