Bug closed due to lack of activity, please feel free to reopen if
needed.
** Changed in: neutron
Status: Triaged => Won't Fix
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https://bugs.launchpad.net/bugs/1630981
Title:
[rfe] Implement l2pop driver functionality in l2 agent
Status in neutron:
Won't Fix
Bug description:
Summary
=======
We can implement l2pop driver functionality in l2 agent. Then we don't need a
separate l2pop driver(we can still maintain it for backward compatibility)
L2 agents(in master code base) already has all the information(some changes
needed) to create flows on its own without l2pop driver.
Existing functionality of l2pop:
===============================
L2pop driver on server side -
1) when port binding or status or ip_address(or mac) is updated, notify this
port's FDB(i.e port's ip address, mac, hosting agent's tunnel ip) to all agents
2) also checks if it is the first or last port on the hosting agent's
network, if so
a) notifies all agents to create/delete tunnels and flood flows to hosting
agent
b) notifies hosting agent about all the existing network ports on other
agents(so that hosting agent can create tunnels, flood and unicast flows to
these ports).
L2pop on agent side, after receiving notification from l2pop driver,
creates/deletes tunnel endpoints, flood, unicast and ARP ovs flows to other
agent's ports.
New Implementation:
==================
But the same functionality can be achieved without l2pop. Whenever a port is
created/updated/deleted, l2 agents get that port(ip, mac and host_id) through
port_update and port_delete RPC notifications. Agents can get get hostname[1]
and tunnel_ip of other agents through tunnel_update(and agents can locally save
this mapping).
As we are getting port's FDB trough these API, we can build the ovs flows
without l2pop FDB.
L2pop driver uses port context's original_port and new_port, to identify
changes to port's FDB. In the new implementation, agent can save port's
FDB(only required fields), so that new port update can be always compared with
saved FDB, and then identify changes to port's FDB.
We can use port's revision_number to maintain order of port's updates.
When l2 agent adds first port on a network(i.e Provisions a local VLAN
for the network), it can request server with a new RPC call to provide
all network port's FDB on other agents. Then it can create flows to
all these existing ports.
Implications:
============
DVR - Currently when DVR router port is bound, it notifies all agents[2]. But
server will set port's host_id to ''[3]. Need to change it to calling host and
check the implications.
HA - Port's host_id will always be set to master host. This allows
other agents to create flows to master host only. Need to update HA to
use existing DVR multiple portbinding approach, to allow other agents
to create flows to all HA agents.
Other TODO:
1) In existing implementation, port status updates(update_port_status) won't
notify agent. Need to enhance it.
Advantages:
==========
1) Existing l2pop driver code to identify 'active port count' on agent with
multiple servers can be buggy[4].
2) L2pop driver identifies first port on a agent and notifies it other port's
FDB through RPC. If this RPC is not reaching the agent for any reason(example,
that rpc worker dead),then agents can never establish tunnels and flows to
other agents.
3) We can remove additional l2pop mechanism driver on the server. Also can
avoid separate l2pop RPC consumer threads on agent and related concurrency
issues[5].
[1] need to patch type_tunnel.py to send hostname as argument for
tunnel_update.
[2]
https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/plugin.py#L1564
[3]
https://github.com/openstack/neutron/blob/master/neutron/plugins/ml2/plugin.py#L542
[4] Got stabilized with https://review.openstack.org/#/c/300539/
[5] https://bugs.launchpad.net/neutron/+bug/1611308
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