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Message #76649
[Bug 1803494] Re: [RFE] Add l2pop support for floating IP resources
Thanks for the update and the submission
** Tags removed: rfe
** Tags added: rfe-postponed
** Changed in: neutron
Status: New => Won't Fix
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https://bugs.launchpad.net/bugs/1803494
Title:
[RFE] Add l2pop support for floating IP resources
Status in neutron:
Won't Fix
Bug description:
Layer 2 population (l2pop) mechanism driver implements the ML2 driver
to improve open source plugins overlay implementations (VXLAN with
Linux bridge and GRE/VXLAN with OVS)[1]. L2pop avoid the broadcast in
MAC learning and ARP resolution by prepopulate the bridge forwarding
table[2]. However l2pop doesn’t have support for floating IP
resources. If the floating IP resources can be prepopulated, the
broadcast for scenarios when two VM instances, residing on different
networks, communicate via their respective FIP addresses can be
avoided.
Problem Description
==========================================================
Figure-1 illustrates the scenarios for floating IP. The IP address “182.34.4.2” in Port3 is the IP address in floating IP resources. When the client in the external network tries to access VM1, the destination IP “182.34.4.2” is replaced by the IP address “10.0.0.3” of the Port1. Notice that the IP address of Port1 is the IP address of VM1. When VM1 send packets back to client, the source IP “10.0.0.3” will be replaced by “182.34.4.2”.
(Attached in the comment)
Figure-1
Port1 10.0.0.3, Port2 10.0.0.1
Port3 182.34.4.2, Port4 188.34.4.1
When users want to use floating IP, they should first require
allocating a floating IP from floating IP pool or choose a pre
allocated floating IP. Allocating floating IP will create a new port
and also updates the new port. Creating port will never trigger l2pop
but updating port will trigger l2pop on the condition that the port’s
new status is ACTIVE or DOWN. However the status of the port for
floating IP will always be N/A. Thus allocating floating IP won’t
trigger l2pop.
After getting the available floating IP, users can require to
associate the VM and the floating IP. Associating the IP address of
the VM with the floating IP only updates the floating IP object and
doesn’t update the port for floating IP. Thus associating the VM and
the floating IP won’t trigger l2pop.
Based on the above analysis, the FDB of floating IP is not
prepopulated. It seems that to we can simply change the status of
Port3 from N/A to ACTIVE/DOWN to prepopulate the pair (MAC, IP) of
Port3 . But we can’t do that because the MAC address of Port3 is never
used. In the non-DVR scenario, the MAC address of router gateway will
be replied to answer the ARP request for floating IP. In the DVR
scenario, the MAC address of floating IP agent gateway will be replied
to answer the ARP request for floating IP.
In the following use case, ARP request will be sent out to query the
MAC address related to the specific floating IP. Figure-2 illustrates
an environment (DVR disabled) that there are two network nodes and two
compute nodes.
(Attached in the comment)
Figure-2
Port1 10.0.0.1, Port2 198.0.0.2
Port5 182.34.4.5, Port6 182.34.4.6
Use Case 1
1. Tenant-1 creates Network-1 and Tenant-2 creates Network-2.
2. Tenant-1 creates Subnet-1 belonging to Network-1 and Tenant-2 creates
Subnet-2 belonging to Network-2.
3. Tenant-1 creates Router-1 and links the Router-1 to the external provider
network External_Provider_Network. Tenant-2 creates Router-2 and links the
Router-2 to the same external provider network External_Provider_Network.
4. Tenant-1 links the Router-1 to the Subnet-1 and Tenant-2 links Router-2 to
the Subnet-2.
5. Tenant-1 creates VM-1 in Subnet-1 and Tenant-2 creates VM-2 in Subnet-2.
6. Tenant-1 creates FloatingIP-1 and Tenant-2 creates FloatingIP-2.
7. Tenant-1 associates VM-1 with FloatingIP-1 and Tenant2 associates VM-2 with
FloatingIP-2.
8. VM-1 communicates VM-2 by floating IP. For example: VM-1 pings FloatingIP-2
for the first time.
VM-1 has the IP address “10.0.0.1” which is the IP address of Port1
and VM-2 has the IP address “198.0.0.2” which is the IP address of
Port2. FloatingIP-1 has the IP address “182.34.4.5” and FloatingIP-2
has the IP address “182.34.4.6”(The related ports are not drawn). The
MAC address of Router-1 gateway(Gateway-1) is “fa:16:3e:1b:ee:2b” and
the MAC address of Router-2 gateway(Gateway-2) is “fa:16:3e:ab:cf:34”.
VM-1 and VM-2 reside on different networks and communicate via their
respective floating IP addresses. When VM-1 pings FloatingIP-2 for the
first time, since FloatingIP-2 is not in the same subnet as Port1,
VM-1 will send the the ICMP echo request directly to its default
gateway which is Gateway-1. And Gateway-1 will first send out an ARP
request for a FloatingIP-2 to resolve its MAC address. And the MAC
address “fa:16:3e:ab:cf:34” of Gateway-2 will be answered. After L2
MAC address resolution succeeding, L3 level protocols will route the
request to the correct destination. If the FDB is pre-populated, the
ARP request between the two router gateway interfaces can be avoided.
For non-DVR use case, (host_ip, router_gateway_mac_address,
floating_ip_address) should be prepopulated.
The figure-3 illustrates an environment (DVR enabled). The use case is
listed below:
Use Case 2
1. Tenant-1 creates Network-1 and Tenant-2 creates Network-2.
2. Tenant-1 creates Subnet-1 belonging to Network-1 and Tenant-2 creates
Subnet-2 belonging to Network-2.
3. Tenant-1 creates a distributed virtual router DVR-1 and Router-1 is the
distributed router on compute-1. Tenant-2 creates a distributed virtual
router DVR-2 and Router-2 is the distributed router on compute-2.
4. Tenant-1 links the DVR-1 to the external provider network
External_Provider_Network. Tenant-2 links the DVR-2 to the same external
provider network External_Provider_Network.
5. Tenant-1 links the DVR-1 to the Subnet-1 and Tenant-2 links DVR-2 to the
Subnet-2.
6. Tenant-1 creates VM-1 in Subnet-1 and Tenant-2 creates VM-2 in Subnet-2.
7. Tenant-1 creates FloatingIP-1 and Tenant-2 creates FloatingIP-2.
8. Tenant-1 associates VM-1 with FloatingIP-1 and Tenant2 associates VM-2 with
FloatingIP-2.
9. VM-1 communicates VM-2 by floating IP. For example: VM-1 pings FloatingIP-2
for the first time.
(Attached in the comment)
Figure-3
VM-1 has the IP address “10.0.0.1” which is the IP address of Port1
and VM-2 has the IP address “190.0.0.2” which is the IP address of
Port2. FloatingIP-1 has the IP address “182.34.4.5” which is the IP
address of Port5 and FloatingIP-2 has the IP address “182.34.4.6”
which is the IP address of Port6. When a floating IP is attached to a
VM, the L3 agent will create a FIP namespace (If one does not already
exist) for the external network that the FIP belongs to. After the
step 8, FIP-1 and FIP-2 will be created. Port9 is FIP-1 floating IP
agent gateway and Port10 is FIP-2 floating IP agent gateway. The MAC
address of Port9 is “fa:16:3e:e9:87:24” and the MAC address of Port10
is “fa:16:3e:e7:86:db”.
VM-1 and VM-2 reside on different networks and communicate via their
respective floating IP addresses. When VM-1 pings FloatingIP-2 for the
first time, since FloatingIP-2 is not in the same subnet as Port1,
VM-1 will send the the ICMP echo request directly to its default
gateway which is FIP-1 floating IP agent gateway. And FIP-1 floating
IP agent gateway will first send out an ARP request for a FloatingIP-2
to resolve its MAC address And the MAC address “fa:16:3e:e7:86:db” of
FIP-2 floating IP agent gateway will be answered. After L2 MAC address
resolution succeeding, L3 level protocols will route the request to
the correct destination. If the FDB is prepopulated, the ARP request
between the two floating IP agent gateway interfaces can be avoided.
For DVR use case, (host_ip, floatingip_agent_gateway_mac_address,
floating_ip_address) should be prepopulated.
Proposed Change
==================================================================
The idea is that advertising the FDBs for floating IP when the FIP status changes to "ACTIVE" and withdraw the FDBs for floating IP whenever the status is set to "DOWN" or the resource is deleted or disassociated.
Function _notify_fip_status will be added to send an event after
updating floating IPs. Function _delete_floatingip should be modified
to use _notify_fip_status to notify the floating IP status. Function
_update_fip_assoc is used by function _create_floatingip and
_update_floatingip. Both functions will send events after updating
floating IP with the result from _update_fip_assoc. Thus we can just
insert the status of floating IP into the result of _update_fip_assoc.
Function disassociate_floatingips already sends event out after
updating floating IP. However after disassociating floating IPs, the
router_id and fixed_port_id both are None. Thus need to insert
floating IP status, last_known_router_id and last_fixed_port_id into
the event.
A class L3RouterL2PopMixin should be added to process the event sent
after updating floating IP. This class should subscribe the event and
register the callback to l2pop mechanism driver to extend the l2pop
FDBs (Depends on RFE:
https://bugs.launchpad.net/neutron/+bug/1793653). Thus Callback
l3_fdb_extend_func should be added. Function handle_fip_status_update
should be added to process the event and send the l2pop FDBs out. For
non-DVR, (host_ip, router_gateway_mac_address, floating_ip_address)
should be prepopulated. For DVR, (host_ip,
floatingip_agent_gateway_mac_address, floating_ip_address) should be
prepopulated. What’s more, some other functions used by the functions
described above should be added.
All changes can be viewed through the link below:
https://review.openstack.org/#/c/611261/
https://review.openstack.org/#/c/611284/
Data Model Impact
============================================================
None
REST API Impact
============================================================
None
Command Line Client Impact
============================================================
None
Other Impact
============================================================
None
Other Deployer Impact
============================================================
None
Performance Impact
============================================================
Performance testing should be conducted to see test the overhead of adding more information to FDB.
Implementation
Assignee(s)
Work Items
===========================================================
Add function _notify_fip_status to neutron/db/l3_db.py and modify some existing functions in l3_db.py.
Add class L3RouterL2PopMixin to neutron/services/l3_router/service_providers/l2pop.py
Add related tests.
Dependencies
============================================================
Need the RFE “Enable other subprojects to extend l2pop FDB information” merged in OpenStack. This RFE enables other subprojects to extend l2pop FDB information. We need to add floating IP related information to l2pop FDB. Thus we need to use the ability provided by the RFE. The link for RFE is below:
https://bugs.launchpad.net/neutron/+bug/1793653
Testing
============================================================
Unit tests are necessary.
Documentation Impact
============================================================
None.
References
============================================================
[1] https://github.com/openstack/neutron/tree/master/neutron/plugins/ml2/drivers/l2pop
[2] https://wiki.openstack.org/wiki/L2population_blueprint
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