Open Stack

x-post from the dev list but also wanted to get any feedback or comments you all had.

Hi,

At Rackspace, we have a need to create a higher level networking service primarily for the purpose of creating a Floating IP solution in our environment. The current solutions for Floating IPs, being tied to plugin implementations, does not meet our needs at scale for the following reasons:

1. Limited endpoint H/A mainly targeting failover only and not multi-active endpoints,
2. Lack of noisy neighbor and DDOS mitigation,
3. IP fragmentation (with cells, public connectivity is terminated inside each cell leading to fragmentation and IP stranding when cell CPU/Memory use doesn't line up with allocated IP blocks. Abstracting public connectivity away from nova installations allows for much more efficient use of those precious IPv4 blocks).
4. Diversity in transit (multiple encapsulation and transit types on a per floating ip basis).

We realize that network infrastructures are often unique and such a solution would likely diverge from provider to provider. However, we would love to collaborate with the community to see if such a project could be built that would meet the needs of providers at scale. We believe that, at its core, this solution would boil down to terminating north<->south traffic temporarily at a massively horizontally scalable centralized core and then encapsulating traffic east<->west to a specific host based on the association setup via the current L3 router's extension's 'floatingips' resource.

Our current idea, involves using Open vSwitch for header rewriting and tunnel encapsulation combined with a set of Ryu applications for management:

https://i.imgur.com/bivSdcC.png

The Ryu application uses Ryu's BGP support to announce up to the Public Routing layer individual floating ips (/32's or /128's) which are then summarized and announced to the rest of the datacenter. If a particular floating ip is experiencing unusually large traffic (DDOS, slashdot effect, etc.), the Ryu application could change the announcements up to the Public layer to shift that traffic to dedicated hosts setup for that purpose. It also announces a single /32 "Tunnel Endpoint" ip downstream to the TunnelNet Routing system which provides transit to and from the cells and their hypervisors. Since traffic from either direction can then end up on any of the FLIP hosts, a simple flow table to modify the MAC and IP in either the SRC or DST fields (depending on traffic direction) allows the system to be completely stateless. We have proven this out (with static routing and flows) to work reliably in a small lab setup.

On the hypervisor side, we currently plumb networks into separate OVS bridges. Another Ryu application would control the bridge that handles overlay networking to selectively divert traffic destined for the default gateway up to the FLIP NAT systems, taking into account any configured logical routing and local L2 traffic to pass out into the existing overlay fabric undisturbed.

Adding in support for L2VPN EVPN (https://tools.ietf.org/html/draft-ietf-l2vpn-evpn-11) and L2VPN EVPN Overlay (https://tools.ietf.org/html/draft-sd-l2vpn-evpn-overlay-03) to the Ryu BGP speaker will allow the hypervisor side Ryu application to advertise up to the FLIP system reachability information to take into account VM failover, live-migrate, and supported encapsulation types. We believe that decoupling the tunnel endpoint discovery from the control plane (Nova/Neutron) will provide for a more robust solution as well as allow for use outside of openstack if desired.


________________________________________

Ryan Clevenger
Manager, Cloud Engineering - US
m: 678.548.7261
e: ryan.clevenger at rackspace.com<mailto:ryan.clevenger at rackspace.com>
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