Revision as of 20:32, 17 November 2014

Mission statement and scope

The working group aims to define the use cases and identify and prioritise the requirements which are needed to deploy, manage, and run telecommunication services on top of OpenStack. This work includes identifying functional gaps, creating blueprints, submitting and reviewing patches to the relevant OpenStack projects and tracking their completion in support of telecommunication services.

The requirements expressed by this group should be made so that each of them have a test case which can be verified using an OpenSource implementation. This is to ensure that tests can be done without any special hardware or proprietary software, which is key for continuous integration tests in the OpenStack gate. If special setups are required which cannot be reproduced on the standard OpenStack gate, the use cases proponent will have to provide a 3rd party CI setup, accessible by OpenStack infra, which will be used to validate developments against.

Meetings

The working group meets alternating on Wednesdays between 1400 UTC in #openstack-meeting-alt and 2200 UTC in #openstack-meeting.

OpenStack IRC details

Upcoming Meetings

Agenda: [1]

Previous Meetings

• Meeting logs
• Juno Design Summit NFV BoF
• Kilo Ops Summit Telco Working Group

What is NFV?

NFV stands for Network Functions Virtualization. It defines the replacement of usually stand alone appliances used for high and low level network functions, such as firewalls, network address translation, intrusion detection, caching, gateways, accelerators, etc, into virtual instance or set of virtual instances, which are called Virtual Network Functions (VNF). In other words, it could be seen as replacing some of the hardware network appliances with high-performance software taking advantage of high performance para-virtual devices, other acceleration mechanisms, and smart placement of instances. The origin of NFV comes from a working group from the European Telecommunications Standards Institute (ETSI) whose work is the basis of most current implementations. The main consumers of NFV are Service providers (telecommunication providers and the like) who are looking to accelerate the deployment of new network services, and to do that, need to eliminate the constraint of slow renewal cycle of hardware appliances, which do not autoscale and limit their innovation.

NFV support for OpenStack aims to provide the best possible infrastructure for such workloads to be deployed in, while respecting the design principles of a IaaS cloud. In order for VNF to perform correctly in a cloud world, the underlying infrastructure needs to provide a certain number of functionalities which range from scheduling to networking and from orchestration to monitoring capacities. This means that to correctly support NFV use cases in OpenStack, implementations may be required across most, if not all, main OpenStack projects, starting with Neutron and Nova.

For more details on NFV, the following references may be useful:

• Definition of NFV by ETSI
• Definition of NFV on Wikipedia

Who we are

Members of the Telco Working Group come from a broad array of backgrounds and include service providers, equipment providers, and OpenStack vendors. We aim to include both operators and developers in an open discussion about the needs of this sector and how to meet them in OpenStack. You can find the current membership list of at TelcoWorkingGroup/Members. Feel free to add your name If you're interested in working with us to improve OpenStack for telecommunications workloads.

Use Cases

ETSI-NFV Use Cases - High Level Description

ETSI NFV gap analysis document: https://wiki.openstack.org/wiki/File:NFV%2814%29000154r2_NFV_LS_to_OpenStack.pdf

Use Case #1: Network Functions Virtualisation Infrastructure as a Service

This is a reasonably generic IaaS requirement.

Use Case #2: Virtual Network Function as a Service (VNFaaS)

This primarily targets Customer Premise Equipment (CPE) devices such as access routers, enterprise firewall, WAN optimizers etc. with some Provider Edge devices possible at a later date. ETSI-NFV Performance & portability considerations will apply to deployments that strive to meet high performance and low latency considerations.

Use Case #3: Virtual Network Platform as a Service (VNPaaS)

This is similar to #2 but at the service level. At larger scale and not at the "app" level only.

Use Case #4: VNF Forwarding Graphs

Dynamic connectivity between apps in a "service chain".

Use Case #5: Virtualisation of Mobile Core Network and IMS

Primarily focusing on Evolved Packet Core appliances such as the Mobility Management Entity (MME), Serving Gateway (S-GW), etc. and the IP Multimedia Subsystem (IMS).

Use Case #6: Virtualisation of Mobile base station

Focusing on parts of the Radio Access Network such as eNodeB's, Radio Link Control and Packet Data Convergence Protocol, etc..

Use Case #7: Virtualisation of the Home Environment

Similar to Use Case 2, but with a focus on virtualising residential devices instead of enterprise devices. Covers DHCP, NAT, PPPoE, Firewall devices, etc.

Use Case #8: Virtualisation of CDNs

Content Delivery Networks focusing on video traffic delivery.

Use Case #9: Fixed Access Network Functions Virtualisation

Wireline related access technologies.

Contributed Use Cases

Session Border Controller

Contributed by: Calum Loudon

Description

Perimeta Session Border Controller, Metaswitch Networks. Sits on the edge of a service provider's network and polices SIP and RTP (i.e. VoIP) control and media traffic passing over the access network between end-users and the core network or the trunk network between the core and another SP.

Characteristics

• Fast and guaranteed performance:
  • Performance in the order of several million VoIP packets (~64-220 bytes depending on codec) per second per core (achievable on COTS hardware).
  • Guarantees provided via SLAs.
• Fully high availability
  • No single point of failure, service continuity over both software and hardware failures.
• Elastically scalable
  • NFV orchestrator adds and removes instances in response to network demands.
• Traffic segregation (ideally)
  • Separate traffic from different customers via VLANs.

Requirements

• Fast & guaranteed performance (network)
  • Packets per second target -> either SR-IOV or an accelerated DPDK-like data plane:
    • "SR-IOV Networking Support" (https://blueprints.launchpad.net/nova/+spec/pci-passthrough-sriov) -completed 2014.2
    • "Open vSwitch to use patch ports" (https://blueprints.launchpad.net/neutron/+spec/openvswitch-patch-port-use) - patched 2014.2
    • "userspace vhost in ovd vif bindings" (https://blueprints.launchpad.net/nova/+spec/libvirt-ovs-use-usvhost) - BP says Abandoned?
    • "Snabb NFV driver" (https://blueprints.launchpad.net/neutron/+spec/snabb-nfv-mech-driver) - Not clear reasons of hold up (-2status )?
    • "VIF_VHOSTUSER" (https://blueprints.launchpad.net/nova/+spec/vif-vhostuser) -In code review, awaiting approval, kilo-1?

• Fast & guaranteed performance (compute):
  • To optimize data rate we need to keep all working data in L3 cache:
    • "Virt driver pinning guest vCPUs to host pCPUs" (https://blueprints.launchpad.net/nova/+spec/virt-driver-cpu-pinning) - Needs code review, kilo-1?
  • To optimize data rate need to bind to NIC on host CPU's bus:
    • "I/O (PCIe) Based NUMA Scheduling" (https://blueprints.launchpad.net/nova/+spec/input-output-based-numa-scheduling) - targeted kilo-1
  • To offer guaranteed performance as opposed to 'best efforts' we need:
  • To control placement of cores, minimise TLB misses and get accurate info about core topology (threads vs. hyperthreads etc.); maps to the remaining blueprints on NUMA & vCPU topology:
    • "Virt driver guest vCPU topology configuration" (https://blueprints.launchpad.net/nova/+spec/virt-driver-vcpu-topology) - implemented 2014.2
    • "Virt driver guest NUMA node placement & topology" (https://blueprints.launchpad.net/nova/+spec/virt-driver-numa-placement) - implemented 2014.2
    • "Virt driver large page allocation for guest RAM" (https://blueprints.launchpad.net/nova/+spec/virt-driver-large-pages) - proposed kilo, target for kilo-1
  • May need support to prevent 'noisy neighbours' stealing L3 cache - unproven, and no blueprint we're aware of.

• High availability:
  • Requires anti-affinity rules to prevent active/passive being instantiated on same host - already supported, so no gap.

• Elastic scaling:
  • Readily achievable using existing features - no gap.

• VLAN trunking:
  • "VLAN trunking networks for NFV" (https://blueprints.launchpad.net/neutron/+spec/nfv-vlan-trunks et al). - Needs resubmission by Ian Wells for approval

• "GTP tunnel support for mobile network for NFV VNFs like SGW, PGW, MME (https://blueprints.launchpad.net/neutron/+spec/provider-network.type-gtp -needs update for resubmission)

• Other:
  • Being able to offer apparent traffic separation (e.g. service traffic vs. application management) over single network is also useful in some cases.
    • "Support two interfaces from one VM attached to the same network" (https://blueprints.launchpad.net/nova/+spec/multiple-if-1-net) - implemented 2014.2

Virtual IMS Core

Contributed by: Calum Loudon

Description

Project Clearwater, http://www.projectclearwater.org/. An open source implementation of an IMS core designed to run in the cloud and be massively scalable. It provides SIP-based call control for voice and video as well as SIP-based messaging apps. As an IMS core it provides P/I/S-CSCF function together with a BGCF and an HSS cache, and includes a WebRTC gateway providing interworking between WebRTC & SIP clients.

Characteristics relevant to NFV/OpenStack

• Mainly a compute application: modest demands on storage and networking.
• Fully HA, with no SPOFs and service continuity over software and hardware failures; must be able to offer SLAs.
• Elastically scalable by adding/removing instances under the control of the NFV orchestrator.

Requirements

• Compute application:
  • OpenStack already provides everything needed; in particular, there are no requirements for an accelerated data plane, nor for core pinning nor NUMA

• HA:
  • implemented as a series of N+k compute pools; meeting a given SLA requires being able to limit the impact of a single host failure
  • potentially a scheduler gap here: affinity/anti-affinity can be expressed pair-wise between VMs, which is sufficient for a 1:1 active/passive architecture, but an N+k pool needs a concept equivalent to "group anti-affinity" i.e. allowing the NFV orchestrator to assign each VM in a pool to one of X buckets, and requesting OpenStack to ensure no single host failure can affect more than one bucket
  • (there are other approaches which achieve the same end e.g. defining a group where the scheduler ensures every pair of VMs within that group are not instantiated on the same host)
  • for study whether this can be implemented using current scheduler hints

• Elastic scaling:
  • as for compute requirements there is no gap - OpenStack already provides everything needed.

VLAN Trunking

The big picture is that this is about how service providers can use virtualisation to provide differentiated network services to their customers (and specifically enterprise customers rather than end users); it's not about VMs want to set up networking between themselves.

A typical service provider may be providing network services to thousands or more of enterprise customers. The details of and configuration required for individual services will differ from customer to customer. For example, consider a Session Border Control service (basically, policing VoIP interconnect): different customers will have different sets of SIP trunks that they can connect to, different traffic shaping requirements, different transcoding rules etc.

Those customers will normally connect in to the service provider in one of two ways: a dedicated physical link, or through a VPN over the public Internet. Once that traffic reaches the edge of the SP's network, then it makes sense for the SP to put all that traffic onto the same core network while keeping some form of separation to allow the network services to identify the source of the traffic and treat it independently. There are various overlay techniques that can be used (e.g. VXLAN, GRE tunnelling) but one common and simple one is VLANs. Carrying VLAN trunking into the VM allows this scheme to continue to be used in a virtual world.

In this set-up, then any VMs implementing those services have to be able to differentiate between customers. About the only way of doing that today in OpenStack is to configure one provider network per customer then have one vNIC per provider network, but that approach clearly doesn't scale (both performance and configuration effort) if a VM has to see traffic from hundreds or thousands of customers. Instead, carrying VLAN trunking into the VM allows them to do this scalably.

The net is that a VM providing a service that needs to have access to a customer's non-NATed source addresses needs an overlay technology to allow this, and VLAN trunking into the VM is sufficiently scalable for this use case and leverages a common approach.

From: http://lists.openstack.org/pipermail/openstack-dev/2014-October/047548.html

References:

• Network Functions Virtualization NFV Performance & Portability Best Practices - DRAFT
• ETSI-NFV Use Cases V1.1.1 [2]

Related Teams and Projects

• OpenStack Congress - Policy as a Service [3]

Development Efforts

Active Bugs

Add the "nfv" tag to bugs to have them appear in these queries:

• Nova: https://bugs.launchpad.net/nova/+bugs?field.tag=nfv
• Neutron: https://bugs.launchpad.net/neutron/+bugs?field.tag=nfv

Active Blueprints

The NFV use case mappings identified below are from the perspective of higher performing use cases. Please note that there are many possible configurations of devices for each of these use cases and it is not implied that they will all need the proposed capability in the relevant blueprint.

There is an automatically updated gerrit dashboard for all specs and code under review here: http://nfv.russellbryant.net

PRIORITY - repeatedly mentioned at the BOF as blockers:

The rest:

neutron port enhancement related to servicevm is summarized at https://wiki.openstack.org/wiki/ServiceVM/neutron-port-attributes

Implemented (Juno)

Needed Development Not Yet Started