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TelcoWorkingGroup/UseCases

< TelcoWorkingGroup
Revision as of 18:09, 25 November 2014 by Sgordon (talk | contribs) (→‎Overview)

Overview

Workload Type Description Characteristics Examples Requirements
Data plane Tasks related to packet handing in an end-to-end communication between edge applications.
  • Intensive I/O requirements - potentially millions of small VoIP packets per second per core
  • Intensive memory R/W requirements
  • CDN cache node
  • Router
  • IPSec tunneller
  • Session Border Controller - media relay function
 -
Control plane Any other communication between network functions that is not directly related to the end-to-end data communication between edge applications.
  • Less intensive I/O and R/W requirements than data plane, due to lower packets per second
  • More complicated transactions resulting in (potentially) higher CPU load per packet.
  • PPP session management
  • Border Gateway Protocol (BGP) routing
  • Remote Authentication Dial In User Service (RADIUS) authentication in a Broadband Remote Access Server (BRAS) network function
  • Session Border Controller - SIP signaling function
  • IMS core functions (S-CSCF / I-CSCF / BGCF)
 -
Signal processing All network function tasks related to digital processing
  • Very sensitive to CPU processing capacity.
  • Delay sensitive.
  • Fast Fourier Transform (FFT) decoding
  • Encoding in a Cloud-Radio Access Network (C-RAN) Base Band Unit (BBU)
  • Audio transcoding in a Session Border Controller
 -
Storage All tasks related to disk storage.
  • Varying disk, SAN, or NAS, I/O requirements based on applications, ranging from low to extremely high intensity.
  • Logger
  • Network probe
 -

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

  • 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.
  • Other:

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:

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.

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