Physical CPU architecture

A physical CPU in its simplest terms refers to a physical CPU core, that is, a physical hardware execution context (HEC), but can refer to a processor that manufactured to contain multiple physical cores.

If the physical CPU supports hyperthreading, then that enables a single processor core to act like two processors, that is, logical processors.

[ETSI definition: Device in the compute node, which provides the primary container interface. This is the generic processor, which executes the code of the VNFC⁽¹⁾.]

Physical CPUs with x86_64 architecture in the host that also supports: VT-x/AMD-V hardware acceleration and hyper-threading technology.

Hyper-threading is recommended to be enabled.

The identification of the virtualized MTAS infrastructure requirement was performed on Generic Ericsson Processor 5 (GEP5) boards which are equipped with Intel XEON E5-2658v2 (Ivy Bridge) processor.

vCPU⁽²⁾

[ETSI definition: The vCPU created for a VM⁽³⁾ by a hypervisor (see Section 6 Other Requirements). In practice, a vCPU can be a time sharing of a real CPU and/or in the case of multicore CPUs, it may be an allocation of one or more cores to a VM.]

vCPU-affinity can be used to isolate a physical CPU to a vCPU, by pinning the vCPU to a dedicated physical CPU.

vCPU affinity should be used to ensure that vCPUs of a VM never share (threads within) a physical CPU core with vCPUs of other VMs.

Number of vCPUs

[ETSI definition: VM is a virtualized computation environment that behaves very much like a physical computer or server. A VM has all its ingredients (processor, memory/storage, interfaces/ports) of a physical computer or server and is generated by a hypervisor (see Section 6 Other Requirements), which partitions the underlying physical resources and allocates them to VMs. VMs are capable of hosting a VNFC.]

The required minimum number of vCPUs per VM is 3.

The recommended minimum number of vCPUs per VM is 4.

Memory

Volatile RAM⁽⁴⁾ requires power to maintain the stored information. It retains its contents while powered on, but when the power is interrupted the stored data is lost rapidly or immediately.

[ETSI definition: This represents the virtual memory needed for the VDU⁽⁵⁾ or VM. VDU is a construct used in an information model and the VNF can be modeled using one or multiple such constructs, as applicable.]

The required minimum amount of memory of a VM with 4 vCPU is 25GB

The memory usage is dependent on the compute node hardware characteristics the VM size and the traffic model of the network. The number mentioned above is indicative of the memory usage required for a 4vCPU VM with a VoLTE traffic model in on GEP5 (6) hardware.

The characteristics and dimensioning documentation shall be used to determine the actual VM memory usage.

If available, it is recommended to use Huge pages (typically 1GB page size) for the memory of MTAS VMs.

Compute host

A compute host (or simply host) is the whole server entity providing computing resources, composed of the underlying hardware platform: processor, memory, I/O devices, and disk. The hypervisor (see Section 6 Other Requirements) may or may not be seen as part of the host.

[No ETSI definition]

The recommended minimum number of compute hosts with hardware and software redundancy is at least four.

Separate compute hosts are recommended for each of the four VMs (that is, 2 SC and 2 PL VMs).

In case persistent block storage service (such as Cinder) is not provided by the cloud environment, ephemeral storage should be used for the disk resources associated with the SC VMs. Thus the SC VMs should run on server blades with sufficient disk capacity.

Overcommitting CPU

CPU overcommitting is a hypervisor feature (see Section 6 Other Requirements) that allows a VM to allocate more virtualized CPUs than physical CPUs the host has available.

The term overallocation is also used for this feature.

[ETSI definition: The VDU can coexist on a platform with multiple VDUs or VMs and is as such sharing CPU core resources available in the platform. It can be necessary to specify the CPU core oversubscription policy in terms of virtual cores to physical cores/threads on the platform. This policy can be based on required VDU deployment characteristics such as high performance, low latency, and/or deterministic behavior.]

Overcommitting CPU is not allowed.

It compromises the predictability and dimensioning of capacity, latency, quality of service and other characteristics of the VM.

Overcommitting memory

Memory overcommitting is a hypervisor feature (see Section 6 Other Requirements) that allows the sum of all VM memory allocations to be bigger than the total memory of the host.

The term overallocation is also used for this feature.

[No ETSI definition]

Overcommitting memory is not allowed.

It compromises the predictability and dimensioning of capacity, latency, quality of service and other characteristics of the VM.

vNICs⁽¹⁾ per VM

[ETSI definition: NIC is a device in a compute node that provides a physical interface with the infrastructure network.]

[ETSI definition: vNIC is a virtualized NIC created for a VM by a hypervisor.]

An MTAS VM requires 4 vNICs with Virtio/vmxnet3 drivers:

• eth0 - <MTAS VNF>_internal network

• eth1 - <MTAS VNF>_OM_int network

• eth2 - <MTAS VNF>_om_sc_sp network

• eth3 - <MTAS VNF>_sig_sc_sp network

vNICs must be presented to the VM in a deterministic order during boot, since different networks and functions are statically assigned to the vNIC based on the order as they appear in the VM.

Virtual networks or VLANs⁽²⁾ per vNIC

[ETSI definition: Virtual network is a topological component used to affect forwarding of specific characteristic information.

The virtual network is bounded by its set of permissible network interfaces.

Virtual network forwards information among the network interfaces of VM instances and physical network interfaces, providing the necessary connectivity and ensures secure isolation of traffic from different virtual networks.]

A VLAN is the logical grouping of network nodes, which allows geographically dispersed network nodes to communicate as if they were physically on the same network.

The following four VLAN separated virtual networks are required by MTAS each having its own vNIC:

• <MTAS VNF>_internal

• <MTAS VNF>_OM_int

• <MTAS VNF>_om_sc_sp

• <MTAS VNF>_sig_sc_sp

It is recommended to use VLAN segmentation to separate virtual network.

Bandwidth of internal network

Internal network is a virtual network used for TIPC, Internal INET, and boot traffic.

The bandwidth is measured on the vNIC assigned to the internal network.

The cloud infrastructure must provide at least around 40 Mb/s per VM of bandwidth for a 2+2 MTAS VNF with 4 vCPU VMs.

• During PL/cluster reboot, the throughput can increase to 200 Mb/s

The bandwidth of the VNF internal network has impact on the duration of for example, the synchronization between the block storage on SCs (during installation), scaling of the VNF, and VM/VNF reboot.

The bandwidth usage is dependent on the compute node hardware characteristics and traffic model of the network. The numbers mentioned above are indicative of the bandwidth on the internal network required for a VM with VoLTE traffic model on GEP5 hardware. The characteristics and dimensioning documentation shall be used to determine the actual internal network bandwidth.

Bandwidth of the total virtual networks

The sum of the measured bandwidth of all vNICs connected to the VM.

The cloud infrastructure must provide at least the following bandwidth per VM for:

• vNIC eth1 <<1 Mb/s

• vNIC eth2 typically < 8 Mb/s (but it depends on: 1. How fast the charging data buffer is supposed to be emptied in the case of Rf link reestablishment, 2. How fast the charging data is supposed to be fetched from the ACR storage)

• vNIC eth3 8 Mb/s for a 2+2 cluster with 4 vCPUs (around 64 Mb/s for a 2+10 cluster with 9 vCPUs)

Total throughput of 57 Mb/s non-blocking switching is required from the underlying virtual switching infrastructure per VM for a 2+2 cluster with 4vCPU.

The bandwidth usage is dependent on the compute node hardware characteristics and traffic model of the network. The numbers mentioned above are indicative of the bandwidth of the external network required for a VM with VoLTE traffic on GEP5 hardware. The characteristics and dimensioning documentation shall be used to determine the actual bandwidth for external networks.

Pinning vNICs

Pinning vNICs to physical ports enables to manage the distribution of traffic. When pinning is set, all traffic from the vNIC travels through the I/O module to the specified Ethernet port.

[No ETSI definition]

Pinning vNICs to physical ports is not required.

L2 redundancy

To achieve telecom grade failure recovery, the vNIC interface is protected in the L2 infrastructure, for example, by using two physical NICs to achieve resiliency in the external switches, in case one switch plane is broken (assuming duplicated L2 switch).

[No ETSI definition]

Telecom grade availability of the virtual network is required for MTAS therefore L2 redundancy must be secured by the virtualization infrastructure.

L2/L3 QoS⁽³⁾

QoS settings at L2/L3 for the traffic are not changed within the virtual network boundaries.

[ETSI definition: Describes the QoS options to be supported on the VL, for example, latency and jitter.]

MTAS supports DSCP marking of outgoing packets therefore it is recommended that the Differentiated Services Code Points are considered at the L3 boundaries of the virtual networks.

L3 network separation

Overlap between the IP addresses used for a given network, and the IP addresses used for part of another network, where these networks are adjacent in the communication path.

[No ETSI definition]

L3 network separation is not required for MTAS on the <MTAS VNF>_internal and <MTAS VNF>_OM_int networks. On the other hand globally routable subnets have to be reserved for the OM (sysmgmt) and VIP FEE networks.

vNIC type

vNIC can be of access or trunk type. Each vNIC can have multiple IP interfaces either of the same or different type.

IP aliasing is the concept of creating or configuring multiple IP addresses on a single network interface.

In dual-stack configuration, the device is configured for both IPv4 and IPv6 network stacks. The dual-stack configuration can be implemented on a single interface or with multiple interfaces. In this configuration, the device decides how to send the traffic based on the destination address of the other device.

[No ETSI definition]

Support of multiple IP interfaces on access vNICs is provided. This includes the following:

• Multiple IP interfaces of the same IP version (alias interfaces) are required on the <MTAS VNF>_internal network (NFS, CP-M MIP addresses).

• Dual stack configuration, that is, both IPv4 and IPv6 interfaces.

IP address allocation

The process of assigning IP addresses to the vNICs that are associated to the VNF, including the permission for the assigning.

[No ETSI definition]

The MTAS application must be able to create its own IP interfaces. The cloud manager can assign subnets to the MTAS as long as the IP addresses in these subnets can be used freely by the MTAS application.

Moreover the virtualization infrastructure must allow packets to pass through virtual ports regardless of the subnet associated with the network.

Path supervision

Any path supervision protocols can be used, such as Gratuitous ARP⁽⁴⁾, ICMP⁽⁵⁾, or BFD⁽⁶⁾.

[No ETSI definition]

The virtualization infrastructure should support one of the following combinations:
1. Static Routing with BFD (preferred)
2. OSPFv2/OSPFv3 with BFD
3. OSPFv2/OSPFv3 with short OSPF timer. Gratuitous ARP and ICMP is required.

For further details refer to MTAS Internal and External Connectivity.

L3 redundancy

L3 redundancy can be provided by the VRRP⁽⁷⁾.

[No ETSI definition]

Redundant L3 routers (gateway routers) are required to provide the redundant static default routes on the VIP FEE networks.

Redundant gateways must provide a VRRP protected default route on the OM_ext infrastructure.

Booting network

The PXE⁽⁸⁾ specification describes a standardized client-server environment that boots a software assembly, retrieved from a network, on PXE-enabled clients. On the client side, it requires only a PXE-capable NIC, and uses a small set of industry-standard network protocols, such as DHCP⁽⁹⁾ and TFTP⁽¹⁰⁾.

The Dynamic Host Configuration Protocol (DHCP) is a standardized network protocol used on IP networks for dynamically distributing network configuration parameters, such as IP addresses for interfaces and services.

[No ETSI definition]

The virtualization infrastructure must not block PXE booting traffic generated by the MTAS. The cloud infrastructure provided DHCP service must be disabled.

IPv4 or IPv6

Internet Protocol version 4 (IPv4) and 6 (IPv6).

[No ETSI definition]

Virtualization infrastructure must support IPv4/IPv6 at the transport layer.

Routing protocol

OSPF⁽¹¹⁾ is an Interior Gateway Routing Protocol for IP networks based on the shortest path first or link-state algorithm.

BFD is a network protocol used to detect faults between two forwarding engines connected by a link, even on physical media that do not support failure detection of any kind.

Static routing is a form of routing that occurs when a router uses a manually configured routing entry, rather than information from a dynamic routing traffic. Static routes are fixed and do not change if the network is changed or reconfigured.

[No ETSI definition]

The virtualization infrastructure should support one of the following combinations:
1. Static Routing with BFD (recommended)
2. OSPFv2/OSPFv3 with BFD
3. OSPFv2/OSPFv3 with short OSPF timer.

The virtualization infrastructure shall support flow based Equal-Cost Multi-Path routing (ECMP).

For further details refer to MTAS Internal and External Connectivity.

NTP⁽¹²⁾

NTP is a networking protocol for clock synchronization between computer systems over packet-switched, variable-latency data networks.

[No ETSI definition]

All the VM instances must be able to access an appropriate NTP server.

DNS

The DNS is a hierarchical distributed naming system for computers, services, or any resource connected to Internet or to a private network. It translates domain names, which can be easily memorized by humans, to the numerical IP addresses.

[No ETSI definition]

All the VM instances must be able to access an appropriate DNS server.

Latency

Network latency in a packet switched network is measured either one way (the time from the source sending a packet to the destination receiving it), or round-trip delay time (the one-way latency from source to destination plus the one-way latency from the destination back to the source).

For a definition, refer to ITU-T Y.1540 and ITU-T G.1020.

For the recommended values, refer to ITU-T Y.1541 and ITU-T G.114.

[ETSI definition: Packet delay is the elapsed time between a packet being presented to the NFV⁽¹³⁾ virtual network from one VNFC guest OS instance to that same packet being presented to the destination VNFC guest OS instance. Packets that are delivered with more than the maximum acceptable packet delay for the VNF are counted as packet loss events and excluded from packet delay measurements.]⁽¹⁴⁾

Latency is required to meet general Telecom grade requirements.

Jitter

In packet switched networks, jitter is the variation in latency as measured in the variability over time of the packet latency across a network. Packet jitter is expressed as an average of the deviation from the network mean latency.

For a definition, refer to ITU-T Y.1540, ITU-T G.1020, and RFC 3393.

For the recommended values, refer to ITU-T Y.1541.

[ETSI definition: Packet delay variance (that is, jitter) is the variance in packet delay.]

Jitter is required to meet general Telecom grade requirements.

Packet loss

Packet loss occurs when one or more packets of data traveling across a computer network fail to reach their destination. Packet loss is measured as a percentage of packets lost divided by packets sent.

For a definition, refer to ITU-T Y.1540 and ITU-T G.1020.

For the recommended values, refer to ITU-T Y.1541.

[ETSI definition: Packet loss is the rate of packets that are either never delivered to the destination or delivered to the destination after the maximum acceptable packet delay of the VNF.]

Packet loss is required to meet general Telecom grade requirements.

VLAN tagging

VLAN Tagging is used to separate the traffic of different VLANs when VLANs span multiple switches. VLAN Tagging is done by inserting a VLAN ID into a packet header to identify to which VLAN the packet belongs. [No ETSI definition]

No specific requirements apply. When using VLAN network separation, VLAN tagging is performed by the vSwitch and other physical network infrastructure, but is not visible to the VNF. (e.g. MTAS sees all packets as ‘untagged’ by the different access vNICs).

MTU Size

The maximum transmission unit (MTU) is the largest packet size, measured in bytes that can be transmitted over a network. Any messages larger than the MTU are divided into smaller packets before being sent. Breaking them up slows down transmission speeds. Ideally, the MTU size should be the same as the smallest MTU size of all the networks between the local computer and a message's final destination. Note: Fragmentation in IPv6 is performed only by source nodes, not by routers along a packet's delivery path.

The recommended default IP MTU setting for IMSv VNF applications is 1452 on the core network interfaces.

Storage

Persistent storage space used for storing and retrieving digital information.

[ETSI definition: Required storage characteristics (for example, size), including KQIs⁽¹⁾ for performance and reliability/availability.]

Each System Controller (SC) VM must be configured with a disk.

The supported disk sizes:

• 200 GB

• 600 GB

• 950 GB

The chosen storage size of a SC VM must be able to hold all charging data (from all PL VMs) in the charging backup handler (ACR storage) in case of Rf communication failures.

The use of persistent block storage (Cinder volume) as SC disk resources is recommended however if no persistent block storage service is provided by the cloud environment ephemeral storage can be used for the disk resources associated with the SCs.

Storage performance

Performance capability of a storage device is determined by the following three factors:

• Speed or throughput or bandwidth: the speed at which data is transferred out of or into the storage device (normally measured in megabytes per second)

• IOPS: Input/Output Operations per Second (read and write)

• Latency: how long it takes for a storage device to start an I/O task (measured in fractions of a second).

Speed and IOPS values vary depending on the access operation (sequential or random).

[ETSI definition for latency: The latency in accessing a specific state held in storage to execute an instruction cycle.]

Typical read and write speed of block storage is 40 Mb/s which can increase to 120 Mb/s during upgrade

The required storage performance is dependent on the compute node hardware characteristics and traffic model of the network. The numbers mentioned above are indicative of storage performance for a VM with VoLTE traffic model on GEP5 hardware. The characteristics and dimensioning documentation shall be used to determine the actual required storage performance.

vNIC traffic separation

Different types of traffic are separated to provide security.

Traffic separation is secured in-line with Ericsson IMS security principles for further details refer to MTAS Internal and External Connectivity.

Trunk vNIC support

To support a high number of VLANs.

Trunk vNICs are not used by the virtualized MTAS for further details refer to MTAS Internal and External Connectivity.

Virtual Switch traffic separation

Different types of traffic are separated to provide security.

Virtual Switches in the hypervisor must be capable of switching packets based on the VLAN tags and provide separation for traffic with different VLAN tags.

Physical interfaces traffic separation

Different types of traffic are separated to provide security.

No hard requirement on physical separation. Traffic separation to be sorted out with VLAN segmentation on L2 level.

VNF isolation

VNFs are to be protected and isolated from other VNFs in the environment.

The hypervisor must ensure the security of VNFs by preventing interferences from other VNFs in the deployment that is memory, storage, and other resources assigned to a VNF are not to be accessible to other VNFs.

Hypervisor security against VNF escape attempts

VNFs are protected and isolated from other VNFs in the environment.

The hypervisor must prevent VNFs from “escaping” to the hypervisor. The hypervisor software is to be upgraded to remove security issues (several vulnerabilities on different hypervisors have been reported, which allows VNF to escape to the hypervisor).

OAM authentication and authorization

OAM protection of the hypervisor.

The hypervisor must implement proper authentication and authorization mechanisms to prevent users from accessing the hypervisor and perform malicious activities. Different accounts with different roles must be implemented. Audit trails logs must be implemented.

OAM access control to VNFs

Restrict access to VNFs.

OAM access control is required.

Hypervisor

A hypervisor, or VMM⁽¹⁾, is a piece of computer software, firmware, or hardware that creates and runs VMs. A computer on which a hypervisor is running one or more VMs is defined as a host machine. Each VM is called a guest machine. The hypervisor presents the guest operating systems with a virtual operating platform and manages the execution of the guest operating systems. Multiple instances of various operating systems can share the virtualized hardware resources.

[ETSI: Hypervisor is a piece of software that partitions the underlying physical resources and creates VMs, and isolates the VMs from each other.

The hypervisor is a piece of software running either directly on top of the hardware (bare metal hypervisor) or running on top of a hosting operating system (hosted hypervisor). The abstraction of resources comprises all those entities inside a computer or server that are accessible, like processor, memory/storage, or NICs. The hypervisor enables the portability of VMs to different hardware.]

MTAS is verified with qemu-KVM on X86_64 processors with VT-x extension

In theory any kind of hypervisor can be suitable that meets the computing, virtual networking and storage-related minimum cloud requirements as detailed above.

The hypervisor shall support “linux distribution” guest operating system.

Para-virtualized drivers

Para-virtualization is a virtualization technique that presents a software interface to VMs that is similar, but not identical to, the underlying hardware. The intent of the modified interface is to reduce the portion of the execution time spent for the guest performing operations that are substantially more difficult to run in a virtual environment compared to a non-virtualized environment.

Para-virtualized drivers are I/O device drivers that interact directly with the virtualization platform (with no emulation) to deliver disk and network access. This allows the disk and network subsystems to operate at near native speeds even in a virtualized environment, without requiring changes to existing guest operating systems.

[No ETSI definition]

MTAS requires support for para-virtualized drivers. This is required to achieve high performance and capacity characteristics in the system.

Installation

Any tools and environment-related software that is needed for installation.

In an Openstack environment Heat Orchestration Template (HOT) based deployment method shall be used.