NFV – Networking Concepts

5G, Cloud Computing, NFVI, Telco Cloud

NVF is consist of Compute, Storage and Networking functions. In this post, we will discuss some definitions related to Networking function of NFV.

  • TOR: TOR is Top of Rack. It is a switches sit at the very top of a Telco cabinet and aggregates data flow from chassis in the cabinet
  • EOR: EOR is End of Row. These are independent switches connected to each device in multiple cabinets and aggregates traffic from TOR switches
  • VLAN: It is Virtual local area network, helps devices in a LAN to logically partition multiple network segments to isolate broadcast domains in the same LAN. VLANs isolate communication between layer 2 and 3 over some ports on switches. Different VLANs can run simultaneously on the same switch.
    • Tag/Untag: A tag is a VLAN ID and identifies the VLAN of data packets. If a data packet is untagged, it does not belong to any VLAN.
    • PVID : Default VLAN ID of a port. It is allocated to a data frame if the frame carries no VLAN tag when reaching the port. Each port has a PVID, which is normally set to 1.
    • VLANIF: It is an independent logical interface that is not bound to any physical port. VLANs  interwork with each other at layer 2 according to MAC addresses rather than IP addresses.
      • To enable communication between layers 2 and 3, you must assign a VLANIF for a specified VLAN and configure a VLANIF IP address.
      • For example, after VLAN 10 is created, you can assign VLANIF 10 to it and configure the IP address for this VLANIF. VLANIF 10 serves as a layer-3 gateway for VLAN 10.
      • When users attempt to access external networks from VLAN 10, their data is sent to VLANIF 10, and the layer-3 switches obtain the data and routes it out.
  • VXLAN: It is Virtual Extensible LAN. With the help of the VXLAN technology, users can create about 16 million (rather than 4094 when VLAN technology is used) virtual networks that are isolated from each other. The VXLAN ID ranges from 1 to 2^24-1.
  • Trunk: Trunk is a linktype of an interface. A trunk interface connects to a switch and can connect only to a trunk link. A trunk interface allows frames from multiple VLANs to pass.
  • VRF: It is Virtual routing and forwarding. A switch can be virtualized into multiple VRFs, each of which has its own forwarding table and routing process. With only one switch, carriers can use multiple VRFs to simultaneously provide services to multiple users.
    • You can add layer-3 interfaces to different VRFs to logically separate a physical switch.
    • VRFs are isolated from each other at layer 3. If they must interwork with each other, route leaking technology is required.VRF technology can be used only at layer 3.
    • We can not add layer-2 interfaces to VRFs but must use VLANs to isolate networks at layer 2
  • Bonding: It is used to virtualize multiple NICs into one NIC to enable them to use the same IP address. This technology increases network throughput on hosts and improves availability.
  • SR-IOV: Single-root I/O virtualization. This is a hardware-based virtualization technology helps to efficiently share PCIe devices among VMs and directly mount virtualized PCIe devices to VMs. In this way, I/O performance on the VMs is similar to that provided by physical NICs.
  • Eth-trunk: An Eth-trunk is used to bind multiple physical Ethernet ports to a logical interface to increase the interface bandwidth, balance traffic loads, and back up links.
  • vNIC: Virtual network interface card.
    • The relationship between physical NICs on servers and physical networks is defined on the OpenStack web client.
    • VLAN information of virtual networks and physical networks which the virtual networks belong to are defined when you create virtual networks on OpenStack OM.
    • Mapping between vNICs and virtual networks is defined in the VNFD.
  • Stacking : Stacking is to combine one or more switches so that they function as only one switch. In this way, more ports are provided within limited space. Stacking technology provides high network reliability and scalability, while simplifying network management.
  • COTS: Commercial off-the-shelf. It refers to universal hardware.
  • East-West Traffic: The traffic between different VMs within a VNF is called east-west traffic.
  • North-South Traffic: The traffic between a VNF and other network elements including OM traffic is called north-south traffic.
  • PXE: Pre-boot execution environment. It is an Intel tool that helps users install an OS only with physical network connections.
  • First Node: The first host installed using a local PC is called the first node.
  • Plan: A plan in a VNFD contains detailed deployment information, such as the cluster information, server information, VLANs, IP addresses of interfaces, and the deployment scale. During network design, VNF virtual networks are classified into internal and external networks:
      • Networks that do not require external communication, such as data switching and data storage networks within a VNF, are planned as internal networks.
      • Networks that require external communication, such as the O&M and service networks between VNFs, are planned as external networks.

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