Virtual Networking Devices

Overview

Virtual Networking Devices에 대한 기술 문서입니다.

Summary

• 무엇인가? - Virtual Networking Devices
• 왜 필요한가? - HPC 및 서버 환경에서 필수 개념
• 언제 사용하는가? - 서버 구성, 성능 튜닝, 문제 해결 시

Purpose

이 문서가 존재하는 이유

• Goal: Virtual Networking Devices에 대한 기술 정보 제공
• Scope: Virtual Networking Devices의 개념, 사용법, 설정
• Non-goals: 다른 주제로의 확장

Key Concepts

Concept	Description	Related
Virtual Networking Devices	HPC/서버 환경에서 중요한 기술 개념	Linux, Server

Detailed Explanation

In physical world, computer systems typically consist of one or more physical network adapter something like ethx, enox. However, in virtual networking world, TUN, TAP and veth Pairs are used for virtual network connectivity on host. which we can assign an IP to it, analyze the traffic, route traffic to it etc.

Ref - packetcoders io

• A “tap” device attached to one Linux bridge cannot be attached to another Linux bridge.
• All attached devices are switched into the promiscuous mode.
• The bridge itself (not a tap device at a port!) can get an IP address and may work as a standard Ethernet device. The host can communicate via this address with other guests attached to the bridge.
• Properly configured the bridge transfers packets directly between two specific bridge ports related to the communication stream of 2 attached guests – without exposing the communication to other ports and other guests. The bridge may learn and update the relevant association of MAC addresses to bridge ports.
• The virtual bridge device itself – in its role as an Ethernet device – does not work in promiscuous mode. However, packets arriving through one of its ports for (yet) unknown addresses may be flooded to all ports.
• You cannot bridge a Linux bridge directly by or with another Linux bridge (no Linux bridge cascading). You can neither connect a Linux bride to another Linux bridge via a “tap” device.

A virtual “tap” device is a virtual single point to point device - a file descriptor (fd) is read/written, operates in layer 2 carrying raw Ethernet frames - in user space program or inside of virtual machine. KVM/qemu virtualization uses vtap. Because it works at layer two, vtap transport any network protocols (IPv4, IPv6, Netalk, IPX, etc) and Ethernet frames but non-IP based traffic that can work with bridge not router. like vtap, vtun device is a single point to point device in user space program. however, it operates at layer 3 carrying IP based packets. vtun is commonly used by VPN clients to establish a connection between the client and the OS networking stack. This allows a VPN to encrypt your data before forwarding it onto the VPN server through the tunnel. Because vtun works at layer three of the networking stack, it deals exclusively in network protocol packets (IPv4 and IPv6 packets) and can only be used for routing (not for bridging) Both vtun and vtap devices are used by VPN clients to establish the tunnel. Without them, data encrypted by a VPN client would not be able to move from the client to the networking stack. In the case of VPNs, TAP is used to carry Ethernet frames and for bridging and TUN is used to carry IP packets (routing) Because VPN clients install TUN/TAP drivers on host system for you when you... [내용 계속]

Best Practices

• 최신 버전 사용 권장
• 공식 문서 참고
• 테스트 환경에서 먼저 검증

References

• Virtual Networking Devices

Related Pages

• Linux
• Server
• Hardware
• Network

Knowledge Graph

Related

→ Network → NIC Bonding → SDN → Linux → Docker