Switch high availability options


There are various [Switch high availability options](/switch-high-availability-options) that can be used to provide redundancy and resiliency to a network.  The way these solutions deal with the [control plane](/network-control-plane) is an important part of deciding which to use.

VSS and StackWise (including [StackWise Virtual](/stackwise-virtual))  are designed to merge multiple physical switches into one logical unit, but they operate **with a single control plane**. This means there is only one physical switch that is actively using its control plane, managing the entire stack or VSS system. This provides equipment-level redundancy. If the control plane fails, the whole stack or VSS system is affected. However, this does not mean that the whole logical switch has failed. The other switch or switches will take over control plane operations almost immediately, with little to no downtime.

[vPC](/nexus-what-is-vpc) can also make multiple switches appear as a single logical unit, but with a crucial difference: each switch retains its own control plane. This independent control plane setup provides system-level redundancy because they both operate at the same time. This adds an additional aspect of redundancy. 

However, vPC can incorporate no more than two switches in a single vPC arrangement.  Also, vPC is only available on Cisco Nexus switches, which are designed for data centers and other high-availability applications. This is why vPC offers a higher level of redundancy compared to VSS or StackWise.

Links:

https://forum.networklessons.com/t/cisco-switch-virtualization/1164/20?u=lagapidis

https://networklessons.com/switching/cisco-switch-virtualization

Switch High Availability and the Control Plane

Security - GETVPN

Security - IEEE 802.1X

Security - IOS Usernames and Passwords

Security - IPsec nonce

Security - Kerberos

Security - MAC Authentication Bypass

Security - Network Access Control (NAC)

Security - Next Generation Firewall

Security - Secure Unique Device Identifier (SUDI)

Security - WPA 4-way handshake

Security - WebVPN

Security - accessing VTY from another VRF

Security - assigning privilege levels, syntax and behavior

Security - bogons

Security - broadcast-multicast storm

Security - configuring TACACS from another VRF

Security - privilege levels and command output

Security - privilege levels and enable keyword

Security - public key exchange

Security - root CAs and private keys

Security - spoofing

Security - storm control algorithm

Security IKE policy hash command

Security Trusted Platform Module (TPM)

Security aaa new-model

Security authentication on VTY lines

Security keyrings

Segment Routing

Serial - Data Communication Equipment (DCE)

Serial - Data Terminal Equipment(DTE)

Serial - Link between two routers

Serial Interface - Clock Rate

Serial Interface default broadcast address

Session Border Controller

Session Initiation Protocol

Show open TCP-UDP ports on Cisco router

Spanning Tree Protocol (STP)

Spine and leaf architecture - connections to leaf switches

Spine and leaf architecture - connections to spine switches

Spine and leaf architecture - reducing latency

Split-horizon

StackWise - IOS upgrade switch reboot sequence

StackWise Virtual

Stackwise - IOS install mode vs bundle mode

Stackwise election process

Stackwise user priority

Subscriber templating

Summarization

Supernetting

Switch configuring a routed port

Switch protected port limitations

Switch protected port

Switching -  CEF Adjacency Table

Switching - CEF

Switching - Media Access Control (MAC) addresses

Switching - Process switching

Switching - backplane

Switching - cut through

Switching - fast switching

Switching - show cable-diagnostics

Switching - store and forward

Switching - switch fabric

Switching - switched virtual interface (SVI)

Switching - switchport autostate command

Switching

Switchport - IEEE 802.1q

Switchport - ISL

Switchport - show vlan internal usage

Switchport access

Switchport modes

Switchport trunk configuration ignores access commands

Switchport trunk encapsulation

Switchport trunk

Symmetric Digital Subscriber Line (SDSL)

Syslog - Logging buffered command

Syslog - logging discriminator

Syslog - terminal monitor

Syslog relay or proxy

Syslog severity levels

Syslog

TCP - Congestion control

TCP - Determining the MSS

TCP - Header

TCP - SEQ and ACK values

TCP - Slow start

TCP - Three-way handshake

TCP - Urgent pointer field

TCP - Window Size Scaling

TCP - factors affecting segment size

TCP - role of checksum field

TCP MSS and window size

TCP RST flag

TCP SYN timeout

TCP header options

TCP phantom byte

TCP-IP model

TFTP

Switch High Availability and the Control Plane

Links to this page: