VLAN family history

 

Early Stage

In the early days, a vswitch was only a physical device and had no logic functions or IP addresses. It forwards data packets like a hub. The only advantage is that it does not live in a large conflict domain like a hub, causing a traffic accident all day long.

　　

Differences between VLANs and CIDR blocks: CIDR blocks are IP address segmentation specifications, which are private CIDR blocks, and which are public CIDR blocks, the number of available IP addresses in each CIDR block.

Vlan is a technology that isolates broadcast domains without geographic restrictions. It is equivalent to a vro interface with logical virtualization.

　　

1. Dark Age:

In the dark age, a switch can only forward data without vlan.

What? Do you want multiple CIDR blocks? Buy routing interfaces and switches!

A vro can separate broadcast domains. An interface is a vlan.

Drag the vswitch under each route interface of the vro !!!

(Hia ~, Black-hearted merchant's smile came from a distance)

　　

Ii. sprout

In this era, switches that support VLANs have finally emerged.

What should I do if I only support vlan without other technologies? First, select a vlan on the vswitch, and then attach N route interfaces to the vro. How about inserting each interface into different VLANs of the vswitch? Please?

However, you do not need to drag a vswitch behind each vro port to divide a vswitch into multiple vswitches. Saved some expenses

　　

Three-arm routing and trunk

A single-arm route refers to virtualizing multiple sub-interfaces on a single routing interface, and each sub-interface becomes a vlan gateway. VLANs can exchange data through sub-interfaces. Physically, we only need a vro to drag a vswitch with a network cable. We call it a single arm because only one network cable is used .. There is only one arm.

The link carried by the network cable connecting the vro to the vswitch is also called trunk.

The trunk can also be used to connect multiple switches so that a vlan can be transmitted across multiple switches.

Its working principle (802.1Q) is to label the packets in each vlan. In this way, the trunk can distinguish which vlan the packet belongs.

　　

　　

　　

Now

As the scale of the network expands, applications become increasingly diversified and complicated. The customer's demand for network stability is also growing. The industry has put forward a hierarchical design and modular functions. Each device or even multiple devices are used to complete an independent function. In this way, redundancy and hot backup can be performed on the device. In addition, if a feature is faulty, you can find the correct device.

This gave birth to a layer-3 Switch, that is, not only the layer-2 switching function but also the layer-3 routing function. From now on, the vswitch can do what the vro can do.

　　

SVI vswitch Virtual Interface

Vswitch Virtual Interface means that different VLANs in the LAN can be interconnected through the vswitch through a virtual outbound gateway. In terms of cost, there is no need for an external router. Disadvantage: A vswitch is a device that only needs to quickly exchange and forward data quickly. With the addition of the routing function, the vswitch is limited by the cpu query route table capability of the built-in router. The vswitch needs to query the route table every time it needs to be transmitted across vlan CIDR blocks.

　　

Five-time route multiple exchanges

The vswitch uses a stream mask. netflow mask records the source and destination ip addresses and port numbers.

You only need to route it once to switch it multiple times without needing to query it every time.

　　

Six CEF

CEF-Based Multi-layer switch cisco pxpress forwarding (three tables)

FIB table (forwarding information database)

Joining relationship table

Stream mask table

Direct Multiple exchanges without routing

This article is from "Xu Kai's IT blog ".