A new MPLS note from quigo, which must be read when taking the IE exam ---- quigo of Shangwen network

This technology sharing will help you understand MPLS VPN Related knowledge , As we all know, whether Huawei, Cisco or Ruijie MPLS VPN Is a required knowledge , Now let's understand MPLS VPN.

MPLS VPN Equipment name
CE User edge devices
PE Operator edge devices
P Backbone equipment of operators

characteristic
PE and PE Establish between VPN Tunnel ,CE Users don't need to know vpn Related content , Just a user
It's dynamic VPN,MPLS Of LSP It is a natural tunnel , And this tunnel is through LDP The protocol is dynamically established , So the difference is GRE VPN Something static VPN

Problems to be solved
Address space overlaps

MPLS VPN working principle

Control plane （ Routing delivery ）
CE1-PE1 The routing
Enable any routing protocol
PE How to deal with overlapping address spaces
VRF Virtual routing forwarding （ In essence, it is a physical PE The equipment becomes several dedicated PE, Each virtual private PE Connect to a user , fictitious PE Separate from each other ）
Interface
agreement
Routing table
PE1-PE2 The routing
You have to use MPBGP
You can establish neighbors across routers
Support a large amount of routing information
High scalability , It can be easily compatible with new vpnv4 route
VPNv4 The birth of routing
VRF It is a concept of router locality , therefore PE1 Route to PE2 It's gone VRF, Cannot continue to distinguish conflicting routes
In order to distinguish conflicting routes in the delivery process , Added a new RD（ Route identifier ）, adopt RD The uniqueness of makes the route unique
RD Value guarantee is unique in the world
VPNv4=RD+IPv4
PE2-CE2 The routing
PE2 received PE1 After routing , How to determine which one you need to enter VRF example
adopt RT value
import RT
Compare the value when receiving the route
export RT
Carry this value when sending a route
Make sure to enter that VRF, Because of every VRF For one CE service , Then you can know the item is for that CE
Forwarding plane （ Message forwarding ）

Outer label （ Public label ）
Problem solved ： When routing P The device does not participate in the transmission, and there is no relevant routing information , There will be a routing black hole problem
MPLS LDP The agreement came into being
PE2 The next hop of sending data is PE1, And because the LDP Produced PE1 and PE2 Between LSP, Therefore, tag forwarding is performed , here P The device will receive MPLS message , Perform tag forwarding
Inner label
Problem solved ：PE2 Send the data to PE1 when ,PE1 How to know that you need to enter VRF Forward
Be careful ：RT Cannot do this job ,RT Route attributes when routing for the control plane , Here is the data sending process , Package source IP、 Purpose IP、MAC Address 、 Port number, etc , non-existent RT
MPBGP Allocated
When PE1 adopt MPBGP Pass routing information to PE2 when , except RD、RT It will also carry a label .PE2 The tag can be carried when sending data , Opposite end PE1 Check the inner label after receiving the data , Naturally, you can know to give that VRF

The whole is here
Join a group to talk about technology , If you have any questions, you can share them directly QQ Group ：316317765, You can also pay attention to the next official account. , More information will be released later .
----- Original by Kuige of Shangwen network