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Data communication foundation smart_ Link_&_ Monitor_ Link
2022-07-05 15:36:00 【GALi_ two hundred and thirty-three】
SmartLink
Technical background
When downstream equipment is connected to upstream equipment , Single uplink mode is prone to single point of failure , Cause business interruption . Therefore, double uplink mode is usually adopted , That is, one downstream device is connected to two upstream devices at the same time , To avoid single point of failure to the greatest extent , Improve network reliability .
The dual uplink networking shown in the above figure is a common networking model , There is a triangular layer-2 loop in the switching network , The conventional solution is to use spanning tree protocol to ensure redundancy and solve the loop problem , But the convergence rate of spanning tree protocol can only reach second level at most , This is unacceptable for some sensitive businesses .
In order to meet the user's requirements for rapid link convergence and simplify the configuration , We propose Smart Link Solution , Redundant backup of primary and standby links is realized , After the failure of the primary link, the traffic can be quickly switched to the standby link , Therefore, it has a high convergence speed .
Smart Link The main features are as follows :
Dedicated to dual uplink networking ;
Fast convergence ( Sub second level );
Simple configuration , It is convenient for users to operate .
Smart Link Technical advantages
Deploy on two-way devices , When the network is normal , In the two uplinks , One is active , The other one is in the backup state ( It does not carry business traffic ). In this way, the second floor loop will be broken .
When the primary link fails , Traffic will quickly switch to the standby link in milliseconds , Ensure the normal forwarding of data .
Smart Link Simple configuration , It is convenient for users to operate .
No protocol message interaction , The convergence speed and reliability are greatly improved .
Smart Link Group
One Smart Link The group contains two member interfaces , A main interface (Master Port) And a slave interface (Slave Port). Under normal circumstances , There's only one interface (Master or Slave) Be active (Active) state , The other interface is inactive (Inactive) The state is thus blocked .
When in Active When the interface of state fails ( The faults here include interfaces down、OAM Single pass, etc ),Smart Link The group will automatically block the interface , And will be in Inactive The state of the interface is switched to Active state .
Master/Slave Interface
- Master/Slave Interface is Smart Link Two interface roles in the Group , It is specified through the command line . When both interfaces are UP when ,Master Interface into Active state , You can send and receive data , and Slave The interface is Inactive state , Prohibit sending and receiving data .
- When Master When the interface or its link fails ,Slave The interface is switched to Active state .
Master link /Slave link
- We put Master The link where the interface is located is called Master link ( Or primary link ),Slave The link where the interface is located is called Slave link ( Or backup link ).
Send control VLAN
Send control VLAN(Send Control VLAN) yes Smart Link Groups are used to send Flush The message VLAN, The VLAN Specify... By command .
If in SW3 Open the Flush Message sending function and specified sending control VLAN, So when Smart Link When the group switches , The device will start from the new main interface 、 In sending control VLAN Send inside Flush message .
Receiving control VLAN
Receiving control VLAN It is an upstream device used to receive and process Flush The message VLAN.
If upstream equipment SW1、SW2 Able to identify Flush message , And turned on Flush Message receiving and processing function , When link switching occurs , The upstream equipment will process the received, which belongs to the receiving control VLAN Of Flush message , And then perform MAC Address table entries and ARP Refresh operation of table item .
Smart Link Working mechanism
Under normal circumstances ,Master Port be in Active state , and Slave Port be in inactive state . Therefore, the business traffic is forwarded according to the path shown in the figure . At this time, there is no layer 2 loop in the network .
When the link shown in the figure fails ,Port1 The state of becomes Down,SW3 Immediately perceive the change and trigger Smart Link State switching ( millisecond ),Port2 Immediately transition to Active state , The uplink traffic is forwarded as shown .
It is worth noting that , At this time, the upstream switch MAC Address table 、ARP Tables may still be entries before topology changes , Therefore, when going to the data of the business board ( Downstream traffic ) arrive SW1 or SW2 when , It may not be forwarded normally . At this point, you need to consider how to refresh SW1/SW2 Related forwarding table entries of .
Smart Link Network topology change mechanism
When Smart Link When link switching occurs , Of all devices in the network MAC Address forwarding table entries and ARP/ND Table entries may not be up-to-date , To ensure the correct sending of messages , Need to provide a MAC Address forwarding table entries and ARP/ND Update mechanism of table entries . At present, there are two update mechanisms :
from Smart Link The device sends from the new link Flush message . This method requires that all uplink devices can recognize Smart Link Of Flush Message and update MAC Address forwarding table entries and ARP/ND Processing of table items .
Automatically refresh through traffic MAC Address forwarding table entries and ARP/ND Table item . This method applies to and does not support Smart Link Functional devices ( Including equipment from other manufacturers ) Docking situation , Upstream traffic trigger is required .
Flush Mechanism
This solution requires :
1、 Upstream switch SW1 And SW2 Able to identify Smart Link Flush message , And configure processing and receiving Flush Message control VLAN.
2、SW3 Configure send Flush Message control VLAN
SW3 happen Smart Link After link switching , It's going to be new Active Interface (Port2) send out Flush message , The purpose is to quickly refresh the upstream switch SW1 And SW2 Related forwarding table entries of .
When the upstream equipment receives Flush When the message , Judge the sending control of the message VLAN Whether the receiving control of the interface receiving the message VLAN In the list . If not receiving control VLAN In the list , The device is not responsible for this Flush Messages are not processed , Forward directly ; If receiving control VLAN In the list , The device will extract Flush In the message VLAN Bitmap data , Put the equipment in these VLAN Learned in MAC And ARP Table entry deletion .
In order to ensure Flush The message is sending control VLAN Transmit correctly in , Please ensure that all interfaces on the dual uplink network allow sending control VLAN Colleague . otherwise , Flush The message will fail to be sent or forwarded .
Users are advised to keep Tag By sending Flush message , If you want to get rid of Tag By sending Flush message , Ensure that the peer interface defaults VLAN And send control VLAN Agreement , Otherwise, it will lead to Flush The message is not in transmission control VLAN Internal transmission .
Receiving is configured Flush In the case of messages ,Flush The message will trigger the device MAC Clear and ARP Aging learning action . This will take up a lot of equipment resources , In order to prevent network shock , It is not recommended to work in large-scale Smart Link Deploy receiving in the network Flush Message function .
Refresh table items through business traffic
This way applies to SW3 And don't support Smart Link Functional devices ( Including equipment from other manufacturers ) Docking situation , At this time, upstream traffic is required to trigger the upstream switching device SW1 And SW2 Refresh the related table items of ( Not like it Flush That kind of active refresh ).
SW2 And SW1 After receiving the traffic sent by the service board , Refresh your related table entries .
Link recovery mechanism
When Smart Link In the group Master Port When it breaks down ,Slave Port Will automatically switch to Active state . When Master Port After recovery , In order to keep the flow stable , It will remain at Inactive state , No preemption . If you need to restore it Active, It can be achieved in the following two ways :
Can make Smart Link Group failback function . After the failback timer expires, the main link will be automatically switched .
Use smart-link manual switch Command forced link switching .
if SW3 Of Smart Link Group activation failback function :
be Master Interface Port1 After recovering from a failure , Will be carried out in “ Role preemption ”, At a certain time delay ( default 60s) After the transition to Active state , and Port2 Then transition to Inactive state .
if SW3 Of Smart Link Group does not activate failback ( Not activated by default ):
be Master Interface Port1 After recovering from a failure , No state switching , Unless Port2 failure , Otherwise, maintain at Inactive state .
Basic configuration
There is a triangular layer-2 loop in the network , stay SW3 Upper Department Smart Link,GE0/0/21 Configure to Master Port,GE0/0/22 Configure to Slave Port. When the network is normal , By default, the business flow is from GE0/0/21 Interface forward , When the interface fails , Auto switch to GE0/0/22. When GE0/0/21 Recover from failure , Then the flow is switched back to GE0/0/21 Interface .
Intranet business VLAN by 10 And 20.
VLAN99 by Smart Link control VLAN
SW3 To configure :
[SW3]vlan batch 10 20 99
# stay Smart Link Close on the group member interface STP:
[SW3]interface GigabitEthernet 0/0/21
[SW3-GigabitEthernet0/0/21]stp disable
[SW3]interface GigabitEthernet 0/0/22
[SW3-GigabitEthernet0/0/22]stp disable
# The configuration interface type is trunk And release relevant VLAN( user VLAN And control VLAN)
[SW3]interface GigabitEthernet 0/0/21
[SW3-GigabitEthernet0/0/21]port link-type trunk
[SW3-GigabitEthernet0/0/21]port trunk allow-pass vlan 10 20 99
[SW3]interface GigabitEthernet 0/0/22
[SW3-GigabitEthernet0/0/22]port link-type trunk
[SW3-GigabitEthernet0/0/22]port trunk allow-pass vlan 10 20 99
( The system view ) establish Smart Link Group 1
[SW3]smart-link group 1
# To configure Master And Slave Interface :
[SW3-smlk-group1]port GigabitEthernet 0/0/21 master
[SW3-smlk-group1]port GigabitEthernet 0/0/22 slave
# Configure send control VLAN(99)
[SW3-smlk-group1]flush send control-vlan 99
# Activate the failback function :
[SW3-smlk-group1]restore enable
[SW3-smlk-group1]timer wtr 30 # Wait-to-restore, default 60s
[SW3-smlk-group1]smart-link enable
SW1 and SW2 To configure :
SW1:
[SW1]vlan batch 10 20 99
[SW1]interface GigabitEthernet 0/0/21
[SW1-GigabitEthernet0/0/21]port link-type trunk
[SW1-GigabitEthernet0/0/21]port trunk allow-pass vlan 10 20 99
[SW1-GigabitEthernet0/0/24]stp disable # close stp
[SW1-GigabitEthernet0/0/21]smart-link flush receive control-vlan 99 # Allow reception control vlan data
[SW1]interface GigabitEthernet 0/0/24
[SW1-GigabitEthernet0/0/24]port link-type trunk
[SW1-GigabitEthernet0/0/24]port trunk allow-pass vlan 10 20 99
[SW1-GigabitEthernet0/0/24]stp disable
[SW1-GigabitEthernet0/0/24]smart-link flush receive control-vlan 99
SW2:
[SW2]vlan batch 10 20 99
[SW2]interface GigabitEthernet 0/0/22
[SW2-GigabitEthernet0/0/22]port link-type trunk
[SW2-GigabitEthernet0/0/22]port trunk allow-pass vlan 10 20 99
[SW2-GigabitEthernet0/0/22]stp disable
[SW2-GigabitEthernet0/0/22]smart-link flush receive control-vlan 99
[SW2]interface GigabitEthernet 0/0/24
[SW2-GigabitEthernet0/0/24]port link-type trunk
[SW2-GigabitEthernet0/0/24]port trunk allow-pass vlan 10 20 99
[SW2-GigabitEthernet0/0/24]stp disable
[SW2-GigabitEthernet0/0/24]smart-link flush receive control-vlan 99
see smart Group Information
Turn off the interface test
[SW3]interface GigabitEthernet 0/0/21
[SW3-GigabitEthernet0/0/21]shutdown
After topology change ,G0/0/22 Will be sent in control vlan99 send out Flush package , Let the upper device refresh the topology
Monitor Link
Technical background
SW3 Deployed Smart Link Group , stay Port1 When the link to which it is connected fails ,Smart Link Be able to sense and realize fast switching , But when SW1 When the uplink link of fails ,Smart Link But I can't feel , There will be no switching .
Monitor Link It's right Smart Link A powerful complement to technology .Monitor Link Used to monitor the uplink , To achieve the purpose of synchronizing the downlink with the uplink state , send Smart Link The backup function of is more perfect .
Monitor Link Technical realization
Monitor Link Groups are also called monitoring link groups , By one or more uplink (Uplink) And down (Downlink) Interface composition . The state of the downlink interface changes with the state of the uplink interface .
Uplink interface (Uplink Port) yes Monitor Link Monitoring objects in the Group , It is specified through the command line Monitor Link An interface role of a group .
If multiple interfaces are configured as Monitor Link Group uplink interface , As long as one of these interfaces is in forwarding state , that Monitor Link The status of the group is UP;
Only when all The uplink interface fails when ,Monitor Link The status of the group is Down, At this time All downlink interfaces will be closed . When Monitor Link When the uplink interface of the group is not specified , It is considered that the uplink interface is faulty , All downlink interfaces will be closed .
Downlink interface (Downlink Port) yes Monitor Link Monitors in the Group , It is specified through the command line Monitor Link Another interface role of the Group .Monitor Link The downlink interface of the group can be Ethernet interface ( Electric port or optical port ) Or aggregate interface .
When Monitor Link When the uplink interface of the group returns to normal ,Monitor Link Only the downlink interface blocked due to uplink interface failure will be opened , The manually closed downlink interface cannot be opened . And a downlink interface failure has no impact on the uplink interface and other downlink interfaces .
Basic configuration
SW1 The configuration is as follows :
( The system view ) establish monitor link Group :
monitor-link group 1
# To configure monitor link Group uplink interface :
port gigabitethernet0/0/1 uplink
# To configure monitor link Downlink interface of the Group :
port gigabitethernet0/0/2 downlink
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