1. principle
VSS is to virtualize two or more physical devices into one logical device, which can be stacked similarly. VSS can be divided into master switch and slave switch in the control layer, but the processing in the data layer is active and passive. From the point of view of network control level and management, it is an independent device entity on the network.
For neighbors, this virtual switching system is equivalent to a separate switch or router. In a virtual switching system, one chassis is designated as the active switch and the other is designated as the backup virtual switch. All control layer functions, including management (SNMP, Telnet, SSH, etc. ), Layer 2 protocols (BPDU, PDU, LACP, etc.). ), the third layer protocol (routing protocol, etc. ) and software data are managed by the engine of the active switch.
From the data layer and traffic forwarding, all switches in the virtual switching system participate in traffic forwarding. PFC on the super engine of the virtual master switch performs traffic forwarding lookup for all incoming active virtual switches, while PFC on the switch engine in backup state performs traffic forwarding lookup for all switches in backup state.
VSS improves the overall performance of the switch, simplifies management and reduces network protocols without using MSTP+VRRP scheme, and accelerates convergence performance. Realize network system virtualization, provide inter-chassis state switching (SSO), improve uninterrupted communication, and the switching time is less than < 〈200 ms；; ; Optimal path selection of cross-chassis ethernet channel.
Virtual switching system technology is to bind two chassis into a virtual switching system through a special link, which is called Virtual Switch Link (VSL). The protocol message processed by the master chassis is forwarded to the slave chassis through VSL.
? The function of VSS is to simplify the network topology, reduce the network complexity, shorten the recovery time and business interruption time, and improve the utilization rate of network resources.
Compared with the traditional L2/L3 network design, VSS provides outstanding advantages, which can be divided into the following four categories:
1)VSS improves the operational efficiency by simplifying the network and reduces the management overhead of the switch by at least 50%.
Provide a single management point, IP address and routing instance for the Cisco Catalyst 6500 virtual switch.
-Manage individual profiles and nodes. There is no need to configure redundant switches twice with the same policy.
-Only one gateway IP address is required for each VLAN, instead of using three IP addresses for each VLAN as it is now.
There is no need to use HSRP, VRRP and GLBP.
-Cisco Works LAN Management System (LMS) 3.0 can be used to centrally manage the Cisco Catalyst 6500 virtual switch as a single entity.
2) Multi-chassis Ethernet channel? (MEC) is an L2 multipath technology, which creates a simplified loop-free technology. It can still be activated without using spanning tree protocol, strictly preventing users from misconfiguring.
3) Flexible deployment options. The underlying physical switch does not have to be * * *. The two physical switches are connected through the standard 10 Gigabit Ethernet interface, and the distance between them is only limited by the selected 10 Gigabit Ethernet fiber length. For example, if you use X2- 10GB-ER 10 Gigabit Ethernet fiber, two switches can be 40 kilometers apart.
deploy
When configuring VSS, if two switches are interconnected, never select the same port channel group.
For example, T11/32 and T2/ 1/32 are port channels 9, so the port channels of T11/365438 and T2/ 1/32 are 65432.
If both port channels are 9 at the same time, the second switch will be restarted repeatedly after performing switch switching mode virtualization.
The VSS configuration of the startup-config configuration file on both switches must be consistent. If the priority or preemption function of the switch is updated, the configuration will not take effect until the configuration file is saved and the switch is turned on.
For line redundancy, configure at least 2 ports for each switch during VSL configuration; For module redundancy, 2 ports can be located on different switching modules of the chassis. ?
1) Configure vss domain and switch ID on CISCO 1. Both devices must be in the same domain.
Cisco- 1 (Configuration) # Switch Virtual Domain 100? //Configure the virtual switch domain on Cisco- 1 Cisco- 1 (configuration and domain) # switch 1? //Configure the virtual switch number from Cisco- 1 to 1.
Cisco-2(confgi)# switch virtual domain 100? //Configure a virtual switch domain on Cisco-2?
Cisco-2 (Configuration and Domain) # Switch 2? //Configure the virtual switch number of Cisco-2 to 2.
? 2) Switch priority setting
The high-priority switch becomes the active switch and the low-priority switch becomes the standby switch. If the priorities are the same, the switch ID is active and the switch ID is standby. ?
Independent switch 1:
Cisco- 1 (Configuration) # Switch Virtual Domain 100
Cisco- 1 (configuration and domain) # switch 1 priority 1 10
Cisco- 1 (Configuration and Domain) # Switch 2 Priority 100
Independent switch 2:
Cisco-2 (Configuration) # Switch Virtual Domain 100
Cisco-2 (configuration and domain) # switch 1 priority 1 10
Cisco-2 (Configuration and Domain) # Switch 2 Priority 100
? 3) configuration? Virtual switch links (VSL) and ports?
VSL is a dedicated Ethernet channel link that contains one or more (up to 8) physical ports. VSL has two functions:
1, in which only one physical member interface is selected as the control link to carry the system control information between chassis.
2. The remaining physical member interfaces carry network control information, and can also carry ordinary data traffic when necessary.
Cisco- 1 (Configuration) # Interface Port Channel 10// Configure the port channel on Cisco 1 to 10.
Cisco- 1(config-if)# Switch Virtual Link 1
//Configure Cisco 1 port Chanel 10 as a vsl link.
Cisco- 1 (configuration -if)# Do not shut down.
//Activate the port channel.
Cisco- 1 (configuration) # Interface range Tenigabit Ethernet11-2
Cisco-1(config-if) # channel-group 10 mode on//adds these interfaces to the channel group10.
Cisco- 1 (configuration -if)# Do not shut down.
Cisco-2 (Configuration) # Interface Port Channel 10// Configure the port channel on Cisco2 to 10.
Cisco-2 (config-if) # switchvirtuallink2//Configure the Cisco 2-port channel 10 as a vsl link.
Cisco-2 (config-if) # does not shut down//activate the port channel.
Cisco-2 (Configuration) # Interface Range tenigabitethernet 1/2-3
Cisco-2 (config-if) # channel-group 10 mode on//adds these interfaces to the channel group10.
Cisco-2(config-if)# does not shut down.
Because VSL Ethernet channel uses LMP for each member link, there is no need for link aggregation protocols such as PAgP and LACP. Each member link must be configured as unconditional Ethernet channel mode using the channel-group-group-number on mode on the command.
? 4) Finally, switch the two devices to virtual mode, that is, build VSS. ?
Independent Cisco- 1:
Cisco- 1# Switch Switching Mode Virtual
This command will convert all interface names.
According to the naming convention "Interface Switch-Number/Slot/Port",
Save the running configuration to the startup configuration, and
Reload the switch.
Do you want to continue? [Yes/No]: Yes
Translation interface name
Building structure ...
Independent Cisco-2:
Cisco-2# Switch Switching Mode Virtual
This command will convert all interface names.
According to the naming convention "Interface Switch-Number/Slot/Port",
Save the running configuration to the startup configuration, and
Reload the switch.
Do you want to continue? [Yes/No]: Yes
Translation interface name
Building structure ...
? Remember that VSS will not take effect until the configuration is saved and restarted.
The function of restarting the device:
1)2 configurations are merged into 1 configurations.
2) Renumber the ports-from slot/port to switch-number/slot/port.
3) Only by restarting the equipment can the A/S role be negotiated through NSF/SSO.
? 5) In VSS mode, you will enter all configuration commands on the active switch, and the startup configuration file will be automatically synchronized to the backup switch. In order to make VSS run normally, the main switch needs the VSL link configuration information of the backup switch at the other end.
? After the virtual command of switch acceptance mode is entered on the main switch, the updated configurations on the main switch and the backup switch will be automatically saved in their startup configuration files.
3. View VSS:
Display virtual switch
Display switch virtual roles
Display switch virtual links
Show all modules?
Display virtual redundancy of switch
Display redundancy status
Cisco said that under normal circumstances, the traffic on the VSL link between virtual switching systems is about 5% of the 10 Gigabit interface.
4. Design and configuration of 4.VSS active and passive manager.
? VSL link loss and recovery: If VSL fails, the standby chassis cannot determine the status of the active chassis. To ensure that there is no delay in the switchover, the standby chassis assumes that the active chassis fails and initiates the switchover to take over the active role.
? If the original active chassis is still running normally, then both chassis are active at this time. This situation is called a dual activity situation. The active-passive scheme will adversely affect the network stability, because the two chassis will use the same IP address, SSH key and STP bridge ID. The virtual switching system (VSS) must detect the double activity and perform the recovery operation. VSS supports enhanced PAgP, IP Bidirectional Forwarding Detection (BFD) and Double Activity Quick Greeting to detect double activities. Suggestion: If possible, please enable the VSLP fast Hello method based on ePAgP and direct heartbeat link.
? Configure VSLP Fast Hello of direct heartbeat link on the interconnection port of independent master-slave machine?
Quick Greeting Configure and Monitor VSS Active Virtual Switch: CISCO-VSS (Configuration) # Switch Virtual Domain 10CISCO-VSS (Configuration and Domain) # Double Active Detection Quick Greeting
CISCO-VSS (configuration) #intgi 1/4/48CISCO-VSS (configuration -if)# active fast-hello
CISCO-VSS (configuration -if)#intgi2/4/48CISCO-VSS (configuration -if)# Active-Active Fast Call %VSDA-SW2_SPSTBY-5-LINK_UP: Interface gi 1/4/48 now supports active detection% VSDA-SW/KLOC-.
Cisco-VSS # showswitch virtual dual-activefast-hello//View the fast-hello configuration.
EPAgP configures and monitors VSS active virtual switch: CISCO-VSS(config)# switch virtual domain10 Cisco-VSS (config-vs-domain) # dual active detection PAgP trust channel group 205CISCO-VSS# displays switch virtual dual active pagp.
PAgP dual active detection enable: Yes.
PAgP duplex: 1. 1! & lt& ltSnip & gt& gt
Neighbor switches supporting enhanced PAgP:
CISCO-VSS# displays PAgP active pagp.
double
-Active detection enabled: Yes
Double PAgP
-Active version: 1. 1
Dual active detection-exclusion interface
Once the active switch is detected, all ports on it will be disabled to ensure that the normal work of other networks will not be affected. However, we don't want the port used for management purposes to be disabled, because after the management port is disabled, the switch can't be managed remotely.
Cisco -VSS # conference test
Enter configuration commands, one per line. It ends with cntl/z.
CISCO-VSS (Configuration) #) # Switch Virtual Domain 10CISCO-VSS (Configuration-Domain) # Active Exclusion Interface Gig1/51Cisco-VSS (Configuration-Domain) # Active Exclusion Interface Gig 2/5//Kloc-.
4. Manual failover
Enter the command on the active switch to manually perform failover (after entering the command, the local switch will automatically restart and the standby machine will receive the active service):
Switch-1 # redundant forced switching
This will reload the active unit and force the switch to standby mode [OK].
Ready to switch ..
00:15:17:% sys-SW1_ sp-3-logger _ flushing: The system pauses to ensure the debugging output of the console.
5. What happens if all VSL connections between virtual switch members are lost?
VSL can configure up to 8 links between two switches and use any combination of line cards or management engine ports to provide high redundancy. If all VSL connections between members of the virtual switch are lost under extremely unexpected circumstances, and all members of the virtual switch are operating normally, VSS will turn to the active-passive recovery mode.
Dual activation status can be detected quickly (within one second) by one of the following two methods:
Connect a Cisco switch to improve the PAgP used by MEC.
L3 Bidirectional Forwarding Detection (BFD) configuration is performed on the direct link (except VSL) between members of the virtual switch, or through the L2 link of the access layer switch.
In the active-passive recovery mode, all interfaces except the VSL interface of the original active virtual switch member are in an operational shutdown state. The new primary virtual switch continues to forward traffic on all links.
6. Similar technologies are called CSS by Huawei, IRF by H3C and VSU by Ruijie.