VSS – Virtual Switching System
– CISCO Protocol.
– Replaced by the Virtual Stackwise (same operating principle – in CISCO certifications, we only speak of VSS).
– Only available on the Catalyst 6500 and 4500 series running an IOS-XE.
The VSS protocol is a CISCO protocol that merges two CISCO Switches.
Advantage of the VSS:
– Simple to set up.
– Convergence rate between 100 and 200 ms in the event of a breakdown.
– No need for FHRP protocols such as HSRP, VRRP and GLBP.
– A single gateway IP address by VLAN instead of 3 (1 Active IP – 1 Passive IP – 1 Virtual IP).
– All our links are activated !!! (Unlike the Spanning Tree).
In order to merge our two Switches, we will have to:
– Create a VSS domain.
– Create a link between them (VSL link).
– Apply the configuration so that our two Switch reboot and merge.
– Choose a redundancy model.
Warning /!- Don't confuse the VSS with the StackWise !!!
– A VSS link is via "Normal" physical interfaces (Ethernet / Fibre)
– A StackWise link is done at the bottom of the basket with specific ports and cables !!!!
One Switch will become "Active" and the other will become "Standby". This helps to define who will be the conductor.
– Both of our equipment works simultaneously.
– The ARP and MAC tables are synchronized between our two equipments.
Switch-01 (config) - switch virtual domain 1 Switch-01 (config-vs-domain) - switch 1 Switch-01 (config-vs-domain) - switch 1 priority 110 Switch-01 (config-vs-domain) - switch 2 priority 100
Switch-02 (config) - virtual domain switch 1 Switch-02 (config-vs-domain) - switch 2 Switch-02 (config-vs-domain) - switch 1 priority 110 Switch-02 (config-vs-domain) - switch 2 priority 100
Switch-01 (config) - port-channel interface 1 Switch-01 (config-if) - virtual link switch 1 Switch-01 (config-if) no shutdown Switch-01 (config-if) Switch-01 (config) - TenGigaBitEthernet range interface 1/1 - 2 Switch-01 (config-if-range) channel-group 1 mode on Switch-01 (config-if-range) no shut
Switch-02 (config) - port-channel interface 1 Switch-02 (config-if) - virtual link switch 1 Switch-02 (config-if) no shutdown Switch-02 (config-if) Switch-02 (config) - TenGigaBitEthernet range interface 1/1 - 2 Switch-02 (config-if-range) channel-group 1 mode on Switch-02 (config-if-range) no shutdown
Switch-01 switch convert virtual mode Do you want to proceed[yes/no]? Yes
Switch-02 switch convert virtual mode Do you want to proceed[yes/no]? Yes
There are three modes of VSS redundancy:
– RPR – Route Processor Redundancy
– RPR – Route Processor Redundancy
– SSO – Stateful SwitchOver
RPR mode takes 2 minutes to switch.
It takes 30 seconds to switch to RPR mode.
SSO mode takes less than 1 second to switch.
Switch (config) - redundancy Switch (config-red) mode [ rpr | rpr-plus | sso ]
Switch (config) - redundancy Switch (config-red) - hand-cpu Switch (config-r-mc) auto-sync [ startup-config | config-register | bootvar ]
Nonstop Forwarding (NSF)
The NSF (NonStop Forwarding) only works with SSO mode.
It allows you to instantly converge from one switch to another when it comes to routing in the event of a breakdown!
Imagine that you are in Skype conversation and that the Switch (belonging to the VSS) through which your packages pass through breaks down.
Thanks to the NSF, this outage will become transparent to you!!
Switch (config) - router bgp as-number Switch (config-router) - bgp graceful-restart
Switch (config) - router eigrp as-number Switch (config-router)
Switch (config) - router ospf process-id Switch (config-router)
I found this video made by CISCO on Youtube, I strongly advise you to watch it 😉
I had to put it on !!!!
Hoping this article has been helpful to you! Don't hesitate to let me know!!
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