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What is a Virtual Router?

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TitleWhat is a Virtual Router?
Question
  • What is a virtual router in EXOS?
Environment
  • EXOS All
Answer

Virtual routers allow a single physical switch to be split into multiple VRs. Each VR maintains separate logical forwarding tables, allowing VRs to have overlapping IP addressing.
This virtual router (VR) is part of the embedded system in Extreme Networks switches.

Because a switch may have multiple VRs, some EXOS commands require specifying the VR to which the command applies.

Three VRs are created by default, VR-Mgmt, VR-Control, and VR-Default.

  • VR-Mgmt enables remote management stations to access the switch through Telnet, SSH, and SNMP sessions; it also owns the management port. No other ports can be added to VR-Mgmt, and the management port cannot be deleted from this VR, and no other ports can be added. The Mgmt VLAN (Virtual LAN) is created in VR-Mgmt during ExtremeXOS system boot-up, it cannot be deleted; you cannot add or delete any other VLANs or any routing protocols to this VR. (Referred to as VR-0 in earlier ExtremeXOS software versions.), and the Mgmt VLAN cannot be deleted from it. 
    There are 2 main reasons why VR Mgmt is preferred; Accessibility and Security
        1. Accessibility: Management traffic should be separated from user traffic to provide both access and reporting if there is a problem in the user traffic flow (loop, link problems, et cetera)
        2. Security: Separation of VR Mgmt from the VR Default, allows admins to ensure there is no management access to the devices from the user network.

  • VR-Control is used for internal communications between all the modules and subsystems in the switch. It has no external visible ports, and you cannot assign any port to it. VR-Control has no VLAN interface, and no VLAN can be created for it. No routing protocol is running on or can be added to VR-Control.

  • VR-Default is the default VR created by the ExtremeXOS system. By default, all data ports in the switch are assigned to VR-Default. Any data port can be added to and deleted from VR-Default. Users can create and delete VLANs in VR-Default. The Default VLAN is created in VR-Default during the ExtremeXOS system boot-up. The Default VLAN cannot be deleted from VR-Default. One instance of each routing protocol is spawned for VR-Default during the ExtremeXOS system boot-up, and these routing instances cannot be deleted. 

Additional notes
For further information on virtual routers, see the Virtual Routers" section of the EXOS User Guide.
The primary purpose for the VR Mgmt: http://documentation.extremenetworks.com/200_commands/_common/glossary/g_vr_mgmt.shtml
 

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