V
virtual router
In the Extreme Networks implementations, virtual routers allow a single physical switch to
be split into multiple virtual routers. Each virtual router has its own IP address and
maintains a separate logical forwarding table. Each virtual router also serves as a
configuration domain. The identity of the virtual router you are working in currently
displays in the prompt line of the CLI. The virtual routers discussed in relation to Extreme
Networks switches themselves are not the same as the virtual router in VRRP.
In VRRP, the virtual router is identified by a virtual router (VRID) and an IP address. A
router running VRRP can participate in one or more virtual routers. The VRRP virtual router
spans more than one physical router, which allows multiple routers to provide redundant
services to users.
VEPA
Virtual Ethernet Port
Aggregator. This is a Virtual Machine (VM) server feature that works with the ExtremeXOS
Direct Attach Feature to support communications between VMs.
virtual link
In
OSPF, when a new area is introduced that does not have a direct
physical attachment to the backbone, a virtual link is used. Virtual links are also used to
repair a discontiguous backbone area.
virtual router
In the Extreme Networks implementations, virtual routers allow a single physical switch to
be split into multiple virtual routers. Each virtual router has its own IP address and
maintains a separate logical forwarding table. Each virtual router also serves as a
configuration domain. The identity of the virtual router you are working in currently
displays in the prompt line of the CLI. The virtual routers discussed in relation to Extreme
Networks switches themselves are not the same as the virtual router in VRRP.
In VRRP, the virtual router is identified by a virtual router (VRID) and an IP address. A
router running VRRP can participate in one or more virtual routers. The VRRP virtual router
spans more than one physical router, which allows multiple routers to provide redundant
services to users.
virtual router MAC address
In VRRP, RFC 2338 assigns a static MAC address for the first five octets of the VRRP
virtual router. These octets are set to 00-00-5E-00-01. When you configure the VRRP VRID, the
last octet of the MAC address is dynamically assigned the VRID number.
VLAN
Virtual LAN. The term VLAN is used to refer to a collection of devices that
communicate as if they are on the same physical LAN. Any set of ports (including all ports on
the switch) is considered a VLAN. LAN segments are not restricted by the hardware that
physically connects them. The segments are defined by flexible user groups you create with the
CLI.
VLSM
Variable-length subnet
masks. In
OSPF, VLSMs provide subnets of different sizes
within a single IP block.
VM
Virtual Machine. A VM is a logical machine that runs on a VM server, which can host
multiple VMs.
VMAN
Virtual MAN. In ExtremeXOS software, VMANs are a bi-directional virtual data
connection that creates a private path through the public network. One VMAN is completely
isolated from other VMANs; the encapsulation allows the VMAN traffic to be switched over Layer
2 infrastructure. You implement VMAN using an additional 892.1Q tag and a configurable
EtherType; this feature is also known as Q-in-Q switching.
VNS
Virtual Network
Services. An Extreme Networks-specific technique that provides a means of mapping wireless
networks to a wired topology.
VoIP
Voice over Internet Protocol is an Internet telephony technique. With VoIP, a voice
transmission is cut into multiple packets, takes the most efficient path along the Internet,
and is reassembled when it reaches the destination.
VPN
Virtual private network. A VPN is a private network that uses the public network
(Internet) to connect remote sites and users. The VPN uses virtual connections routed through
the Internet from a private network to remote sites or users. There are different kinds of
VPNs, which all serve this purpose. VPNs also enhance security.
VR-Control
This virtual router (VR) is part of the embedded system in Extreme Networks switches.
VR-Control is used for internal communications between all the modules and subsystems in the
switch. It has no ports, and you cannot assign any ports to it. It also cannot be associated
with VLANs or routing protocols. (Referred to as VR-1 in earlier ExtremeXOS software
versions.)
VR-Default
This VR is part of the embedded system in Extreme Networks switches. VR-Default is the
default VR on the system. All data ports in the switch are assigned to this VR by default; you
can add and delete ports from this VR. Likewise, VR-Default contains the default VLAN.
Although you cannot delete the default VLAN from VR-Default, you can add and delete any
user-created VLANs. One instance of each routing protocol is spawned for this VR, and they
cannot be deleted. (Referred to as VR-2 in earlier ExtremeXOS software versions.)
VR-Mgmt
This VR is part of the embedded system in Extreme Networks switches. VR-Mgmt enables
remote management stations to access the switch through Telnet, SSH, or SNMP sessions; and it
owns the management port. The management port cannot be deleted from this VR, and no other
ports can be added. The Mgmt VLAN is created VR-Mgmt, and 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.)
VRID
In VRRP, the VRID identifies the VRRP virtual router. Each VRRP virtual router is
given a unique VRID. All the VRRP routers that participate in the VRRP virtual router are
assigned the same VRID.
VRRP
Virtual Router Redundancy Protocol. VRRP specifies an election protocol that
dynamically assigns responsibility for a virtual router to one of the VRRP routers on a LAN.
The VRRP router controlling the IP address(es) associated with a virtual router is called the
master router, and forwards packets sent to these IP addresses. The election process provides
dynamic failover in the forwarding responsibility should the master router become unavailable.
In case the master router fails, the virtual IP address is mapped to a backup router's IP
address; this backup becomes the master router. This allows any of the virtual router IP
addresses on the LAN to be used as the default first-hop router by end-hosts. The advantage
gained from using VRRP is a higher availability default path without requiring configuration
of dynamic routing or router discovery protocols on every host. VRRP is defined in RFC
2338.
VRRP router
Any router that is running VRRP. A VRRP router can participate in one or more virtual
routers with VRRP; a VRRP router can be a backup router for one or more master
routers.
VSA
Vendor Specific
Attribute. An attribute for a
RADIUS server defined by the
manufacturer.(compared to the RADIUS attributes defined in the original RADIUS protocol RFC
2865). A VSA attribute is defined in order that it can be returned from the RADIUS server in
the Access Granted packet to the Radius Client.