The documentation set for this product strives to use bias-free language. For the purposes of this documentation set, bias-free is defined as language that does not imply discrimination based on age, disability, gender, racial identity, ethnic identity, sexual orientation, socioeconomic status, and intersectionality. Exceptions may be present in the documentation due to language that is hardcoded in the user interfaces of the product software, language used based on RFP documentation, or language that is used by a referenced third-party product. Learn more about how Cisco is using Inclusive Language.
Easy Virtual Network (EVN) is an IP-based virtualization technology that provides end-to-end virtualization of two or more
Layer-3 networks. You can use a single IP infrastructure to provide separate virtual networks whose traffic paths remain isolated
from each other.
EVN builds on the existing IP-based virtualization mechanism known as VRF-Lite. EVN provides enhancements in path isolation,
simplified configuration and management, and improved shared service support. EVN is backward compatible with VRF-Lite to
enable seamless network migration from VRF-Lite to EVN.
EVN supports IPv4, static routes, Open Shortest Path First version 2 (OSPFv2), and Enhanced Interior Gateway Routing Protocol
(EIGRP) for unicast routing, and Protocol Independent Multicast (PIM) and Multicast Source Discovery Protocol (MSDP) for
IPv4 Multicast routing. EVN also supports Cisco Express Forwarding (CEF) and Simple Network Management Protocol (SNMP).
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information,
see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module,
and to see a list of the releases in which each feature is supported, see the feature information table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature
Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Configuring EVN
Implementing EVN in a network requires a single IP infrastructure that you want to virtualize into two or more logical networks
or L3VPNs. EVN provides path isolation for the traffic on the different virtual networks.
You must have a functioning campus design in place before adding virtualization to a network.
You should understand virtual routing and forwarding (VRF) instances and how they are used to maintain traffic separation
across the network.
Restrictions for EVN
An EVN trunk is allowed on any interface that supports 802.1q encapsulation, such as Fast Ethernet, Gigabit Ethernet, and
port channels.
There are additional platform and line-card restrictions for an EVN trunk. Check Cisco Feature Navigator, www.cisco.com/go/cfn for supported platforms and line cards.
A single IP infrastructure can be virtualized to provide up to 32 virtual networks end-to-end.
If an EVN trunk is configured on an interface, you cannot configure VRF-Lite on the same interface.
OSPFv3 is not supported; OSPFv2 is supported.
The following are not supported by EVN:
IS-IS
RIP
Route replication is not supported with BGP
Certain SNMP set operations
The following are not supported on an EVN trunk:
Access control lists (ACLs)
BGP interface commands are not inherited
IPv6, except on vnet global
Network address translation (NAT)
NetFlow
Web Cache Communication Protocol (WCCP)
Information About EVN
Benefits of EVN
Easy Virtual Network (EVN) is an IP-based virtualization technology that provides end-to-end virtualization over Layer-3
networks. Network virtualization can be used to secure a network and to reduce network expenses by utilizing the same network
infrastructure for multiple virtual networks. You can leverage the same physical infrastructure multiple times by supporting
multiple groups, each with their own logical network and unique routing and forwarding tables.
Prior to network virtualization, path isolation can be achieved by:
Separating pathis using dedicated routers which is more expensive than virtual networks.
Using access control lists (ACLs), but ACLs do not support unique routing and forwarding tables, can be expensive to maintain,
and more prone to error than virtual networks.
EVN provides the following benefits:
Reduced capital expenditures by not having to maintain separate physical infrastructures to keep traffic isolated. One IP
network has two or more virtual networks with traffic path isolation thereby saving the expense of additional hardware.
Increased business flexibility, due to the ease of network integration for mergers, acquisitions, and business partners.
Reduced network complexity due to a decrease in the infrastructure requirements for maintaining traffic separation through
the core of the network.
Build on the existing mechanism known as Multi-VRF (VRF-Lite). EVN is compatible with VRF-Lite. See the EVN Compatibility
with VRF-Lite section. EVN is recommended over VRF-Lite because EVN provides enhancements in path isolation, simplified configuration
and management, and improved shared service support.
In addition to maintaining traffic separation between business units within a company, there are other scenarios in which
path isolation is beneficial, including the following:
Guest access to the Internet—Restricting a guest’s network access to the Internet, using a predetermined data path through
the customer’s network, and being able to define a unique default route for guest traffic.
Network Admission Control (NAC) isolation—Isolating the traffic sourced from a noncompliant desktop.
Partner access—Restricting partners and contractors to access a network's shared services, such as the Internet, e-mail,
DNS, DHCP, or an application server.
Application and device isolation—Securing services and devices by “forcing” traffic to a centralized firewall where the traffic
is subject to inspection.
Outsourcing services—Separating data traffic of various clients from each other.
Scalable network—Restricting a portion of the network to traffic that requires a very strict service level, which can lower
costs by providing those requirements only where needed.
Subsidiaries/mergers/acquisitions—Consolidating companies or networks in stages, while enabling them to share services, when
required.
Enterprise acting as a service provider—Requiring a separate network under a single authority for autonomous groups. An example
is an airport authority supporting a virtual network per airline.
Virtual Network Tags Provide Path Isolation
It is not uncommon to have different user groups running on the same IP infrastructure. Various business reasons require
traffic isolation between different groups. The figure below shows two user groups, Red and Green, running on the same network.
Prior to network virtualization, there is no separation of traffic between the two groups. Users in the Red user group can
access the server in the Green user group, and vice versa.
Without network virtualization, path isolation can be achieved by using access control, which is expensive to maintain, prone
to error and does not support unique routing and forwarding tables per network.
Figure 1. Network without Virtualization
Virtual networks provide a coarse-grained segmentation of different user groups on one physical network. By configuring virtual
networks, you can virtualize a single IP infrastructure to provide a number of virtual networks end to end. In the figure
below, a single IP infrastructure is virtualized into two VPNs by creating two VRFs, Red and Green.
Figure 2. Network with Virtualization
In addition to utilizing VRFs to provide device-level separation, each virtual network has path isolation from the other.
Path isolation is achieved by tagging the traffic so it carries the same tag value throughout the same virtual network. Each
network device along the path uses the tags to provide separation among different VRFs. A single tag number ties VRF red,
for example, on one router to VRF red on another router.
Virtual Network Tag
Each VPN and associated EVN has a tag value that you assign during configuration. The tag value is global, meaning that on
each router, the same EVN must be assigned the same numerical tag value. Tag values range from 2 to 4094.
Note
When configuring EVN on a Cisco Catalyst 6500 Family networking device, we recommend you assign a vnet tag in the range 2
to1000. Beginning with Cisco IOS Release 15.1(1)SY, on the Sup2T platform of the Cisco Catalyst 6000 product lines, if the vlan internal allocation policy descending command is configured, the
vnet tag range is from 2 to 3900.
An EVN is allowed on any interface that supports 802.1q encapsulation, such as Fast Ethernet, Gigabit Ethernet, and port channels.
To allow for backward compatibility with the VRF-Lite solution, the vLAN ID field in the 802.1q frame is used to carry the
virtual network tag.
Traffic that carries a virtual network tag is called tagged traffic. Traffic that does not carry a virtual network tag is
called untagged traffic.
Tags are illustrated in the following configuration with two VRFs, red and green:
! Define two VRFs, red and green.
vrf definition red
vnet tag 101
!
address-family ipv4
exit-address-family
!
vrf definition green
vnet tag 102
!
address-family ipv4
exit-address-family
!
A virtual network is defined as a VRF instance with a virtual network tag assigned.
vnet Global
A predefined EVN known as “vnet global” is on the device. It refers to the global routing context and it corresponds to the
default RIB. In figure 2 and figure 3, vnet global is represented by a black line connecting routers. The vnet global carries
untagged traffic. By default, interfaces belong to the vnet global. Furthermore, vnet global is always running on trunk interfaces.
The vnet global is also known as the default routing table.
Note
IPv6 traffic is supported in vnet global only.
Edge Interfaces and EVN Trunk Interfaces
User devices are connected to a Layer 2 switch port, which is assigned to a VLAN. A VLAN can be thought of as a Layer 2 VPN.
Customers will group all of the devices that need to be supported in a common Layer 3 VPN in a single VLAN. The point where
data traffic is handed off between a VLAN and VRF is called an edge interface.
An edge interface connects a user device to the EVN and in effect defines the boundary of the EVN. Edge interfaces connect
end devices such as hosts and servers that are not VRF-aware. Traffic carried over the edge interface is untagged. The edge
interface classifies which EVN the received traffic belongs to. Each edge interface is configured to belong to only one EVN.
An EVN trunk interface connects VRF-aware routers together and provides the core with a means to transport traffic for multiple
EVNs. Trunk interfaces carry tagged traffic. The tag is used to de-multiplex the packet into the corresponding EVN. A trunk
interface has one subinterface for each EVN. The
vnettrunk command is used to define an interface as an EVN trunk interface.
An EVN interface uses two types of interfaces: edge interfaces and trunk interfaces. An interface can be an edge or trunk
interface, but not both. Figure 3 illustrates Routers A and D, which have edge interfaces that belong to VRF Red. Routers
D and E have edge interfaces that belong to VRF Green.
Routers B, C, D, F, and G have trunk interfaces that make up the EVN core. These five routers have interfaces that belong
to both VRF Red and VRF Green.
Figure 3. EVN Edge and EVN Trunk Interfaces
Identifying Trunk Interfaces in Display Output
Because a trunk interface carries multiple EVNs, sometimes it is not sufficient to display only the trunk interface name.
When it is necessary to indicate that display output pertains to a particular EVN running on the trunk interface, the convention
used is append a period and the virtual network tag, making the format
interface.virtual-network-tag. Examples are gigabitethernet1/1/1.101 and gigabitethernet1/1/1.102.
By default, when a trunk interface is configured, all of the EVNs and associated virtual network tags are configured, and
a virtual network subinterface is automatically created. As stated above, a period and the virtual network tag number are
appended to the interface number.
In the following example, VRF red is defined with virtual network tag 3. Hence, the system created Fast Ethernet 0/0/0.3
(in VRF red).
Router# show running-config vrf red
Building configuration...
Current configuration : 1072 bytes
vrf definition red
vnet tag 3
!
address-family ipv4
exit-address-family
!
You can display this hidden interface with the
showderived-config command and see that all of the commands entered on Fast Ethernet 0/0/0 have been inherited by Fast Ethernet 0/0/0.3:
Router# show derived-config interface fastethernet0/0/0.3
Derived configuration : 478 bytes
!
interface FastEthernet0/0/0.3
description Subinterface for VRF NG red
vrf forwarding red
encapsulation dot1Q 3
ip address 10.1.1.1 255.255.255.0
ip authentication mode eigrp 1 md5
ip authentication key-chain eigrp 1 x
ip bandwidth-percent eigrp 1 3
ip hello-interval eigrp 1 6
ip hold-time eigrp 1 18
no ip next-hop-self eigrp 1
no ip split-horizon eigrp 1
ip summary-address eigrp 1 10.0.0.0 255.0.0.0
end
Single IP Address on Trunk Interfaces
A trunk interface can carry traffic for multiple EVNs. To simplify the configuration process, all the subinterfaces and associated
EVNs have the same IP address assigned. In other words, a trunk interface is identified by the same IP address in different
EVN contexts. This is because each EVN has a unique routing and forwarding table, thereby enabling support for overlapping
IP addresses across multiple EVNs.
Relationship Between VRFs Defined and VRFs Running on a Trunk Interface
By default, the trunk interfaces on a router will carry traffic for all VRFs defined by the vrfdefinition command. For example, in the following configuration, every VRF defined on the router is included on the interface:
interface FastEthernet 1/0/0
vnet trunk
ip address 10.1.1.1 255.255.255.0
However, you might want to enable only a subset of VRFs over a certain trunk interface for traffic separation purposes. This
is achieved by creating a VRF list, which is referenced in the vnettrunk command. When a trunk interface is enabled with a VRF list, only VRFs on the list are enabled on the interface. The exception
is that vnetglobal is always enabled on the trunk interface.
In the following example, only the two specified VRFs on the list (red and green) are enabled on the interface:
vrf list mylist
member red
member green
!
interface FastEthernet 1/0/0
vnet trunk list mylist
ip address 10.1.1.1 255.255.255.0
VRF Awareness
A device connected to a virtual network may not understand virtual network tags and can send and receive only untagged traffic.
Such a device is referred to as VRF unaware. For example, a laptop computer is usually VRF unaware.
By contrast, a device that can send and receive tagged traffic and therefore takes the tag value into account when processing
such traffic is known as VRF aware. For example, a VRF-aware server shared among different EVNs could use the virtual network
tag to distinguish requests received and send responses. A VRF-aware device is connected to the EVN using a trunk interface,
as shown in figure 4.
Figure 4. VRF Aware Server
The term “VRF aware” can also be used to describe a software component running on the router. A software component is VRF
aware if it can operate on different EVNs. For example, ping is VRF aware because it allows you to choose which EVN to send
the ping packet over.
Routing Protocols Supported by EVN
Each EVN runs a separate instance of a routing protocol. This allows each EVN to fine-tune its routing separately and also
limits fate sharing. Different virtual networks may run different routing protocols concurrently.
EVN supports static routes, OSPFv2, and EIGRP for unicast routing, and PIM, MSDP, and IGMP for multicast routing.
Packet Flow in a Virtual Network
Packets enter an EVN through an edge interface, traverse multiple trunk interfaces, and exit the virtual network through
another edge interface. At the ingress edge interface, packets are mapped from a VLAN into a particular EVN. Once the packet
is mapped to an EVN, it is tagged with the associated virtual network tag. The virtual network tag allows the trunk interface
to carry packets for multiple EVNs. The packets remain tagged until they exit the EVN through the egress edge interface.
On the edge interface, the EVN associated with the interface is used for route lookup. On the trunk interface, the virtual
network tag carried in the packet is used to locate the corresponding EVN for routing the packets.
If the egress interface is an edge interface, the packet is forwarded untagged. However, if the egress interface is a trunk
interface, the packet is forwarded with the tag of the ingress EVN.
The figure below illustrates how traffic from two VRFs, red and green, can coexist on the same IP infrastructure, using the
tags 101 and 102.
Figure 5. Packet Flow in a Virtual Network
The packet flow from Laptop 1 to Server 1 in VRF red occurs as follows:
Laptop 1 send an untagged packet to Server 1.
Router A receives the packet over an edge interface, which is associated with VRF red.
Router A does route lookup in VRF red and sees that the next hop is Router B through a trunk interface.
Router A encapsulates the packet with VRF red’s tag (101) and sends it over the trunk interface.
Router B receives the packet over a trunk interface. Seeing virtual network tag 101, Router B identifies that the packet
belongs to VRF red.
Router B does route lookup in VRF red and sees that the next hop is Router C through a trunk interface.
Router B encapsulates the packet with VRF red’s tag (101) and sends it over the trunk interface.
Router C receives the packet over a trunk interface. Using virtual network tag 101, Router C identifies that the packet belongs
to VRF red.
Router C does route lookup in VRF red and sees that the next hop is Router D through a trunk interface.
Router C encapsulates the packet with VRF red’s tag (101) and sends it over the trunk interface.
Router D receives the packet over a trunk interface. Using virtual network tag 101, Router D identifies that the packet belongs
to VRF red.
Router D does route lookup in VRF red and sees that the next hop is through an edge interface.
Router D sends the untagged packet over the edge interface to Server 1.
Server 1 receives the untagged packet originated from Laptop 1.
Command Inheritance on EVN Trunk Interfaces
One of the benefits of EVN is the ability to easily configure multiple EVNs on a common trunk interface without the need
to configure each interface associated with an EVN individually. An EVN trunk interface takes advantage of the fact that the
configuration requirements for different EVNs will be similar over a single trunk interface. When specific commands are configured
on the trunk interface, they define default values that are inherited by all EVNs running over the same interface, including
vnetglobal. If you feel that the settings are acceptable for all of the EVNs sharing an interface, then no individual configuration
is necessary.
For example, the OSPF hello interval can be set for all EVNs over the trunk interface with one line of configuration, as
follows:
interface gigabitethernet1/1/1
vnet trunk
ip address 10.1.2.1 255.255.255.0
! set OSPF hello interval for all VRFs on this interface.
ip ospf hello-interval 20
The list of commands configured on the trunk interface whose values are inherited by all EVNs running on the same interface
is provided in the table in "Commands Whose Values Can be Inherited Or Overridden by a Virtual Network on an Interface" section.
For more examples of command inheritance, see the configuration examples in the Configuring Easy Virtual Networks module.
You might want some EVNs on the same trunk interface to have different configurations. An alternative to command inheritance
is to selectively override inherited values by using specific commands in virtual network interface mode for individual EVNs.
In this mode, the command’s settings override the Cisco default value or the value you set in interface configuration mode.
In interface configuration mode, entering the
vnetname command causes the system to enter virtual network interface mode. The system prompt for this mode is Router(config-if-vnet)#.
The list of commands whose inherited values can be overridden is provided in the table in the “Commands Whose Values Can
be Inherited Or Overridden by a Virtual Network on an Interface” section in this module.
Example: Overriding Command Inheritance
In the following example, the OSPF cost of 30 for VRF blue overrides the OSPF cost of 20 for the other VRFs on the interface:
interface gigabitethernet 2/0/0
vnet trunk
ip address 10.1.1.1 255.255.255.0
! Set OSPF cost for all VRFs on this interface to 20.
ip ospf cost 20
vnet name blue
description Subinterface for VRF NG blue
! Set OSPF cost for blue to 30.
ip ospf cost 30
The showderived command indicates the subinterface changed to a cost of 30:
Router(config-if-vnet)# do show derived | s interface GigabitEthernet2/0/0
interface GigabitEthernet2/0/0
vnet trunk
ip address 10.1.1.1 255.255.255.0
ip ospf cost 20
interface GigabitEthernet2/0/0.200
description Subinterface for VRF NG blue
vrf forwarding blue
ip address 10.1.1.1 255.255.255.0
ip ospf cost 30
Router(config-if-vnet)#
Example: Enabling an Attribute to vnet Global Only
Similarly, you might want to enable an attribute to vnet global only. To do so, use thevnetglobal interface submode, as follows:
interface gigabitethernet1/1/1
vnet trunk
ip address 10.1.2.1 255.255.255.0
vnet global
! Set OSPF cost for global to 40.
ip ospf cost 40
In this example, a user wants an EIGRP interface attribute set for all EVNs except vnet global. All EVNs inherit a hold time
of 20 seconds, except vnet global, which overrides 20 with a hold time of 40 seconds.
interface fastethernet 1/0/0
vnet trunk
ip address 10.1.3.1 255.255.255.0
ip hold-time eigrp 1 20
vnet global
ip hold-time eigrp 1 40
Removing Overrides and Restoring Values Inherited from EVN Trunk
The
no and
default keywords result in different outcomes, depending on whether they are used for a trunk interface or in virtual network interface
mode. This section describes the different outcomes.
When the
no or
default keyword is entered before a command on a trunk interface, the trunk is restored to the system’s default value for that command.
(This is standard behavior resulting for the
no or
default keyword).
When the
default keyword is entered before a command in virtual network interface mode, the override value is removed and the value that is
inherited from the trunk is restored. The override value for the specific EVN is no longer in effect.
In the following example, the trunk interface is configured with an OSPF cost of 20, but VRF blue overrides that value with
an OSPF cost of 30:
interface gigabitethernet 2/0/0
vnet trunk
ip address 10.1.1.1 255.255.255.0
! Set OSPF cost for all VRFs on this interface to 20.
ip ospf cost 20
vnet name blue
! Set OSPF cost for blue to 30.
ip ospf cost 30
When the following commands are entered, the OSPF cost value is restored to 20, which is the cost inherited from the trunk
interface. (Note that 20 is not the default value of the
ipospfcost command.)
Router(config-if)# vnet name blue
Router(config-if-vnet)# default ip ospf cost
The
default keyword entered before a command in virtual network interface mode restores the default state, but the
no keyword does not always do that. In the following example,
noipdampening-changeeigrp1 disables dampening change.
interface Ethernet1/1
vnet trunk
ip dampening-change eigrp 1 50
shutdown
vnet name red
no ip dampening-change eigrp 1
! Make sure vnet red does NOT have dampening change enabled, regardless of trunk setting. !
Determining if No Form of Command Appears in Configuration File
If a command is the type of command that switches a feature on or off, the
no form of the command will appear in the configuration file when configured. That is, nonvolatile generation (NVGEN) overrides
the setting from the EVN trunk, as shown in the following example:
interface gigabitethernet 2/0/0
vnet trunk
ip access-group 1 in
vnet name red
no ip pim sparse-mode
no ip route-cache cef
no ip access-group in
vnet global
ip ospf cost 100
If a command takes an argument in its syntax, such as
ipospfcostcost , the
no form of the command will remove the configuration, but does not appear in the configuration file. That is, it will not be
NVGEN’ed because the user could enter
ipospfcostdefault-value to override the inherited value in a more direct way.
EXEC Commands Routing Context
There may be occasions when you want to issue several EXEC commands to apply to a single EVN. In order to reduce the repetitive
entering of VRF names for multiple EXEC commands, the
routing-contextvrf command allows you to set the VRF context of EXEC commands once, and then proceed using EXEC commands.
The table below shows four EXEC commands without routing context and in routing context. Note that in the left column, each
EXEC command must identify the VRF. In the right column, the VRF content is identified once and the prompt changes to reflect
that VRF; there is no need to identify the VRF in each command.
Table 1. EXEC Commands Routing Context
EXEC Commands Without Routing Context
EXEC Commands Routing Context
—
Router# routing-context vrf red
Router%red#
Router# show ip route vrf red
[Routing table output for VRF red]
Router%red# show ip route
[Routing table output for VRF red]
Router# ping vrf red 10.1.1.1
[Ping result using VRF red]
Router%red# ping 10.1.1.1
[Ping result using VRF red]
Router# telnet 10.1.1.1 /vrf red
[Telnet to 10.1.1.1 in VRF red]
Router%red# telnet 10.1.1.1
[Telnet to 10.1.1.1 in VRF red]
Router# traceroute vrf red 10.1.1.1
[Traceroute output in VRF red]
Router%red# traceroute 10.1.1.1
[Traceroute output in VRF red]
EVN Compatibility with VRF-Lite
EVN is wire compatible with VRF-Lite. In other words, on the outside, 802.1q, SNMP MIBs, and all the EVN infrastructure
will look exactly the same as VRF-Lite.
In the figure below, both routers have VRFs defined. The router on the left uses VRF-Lite, and the router on the right uses
an EVN trunk with tags. The two configurations follow the figure.
VRF-Lite Subinterface Configuration EVN Trunk Configuration
interface TenGigabitEthernet1/1/1 interface TenGigabitEthernet 1/1/1
ip address 10.122.5.31 255.255.255.254 vnet trunk
ip pim query-interval 333 msec ip address 10.122.5.32 255.255.255.254
ip pim sparse-mode pim sparse-mode
logging event link-status logging event link-status
interface TenGigabitEthernet1/1/1.101 Global Configuration:
description Subinterface for Red VRF vrf definition red
encapsulation dot1Q 101 vnet tag 101
ip vrf forwarding Red
ip address 10.122.5.31 255.255.255.254 vrf definition green
ip pim query-interval 333 msec vnet tag 102
ip pim sparse-mode
logging event subif-link-status
interface TenGigabitEthernet1/1/1.102
description Subinterface for Green VRF
encapsulation dot1Q 102
ip vrf forwarding Green
ip address 10.122.5.31 255.255.255.254
ip pim query-interval 333 msec
ip pim sparse-mode
logging event subif-link-status
Multiaddress Family VRF Structure
Prior to Cisco IOS Releases 12.2(33)SB and 15.0(1)M, the CLI for a VRF applied to only one address family at a time. For example,
the ipvrfblue command applies only to the IPv4 address family.
In Cisco IOS Releases 12.2(33)SB and 15.0(1)M, the CLI for a VRF applies to multiple address families under the same VRF.
This is known as multiprotocol VRF. For example, the vrfdefinitionblue command applies to IPv4 and IPv6 VPNs at the same time, but the routing tables for the two protocols are still different.
Note
In Cisco IOS XE Release 3.2S, virtual networks do not support IPv6 except in vnetglobal.
QoS Functionality with EVN
Quality of Service (QoS) configurations are applied to the main physical interface on an EVN trunk. The QoS policy affects
all traffic that flows out the physical interface in all the VRFs at the same time. In other words, QoS and network virtualization
are mutually independent. For example, traffic marked with the DSCP value specified for voice will be put into the voice queue
if the packet is from the red VRF, blue VRF, or green VRF. The traffic for all the VRFs will be queued together.
Commands Whose Values Can be Inherited Or Overridden by a Virtual Network on an Interface
As explained in the "Command Inheritance on EVN Trunk Interfaces" section, there are interface commands that are defined
once for a trunk interface, and the value is inherited by each EVN sharing the interface. These commands are sometimes referred
to as trunk commands.
A subset of the trunk commands are commands whose values can be overridden by specifying the command in virtual network interface
mode. This is explained in the "Overriding Command Inheritance Virtual Network Interface Mode" section.
The table below lists interface commands and indicates whether the values are inherited by the EVNs on the interface and
whether the commands can be overridden for a specific EVN.
Table 2. Interface Command Values Inherited or Overridden by a Virtual Network on an Interface
Values Inherited by EVNs on Interface?
Values Can Be Overriden in Virtual Network Interface Mode?
IP Commands
ipaccounting
Yes
No
ipaddress
Yes
No
ipbroadcast-address
Yes
No
ipdirectedbroadcast
Yes
No
ipinformation-reply
Yes
No
ipirdp
Yes
No
ipload-sharing
Yes
No
ipmask-reply
Yes
No
ipmtu
Yes
No
ipproxy-arp
Yes
No
ipredirects
Yes
No
ipunnumbered
Yes
No
ipunreachables
Yes
No
EIGRP Commands
ipauthenticationkey-chaineigrp
Yes
Yes
ipauthenticationmodeeigrp
Yes
Yes
ipbandwidth-percenteigrp
Yes
Yes
ipdampening-changeeigrp
Yes
Yes
ipdampening-intervaleigrp
Yes
Yes
iphello-intervaleigrp
Yes
Yes
iphold-timeeigrp
Yes
Yes
ipnext-hop-selfeigrp
Yes
Yes
ipsplit-horizoneigrp
Yes
Yes
ipsummary-addresseigrp
Yes
Yes
Commands that Affect how EIGRP Determines Cost for an Interface
bandwidth(interface)
Yes
Yes
delay (interface)
Yes
Yes
OSPF Commands
ipospfprocess-idarea
No
Yes
ipospfauthentication
Yes
Yes
ipospfauthentication-key
Yes
Yes
ipospfbfd
Yes
Yes
ipospfcost
Yes
Yes
ipospfdatabase-filter
Yes
Yes
ipospfdead-interval
Yes
Yes
ipospfdemand-circuit
Yes
Yes
ipospfflood-reduction
Yes
Yes
ipospfhello-interval
Yes
Yes
ipospflls
Yes
Yes
ipospfmessage-digest-key
Yes
Yes
ipospfmtu-ignore
Yes
Yes
ipospfnetwork
Yes
Yes
ipospfpriority
Yes
Yes
ipospfresync-timeout
Yes
Yes
ipospfshutdown
Yes
Yes
ipospftransmit-delay
Yes
Yes
ipospftransmit-interval
Yes
Yes
ipospfttl-security
Yes
Yes
ipospfvnetarea
No
No
IP Multicast Commands
ipigmpaccess-group
Yes
Yes
ipigmpexplicit-tracking
Yes
Yes
ipigmphelper-address
Yes
Yes
ipigmpimmediate-leave
Yes
Yes
ipigmplast-member-query-count
Yes
Yes
ipigmplast-member-query-interval
Yes
Yes
ipigmplimit
Yes
Yes
ipigmpmroute-proxy
Yes
Yes
ipigmpproxy-service
Yes
Yes
ipigmpquerier-timeout
Yes
Yes
ipigmpquery-interval
Yes
Yes
ipigmpquery-max-response-time
Yes
Yes
ipigmptcn
Yes
Yes
ipigmpunidirectional-link
Yes
Yes
ipigmpv3lite
Yes
Yes
ipigmpversion
Yes
Yes
ipmulticastboundary
Yes
Yes
ippimbidir-neighbor-filter
Yes
Yes
ippimbsr-border
Yes
Yes
ippimdense-mode
Yes
Yes
ippimdr-priority
Yes
Yes
ippimnbma-mode
Yes
Yes
ippimneighbor-filter
Yes
Yes
ippimpassive
Yes
Yes
ippimquery-interval
Yes
Yes
ippimsparse-dense-mode
Yes
Yes
ippimsparse-mode
Yes
Yes
ippimstate-refresh
Yes
Yes
Multicast Forwarding Information Base (MFIB) Commands
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use
these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products
and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password.
Feature Information for Overview of Easy Virtual Network
The following table provides release information about the feature or features described in this module. This table lists
only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise,
subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco
Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Table 3. Feature Information for Overview of Easy VIrtual Network
Feature Name
Releases
Feature Information
EVN VNET Trunk
Cisco IOS XE Release 3.2S
15.0(1)SY
15.1(1)SG
Cisco IOS XE Release 3.3SG
15.3(2)T
Easy Virtual Network is an IP-based virtualization technology that provides end-to-end virtualization of the network. You
can use a single IP infrastructure to provide separate virtual networks with isolated traffic paths.
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