Information About IVR
Virtual SANs (VSANs) improve storage area network (SAN) scalability, availability, and security by allowing multiple Fibre Channel SANs to share a common physical infrastructure of switches and ISLs. These benefits are derived from the separation of Fibre Channel services in each VSAN and the isolation of traffic between VSANs. Data traffic isolation between the VSANs also inherently prevents sharing of resources attached to a VSAN, such as robotic tape libraries. Using IVR, you can access resources across VSANs without compromising other VSAN benefits.
IVR supports the following features:
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Accesses resources across VSANs without compromising other VSAN benefits
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Transports data traffic between specific initiators and targets on different VSANs without merging VSANs into a single logical fabric.
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Establishes proper interconnected routes that traverse one or more VSANs across multiple switches. IVR is not limited to VSANs present on a common switch.
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Shares valuable resources (such as tape libraries) across VSANs without compromise. Fibre Channel traffic does not flow between VSANs, nor can initiators access resources across VSANs other than the designated VSAN.
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Provides efficient business continuity or disaster recovery solutions when used in conjunction with FCIP.
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Is in compliance with Fibre Channel standards.
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Incorporates third-party switches, however, IVR-enabled VSANs may need to be configured in one of the interop modes.
IVR Terminology
The following IVR-related terms are used in the IVR documentation:
- Native VSAN
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The VSAN to which an end device logs on is the native VSAN for that end device.
- Inter-VSAN Routing zone (IVR zone)
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Inter-VSAN Routing zone (IVR zone)-A set of end devices that are allowed to communicate across VSANs within their interconnected SAN fabric. This definition is based on their port world-wide names (pWWNs) and their native VSAN associations
- Inter-VSAN routing zone sets (IVR zone sets)
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Inter-VSAN routing zone sets (IVR zone sets)-One or more IVR zones make up an IVR zone set.
- IVR path
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An IVR path is a set of switches and Inter-Switch Links (ISLs) through which a frame from an end device in one VSAN can reach another end device in some other VSAN. Multiple paths can exist between two such end devices.
- IVR-enabled switch
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A switch on which the IVR feature is enabled.
- Edge VSAN
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A VSAN that initiates (source edge-VSAN) or terminates (destination edge-VSAN) an IVR path. Edge VSANs may be adjacent to each other or they may be connected by one or more transit VSANs.
Note
An edge VSAN for one IVR path can be a transit VSAN for another IVR path.
- Transit VSAN
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A VSAN that exists along an IVR path from the source edge VSAN of that path to the destination edge VSAN of that path.
Note
When the source and destination edge VSANs are adjacent to each other, then a transit VSAN is not required between them
- Border switch
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An IVR-enabled switch that is a member of two or more VSANs.
- Edge switch
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A switch to which a member of an IVR zone has logged in to. Edge switches are unaware of the IVR configurations in the border switches. Edge switches do not need to be IVR-enabled.
- Autonomous Fabric Identifier (AFID)
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Allows you to configure more than one VSAN in the network with the same VSAN ID and avoid downtime when configuring IVR between fabrics that contain VSANs with the same ID.
- Service group
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Allows you to reduce the amount of IVR traffic to non-IVR-enabled VSANs by configuring one or more service groups that restrict the traffic to the IVR-enabled VSANs.
Fibre Channel Header Modifications
IVR virtualizes the remote end devices in the native VSAN using a virtual domain. When IVR is configured to link end devices in two disparate VSANs, the IVR border switches are responsible for modifying the Fibre Channel headers for all communication between the end devices. The sections of the Fibre Channel frame headers that are modified include:
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VSAN number
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Source FCID
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Destination FCID
When a frame travels from the initiator to the target, the Fibre Channel frame header is modified such that the initiator VSAN number is changed to the target VSAN number. If IVR Network Address Translation (NAT) is enabled, then the source and destination FCIDs are also translated at the edge border switch. If IVR NAT is not enabled, then you must configure unique domain IDs for all switches involved in the IVR path.
IVR Database Merge
A database merge refers to the combination of the configuration database and static (unlearned) entries in the active database.
Consider the following when merging two IVR fabrics:
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The IVR configurations are merged even if two fabrics contain different configurations.
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If dissimilar zones exist in two merged fabrics, the zone from each fabric is cloned in the distributed zone set with appropriate names.
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You can configure different IVR configurations in different Cisco SAN switches.
To avoid traffic disruption, after the database merge is complete, the configuration is a combination of the configurations that were present on the two switches involved in the merge, as follows:
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A combination of zones and zone sets are used to get the merged zones and zone sets. If a dissimilar zone exists in two fabrics, the dissimilar zones are cloned into the zone set with appropriate names so both zones are present.
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The merged topology contains a combination of the topology entries for both fabrics.
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The merge will fail if the merged database contains more topology entries than the allowed maximum.
The following total number of items across the two fabrics cannot exceed the maximum allowed in one fabric:
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VSANs.VSANs with the same VSAN ID but different AFIDs are counted as two separate VSANs.
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IVR-enabled switches.
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Zone members. A zone member is counted twice if it exists in two zones.
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Zones.
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Zone sets.
IVR Fabric 1 | IVR Fabric 2 | Merged Fabric |
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NAT enabled | NAT disabled | Merge succeeds and NAT is enabled |
Auto mode enabled | Auto mode disabled | Merge succeeds and IVR auto topology mode is enabled |
Conflicting AFID database | Merge fails | |
Conflicting IVR zone set database | Merge succeeds with new zones created to resolve conflicts | |
Combined configuration exceeds limits (such as maximum number of zones or VSANs) | Merge fails | |
Service group 1 | Service group 2 | Merge succeeds with service groups combined |
User-configured VSAN topology configuration with conflicts | Merge fails | |
User-configured VSAN topology configuration without conflicts | Merge succeeds |
Caution |
If you do not follow these conditions, the merge will fail. The next distribution will forcefully synchronize the databases and the activation states in the fabric. |