HP Virtual Connect Multi-Enclosure Stacking Reference Guide

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Executive Summary
Customers today are challenged with simplifying the network edge by reducing complexity and cost. HP’s Virtual
Connect solution helps customers simplify server network connections by cleanly separating the server enclosure from
the data center network. Stacking multiple enclosures enables the management of up to four enclosures from a single
control point.
ME Stacking provides the following benefits:
 Provide connectivity for any blade server to any uplink port in the VC domain, regardless of location
 Reduce the overall number of cables needed for uplink connectivity
 Ability to move a profile between enclosures
 Reduce the datacenter core switch traffic, as internal communication stays inside the Virtual Connect domain
 Reduces the management touch points by consolidating Virtual Connect manager interfaces
Within environments where the 10Gb uplink ports are a premium, VC Flex-10 and FlexFabric can be used with a minimal
number of uplink ports in order to provide connectivity for multiple enclosures. The stack links provide high speed
connections between enclosures that can be adjusted by adding more physical links to the stack. This enables the ability
to create a high speed private network connection between blades for services such as VMotion, Cluster heart beats,
backups, and IP Storage to name a few.
This reference guide will provide best practices to designing a multi-enclosure stack, and provide guidance on various
approaches.
Multi-Enclosure Stacking Guidelines
Multi-Enclosure (ME) Stacking enables a base enclosure to have external physical connections to multiple remote
enclosures, by using the physical uplink ports (called Stack Links) of the Virtual Connect (VC) modules. Up to 4 Virtual
Connect-enabled C7000 enclosures can be stacked together and managed as one Virtual Connect domain for 128
servers, not to exceed a total of 16 VC-Enet and 16 VC-FC modules (a Virtual Connect FlexFabric module counts as both
one VC-Enet module and one VC-FC module towards these limits). Any available Ethernet uplink port not assigned to a
Virtual Connect Network or SUS can become a stack link. Stacking of Virtual Connect Fibre Channel is not provided or
supported. All VC Ethernet modules must be stacked together, to form a valid L2 ring topology. Having Ethernet
module(s) physically present but not linked to the other Ethernet modules in the domain is an invalid and unsupported
configuration.
The ME Stacking feature was designed and tested for enclosures that are physically close to each other, in a single rack
or in a few racks side-by-side. However, stacking can be achieved and is supported with any of the cabling options
supported by Virtual Connect, including optical fiber on longer distances. As the distance between enclosures in the
stack increases, so will the network latency over the management network (connected through the Onboard
Administrators) which will have an impact on Virtual Connect Manager performance, so it is advisable to keep distances
between enclosures in a stack to a minimum.
In order to configure ME Stacking, the base enclosure must have 1/10Gb-F Virtual Connect Ethernet Modules or Virtual
Connect Flex-10, Flex-10/10D or FlexFabric Modules in bay 1 or redundant pairs installed in bays 1 and 2. The original
HP 1/10Gb Virtual Connect Copper Ethernet Modules
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are not supported in bay 1 and 2 of the base enclosure. The HP
1/10Gb VC Copper module does not contain the required amount of system resources to manage multiple enclosure
configurations. Remote enclosures may be populated with any Virtual Connect Ethernet modules. The HP 1/10Gb-F
Ethernet Modules can be the management modules of a Multi Enclosure Domain ONLY if the stack does NOT contain any
Flex-10, Flex-10/10D or FlexFabric module, i.e. it only has 1/10Gb and 1/10Gb-F modules (plus VC-FC modules), again
because of limited system resources.
Virtual Connect Enterprise Manager (VCEM) is not required to manage a ME Stacked Domain. VCEM provides a central
console to administer LAN and SAN address assignments, perform group-based configuration management, and
execute rapid deployment, movement and failover of server connections and their workloads for 250 Virtual Connect
domains (up to 1,000 enclosures and 16,000 server blades). ME Stacking and VCEM can be used together to provide the
stacking benefits listed above and all the benefits of VCEM for central management of all the domains.
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HP Part Number 399593-B22