HP Cisco MDS 8/12c HP Virtual Connect: Common Myths, Misperceptions, and Objec - Page 12

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always used by the active VC module within a VC Domain.

This optional feature is called the “Virtual

Connect Domain IP Address”.

While only one VC module provides the active VC Domain management interface (Virtual Connect

Manager),

all

VC Ethernet and Fibre Channel modules can be used simultaneously to provide

network connectivity for HP server blades.

In other words, even though only a single VC Ethernet

module is elected to service the VC Manager interface, all VC Ethernet and Fibre Channel modules

and all ports on these modules can be configured to forward traffic simultaneously.

#17: VC only supports a limited number of VLANs

Correct:

The supported limit is 320 VLANs per Virtual Connect Ethernet module when using Shared

Uplink Sets.

The VC architecture supports 1000+ VLANs per c-Class enclosure.

However, Virtual

Connect Manager limits the number of supported VLANs per Ethernet module for backwards

compatibility.

HP has increased the number of VLANs per Shared Uplink Set, from 32 to 128

6

As an alternative to the use of a Shared Uplink Set, if support for a greater number of VLAN is

required, Tunneled VLANs (vs. Mapped VLANs), could be used to support an unlimited number of

VLANs on a vNet.

VLANs.

HP continues to evolve this support, as customer demand increases, and legacy products are

depreciated.

#18: VC Ethernet doesn’t provide Layer 3 routing capabilities

Correct:

Virtual Connect is not a router, therefore, Virtual Connect does not provide Layer 3

capabilities (routing).

Customers that desire to route between HP server blades in the same enclosure

or between HP server blades and an external device will utilize routers in their core network.

Alternatively, should a customer prioritize internal routing of blade-to-blade traffic within the enclosure

above the server management and virtualization features provided by Virtual Connect, HP would

recommend the customer deploy using the Cisco 3120 blade switch (with purchasable IOS upgrade

for full L3 routing) or using one of the other HP c-Class GbE2c blade switch options providing Layer 3

routing capabilities (for example, HP GbE2c Layer 2/3 Ethernet Blade Switch).

Cisco’s Data Center Infrastructure 2.5 Design Guide (

link

: see page 79) advises that data center

access switches and access devices (for example, Virtual Connect Ethernet) are usually deployed in

Layer 2 mode (no routing).

See reference above for a complete discussion.

#19: VC’s CX4 cables are not ideal for 10Gbe uplinks because of

distance limitation

Correct:

CX4 ports have a 15 meter limitation per the IEEE specification, including those used by

VC. For this reason, Virtual Connect also provides IEEE compliant fiber 10GbE ports (10Gbe SR or

LR) in the 1/10Gb-F or Flex-10 Virtual Connect Ethernet modules which support a distance limitation

of up to 10 kilometers.

The Cisco Catalyst 3120X CX4 ports have the same 15 meter limitation. The Cisco Catalyst 3120X

fiber ports offer increased distance limitation similar to VC fiber ports

7

6

Introduced with Virtual Connect Firmware 2.30

.

7

http://www.cisco.com/en/US/prod/collateral/switches/ps6746/ps8742/ps8749/data_sheet_c78-439133.html

Section	Page
Abstract	3
Target Audience	3
Prerequisites and Versioning	3
Introduction	3
Myths, Misconceptions and Objections	5
#1: VC Ethernet is just another switch	5
Comparing VC and Server Virtualization Hypervisor Networking Technology	5
A Description of the Hypervisor Components	5
A Comparative Description of the VC Components	6
#2: VC Ethernet is really a ProCurve switch and may not be interoperable with 3rd party network switches	7
#3: VC Ethernet doesn’t support Spanning Tree (STP)	7
#4: VC can cause duplicate MACs and WWNs on the network.	7
#5: VC users cannot leverage existing network management tools (for example, CiscoWorks)	8
#6: VC doesn’t provide secure external management	8
#7: VC Ethernet doesn’t support Private VLANs	8
#8: VC doesn’t provide deterministic load balancing for multiple LACP channels	9
#9: VC Ethernet doesn’t support VLAN Trunking to Server Blade NICs	9
#10: VC Ethernet and Fibre Channel modules require a clunky hardware failure recovery (RMA) process	9
#11: VC doesn’t provide network visibility into the VC Domain for network administrators	10
#12: Many customers experience problems with VC deployment consistency	10
#13: VC doesn’t support non-disruptive firmware upgrades (“hot code load”)	10
#14: HP server blade NICs stay active even after VC Ethernet uplink failure	11
#15: VC is proprietary to HP; VC locks a user to a single blade vendor	11
#16: VC modules form a master/slave relationship with separate IP addresses that aren’t transferred during a failover. When multiple VC modules are present, only one module is elected to forward traffic	11
#17: VC only supports a limited number of VLANs	12
#18: VC Ethernet doesn’t provide Layer 3 routing capabilities	12
#19: VC’s CX4 cables are not ideal for 10Gbe uplinks because of distance limitation	12
#20: VC doesn’t support stacking multiple VC modules	13
#21: VC doesn’t offer Access Control Lists or VLAN Access Control Lists (ACLs or VACLs)	13
#22: VC Ethernet doesn’t support user configurable Quality of Service (QoS) features	13
#23: VC Ethernet doesn’t provide diagnostic tools (SPAN)	13
#24: VC Ethernet doesn’t support the Cisco Discovery Protocol (CDP)	13
#25: VC requires a separate web management window to manage each VC module	14
#26: VC doesn’t support IGMP Snooping	14
#27: VC Fibre Channel doesn’t support nested NPIV	14
#28: Virtualized MAC and WWN (NAT) features on some switches (for example, Cisco’s FlexAttach8F feature) provide the same benefits as VC’s Managed MAC addresses and WWNs	14
#29: DHCP Option 82 provides the same server redundancy features as Virtual Connect	16
#30: VC-FC doesn’t provide login distribution and failover on FC uplinks to the SAN	17
#31: All VC-FC uplinks have to be connected to the same SAN fabric	17
#32: VC-FC does not support Cisco’s VSAN or Brocades Virtual Fabric features	17
#33: VC implements an immature loop avoidance mechanism	18
#34: VC Uplink failures require re-convergence on the external network and may cause dropped server sessions	18
#35: Cisco’s N-Port Virtualization (NPV10F ) or Brocade Access Gateway11F provide all the same advantages as VC-FC	18
#36: Cisco VFrame Data Center provides the same capabilities as VC	18
#37: VC Ethernet can’t be connected to Cisco 6500 switches using Virtual Switching System (VSS)	19
#38: VC Ethernet does not support Unidirectional Link Detection (UDLD)	19
#39: VC Ethernet only provides port counters on uplinks	19
#40: QoS can provide the same functionality of VC Flex-10	20
Unique Features Provided By HP Virtual Connect	20
Managed Server Identities	21
Internal Server Identity	21
External Server Identity	21
Preprovisioning Using Managed Server Identities	21
“LAN Safe” Network Connectivity	22
Consolidate Network Infrastructure with VC Flex-10	22
Server Adds, Moves, and Replacements are Transparent to LAN & SAN	22
Summary of the Virtual Connect Capabilities	23
Additional Resources and References	26
Appendixes	27
Appendix A: Frequently Asked Questions	27

HP Cisco MDS 8/12c HP Virtual Connect: Common Myths, Misperceptions, and Objec - Page 12

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