HP 1.10GB Virtual Connect Ethernet Module for c-Class BladeSystem - Manual (Page 53)

Network management 53
Network management
Networks overview
The Virtual Connect Ethernet module uses standard Ethernet bridge circuitry with special firmware so that
it functions as a configurable Ethernet port aggregator. For a specific external data center connection,
only the selected server Ethernet NIC ports are visible on what appears to be an isolated, private, loop-
free network. The Virtual Connect Ethernet module uplinks do not participate in the data center Spanning
Tree Protocol or other switch management protocols that could disrupt the data center network.
The Virtual Connect Ethernet module uplinks support link aggregation, link layer discovery protocol (LLDP),
and VLAN tagging. VLAN tagging enables uplinks to be shared to carry multiple networks. Virtual
Connect allows users to identify an associated network as the native VLAN, causing all untagged
incoming Ethernet packets to be placed onto the designated network. Only one associated network can
be designated as the native VLAN. All outgoing Ethernet packets are VLAN tagged.
Each network defined within Virtual Connect may have one or more uplinks. Virtual Connect
independently ensures that no loops are created within the enclosure and that the resulting tree structure is
optimized for the uplinks to the data center.
When multiple uplinks are used on a network, HP Virtual Connect Manager first verifies if any of the ports
can be collected together into an aggregation group (requires connections to go from a single Virtual
Connect Ethernet module to a single data center switch), and then it picks a single link (or aggregation
group) as the connection to the external network. The remaining connections are blocked and held as
standby ports.
TIP: To improve network performance and prevent unnecessary Spanning Tree Topology
Change Notifications (TCN) on the network, configure Ethernet switches connected to Virtual
Connect with the same Spanning Tree settings you would use when connecting to a server
blade NIC. For Cisco switches, use the portfast command to enable ports connected to a
VC-Enet module. This action ensures that link state changes on Virtual Connect do not cause a
TCN.
Smart Link
Enabling Smart Link configures the network so that if all external links lose their link to external switches,
Virtual Connect drops the Ethernet link on all local server blade Ethernet ports connected to that network.
This feature can be useful when using certain server network teaming (bonding) configurations.
Private Networks
The Private Networks option provides extra networking security. When checked, the network is configured
so that all server ports connected to it cannot communicate with each other within the Virtual Connect
domain. All packets from servers are sent through the VC domain and out the uplink ports only. Servers
on the network can only communicate with each other through an external Layer 3 router that redirects the
traffic back to the VC domain.