HP Virtual Connect 8Gb 24-port Fibre Channel Module for c-Class BladeSystem - Manual (Page 146)

Configuring the Virtual Connect domain using the CLI 146
Configuring IGMP settings
To configure Ethernet IGMP snooping settings, use the set igmp command:
>set igmp enabled=true timeout=30
The IGMP Snooping feature enables VC-Enet modules to monitor (snoop) the IGMP IP multicast membership
activities and configure hardware Layer 2 switching behavior of multicast traffic to optimize network
resource usage. IGMP v1, v2, and v3 snooping are supported.
The IGMP Snooping idle timeout interval is set to 260 seconds by default. This value is the "Group
Membership Interval" value as specified by IGMP v2 specification (RFC2236). For optimum network
resource usage, set the interval to match the configuration on the customer network's multicast router settings.
Configuring MAC cache failover settings
• To configure MAC Cache Failover settings, use the set mac-cache command:
>set mac-cache enabled=true refresh=10
• To display MAC Cache Failover settings, use the show mac-cache command:
>show mac-cache
When a VC-Enet uplink that was previously in standby mode becomes active, it can take several minutes for
external Ethernet switches to recognize that the c-Class server blades can now be reached on this
newly-active connection. Enabling Fast MAC Cache Failover causes Virtual Connect to transmit Ethernet
packets on newly-active links, which enables the external Ethernet switches to identify the new connection
(and update their MAC caches appropriately). This transmission sequence repeats a few times at the MAC
refresh interval (5 seconds recommended) and completes in about 1 minute.
IMPORTANT: Be sure to set switches to allow MAC addresses to move from one port to another
without waiting for an expiration period or causing a lock out.
Configuring network loop protection settings
To enable network loop protection, use the set loop-protect command:
>set loop-protect Enabled=true
To reset network loop protection, use the reset loop-protect command:
>reset loop-protect
When a link is established on a VC-Enet module port, the port exchanges LLDP packets with the far-side
connection. This LLDP protocol is an IEEE 802.1 standard that uses special BPDU packets that are not
forwarded by Ethernet bridges or switches.
To avoid network loops, Virtual Connect first verifies that only one active uplink exists per network from the
Virtual Connect domain to the external Ethernet switching environment. Second, Virtual Connect makes sure
that no network loops are created by the stacking links between Virtual Connect modules.
• One active link—A VC uplink set can include multiple uplink ports. To prevent a loop with broadcast
traffic coming in one uplink and going out another, only one uplink or uplink LAG is active at a time. The
uplink or LAG with the greatest bandwidth should be selected as the active uplink. If the active uplink
loses the link, then the next best uplink is made active.
• No loops through stacking links—If multiple VC-Enet modules are used, they are interconnected using
stacking links, which might appear as an opportunity for loops within the VC environment. For each