User guide

126 Implementing Cisco InfiniBand on IBM BladeCenter
Assuming a fresh installation, Figure 7-6 opens.
Figure 7-6 Bridge group page with no bridge groups
2. Click Add to create your first bridge group with the following characteristics:
– The Ethernet port that we use is 4/1. This port is untagged because we want to send
untagged packets to our upstream switch.
– The InfiniBand port is 4/1 in this example and uses the default p_key, ff:ff.
– We do not enable Broadcast forwarding on this bridge group.
– We set Loop Protection Method to one (the default). Regardless of this setting, the
following two loop protection methods are always enabled and cannot be turned off:
• Self-cancelling ARP requests: By default, the self-cancelling ARP requests feature
is always active. It prevents duplicate ARP (requests that have the same target
protocol address) from creating loops. The duplicate ARP is seen by multiple
gateways and discarded.
Tip: If only using a single Ethernet Gateway, you should use InfiniBand port 2 for
connection to the InfiniBand fabric. This is because the design of the 3012 is such
that the module in slot 15 (InfiniBand port 1 on the Ethernet gateway) will not work if
the InfiniBand module in slot 16 is not present or otherwise in a failed state. To state
this a different way, an InfiniBand module in slot 16 will work by itself, but an
InfiniBand module in slot 15 will only work if there is an InfiniBand module in slot 16.
Tip: A note about Broadcast forwarding. In most cases, this is not necessary or
even desired to be enabled. The gateway will still correctly pass ARP packets
without enabling this feature. With that said, if you have an application that requires
Broadcast forwarding enabled, you will need to enable this.
One example of when you will want to enable this feature is if you have InfiniBand
clients using DHCP to obtain an IP address. Do not enable this feature if you plan on
having two gateway modules with bridge groups carrying the same p_key and
VLAN, and hooked to the same InfiniBand and Ethernet fabrics, as this would result
in a network loop.
If you do want to have two gateways configured the same with the same
connectivity, and require Broadcast forwarding, then place the modules into a
Redundancy Group. The Redundancy Group will prevent this design from looping
the network.