User guide

128 Implementing Cisco InfiniBand on IBM BladeCenter

3. After making changes to the Add Bridge Group Groups tab, you need to configure the

Forwarding tab and the Subnet Tab as shown in Figure 7-8 and Figure 7-9 on page 129

Figure 7-8 Forwarding tab on Add Bridge Group window

In the example in Figure 7-8, you set up a default gateway for this bridge group to use on

the upstream Ethernet network.

Some comments about the settings in the Forwarding tab:

– Created by clicking the Add button in this tab (

not the Add button at the bottom of the

page).

– For an InfiniBand client to talk to devices on a different IP subnet, a default gateway

needs to be set in two places:

• On the InfiniBand client itself

• In this tab for the bridge group

– Port Type is set to

ib. This indicates packets coming in from the InfiniBand side will use

this address on the Ethernet side as their next hop.

– Destination address of 0.0.0.0 = all routes, This makes it a default gateway rather than

a simple static route.

– Next Hop is the default gateway on the Ethernet network, and in this example

represents a routed interface on the 4948 that is acting as the default gateway for this

IP subnet.

– While in our example we are setting up a default gateway, you can also use the

Forwarding tab to create static routes to specific subnets. Usually a default gateway is

sufficient, but some users might need to do static routes to networks not known by the

default gateway (again, this is not normally the case, but it is an option that can be

entered in this tab if desired).

Tip: Make sure the Port Type is set to ib or this will not work as a default gateway

for the InfiniBand clients.

Tip: It is important not to confuse the default gateway of the bridge group with the

default gateway for the Ethernet management of the 3012. In almost all cases,

these will be completely different and not interact. On that note, you normally do not

want to put the management IP subnet of the 3012 itself on the same subnet as

what might be used by the InfiniBand clients and this bridge group.