IBM 3110X Supplementary Manual page 11

You need to take several considerations into account when planning VBS deployment:
VBS stacking is well-suited to the concept of rack-level management, so we recommend that you
build one VBS (or more VBSes, if the network paths from different server NICs must be physically
separated) from the switches in the same rack whenever possible.
In case of a master switch failure, any other member switch is eligible to become master to provide
availability and redundancy.
In case of a switch failure, the stack connections are looped back to keep the ring operational.
True active-active NIC teaming (link aggregation of Ethernet NICs) is possible using supported link
aggregation protocols like EtherChannel or 802.3ad LACP. For example, for network
bandwidth-intensive applications it is possible to use up to four Ethernet ports per blade combined
into a single aggregated bundle (integrated Ethernet and Ethernet ports on expansion cards).
Physically, each port is connected to a different physical switch. However, because of VBS,
aggregation is done on a stack level and the blade appears to be connected to the single switch.
Uplink sharing can help simplify design by reducing the number of external links going out of the rack;
that is, not all switches in the stack must have uplinks. For example, instead of using two 1 Gb ports
per switch as a redundant uplink for eight switches for a total of 16 cables going out of rack, you may
choose to use just two 10 Gb links going out of the rack if applicable.
If a fully redundant topology is required, that is, if each blade server must have two separate paths to
the external infrastructure, then you can use two VBS stacks. One stack combines switches from the
upper Ethernet switch bays of a chassis, and the other stack combines switches from the lower
Ethernet switch bays. In this case, the entire rack will be represented as two separate network
switches, both from the blade server side and from the external infrastructure side.
Networking technologies and protocols, including VLANs, STP and its modifications (such as PVST+,
RSTP, MSTP), link aggregation, link state tracking, and routing, are supported on the VBS level as
well.
Note: When the switch stack is formed, the Advanced Management Module cannot manage any member
of the stack (including the master switch) over IP. Management over external ports or a serial console
cable is required.
Cisco Catalyst Switch Modules 3110G and 3110X for IBM BladeCenter 11