General Network Considerations; Teaming Across Switches; Switch-Link Fault Tolerance - Dell Broadcom NetXtreme Family of Adapters User Manual

Dynamic Host Control Protocol (DHCP) and the Trivial File Transfer Protocol (TFTP). Both of these protocols operate over IP
and are supported by all teaming modes.

General Network Considerations

Teaming Across Switches

Spanning Tree Algorithm
Layer 3 Routing/Switching
Teaming with Hubs (for troubleshooting purposes only)
Teaming with Microsoft NLB/WLBS
Teaming Across Switches
SLB teaming can be configured across switches. The switches, however, must be connected together. Generic Trunking and
Link Aggregation do not work across switches because each of these implementations requires that all physical adapters in a
team share the same Ethernet MAC address. It is important to note that SLB can only detect the loss of link between the
ports in the team and their immediate link partner. SLB has no way of reacting to other hardware failures in the switches and
cannot detect loss of link on other ports.

Switch-Link Fault Tolerance

The diagrams below describe the operation of an SLB team in a switch fault tolerant configuration. We show the mapping of
the ping request and ping replies in an SLB team with two active members. All servers (Blue, Gray and Red) have a
continuous ping to each
has the interconnect cable in place, and
scenarios describe the behavior of teaming across the two switches and the importance of the interconnect link.
The diagrams show the secondary team member sending the ICMP echo requests (yellow arrows) while the primary team
member receives the respective ICMP echo replies (blue arrows). This illustrates a key characteristic of the teaming software.
The load balancing algorithms do not synchronize how frames are load balanced when sent or received. In other words,
frames for a given conversation can go out and be received on different interfaces in the team. This is true for all types of
teaming supported by Broadcom. Therefore, an interconnect link must be provided between the switches that connect to ports
in the same team.
In the configuration without the interconnect, an ICMP Request from Blue to Gray goes out port 82:83 destined for Gray port
5E:CA, but the Top Switch has no way to send it there because it cannot go along the 5E:C9 port on Gray. A similar scenario
occurs when Gray attempts to ping Blue. An ICMP Request goes out on 5E:C9 destined for Blue 82:82, but cannot get there.
Top Switch does not have an entry for 82:82 in its CAM table because there is no interconnect between the two switches.
Pings, however, flow between Red and Blue and between Red and Gray.
Furthermore, a failover event would cause additional loss of connectivity. Consider a cable disconnect on the Top Switch port
4. In this case, Gray would send the ICMP Request to Red 49:C9, but because the Bottom switch has no entry for 49:C9 in its
CAM Table, the frame is flooded to all its ports but cannot find a way to get to 49:C9.
Figure 3. Teaming Across Switches Without an Interswitch Link
other.Figure 3 is a setup without the interconnect cable in place between the two switches.
Figure 5 is an example of a failover event with the Interconnect cable in place. These
Figure 4