General network considerations – Dell Broadcom NetXtreme Family of Adapters User Manual
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Broadcom Gigabit Ethernet Teaming Services: Broadcom NetXtreme BCM57XX User Guide
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group. VLANs also enable the administrator to enforce appropriate security and quality of service (QoS) policies. The BASP
supports the creation of 64 VLANs per team or adapter: 63 tagged and 1 untagged. The operating system and system
resources, however, limit the actual number of VLANs. VLAN support is provided according to IEEE 802.1q and is supported in
a teaming environment as well as on a single adapter. Note that VLANs are supported only with homogeneous teaming and
not in a multivendor teaming environment. The BASP intermediate driver supports VLAN tagging. One or more VLANs may be
bound to a single instance of the intermediate driver.
Wake on LAN
Wake on LAN (WOL) is a feature that allows a system to be awakened from a sleep state by the arrival of a specific packet
over the Ethernet interface. Because a virtual adapter is implemented as a software only device, it lacks the hardware
features to implement Wake on LAN and cannot be enabled to wake the system from a sleeping state via the virtual adapter.
The physical adapters, however, support this property, even when the adapter is part of a team.
Preboot Execution Environment (PXE)
The Preboot Execution Environment (PXE) allows a system to boot from an operating system image over the network. By
definition, PXE is invoked before an operating system is loaded, so there is no opportunity for the BASP intermediate driver to
load and enable a team. As a result, teaming is not supported as a PXE client, though a physical adapter that participates in a
team when the operating system is loaded may be used as a PXE client. Whereas a teamed adapter cannot be used as a PXE
client, it can be used for a PXE server, which provides operating system images to PXE clients using a combination of
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 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 other.
is a setup without the interconnect cable in place between the two switches.
has the interconnect cable in place, and
is an example of a failover event with the Interconnect cable in place. These
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.