16–Using Cavium Teaming Services
General Network Considerations
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Teaming Across Switches
QLASP 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 in this section describe the operation of a QLASP SLB team in a
switch fault tolerant configuration. They 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. These scenarios describe the
behavior of teaming across the two switches and the importance of the
interconnect link:
is a setup without the interconnect cable in place
between the two switches.
has the interconnect cable in place.
is an example of a failover event with the
Interconnect cable in place.
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 specific
conversation can go out and be received on different interfaces in the team. This
behavior is true for all types of teaming supported by Cavium. 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.
