Users Guide

12–Marvell Teaming Services
General Network Considerations
Doc No. BC0054508-00 Rev. R
January 21, 2021 Page 173 Copyright © 2021 Marvell
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 figures in this section describe the operation of an SLB team in a switch fault
tolerant configuration. Marvell shows 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.
 Figure 12-3 is a setup without the interconnect cable in place between the
two switches.
 Figure 12-4 has the interconnect cable in place.
 Figure 12-5 is an example of a failover event with the Interconnect cable in
place.
The figures 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 send-receive illustrates a key characteristic of the
teaming software. The load balancing algorithms do not synchronize how frames
are load balanced when sent or received. Frames for a specific conversation can
go out and be received on different interfaces in the team, which is true for all
types of teaming supported by Marvell. 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.