Broadcom Gigabit Ethernet Teaming Services
NetXtreme
User Guide
Broadcom
®
April 2017 • 2CS57XX-CDUM514-R
Page 127
Load Balancing and Failover
As the number of backup streams increases, the overall throughput increases. Each data stream, however, may
not be able to maintain the same performance as a single backup stream of 25 MB/s. In other words, even
though a backup server can stream data from a single client at 25 MB/s, it is not expected that four
simultaneously running backup jobs will stream at 100 MB/s (25 MB/s x 4 streams). Although overall throughput
increases as the number of backup streams increases, each backup stream can be impacted by tape software
or network stack limitations.
For a tape backup server to reliably use adapter performance and network bandwidth when backing up clients,
a network infrastructure must implement teaming such as load balancing and fault tolerance. Data centers will
incorporate redundant switches, link aggregation, and trunking as part of their fault tolerant solution. Although
teaming device drivers will manipulate the way data flows through teamed interfaces and failover paths, this is
transparent to tape backup applications and does not interrupt any tape backup process when backing up
remote systems over the network.
shows a network topology that demonstrates tape backup in a
Broadcom teamed environment and how smart load balancing can
load balance
tape backup data across
teamed adapters.
There are four paths that the client-server can use to send data to the backup server, but only one of these paths
will be designated during data transfer. One possible path that Client-Server Red can use to send data to the
backup server is:
Example Path: Client-Server Red sends data through Adapter A, Switch 1, Backup Server Adapter A.
The designated path is determined by two factors:
1.
Client-Server ARP cache; which points to the backup server MAC address. This is determined by the
Broadcom intermediate driver inbound load balancing algorithm.
2.
The physical adapter interface on Client-Server Red will be used to transmit the data. The Broadcom
intermediate driver outbound load balancing algorithm determines this (see
and
Inbound Traffic Flow (SLB Only)
The teamed interface on the backup server transmits a gratuitous address resolution protocol (G-ARP) to Client-
Server Red, which in turn, causes the client server ARP cache to get updated with the Backup Server MAC
address. The load balancing mechanism within the teamed interface determines the MAC address embedded
in the G-ARP. The selected MAC address is essentially the destination for data transfer from the client server.
On Client-Server Red, the SLB teaming algorithm will determine which of the two adapter interfaces will be used
to transmit data. In this example, data from Client-Server Red is received on the backup server Adapter A
interface. To demonstrate the SLB mechanisms when additional load is placed on the teamed interface,
consider the scenario when the backup server initiates a second backup operation: one to Client-Server Red,
and one to Client-Server Blue. The route that Client-Server Blue uses to send data to the backup server is
dependant on its ARP cache, which points to the backup server MAC address. Because Adapter A of the backup
server is already under load from its backup operation with Client-Server Red, the backup server invokes its
SLB algorithm to
inform
Client-Server Blue (thru an G-ARP) to update its ARP cache to reflect the backup server
Adapter B MAC address. When Client-Server Blue needs to transmit data, it uses either one of its adapter
interfaces, which is determined by its own SLB algorithm. What is important is that data from Client-Server Blue
is received by the Backup Server Adapter B interface, and not by its Adapter A interface. This is important
because with both backup streams running simultaneously, the backup server must
load balance
data streams
from different clients. With both backup streams running, each adapter interface on the backup server is
processing an equal load, thus load-balancing data across both adapter interfaces.
Summary of Contents for NetXtreme BCM57 Series
Page 1: ...Broadcom NetXtreme BCM57XX User Guide Last revised April 2017 2CS57XX CDUM514 R...
Page 16: ...Functionality and Features NetXtreme User Guide Broadcom April 2017 2CS57XX CDUM514 R Page 16...
Page 169: ...Regulatory Information NetXtreme User Guide Broadcom April 2017 2CS57XX CDUM514 R Page 169...
Page 170: ...Regulatory Information NetXtreme User Guide Broadcom April 2017 2CS57XX CDUM514 R Page 170...
Page 171: ...Regulatory Information NetXtreme User Guide Broadcom April 2017 2CS57XX CDUM514 R Page 171...
