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User Guide NetXtreme II
January 2010
Broadcom Corporation
Document ENGSRVT52-CDUM100-R Executive Summary Page 17
TEAMING CONCEPTS
• Network Addressing
• Teaming and Network Addresses
• Description of Teaming Types
• TOE Teaming
The concept of grouping multiple physical devices to provide fault tolerance and load balancing is not new. It has been
around for years. Storage devices use RAID technology to group individual hard drives. Switch ports can be grouped
together using technologies such as Cisco Gigabit EtherChannel, IEEE 802.3ad Link Aggregation, Bay Network Multilink
Trunking, and Extreme Network Load Sharing. Network interfaces on servers can be grouped together into a team of
physical ports called a virtual adapter.
Network Addressing
To understand how teaming works, it is important to understand how node communications work in an Ethernet network.
This document is based on the assumption that the reader is familiar with the basics of IP and Ethernet network
communications. The following information provides a high-level overview of the concepts of network addressing used in an
Ethernet network. Every Ethernet network interface in a host platform, such as a computer system, requires a globally unique
Layer 2 address and at least one globally unique Layer 3 address. Layer 2 is the Data Link Layer, and Layer 3 is the Network
layer as defined in the OSI model. The Layer 2 address is assigned to the hardware and is often referred to as the MAC
address or physical address. This address is pre-programmed at the factory and stored in NVRAM on a network interface
card or on the system motherboard for an embedded LAN interface. The Layer 3 addresses are referred to as the protocol
or logical address assigned to the software stack. IP and IPX are examples of Layer 3 protocols. In addition, Layer 4
(Transport Layer) uses port numbers for each network upper level protocol such as Telnet or FTP. These port numbers are
used to differentiate traffic flows across applications. Layer 4 protocols such as TCP or UDP are most commonly used in
today’s networks. The combination of the IP address and the TCP port number is called a socket.
Ethernet devices communicate with other Ethernet devices using the MAC address, not the IP address. However, most
applications work with a host name that is translated to an IP address by a Naming Service such as WINS and DNS.
Therefore, a method of identifying the MAC address assigned to the IP address is required. The Address Resolution Protocol
for an IP network provides this mechanism. For IPX, the MAC address is part of the network address and ARP is not
required. ARP is implemented using an ARP Request and ARP Reply frame. ARP Requests are typically sent to a broadcast
address while the ARP Reply is typically sent as unicast traffic. A unicast address corresponds to a single MAC address or
a single IP address. A broadcast address is sent to all devices on a network.
Teaming and Network Addresses
A team of adapters function as a single virtual network interface and does not appear any different to other network devices
than a non-teamed adapter. A virtual network adapter advertises a single Layer 2 and one or more Layer 3 addresses. When
the teaming driver initializes, it selects one MAC address from one of the physical adapters that make up the team to be the
Team MAC address. This address is typically taken from the first adapter that gets initialized by the driver. When the system
hosting the team receives an ARP request, it selects one MAC address from among the physical adapters in the team to
use as the source MAC address in the ARP Reply. In Windows operating systems, the IPCONFIG /all command shows the
IP and MAC address of the virtual adapter and not the individual physical adapters. The protocol IP address is assigned to
the virtual network interface and not to the individual physical adapters.
For switch-independent teaming modes, all physical adapters that make up a virtual adapter must use the unique MAC
address assigned to them when transmitting data. That is, the frames that are sent by each of the physical adapters in the