Users Guide

12–Marvell Teaming Services
Executive Summary
Doc No. BC0054508-00 Rev. R
January 21, 2021 Page 146 Copyright © 2021 Marvell
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 Windows Internet
Name Service (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.