680242

Draytek VigorSwitch G2280 Manual

204
Zoom out
Zoom in
Previous page
1/211
Next page
VigorSwitch G2280 User’s Guide
196
A
A
-
-
2
2
M
M
e
e
d
d
i
i
a
a
A
A
c
c
c
c
e
e
s
s
s
s
C
C
o
o
n
n
t
t
r
r
o
o
l
l
(
(
M
M
A
A
C
C
)
)
M
M
A
A
C
C
A
A
d
d
d
d
r
r
e
e
s
s
s
s
i
i
n
n
g
g
Because LAN is composed of many nodes, for the data exchanged among these nodes, each
node must have its own unique address to identify who should send the data or should receive
the data. In OSI model, each layer provides its own mean to identify the unique address in
some form, for example, IP address in network layer.
The MAC is belonged to Data Link Layer (Layer 2), the address is defined to be a 48-bit long
and locally unique address. Since this type of address is applied only to the Ethernet LAN
media access control (MAC), they are referred to as MAC addresses.
The first three bytes are Organizational Unique Identifier (OUI) code assigned by IEEE. The
last three bytes are the serial number assigned by the vendor of the network device. All these
six bytes are stored in a non-volatile memory in the device. Their format is as the following
table and normally written in the form as aa-bb-cc-dd-ee-ff, a 12 hexadecimal digits
separated by hyphens, in which the aa-bb-cc is the OUI code and the dd-ee-ff is the serial
number assigned by manufacturer.
Bit 47 Bit 0
1
st
byte 2
nd
byte 3
rd
byte 4
th
byte 5
th
byte 6
th
byte
OUI code Serial number
The first bit of the first byte in the Destination address (DA) determines the address to be a
Unicast (0) or Multicast frame (1), known as I/G bit indicating individual (0) or group (1). So
the 48-bit address space is divided into two portions, Unicast and Multicast. The second bit is
for global-unique (0) or locally-unique address. The former is assigned by the device
manufacturer, and the later is usually assigned by the administrator. In practice,
global-unique addresses are always applied.
A unicast address is identified with a single network interface. With this nature of MAC
address, a frame transmitted can exactly be received by the target an interface the
destination MAC points to.
A multicast address is identified with a group of network devices or network interfaces. In
Ethernet, a many-to-many connectivity in the LANs is provided. It provides a mean to send a
frame to many network devices at a time. When all bit of DA is 1s, it is a broadcast, which
means all network device except the sender itself can receive the frame and response.
E
E
t
t
h
h
e
e
r
r
n
n
e
e
t
t
F
F
r
r
a
a
m
m
e
e
F
F
o
o
r
r
m
m
a
a
t
t
There are two major forms of Ethernet frame, type encapsulation and length encapsulation,
both of which are categorized as four frame formats 802.3/802.2 SNAP, 802.3/802.2,
Ethernet II and Netware 802.3 RAW. We will introduce the basic Ethernet frame format
defined by the IEEE 802.3 standard required for all MAC implementations. It contains seven
fields explained below.
PRE SFD DA SA Type/Length Data Pad bit if any FCS
7 7 6 6 2 46-1500 4
Preamble (PRE) - The PRE is 7-byte long with alternating pattern of ones and zeros used to
tell the receiving node that a frame is coming, and to synchronize the physical receiver with
the incoming bit stream. The preamble pattern is:
10101010 10101010 10101010 10101010 10101010 10101010 10101010
… 204 …


Need help? Post your question in this forum.

Forumrules


Report abuse

Libble takes abuse of its services very seriously. We're committed to dealing with such abuse according to the laws in your country of residence. When you submit a report, we'll investigate it and take the appropriate action. We'll get back to you only if we require additional details or have more information to share.

Product:

For example, Anti-Semitic content, racist content, or material that could result in a violent physical act.

For example, a credit card number, a personal identification number, or an unlisted home address. Note that email addresses and full names are not considered private information.

Forumrules

To achieve meaningful questions, we apply the following rules:

Register

Register getting emails for Draytek VigorSwitch G2280 at:


You will receive an email to register for one or both of the options.


Get your user manual by e-mail

Enter your email address to receive the manual of Draytek VigorSwitch G2280 in the language / languages: English as an attachment in your email.

The manual is 3,73 mb in size.

 

You will receive the manual in your email within minutes. If you have not received an email, then probably have entered the wrong email address or your mailbox is too full. In addition, it may be that your ISP may have a maximum size for emails to receive.

The manual is sent by email. Check your email

If you have not received an email with the manual within fifteen minutes, it may be that you have a entered a wrong email address or that your ISP has set a maximum size to receive email that is smaller than the size of the manual.

The email address you have provided is not correct.

Please check the email address and correct it.

Your question is posted on this page

Would you like to receive an email when new answers and questions are posted? Please enter your email address.



Info