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* Ethernet II comprise an Ethernet II frame header ( Destination, Source, EtherType ) followed by IPX data.
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Ethernet and II
* A4066 Zorro II Ethernet interface using SMC 91C90QF.
By 1987 Ethernet was clearly winning the standards battle over Token Ring, and in the middle of that year Apple introduced EtherTalk 1. 0 for the newly released Macintosh II computer.
Version 2 was published in November, 1982 and defines what has become known as Ethernet II.
IEEE 802. 3 is an exception ; Ethernet originally used Ethernet II framing, with a 2-octet type field containing an EtherType value, and no 802. 2 header, but the original IEEE 802. 3 specification used a framing wherein the 2-octet field following the 6-octet destination and source MAC addresses contained a frame length, with an 802. 2 LLC header following the length field.
* DynamicAccess software products for Ethernet load balancing, response time, and RMON II distributed monitoring.
As the Ethertype in an Ethernet II framing formatted frame is used to multiplex different protocols on top of the Ethernet MAC header it can be seen as LLC identifier.
This field was first defined by the Ethernet II framing networking standard, and later adapted for the IEEE 802. 3 Ethernet networking standard.
However, for Ethernet, the Ethernet II header is still used.
EAPOL operates at the network layer on top of the data link layer, and in Ethernet II framing protocol has an EtherType value of 0x888E.
On Ethernet, this reduces the size of the available payload for protocols such as the Internet Protocol to 1492 bytes, compared to the use of the Ethernet II framing ; therefore, for protocols that have EtherType values, packets are usually transmitted with Ethernet II headers rather than with LLC and SNAP headers.
As per IETF RFC 1042, IP datagrams and ARP datagrams are transmitted over IEEE 802 networks using LLC and SNAP headers, except on Ethernet / IEEE 802. 3, where they are transmitted with Ethernet II headers, as per RFC 894.
Ethernet and comprise
The Ethernet standards comprise several wiring and signaling variants of the OSI physical layer in use with Ethernet.
Many modern supercomputers comprise giant server farms of high-speed processors connected by either Gigabit Ethernet or custom interconnects such as Infiniband or Myrinet.
Ethernet and frame
A 1500 byte ( 12000-bit ) full-size Ethernet frame takes only 1. 2 µs to transmit on a 10 Gbit / s network, reducing the need for small cells to reduce jitter due to contention.
Features such as the 48-bit MAC address and Ethernet frame format have influenced other networking protocols.
Ethernet frames are said to be self-identifying, because of the frame type.
Despite the evolution of Ethernet technology, all generations of Ethernet ( excluding early experimental versions ) use the same frame formats ( and hence the same interface for higher layers ), and can be readily interconnected through bridging.
A frame begins with preamble and start frame delimiter, followed by an Ethernet header featuring source and destination MAC addresses.
* Priority Code Point, a three-bit priority field within an Ethernet frame header when using IEEE 802. 1q tagged frames.
For example, in Ethernet the maximum frame size 1526 bytes ( maximum 1500 byte payload + 8 byte preamble + 14 byte header + 4 Byte trailer ).
It is also called 100VG-AnyLAN because it was defined to carry both Ethernet and token ring frame types.
In other words, for ATM ( and eventually other protocols such as Ethernet ), the internal complex structure previously used to transport circuit-oriented connections was removed and replaced with a large and concatenated frame ( such as STS-3c ) into which ATM cells, IP packets, or Ethernet frames are placed.
In packet-oriented data transmission, such as Ethernet, a packet frame usually consists of a header and a payload.
The WAN PHY variant encapsulates Ethernet data using a lightweight SDH / SONET frame, so as to be compatible at a low level with equipment designed to carry SDH / SONET signals, whereas the LAN PHY variant encapsulates Ethernet data using 64B / 66B line coding.
According to Ethernet specifications, collisions should be detected during the first 64 bytes of the frame, so frames that are in error because of a collision will not be forwarded.
Layer 2 switching is highly efficient because there is no modification to the data packet, only to the frame encapsulation of the packet, and only when the data packet is passing through dissimilar media ( such as from Ethernet to FDDI ).
The routers in an Ethernet or frame relay network select a designated router ( DR ) and a backup designated router ( BDR ) which act as a hub to reduce traffic between routers.
A full-size ( 1500 byte ) Ethernet frame takes 94 ms to transmit at 128 kbit / s but only 8 ms at 1. 5 Mbit / s.
This " color " is what is now known in the Ethernet frame as the 802. 1Q header, or the VLAN tag.
ISL uses an external tagging process that does not modify the existing Ethernet frame, while 802. 1Q uses a frame-internal field for tagging, and so does modify the Ethernet frame.
Ethernet and header
This worked somewhat differently from an Ethernet bridge, where only the header of the incoming packet would be examined before it was either dropped or forwarded to another segment.
Other protocols, like Ethernet, establish the start of the header and data elements by their location relative to the start of the packet.
ATM has substantial header overhead: 5 / 53 = 9. 4 %, roughly twice the total header overhead of a 1500 byte Ethernet packet.
With ISL, an Ethernet frame is encapsulated with a header that transports VLAN IDs between switches and routers.
With the advent of the IEEE 802 suite of standards, a SNAP header combined with an IEEE 802. 2 LLC header is used to transmit the EtherType of a payload for IEEE 802 networks other than Ethernet, as well as for non-IEEE networks that use the IEEE 802. 2 LLC header, such as FDDI.
* Class of service ( CoS ), a 3 bit field within a layer two Ethernet frame header defined by IEEE 802. 1p
* Mausezahn: Another fast and versatile packet generator that also supports Ethernet header manipulation.
Ethernet and Destination
0 | Ethernet Destination MAC Address |
4 | Ethernet Destination ( cont ) | Ethernet Source MAC Address |
Ethernet and Source
8 | Ethernet Source MAC Address ( cont ) |
Ethernet and EtherType
Since the magic packet is only scanned for the string above, and not actually parsed by a full protocol stack, it may be sent as any network-and transport-layer protocol, although it is typically sent as a UDP datagram to port 7 or 9, or directly over Ethernet as EtherType 0x0842.
The IEEE 802. 2 standard specifies LLC sublayer for all IEEE 802 local area networks, such as IEEE 802. 3 / Ethernet ( if the EtherType field is used ), IEEE 802. 5, and IEEE 802. 11, and in some non-IEEE 802 networks such as FDDI.
However, If Ethernet is used without EtherType field, Ethernet is considered as lacking LLC sublayer.
EtherType is a two-octet field in an Ethernet frame.
In modern implementations of Ethernet, the field within the Ethernet frame used to describe the EtherType also can be used to represent the size of the payload of the Ethernet Frame.
Ethernet v2 framing considered these octets to represent EtherType while the original IEEE 802. 3 framing considered these octets to represent the size of the payload in bytes.
In order to allow packets using Ethernet v2 framing and packets using the IEEE 802. 3 framing to be used on the same Ethernet segment, a unifying standard ( IEEE 802. 3x-1997 ) was introduced that required that EtherType values be greater than or equal to 1536 ( 0x0600 ).
Thus, values of 1500 ( 0x05DC ) and below for this field indicate that the field is used as the size of the payload of the Ethernet Frame while values of 1536 and above indicate that the field is used to represent EtherType.
Instead, for Ethernet frames, it adds a 32-bit field between the source MAC address and the EtherType / Length fields of the original frame, extending the minimum and maximum frame sizes from 64 and 1, 518 bytes ( octets ) to 64 and 1, 522 bytes ( 42 octet minimum applies when 802. 1Q is present.
If the OUI is hexadecimal 000000, the protocol ID is the Ethernet type ( EtherType ) field value for the protocol running on top of SNAP ; if the OUI is an OUI for a particular organization, the protocol ID is a value assigned by that organization to the protocol running on top of SNAP.
0.747 seconds.