If the least significant bit of the most significant address octet is set to 1, the frame will still be sent only once; however, NICs will choose to accept it based on criteria other than the matching of a MAC address: for example, based on a configurable list of accepted multicast MAC addresses. This is called multicast addressing. Oct 23, 2017 When used on an Ethernet or IEEE 802 network, the 23 low-order bits of the IP Multicast address are placed (logical OR) in the low-order 23 bits (or last 3 Hex digits minus the highest order bit) of the Ethernet or IEEE 802 net multicast address 01:00:5e:00:00:00. Example 1: The following multicast IP addresses yield the same multicast MAC.

• Mac Addresses For Multicast Recording
• Mac Address Multicast Range
• Mac Address For Multicast Calculator
• Ipv6 Multicast Mac Address

Discover which company built a networked interface by MAC Address.

Mac Addresses For Multicast Recording

1. Several formats accepted: 00-1C-23-59-5A-92, 001c23595a92, 00:1C:23:59:5A:92
2. Partial searches are accepted: 001c, 2359:92
3. Uses several databases including NMAP, IEEE Official List, Wireshark Info, and more.
4. Never know what else may show up ;)

MAC address

A media access control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are used as a network address for most IEEE 802 network technologies, including Ethernet. Logically, MAC addresses are used in the media access control protocol sublayer of the OSI reference model.

MAC addresses are most often assigned by the manufacturer of a network interface controller (NIC) and are stored in its hardware, such as the card's read-only memory or some other firmware mechanism. If assigned by the manufacturer, a MAC address usually encodes the manufacturer's registered identification number and may be referred to as the burned-in address (BIA). It may also be known as an Ethernet hardware address (EHA), hardware address or physical address. This can be contrasted to a programmed address, where the host device issues commands to the NIC to use an arbitrary address.

A network node may have multiple NICs and each must have one unique MAC address per NIC.

MAC addresses are formed according to the rules of one of three numbering name spaces managed by the Institute of Electrical and Electronics Engineers (IEEE): MAC-48, EUI-48, and EUI-64. The IEEE claims trademarks on the names EUI-48 and EUI-64, in which EUI is an abbreviation for Extended Unique Identifier.

Notational conventions

The standard (IEEE 802) format for printing MAC-48 addresses in human-friendly form is six groups of two hexadecimal digits, separated by hyphens (-) or colons (:), in transmission order (e.g. 01-23-45-67-89-ab or 01:23:45:67:89:ab ). This form is also commonly used for EUI-64. Another convention used by networking equipment uses three groups of four hexadecimal digits separated by dots (.) (e.g. 0123.4567.89ab ), again in transmission order.

Address details

The original IEEE 802 MAC address comes from the original Xerox Ethernet addressing scheme. This 48-bit address space contains potentially 248 or 281,474,976,710,656 possible MAC addresses.

All three numbering systems use the same format and differ only in the length of the identifier. Addresses can either be universally administered addresses or locally administered addresses. A universally administered address is uniquely assigned to a device by its manufacturer. The first three octets (in transmission order) identify the organization that issued the identifier and are known as the Organizationally Unique Identifier (OUI). The following three (MAC-48 and EUI-48) or five (EUI-64) octets are assigned by that organization in nearly any manner they please, subject to the constraint of uniqueness. The IEEE has a target lifetime of 100 years for applications using MAC-48 space, but encourages adoption of EUI-64s instead. A locally administered address is assigned to a device by a network administrator, overriding the burned-in address. Locally administered addresses do not contain OUIs.

Universally administered and locally administered addresses are distinguished by setting the second-least-significant bit of the most significant byte of the address. This bit is also referred to as the U/L bit, short for Universal/Local, which identifies how the address is administered. If the bit is 0, the address is universally administered. If it is 1, the address is locally administered. In the example address 06-00-00-00-00-00 the most significant byte is 06 (hex), the binary form of which is 00000110, where the second-least-significant bit is 1. Therefore, it is a locally administered address. Consequently, this bit is 0 in all OUIs.

If the least significant bit of the most significant octet of an address is set to 0 (zero), the frame is meant to reach only one receiving NIC. This type of transmission is called unicast. A unicast frame is transmitted to all nodes within the collision domain, which typically ends at the nearest network switch or router. A switch will forward a unicast frame through all of its ports (except for the port that originated the frame) if the switch has no knowledge of which port leads to that MAC address, or just to the proper port if it does have knowledge. Only the node with the matching hardware MAC address will accept the frame; network frames with non-matching MAC-addresses are ignored, unless the device is in promiscuous mode.

If the least significant bit of the most significant address octet is set to 1, the frame will still be sent only once; however, NICs will choose to accept it based on criteria other than the matching of a MAC address: for example, based on a configurable list of accepted multicast MAC addresses. This is called multicast addressing.

The following technologies use the MAC-48 identifier format:

• Ethernet
• 802.11 wireless networks
• IEEE 802.5 token ring
• most other IEEE 802 networks
• Fiber Distributed Data Interface (FDDI)
• Asynchronous Transfer Mode (ATM), switched virtual connections only, as part of an NSAP address
• Fibre Channel and Serial Attached SCSI (as part of a World Wide Name)
• The ITU-TG.hn standard, which provides a way to create a high-speed (up to 1 gigabit/s) local area network using existing home wiring (power lines, phone lines and coaxial cables). The G.hn Application Protocol Convergence (APC) layer accepts Ethernet frames that use the MAC-48 format and encapsulates them into G.hn Medium Access Control Service Data Units (MSDUs).

Every device that connects to an IEEE 802 network (such as Ethernet and WiFi) has a MAC-48 address. Common consumer devices to use MAC-48 include every PC, iPhone, iPad, and Android-based devices.

The distinction between EUI-48 and MAC-48 identifiers is purely nominal: MAC-48 is used for network hardware; EUI-48 is used to identify other devices and software. (Thus, by definition, an EUI-48 is not in fact a 'MAC address', although it is syntactically indistinguishable from one and assigned from the same numbering space.)

The IEEE now considers the label MAC-48 to be an obsolete term, previously used to refer to a specific type of EUI-48 identifier used to address hardware interfaces within existing 802-based networking applications, and thus not to be used in the future. Instead, the proprietary term EUI-48 should be used for this purpose.

The EUI-48 is expected to have its address space exhausted by the year 2100.

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EUI-64 identifiers are used in:

• IPv6 (Modified EUI-64 as the least-significant 64 bits of a unicast network address or link-local address when stateless autoconfiguration is used)
• ZigBee / 802.15.4 / 6LoWPAN wireless personal-area networks

The IEEE has built in several special address types to allow more than one network interface card to be addressed at one time:

• Packets sent to the broadcast address, all one bits, are received by all stations on a local area network. In hexadecimal the broadcast address would be FF:FF:FF:FF:FF:FF. A broadcast frame is flooded and is forwarded to and accepted by all other nodes.
• Packets sent to a multicast address are received by all stations on a LAN that have been configured to receive packets sent to that address.
• Functional addresses identify one or more Token Ring NICs that provide a particular service, defined in IEEE 802.5.

These are all examples of group addresses, as opposed to individual addresses; the least significant bit of the first octet of a MAC address distinguishes individual addresses from group addresses. That bit is set to 0 in individual addresses and set to 1 in group addresses. Group addresses, like individual addresses, can be universally administered or locally administered.

In addition, the EUI-64 numbering system encompasses both MAC-48 and EUI-48 identifiers by a simple translation mechanism. To convert a MAC-48 into an EUI-64, copy the OUI, append the two octets FF-FF and then copy the organization-specified extension identifier. To convert an EUI-48 into an EUI-64, the same process is used, but the sequence inserted is FF-FE. In both cases, the process can be trivially reversed when necessary. Organizations issuing EUI-64s are cautioned against issuing identifiers that could be confused with these forms. The IEEE policy is to discourage new uses of 48-bit identifiers in favor of the EUI-64 system.
IPv6 — one of the most prominent standards that uses a Modified EUI-64 — treats MAC-48 as EUI-48 instead (as it is chosen from the same address pool) and toggles the U/L bit (as this makes it easier to type locally assigned IPv6 addresses based on the Modified EUI-64). This results in extending MAC addresses (such as IEEE 802 MAC address) to Modified EUI-64 using only FF-FE (and never FF-FF) and with the U/L bit inverted.

Individual address block

An Individual Address Block is a 24-bit OUI managed by the IEEE Registration Authority, followed by 12 IEEE-provided bits (identifying the organization), and 12 bits for the owner to assign to individual devices. Best free media player mac. An IAB is ideal for organizations requiring fewer than 4097 unique 48-bit numbers (EUI-48).

Mac Address Usage in hosts

Although intended to be a permanent and globally unique identification, it is possible to change the MAC address on most modern hardware. Changing MAC addresses is necessary in network virtualization. It can also be used in the process of exploiting security vulnerabilities. This is called MAC spoofing.

A host cannot determine from the MAC address of another host whether that host is on the same link (network segment) as the sending host, or on a network segment bridged to that network segment.

In IP networks, the MAC address of an interface can be queried given the IP address using the Address Resolution Protocol (ARP) for Internet Protocol Version 4 (IPv4) or the Neighbor Discovery Protocol (NDP) for IPv6. In this way, ARP or NDP is used to translate IP addresses (OSI layer 3) into Ethernet MAC addresses (OSI layer 2). On broadcast networks, such as Ethernet, the MAC address uniquely identifies each node on that segment and allows frames to be marked for specific hosts. It thus forms the basis of most of the link layer (OSI Layer 2) networking upon which upper layer protocols rely to produce complex, functioning networks.

Mac Address Usage in switches

Layer 2 switches use MAC addresses to restrict packet transmission to the intended recipient. However, the effect is not immediate.

Bit-reversed notation

The standard notation, also called canonical format, for MAC addresses is written in transmission bit order with the least significant bit transmitted first, as seen in the output of the iproute2/ifconfig/ipconfig command, for example.

However, since IEEE 802.3 (Ethernet) and IEEE 802.4 (Token Bus) send the bytes (octets) over the wire, left-to-right, with least significant bit in each byte first, while IEEE 802.5 (Token Ring) and IEEE 802.6 send the bytes over the wire with the most significant bit first, confusion may arise when an address in the latter scenario is represented with bits reversed from the canonical representation. For example, an address in canonical form 12-34-56-78-9A-BC would be transmitted over the wire as bits 01001000 00101100 01101010 00011110 01011001 00111101 in the standard transmission order (least significant bit first). But for Token Ring networks, it would be transmitted as bits 00010010 00110100 01010110 01111000 10011010 10111100 in most-significant-bit first order. The latter might be incorrectly displayed as 48-2C-6A-1E-59-3D. This is referred to as bit-reversed order, non-canonical form, MSB format, IBM format, or Token Ring format, as explained in RFC 2469. Canonical form is generally preferred, and used by all modern implementations.

When the first switches supporting both Token Ring and Ethernet came out, some did not distinguish between canonical form and non-canonical form and so did not reverse MAC address bits as required. This led to cases of duplicate MAC addresses in the field.

See also

• Hot Standby Router Protocol or standard alternative VRRP Virtual Router Redundancy Protocol, which allows multiple routers to share one IP address and MAC address to provide router redundancy. The OpenBSD project has an open source alternative, the Common Address Redundancy Protocol (CARP). On Linux, iptables has a CLUSTERIP target.
• NSAP address, another endpoint addressing scheme.
• Sleep Proxy Service, which may 'take over' another device's MAC address during certain periods

References

1. IEEE Std 802-2001. The Institute of Electrical and Electronics Engineers, Inc. (IEEE). 2002-02-07. p. 19. 'The universal administration of LAN MAC addresses began with the Xerox Corporation administering Block Identifiers (Block IDs) for Ethernet addresses.'
2. 'Guidelines for use of the 24-bit Organizationally Unique Identifiers (OUI)'. IEEE-SA.
3. 'Standard Group MAC Addresses: A Tutorial Guide'. IEEE-SA.
4. 'Guidelines for Fibre Channel Use of the Organizationally Unique Identifier (OUI)'. IEEE-SA.
5. 'Network Interface Controller'. Wikipedia.
6. 'Guidelines for 64-bit Global Identifier (EUI-64)'. IEEE-SA.
7. RFC 5342'IANA Considerations and IETF Protocol Usage for IEEE 802 Parameters'. IETF. September 2008.
8. IEEE-RA. 'What is an Individual Address Block?'.

External links

• Wireshark's OUI Lookup Tool and MAC address list

A multicast address is a logical identifier for a group of hosts in a computer network that are available to process datagrams or frames intended to be multicast for a designated network service. Multicast addressing can be used in the link layer (layer 2 in the OSI model), such as Ethernet multicast, and at the internet layer (layer 3 for OSI) for Internet Protocol Version 4 (IPv4) or Version 6 (IPv6) multicast.

Mac Address Multicast Range

IPv4[edit]

IPv4 multicast addresses are defined by the most-significant bit pattern of 1110. This originates from the classful network design of the early Internet when this group of addresses was designated as Class D. The CIDR notation for this group is 224.0.0.0/4. The group includes the addresses from 224.0.0.0 to 239.255.255.255. Address assignments from within this range are specified in RFC 5771, an Internet Engineering Task Force (IETF) Best Current Practice document (BCP 51).

The address range is divided into blocks each assigned a specific purpose or behavior.

Local subnetwork

Addresses in the range of 224.0.0.0 to 224.0.0.255 are individually assigned by IANA and designated for multicasting on the local subnetwork only. For example, the Routing Information Protocol (RIPv2) uses 224.0.0.9, Open Shortest Path First (OSPF) uses 224.0.0.5 and 224.0.0.6, and Multicast DNS uses 224.0.0.251. Routers must not forward these messages outside the subnet from which they originate.

Internetwork control block

Addresses in the range 224.0.1.0 to 224.0.1.255 are individually assigned by IANA and designated as the internetwork control block. This block of addresses is used for traffic that must be routed through the public Internet, such as for applications of the Network Time Protocol using 224.0.1.1.

AD-HOC block

Addresses in three separate blocks are not individually assigned by IANA. These addresses are globally routed and are used for applications that don't fit either of the previously described purposes.^[6]

Source-specific multicast

The 232.0.0.0/8 (IPv4) and ff3x::/32 (IPv6) blocks are reserved for use by source-specific multicast.

GLOP

The 233.0.0.0/8 range was originally assigned by RFC2770 as an experimental, public statically-assigned multicast address space for publishers and Internet service providers that wished to source content on the Internet. The allocation method is termed GLOP addressing and provides implementers a block of 255 addresses that is determined by their 16-bit autonomous system number (ASN) allocation. In a nutshell, the middle two octets of this block are formed from assigned ASNs, giving any operator assigned an ASN 256 globally unique multicast group addresses.^[7] The method is not applicable to the newer 32-bit ASNs. RFC3180, superseding RFC2770, envisioned the use of the range for many-to-many multicast applications. Unfortunately, with only 256 multicast addresses available to each autonomous system, GLOP is not adequate for large-scale broadcasters.^{[citation needed]}

Unicast-prefix-based

The 234.0.0.0/8 range is assigned by RFC6034 as a range of global IPv4 multicast address space provided to each organization that has /24 or larger globally routed unicast address space allocated; one multicast address is reserved per /24 of unicast space. A resulting advantage over GLOP is that the unicast-prefix mechanism resembles the unicast-prefix capabilities of IPv6 as defined in RFC3306.

Administratively scoped

The 239.0.0.0/8 range is assigned by RFC 2365 for private use within an organization. Per the RFC, packets destined to administratively scoped IPv4 multicast addresses do not cross administratively defined organizational boundaries, and administratively scoped IPv4 multicast addresses are locally assigned and do not have to be globally unique. The RFC also discusses structuring the 239.0.0.0/8 range to be loosely similar to the scoped IPv6 multicast address range described in RFC1884.

Notable IPv4 multicast addresses[edit]

Mac burn dvd for dvd players. The following table is a list of notable well-known IPv4 addresses that are reserved for IP multicasting and that are registered with the Internet Assigned Numbers Authority (IANA).^[8]

Mac Address For Multicast Calculator

IPv6[edit]

Multicast addresses in IPv6 use the prefix ff00::/8. IPv6 multicast addresses can be structured using the old format (RFC 2373) or the new format (RFC 3306, updated by RFC 7371).

Ipv6 Multicast Mac Address

The prefix holds the value ff for all multicast addresses.

Currently, 3 of the 4 flag bits in the flags field (ff1) are defined;^[11] the most-significant flag bit is reserved for future use. The other three flags are known as R, P and T.

Similar to a unicast address, the prefix of an IPv6 multicast address specifies its scope, however, the set of possible scopes for a multicast address is different. The 4-bit sc (or scope) field (bits 12 to 15) is used to indicate where the address is valid and unique.

The service is identified in the group ID field. For example, if ff02::101 refers to all Network Time Protocol (NTP) servers on the local network segment, then ff08::101 refers to all NTP servers in an organization's networks. The group ID field may be further divided for special multicast address types.

Notable IPv6 multicast addresses[edit]

The following table is a list notable IPv6 multicast addresses that are registered with IANA.^[17]

Ethernet[edit]

Ethernet frames with a value of 1 in the least-significant bit of the first octet^{[note 3]} of the destination MAC address are treated as multicast frames and are flooded to all points on the network. While frames with ones in all bits of the destination address (FF-FF-FF-FF-FF-FF) are sometimes referred to as broadcasts, Ethernet generally does not distinguish between multicast and broadcast frames. Modern Ethernet controllers filter received packets to reduce CPU load, by looking up the hash of a multicast destination address in a table, initialized by software, which controls whether a multicast packet is dropped or fully received.

The IEEE has allocated the address block 01-80-C2-00-00-00 to 01-80-C2-FF-FF-FF for group addresses for use by standard protocols. Of these, the MAC group addresses in the range of 01-80-C2-00-00-00 to 01-80-C2-00-00-0F are not forwarded by 802.1D-conformant MAC bridges.^[18]

802.11[edit]

802.11 wireless networks use the same MAC addresses for multicast as Ethernet.

See also[edit]

Notes[edit]

1. ^The recommended style for Request for Comments (RFC) documents is 'MSB 0' bit numbering.
2. ^x is a place holder indicating that the value of the flags field is unimportant in the current discussion.
3. ^On Ethernet, the least-significant bit of an octet is the first to be transmitted. A multicast is indicated by the first transmitted bit of the destination address being 1.

References[edit]

1. ^ ^abcIP Multicast Routing Configuration Guide, Cisco, p. 17-19, retrieved 2017-05-27
2. ^AD-HOC Block 1
3. ^AD-HOC Block 2
4. ^Fall, K.R. and Stevens, W.R. (2011). TCP/IP Illustrated. 1. Addison-Wesley. p. 55. ISBN9780321336316.CS1 maint: multiple names: authors list (link)
5. ^AD-HOC Block 3
6. ^RFC 5771 Section 6.
7. ^'Frequently Asked Questions (FAQ) File for Multicasting'. Multicast Tech. Archived from the original on 2011-05-16.
8. ^'IANA IP multicast addresses assignments'. Internet Assigned Numbers Authority.
9. ^RFC 3376 Section 4.2.14
10. ^RFC 4380 item 2.17
11. ^Hinden, R.; Deering, S. (February 2006) IP Version 6 Addressing Architecture, IETF, RFC4291.
12. ^Silvia Hagen (May 2006). IPv6 Essentials (Second ed.). O'Reilly. ISBN978-0-596-10058-2.
13. ^RFC 3956
14. ^RFC 3306
15. ^RFC 4291
16. ^RFC 2365 section 8.
17. ^'IPv6 Multicast Address Space Registry'. Internet Assigned Numbers Authority.
18. ^IEEE. 'Standard Group MAC Address: A Tutorial Guide'(PDF). IEEE Standards Association. pp. 2–3.
19. ^Patton, Michael A. et. al. 'Multicast (including Broadcast) Addresses'. cavebear.com. Karl Auerbach.
20. ^RFC 7042 2.1.1.
21. ^RFC 7042 2.3.1.