M
MAC
Media Access Control
layer. One of two sub-layers that make up the Data Link Layer of the OSI model. The MAC layer
is responsible for moving data packets to and from one
NIC to
another across a shared channel.
MAC address
Media access control address. The MAC address, sometimes known as the hardware
address, is the unique physical address of each network interface card on each
device.
MAN
Metropolitan area network. A MAN is a data network designed for a town or city. MANs
may be operated by one organization such as a corporation with several offices in one city, or
be shared resources used by several organizations with several locations in the same city.
MANs are usually characterized by very high-speed connections.
master node
In
EAPS, the master node is a switch, or node, that is designated the
master in an EAPS domain ring. The master node blocks the secondary port for all non-control
traffic belonging to this EAPS domain, thereby avoiding a loop in the ring.
master router
In
VRRP, the master router is the physical device (router) in the
VRRP virtual router that is responsible for forwarding packets sent to the VRRP virtual router
and for responding to ARP requests. The master router sends out periodic advertisements that
let backup routers on the network know that it is alive. If the VRRP IP address owner is
identified, it always becomes the master router.
master VLAN
In
ESRP, the master VLAN is the VLAN on the ESRP domain that
exchanges ESRP-PDUs and data between a pair of ESRP-enabled devices. You must configure one
master VLAN for each ESRP domain, and a master VLAN can belong to only one ESRP
domain.
MED
Multiple exit
discriminator.
BGP uses the MED metric to select a particular
border router in another AS when multiple border routers exist.
member VLAN
In
ESRP, you configure zero or more member VLANs for each ESRP
domain. A member VLAN can belong to only one ESRP domain. The state of the ESRP device
determines whether the member VLAN is in forwarding or blocking state.
MEP
In
CFM, maintenance end point is an end point for a single domain, or
maintenance association. The MEP may be either an UP MEP or a DOWN MEP.
metering
In
QoS, metering monitors the traffic pattern of each flow against the
traffic profile. For out-of-profile traffic the metering function interacts with other
components to either re-mark or drop the traffic for that flow. In the Extreme Networks
implementation, you use
ACLs to enforce metering.
MIB
Management Information Base. MIBs make up a database of information (for example,
traffic statistics and port settings) that the switch makes available to network management
systems. MIB names identify objects that can be managed in a network and contain information
about the objects. MIBs provide a means to configure a network device and obtain network
statistics gathered by the device. Standard, minimal MIBs have been defined, and vendors often
have private enterprise MIBs.
MIC
Message Integrity Check
or Code (MIC), also called ‘Michael‘, is part of WPA and TKIP. The MIC is an additional 8-byte
code inserted before the standard 4-byte integrity check value (
ICV) that is appended in by standard WEP to the 802.11 message. This greatly
increases the difficulty in carrying out forgery attacks.
Both integrity check mechanisms are
calculated by the receiver and compared against the values sent by the sender in the frame. If
the values match, there is assurance that the message has not been tampered with. (See
WPA,
TKIP, and
ICV.)
MIP
In
CFM, the maintenance intermediate point is intermediate between
endpoints. Each MIP is associated with a single domain, and there may be more than one MIP in
a single domain.
mirroring
Port mirroring configures the switch to copy all traffic associated with one or more
ports to a designated monitor port. The monitor port can be connected to an network analyzer
or RMON probe for packet analyzer.
MLAG
Multi-switch Link
Aggregation Group (a.k.a. Multi-Chassis Link Aggregation Group). This feature allows users to
combine ports on two switches to form a single logical connection to another network device.
The other network device can be either a server or a switch that is separately configured with
a regular LAG (or appropriate server port teaming) to form the port aggregation.
MMF
Multimode fiber. MMF is
a fiber optic cable with a diameter larger than the optical wavelength, in which more than one
bound mode can propagate. Capable of sending multiple transmissions simultaneously, MMF is
commonly used for communications of 2 km or less.
MSDP
Multicast Source
Discovery Protocol. MSDP is used to connect multiple multicast routing domains. MSDP
advertises multicast sources across Protocol Independent Multicast-Sparse Mode (PIM-SM)
multicast domains or Rendezvous Points (RPs). In turn, these RPs run MSDP over TCP to discover
multicast sources in other domains.
MSM
Master Switch Fabric Module. This Extreme Networks-proprietary name refers to the
module that holds both the control plane and the switch fabric for switches that run the
ExtremeXOS software on modular switches. One MSM is required for switch operation; adding an
additional MSM increases reliability and throughput. Each MSM has two CPUs. The MSM has LEDs
as well as a console port, management port, modem port, and compact flash; it may have data
ports as well. The MSM is responsible for upper-layer protocol processing and system
management functions. When you save the switch configuration, it is saved to all
MSMs.
MSTI
Multiple Spanning Tree Instances. MSTIs control the topology inside an MSTP region. An
MSTI is a spanning tree domain that operates within a region and is bounded by that region;
and MSTI does not exchange BPDUs or send notifications to other regions. You can map multiple
VLANs to an MSTI; however, each VLAN can belong to only one MSTI.You can configure up to 64
MSTIs in an MSTP region.
MSTI regional root bridge
In an MSTP environment, each MSTI independently elects its own root bridge. The bridge
with the lowest bridge ID becomes the MSTI regional root bridge. The bridge ID includes the
bridge priority and the MAC address.
MSTI root port
In an MSTP environment, the port on the bridge with the lowest path cost to the MSTI
regional root bridge is the MSTI root port.
MSTP
Multiple Spanning Tree
Protocol. MSTP, based on IEEE 802.1Q-2003 (formerly known as IEEE 892.1s), allows you to
bundle multiple VLANs into one spanning tree (
STP) topology,
which also provides enhanced loop protection and better scaling. MSTP uses RSTP as the
converging algorithm and is compatible with legacy STP protocols.
MSTP region
An MSTP region defines
the logical boundary of the network. Interconnected bridges that have the same MSTP
configuration are referred to as an MSTP region. Each MSTP region has a unique identifier, is
bound together by one
CIST that spans the entire network, and
contains from 0 to 64 MSTIs. A bridge participates in only one MSTP region at one time. An
MSTP topology is individual MSTP regions connected either to the rest of the network with
802.1D and 802.1w bridges or to each other.
MTU
Maximum transmission unit. This term is a configurable parameter that determines the
largest packet than can be transmitted by an IP interface (without the packet needing to be
broken down into smaller units).
Note
Packets that are larger than the configured MTU size are
dropped at the ingress port. Or, if configured to do so, the system can fragment the IPv4
packets and reassemble them at the receiving end.
multicast
Multicast messages are transmitted to selected devices that specifically join the
multicast group; the addresses are specified in the destination address field. In other words,
multicast (point-to-multipoint) is a communication pattern in which a source host sends a
message to a group of destination hosts.
multinetting
IP multinetting assigns multiple logical IP interfaces on the same circuit or physical
interface. This allows one bridge domain (VLAN) to have multiple IP networks.
MVR
Multicast VLAN registration. MVR allows a subscriber on a port to subscribe and
unsubscribe to a multicast stream on the network-wide multicast VLAN; it allows the single
multicast VLAN to be shared in the network while subscribers remain in separate VLANs. MVR
provides the ability to continuously send multicast streams in the multicast VLAN, but to
isolate the The application from the subscriber VLANs for bandwidth and security reasons. MVR
allows a multicast stream received over a Layer 2 VLAN to be forwarded to another VLAN,
eliminating the need for a Layer 3 routing protocol; this feature is often used for IPTV
applications.