Appendix
33
© 2012 Patapsco Designs Ltd
ICMP
Internet Control Message Protocol. Used to send diagnostic messages such as Ping and Trace Route to
Ethernet devices.
IE
Information Element. The pieces of data which make up the protocol used in an ISDN call. These elements
can be manipulated by Patapsco devices in various ways.
IG MP
Internet Group Management Protocol. Used in Multicast communications to transmit to multiple devices.
Ingress
The port on which traffic enters a product – packet traffic entering the device.
IP
Internet Protocol. A protocol for communicating across a Packet Switched Network.
IP MT
Internet Protocol Mapping Table. A way of adding an IP Address and Identifier for each Patapsco device in a
system. Should be used with Dynamic Logical Links.
ISDN
Integrated Services Digital Network. A communications standard for carrying voice and data
communications across the PSTN.
Jitter
See PDV.
Jitter Buffer
Patapsco’s method of counteracting the effects of Jitter (or PDV).
LACP
Link Aggregation Control Protocol. Allows Ethernet devices to have more than one physical connection to a
network. Communications can be shared between the connections, and used as a fallback.
LAN
Local Area Network. A small IP/Ethernet network, typically based in one building or establishment and
consisting of only one segment (i.e. not a network consisting of many routed segments).
Late P ackets
Packets which arrived after the rest of the queue of packets in the Jitter Buffer had already been sent on out
of the buffer to the TDM/ISDN ports. i.e. its sequence number was too far behind the current queue of
packets to be inserted and used.
Latency
The time it takes for a packet to cross a Packet Switched Network. Also known as Delay.
Line Code
A method of encoding T1 data. Patapsco products support AMI and B8ZS encoding.
Local
Pertaining to the unit under scrutiny - the unit currently being monitored.
Logical Link
A connection made over a Packet Switched Network between two Patapsco devices. May contain up to 32 x
64kbps TDM/ISDN timeslots/b-channels.
LoopBacks
A software configured data loop made on a port or Logical Link for testing purposes. Both Local (loop back
to local device) and Remote (loop back to remote device) LoopBacks are available
Lost P ackets
IP packets which do not reach their destination. Patapsco IP devices are aware of the gap in the queue of
packets, and will log the number of missing packets.
MAC
Media Access Control. A unique hardware identifier for an Ethernet device.
Mask
See Subnet Mask.
MDI
Medium Dependent Interface. The standard interface type for Ethernet terminal devices. Connects to switches
and hubs which have MDI-X interfaces.
MDI- X
Medium Dependent Interface X-over (crossover). The standard interface type for switches and hubs. Connects
to Ethernet terminal devices which have MDI interfaces.
Mirror
In terms of packet tracing, a mirror can be set on an Ethernet port so that a second Ethernet port (with a PC
connected running packet tracing software) can ‘sniff’ the traffic for debugging purposes.
MP LS
Multi-Protocol Label Switching. An Ethernet based protocol which directs traffic based entirely on a label
tagged onto packets.
MSN
Multiple Subscriber Number. The same as DDI and DID.