Transition Networks, Inc.
S4224 Web User Guide
33595 Rev. C
Page 644 of 669
FCS
(Frame Check Sequence) per MEF 8, 11, 12.
flow
A given type of traffic sent between a producer device through a network to an endpoint known as
a consumer. As the traffic goes through the network, it “flows” through the network. See also "Per flow QoS".
Foreign master
An ordinary or boundary clock sending Announce messages to another clock that is not the current master
recognized by the other clock.
FPGA
(Field-Programmable Gate Array) a chip that can be programmed in the field after manufacture.
FTP
FTP is an acronym for
F
ile
T
ransfer
P
rotocol. It is a transfer protocol that uses the Transmission Control
Protocol (TCP) and provides file writing and reading. It also provides directory service and security features.
G
G-ACH
Generic Associated Channel (per IETF RFC5586)
GLAG
(Global Link Aggregation Group) is one of two supported types of Link Aggregation Groups. With GLAG, ports in
a GLAG may reside on the same unit, up to two GLAGs are supported per stack, and each of the two GLAGs
may consist of up to eight ports.
For both LLAGs and GLAGs, the egress port is chosen based on an ‘aggregation code’ that is calculated for the
frame. This ensures that frames relating to a given frame flow are forwarded on the LLAG or GLAG member
port, and thus do not risk being re-ordered. See also “LLAG”.
Global address
In IPv6, an address with unlimited scope.
Grandmaster clock
Within a PTP domain, a clock that is the ultimate source of time for clock synchronization using the protocol.
H
HMAC
(Hash-based Message Authentication Code) - a specific construction that calculates a message authentication
code (MAC) involving a cryptographic hash function in combination with a secret key. As with any MAC, it may
be used to simultaneously verify both the data integrity and the authenticity of a message. Any cryptographic
hash function (e.g., MD5 or SHA-1) may be used in the calculation of an HMAC; the resulting MAC algorithm is
termed HMAC-MD5 or HMAC-SHA1 accordingly. The cryptographic strength of the HMAC depends on the
cryptographic strength of the underlying hash function, the size of its hash output length in bits, and on the size
and quality of the cryptographic key.
Host
In IPv6, any node that is not a router.