IEEE 802.1CB-2017 pdf download

IEEE 802.1CB-2017 pdf download.IEEE Standard for Local and metropolitan area networks一Frame Replication and Elimination for Reliability.
5. Conformance
This clause specifies the mandatory and optional capabilities provided by conformant implementations of this standard.
5.1 Requirements terminology
For consistency with existing IEEE and IEEE 802. 1 standards, requirements placed upon conformant implementations of this standard are expressed using the following terminology:
a) Shall is used for mandatory requirements;
b) Mar is used to describe implementation or administrative choices (“may” means “is permitted to,” and hence, “may” and “may not” mean precisely the same thing);
c) Should is used for recommended choices (the behaviors described by “should” and “should not” are both permissible but not equally desirable choices).
The Protocol Implementation Conformance Statement (PICS) proformas (see Annex A) reflect the occurrences of the words “shall,”“may,” and “should” within the standard.
The standard avoids needless repetition and apparent duplication of its formal requirements by using is, is not, are, and are not for definitions and the logical consequences of conformant behavior. Behavior that is permitted but is neither always required nor directly controlled by an implementor or administrator, or whose conformance requirement is detailed elsewhere, is described by call. Behavior that never occurs in a conformant implementation or system of conformant implementations is described by cannot. The word allow is used as a replacement for the phrase “support the ability for,” and the word capability means “can be configured to.”
5.2 Conformant components and equipment
Conformance for Frame Replication and Elimination for Reliability (FRER) is defined for five types of components and equipment:
a) Stream identification components (5.3, 5.4, 5.5), which provide a useful subset of the FRER capabilities for systems that are not talker end systems. listener end systems. or relay systems.
b) Talker end systems (5.6, 5.7, 5.8), which originate Compound Streams.
c) Listener end systems (5.9, 5.10. 5.11), which consume Compound Streams.
d) Relay systems (5.12, 5.13, 5.14), which transfer or discard packets belonging to Compound Streams.
e) One particular type of Relay system, an FRER C-component (5.15).
The Stream identification component can be useful in components or equipment that are not talker end systems, listener end systems, or relay systems as defined in this standard, e.g., bridges or routers that carry packets belonging to Compound Streams, and must identify them, but do not process FRER sequence numbers. Other useful systems can be created using the preceding components listed. For example, a two- port Talker could be modeled and implemented as two Talker end systems in a single chassis, as a single one-port Talker end system that uses IEEE 802. lAX Link Aggregation to combine two physical ports into a single logical port (C. 1), or as a single-port Talker end system connected to a three-port Bridge (C.6).
5.3 Stream identification component required behaviors
A Stream identification component shall be able to instantiate the following out-facing functions on at least one port, for at least one Compound Stream:
a) Stream identification (Clause 6);
b) A Null Stream identification function (6.4); and
c) The managed objects in Clause 9.
5.4 Stream identification component recommended behavior
A Stream identification component should be able to instantiate the following out-facing functions on at least one port, for at least one Compound Stream:
a) An Active Destination MAC and VLAN Stream identification function (6.6).
5.5 Stream identification component optional behaviors
In addition to the requirements of 5.3 and 5.4, a Stream identification component may perform the following ftinctions:
a) The items in 5.3 and 5.4 on more than one port;
b) The items in 5.3 and 5.4 for some number of Compound Streams greater than 1;
c) An IP Stream identification function (6.7); and/or
d) Additional types of Stream identification functions.
5.6 Talker end system required behaviors
A Talker end system shall be able to instantiate the following out-facing functions on at least one port, for at least one Compound Stream:
a) Stream identification (Clause 6);
b) A Null Stream identification function (6.4);
c) A Sequence generation function (7.4.1); and
d) The Redundancy tag Sequence encode/decode function specified in 7.6 and 7.8.
e) The managed objects in Clause 9 and Clause 10, excepting 10.7.
5.7 Talker end system recommended behaviors
A Talker end system should be able to instantiate the following out-facing functions on at least one port, for at least one Compound Stream:
a) An Active Destination MAC and VLAN Stream identification function (6.6); and
h) A Stream splitting function (7.7).