es.tid.pce.pcep.objects

Class Metric

java.lang.Object

es.tid.pce.pcep.objects.PCEPObject

es.tid.pce.pcep.objects.Metric

All Implemented Interfaces:

PCEPElement

public class Metric
extends PCEPObject

Represents a PCEP METRIC Object as defined in RFC 5440

From RFC 5440 Section 7.8. METRIC Object

   The METRIC object is optional and can be used for several purposes.

   In a PCReq message, a PCC MAY insert one or more METRIC objects:

   o  To indicate the metric that MUST be optimized by the path
      computation algorithm (IGP metric, TE metric, hop counts).
      Currently, three metrics are defined: the IGP cost, the TE metric
      (see [RFC3785]), and the number of hops traversed by a TE LSP.

   o  To indicate a bound on the path cost that MUST NOT be exceeded for
      the path to be considered as acceptable by the PCC.

   In a PCRep message, the METRIC object MAY be inserted so as to
   provide the cost for the computed path.  It MAY also be inserted
   within a PCRep with the NO-PATH object to indicate that the metric
   constraint could not be satisfied.

   The path computation algorithmic aspects used by the PCE to optimize
   a path with respect to a specific metric are outside the scope of
   this document.

   It must be understood that such path metrics are only meaningful if
   used consistently: for instance, if the delay of a computed path
   segment is exchanged between two PCEs residing in different domains,
   consistent ways of defining the delay must be used.

   The absence of the METRIC object MUST be interpreted by the PCE as a
   path computation request for which no constraints need be applied to
   any of the metrics.

   METRIC Object-Class is 6.

   METRIC Object-Type is 1.

   The format of the METRIC object body is as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |          Reserved             |    Flags  |C|B|       T       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                          metric-value                         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                   Figure 15: METRIC Object Body Format

   The METRIC object body has a fixed length of 8 bytes.

   Reserved (16 bits):  This field MUST be set to zero on transmission
      and MUST be ignored on receipt.

   T (Type - 8 bits):  Specifies the metric type.

      Three values are currently defined:
  T=1: IGP metric
  T=2: TE metric
  T=3: Hop Counts

   Flags (8 bits):  Two flags are currently defined:

  B (Bound - 1 bit): When set in a PCReq message, the metric-
         value indicates a bound (a maximum) for the path metric that
         must not be exceeded for the PCC to consider the computed path
         as acceptable.  The path metric must be less than or equal to
         the value specified in the metric-value field.  When the B flag
         is cleared, the metric-value field is not used to reflect a
         bound constraint.

  C (Computed Metric - 1 bit): When set in a PCReq message, this
         indicates that the PCE MUST provide the computed path metric
         value (should a path satisfying the constraints be found) in
         the PCRep message for the corresponding metric.

      Unassigned flags MUST be set to zero on transmission and MUST be
      ignored on receipt.

   Metric-value (32 bits):  metric value encoded in 32 bits in IEEE
      floating point format (see [IEEE.754.1985]).

   Multiple METRIC objects MAY be inserted in a PCRep or a PCReq message
   for a given request (i.e., for a given RP).  For a given request,
   there MUST be at most one instance of the METRIC object for each
   metric type with the same B flag value.  If, for a given request, two
   or more instances of a METRIC object with the same B flag value are
   present for a metric type, only the first instance MUST be considered
   and other instances MUST be ignored.

   For a given request, the presence of two METRIC objects of the same
   type with a different value of the B flag is allowed.  Furthermore,
   it is also allowed to insert, for a given request, two METRIC objects
   with different types that have both their B flag cleared: in this
   case, an objective function must be used by the PCE to solve a multi-
   parameter optimization problem.

   A METRIC object used to indicate the metric to optimize during the
   path computation MUST have the B flag cleared and the C flag set to
   the appropriate value.  When the path computation relates to the
   reoptimization of an exiting TE LSP (in which case, the R flag of the
   RP object is set), an implementation MAY decide to set the metric-
   value field to the computed value of the metric of the TE LSP to be
   reoptimized with regards to a specific metric type.

   A METRIC object used to reflect a bound MUST have the B flag set, and
   the C flag and metric-value field set to the appropriate values.

   In a PCRep message, unless not allowed by PCE policy, at least one
   METRIC object MUST be present that reports the computed path metric
   if the C flag of the METRIC object was set in the corresponding path
   computation request (the B flag MUST be cleared).  The C flag has no
   meaning in a PCRep message.  Optionally, the PCRep message MAY
   contain additional METRIC objects that correspond to bound
   constraints; in which case, the metric-value MUST be equal to the
   corresponding computed path metric (the B flag MUST be set).  If no
   path satisfying the constraints could be found by the PCE, the METRIC
   objects MAY also be present in the PCRep message with the NO-PATH
   object to indicate the constraint metric that could be satisfied.

   Example: if a PCC sends a path computation request to a PCE where the
   metric to optimize is the IGP metric and the TE metric must not
   exceed the value of M, two METRIC objects are inserted in the PCReq
   message:

   o  First METRIC object with B=0, T=1, C=1, metric-value=0x0000

   o  Second METRIC object with B=1, T=2, metric-value=M

   If a path satisfying the set of constraints can be found by the PCE
   and there is no policy that prevents the return of the computed
   metric, the PCE inserts one METRIC object with B=0, T=1, metric-
   value= computed IGP path cost.  Additionally, the PCE may insert a
   second METRIC object with B=1, T=2, metric-value= computed TE path
   cost.
 

Author:

Oscar Gonzalez de Dios (ogondio@tid.es)

Field Summary

Fields inherited from class es.tid.pce.pcep.objects.PCEPObject

Ibit, log, object_bytes, ObjectClass, ObjectLength, OT, Pbit, Res

Constructor Summary

Constructors

Constructor and Description
Metric()
Metric(byte[] bytes, int offset) Constructs a new Metric Object from a sequence of bytes

Method Summary

Modifier and Type	Method and Description
void	decode() Decode Metric Object
void	encode() Encode Metric Object
boolean	equals(Object obj)
int	getMetricType()
float	getMetricValue()
int	hashCode()
boolean	isBoundBit()
boolean	isComputedMetricBit()
void	setBoundBit(boolean boundBit)
void	setComputedMetricBit(boolean computedMetricBit)
void	setMetricType(int metricType)
void	setMetricValue(float metricValue)
String	toString()

Methods inherited from class es.tid.pce.pcep.objects.PCEPObject

decode, decodeHeader, encode_header, getBytes, getLength, getObject_bytes, getObjectClass, getObjectClass, getObjectLength, getObjectType, getOT, getRes, isIbit, isPbit, setIbit, setObject_bytes, setObjectClass, setObjectLength, setOT, setPbit, setRes, supportedObject

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Metric

public Metric()

Metric

public Metric(byte[] bytes,
              int offset)
       throws MalformedPCEPObjectException

Constructs a new Metric Object from a sequence of bytes

Parameters:

bytes - Sequence of bytes where the object is present

offset - Position at which the object starts

Throws:

MalformedPCEPObjectException - Thrown if the decoded object is not well formed

Method Detail

encode

public void encode()

Encode Metric Object

Specified by:

encode in interface PCEPElement

Specified by:

encode in class PCEPObject

decode

public void decode()
            throws MalformedPCEPObjectException

Decode Metric Object

Specified by:

decode in class PCEPObject

Throws:

MalformedPCEPObjectException

setComputedMetricBit

public void setComputedMetricBit(boolean computedMetricBit)

setBoundBit

public void setBoundBit(boolean boundBit)

setMetricType

public void setMetricType(int metricType)

setMetricValue

public void setMetricValue(float metricValue)

isBoundBit

public boolean isBoundBit()

getMetricType

public int getMetricType()

getMetricValue

public float getMetricValue()

isComputedMetricBit

public boolean isComputedMetricBit()

toString

public String toString()

Overrides:

toString in class Object

hashCode

public int hashCode()

Overrides:

hashCode in class PCEPObject

equals

public boolean equals(Object obj)

Overrides:

equals in class PCEPObject