rfc3212.txt

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   Message.

   Each ER-Hop TLV has the form:

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|0|                 Type      |      Length                   |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |L|                                  Content //                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+








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RFC 3212          Constraint-Based LSP Setup using LDP      January 2002


   ER-Hop Type
         A fourteen-bit field carrying the type of the ER-Hop contents.
         Currently defined values are:

         Value  Type
         ------ ------------------------
         0x0801 IPv4 prefix
         0x0802 IPv6 prefix
         0x0803 Autonomous system number
         0x0804 LSPID

   Length
         Specifies the length of the value field in bytes.

   L bit
         The L bit in the ER-Hop is a one-bit attribute.  If the L bit
         is set, then the value of the attribute is "loose."  Otherwise,
         the value of the attribute is "strict."  For brevity, we say
         that if the value of the ER-Hop attribute is loose then it is a
         "loose ER-Hop."  Otherwise, it's a "strict ER-Hop."  Further,
         we say that the abstract node of a strict or loose ER-Hop is a
         strict or a loose node, respectively.  Loose and strict nodes
         are always interpreted relative to their prior abstract nodes.
         The path between a strict node and its prior node MUST include
         only network nodes from the strict node and its prior abstract
         node.

         The path between a loose node and its prior node MAY include
         other network nodes, which are not part of the strict node or
         its prior abstract node.

   Contents
         A variable length field containing a node or abstract node
         which is one of the consecutive nodes that make up the
         explicitly routed LSP.

4.3 Traffic Parameters TLV

   The following sections describe the CR-LSP Traffic Parameters.  The
   required characteristics of a CR-LSP are expressed by the Traffic
   Parameter values.

   A Traffic Parameters TLV, is used to signal the Traffic Parameter
   values.  The Traffic Parameters are defined in the subsequent
   sections.






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   The Traffic Parameters TLV contains a Flags field, a Frequency, a
   Weight, and the five Traffic Parameters PDR, PBS, CDR, CBS, EBS.

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |0|0|        Type = 0x0810      |      Length = 24              |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |     Flags     |    Frequency  |     Reserved  |    Weight     |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Peak Data Rate (PDR)                       |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Peak Burst Size (PBS)                      |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Committed Data Rate (CDR)                  |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Committed Burst Size (CBS)                 |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                    Excess Burst Size (EBS)                    |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Type
         A fourteen-bit field carrying the value of the Traffic
         Parameters TLV Type = 0x0810.

   Length
         Specifies the length of the value field in bytes = 24.

   Flags
         The Flags field is shown below:

         +--+--+--+--+--+--+--+--+
         | Res |F6|F5|F4|F3|F2|F1|
         +--+--+--+--+--+--+--+--+

         Res - These bits are reserved.
         Zero on transmission.
         Ignored on receipt.
         F1 - Corresponds to the PDR.
         F2 - Corresponds to the PBS.
         F3 - Corresponds to the CDR.
         F4 - Corresponds to the CBS.
         F5 - Corresponds to the EBS.
         F6 - Corresponds to the Weight.







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RFC 3212          Constraint-Based LSP Setup using LDP      January 2002


         Each flag Fi is a Negotiable Flag corresponding to a Traffic
         Parameter.  The Negotiable Flag value zero denotes
         NotNegotiable and value one denotes Negotiable.

   Frequency
         The Frequency field is coded as an 8 bit unsigned integer with
         the following code points defined:

         0- Unspecified
         1- Frequent
         2- VeryFrequent
         3-255  - Reserved
         Reserved - Zero on transmission.  Ignored on receipt.

   Weight
         An 8 bit unsigned integer indicating the weight of the CR-LSP.
         Valid weight values are from 1 to 255.  The value 0 means that
         weight is not applicable for the CR-LSP.

   Traffic Parameters
         Each Traffic Parameter is encoded as a 32-bit IEEE single-
         precision floating-point number.  A value of positive infinity
         is represented as an IEEE single-precision floating-point
         number with an exponent of all ones (255) and a sign and
         mantissa of all zeros.  The values PDR and CDR are in units of
         bytes per second.  The values PBS, CBS and EBS are in units of
         bytes.

         The value of PDR MUST be greater than or equal to the value of
         CDR in a correctly encoded Traffic Parameters TLV.

4.3.1 Semantics

4.3.1.1 Frequency

   The Frequency specifies at what granularity the CDR allocated to the
   CR-LSP is made available.  The value VeryFrequent means that the
   available rate should average at least the CDR when measured over any
   time interval equal to or longer than the shortest packet time at the
   CDR.  The value Frequent means that the available rate should average
   at least the CDR when measured over any time interval equal to or
   longer than a small number of shortest packet times at the CDR.

   The value Unspecified means that the CDR MAY be provided at any
   granularity.






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RFC 3212          Constraint-Based LSP Setup using LDP      January 2002


4.3.1.2 Peak Rate

   The Peak Rate defines the maximum rate at which traffic SHOULD be
   sent to the CR-LSP.  The Peak Rate is useful for the purpose of
   resource allocation.  If resource allocation within the MPLS domain
   depends on the Peak Rate value then it should be enforced at the
   ingress to the MPLS domain.

   The Peak Rate is defined in terms of the two Traffic Parameters PDR
   and PBS, see section 4.3.1.5 below.

4.3.1.3 Committed Rate

   The Committed Rate defines the rate that the MPLS domain commits to
   be available to the CR-LSP.

   The Committed Rate is defined in terms of the two Traffic Parameters
   CDR and CBS, see section 4.3.1.6 below.

4.3.1.4 Excess Burst Size

   The Excess Burst Size may be used at the edge of an MPLS domain for
   the purpose of traffic conditioning.  The EBS MAY be used to measure
   the extent by which the traffic sent on a CR-LSP exceeds the
   committed rate.

   The possible traffic conditioning actions, such as passing, marking
   or dropping, are specific to the MPLS domain.

   The Excess Burst Size is defined together with the Committed Rate,
   see section 4.3.1.6 below.

4.3.1.5 Peak Rate Token Bucket

   The Peak Rate of a CR-LSP is specified in terms of a token bucket P
   with token rate PDR and maximum token bucket size PBS.

   The token bucket P is initially (at time 0) full, i.e., the token
   count Tp(0) = PBS.  Thereafter, the token count Tp, if less than PBS,
   is incremented by one PDR times per second.  When a packet of size B
   bytes arrives at time t, the following happens:

      -  If Tp(t)-B >= 0, the packet is not in excess of the peak  rate
         and Tp is decremented by B down to the minimum value of 0, else

      -  the packet is in excess of the peak rate and Tp is not
         decremented.




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RFC 3212          Constraint-Based LSP Setup using LDP      January 2002


   Note that according to the above definition, a positive infinite
   value of either PDR or PBS implies that arriving packets are never in
   excess of the peak rate.

   The actual implementation of an LSR doesn't need to be modeled
   according to the above formal token bucket specification.

4.3.1.6 Committed Data Rate Token Bucket

   The committed rate of a CR-LSP is specified in terms of a token
   bucket C with rate CDR.  The extent by which the offered rate exceeds
   the committed rate MAY be measured in terms of another token bucket
   E, which also operates at rate CDR.  The maximum size of the token
   bucket C is CBS and the maximum size of the token bucket E is EBS.

   The token buckets C and E are initially (at time 0) full, i.e., the
   token count Tc(0) = CBS and the token count Te(0) = EBS.

   Thereafter, the token counts Tc and Te are updated CDR times per
   second as follows:

      -  If Tc is less than CBS, Tc is incremented by one, else
      -  if Te is less then EBS, Te is incremented by one, else neither
         Tc nor Te is incremented.

   When a packet of size B bytes arrives at time t, the following
   happens:

      -  If Tc(t)-B >= 0, the packet is not in excess of the Committed
         Rate and Tc is decremented by B down to the minimum value of 0,
         else

      -  if Te(t)-B >= 0, the packet is in excess of the Committed rate
         but is not in excess of the EBS and Te is decremented by B down
         to the minimum value of 0, else

      -  the packet is in excess of both the Committed Rate and the EBS
         and neither Tc nor Te is decremented.

   Note that according to the above specification, a CDR value of
   positive infinity implies that arriving packets are never in excess
   of either the Committed Rate or EBS.  A positive infinite value of
   either CBS or EBS implies that the respective limit cannot be
   exceeded.

   The actual implementation of an LSR doesn't need to be modeled
   according to the above formal specification.




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RFC 3212          Constraint-Based LSP Setup using LDP      January 2002


4.3.1.7 Weight

   The weight determines the CR-LSP's relative share of the possible
   excess bandwidth above its committed rate.  The definition of
   "relative share" is MPLS domain specific.

4.3.2 Procedures

4.3.2.1 Label Request Message

   If an LSR receives an incorrectly encoded Traffic Parameters TLV in
   which the value of PDR is less than the value of CDR then it MUST
   send a Notification Message including the Status code "Traffic
   Parameters Unavailable" to the upstream LSR from which it received
   the erroneous message.

   If a Traffic Parameter is indicated as Negotiable in the Label
   Request Message by the corresponding Negotiable Flag then an LSR MAY
   replace the Traffic Parameter value with a smaller value.

   If the Weight is indicated as Negotiable in the Label Request Message
   by the corresponding Negotiable Flag then an LSR may replace the
   Weight value with a lower value (down to 0).