Ethernet Traffic Parameters with Availability Information

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Network Working Group                                    H. Long, M. Ye 
Internet Draft                             Huawei Technologies Co., Ltd         
Intended status: Standards Track                              G. Mirsky  
                                                   Telecom Italia S.p.A 
                                                                H. Shah 
Expires: February 2018                                   August 8, 2017  
         Ethernet Traffic Parameters with Availability Information  


   A Packet switching network may contain links with variable bandwidth, 
   e.g., copper, radio, etc. The bandwidth of such links is sensitive 
   to external environment. Availability is typically used for 
   describing the link during network planning. This document 
   introduces an optional Availability TLV in Resource ReSerVation 
   Protocol - Traffic Engineer (RSVP-TE) signaling. This extension can 
   be used to set up a Label Switched Path (LSP) in a Packet Switched 
   Network (PSN) that contains links with discretely variable 

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   This Internet-Draft will expire on February 8, 2018. 

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Table of Contents 

   1. Introduction ................................................ 3 
   2. Overview .................................................... 4 
   3. Extension to RSVP-TE Signaling............................... 4 
      3.1. Availability TLV........................................ 4 
      3.2. Signaling Process....................................... 5 
   4. Security Considerations...................................... 6 
   5. IANA Considerations ......................................... 6 
      5.1  Ethernet Sender TSpec TLVs ............................. 6 
   6. References .................................................. 7 
      6.1. Normative References.................................... 7 
      6.2. Informative References.................................. 7 
   7. Appendix: Bandwidth Availability Example..................... 8 
   8. Acknowledgments ............................................. 9 
Conventions used in this document 

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 
   document are to be interpreted as described in RFC-2119 [RFC2119]. 

   The following acronyms are used in this draft: 

   RSVP-TE  Resource Reservation Protocol-Traffic Engineering 

   LSP      Label Switched Path 

   PSN      Packet Switched Network 

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   SNR      Signal-to-noise Ratio 

   TLV      Type Length Value 

   LSA      Link State Advertisement 

1. Introduction 

   The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473] 
   specify the signaling message including the bandwidth request for 
   setting up a Label Switched Path in a PSN network. 

   Some data communication technologies allow seamless change of 
   maximum physical bandwidth through a set of known discrete values. 
   The parameter availability [G.827], [F.1703], [P.530]  is often used 
   to describe the link capacity during network planning. The 
   availability is a time scale, which is a proportion of the operating 
   time that the requested bandwidth is ensured. A more detailed 
   example on the bandwidth availability can be found in Appendix A. 
   Assigning different availability classes to different types of 
   service over such kind of links provides more efficient planning of 
   link capacity. To set up an LSP across these links, availability 
   information is required for the nodes to verify bandwidth 
   satisfaction and make bandwidth reservation. The availability 
   information should be inherited from the availability requirements 
   of the services expected to be carried on the LSP. For example, 
   voice service usually needs "five nines" availability, while non-
   real time services may adequately perform at four or three nines 
   availability. Since different service types may need different 
   availabilities guarantees, multiple <availability, bandwidth> pairs 
   may be required when signaling.  

   If the availability requirement is not specified in the signaling 
   message, the bandwidth will be reserved as the highest availability. 
   For example, the bandwidth with 99.999% availability of a link is 
   100 Mbps; the bandwidth with 99.99% availability is 200 Mbps. When a 
   video application requests for 120 Mbps without availability 
   requirement, the system will consider the request as 120 Mbps with 
   99.999% availability, while the available bandwidth with 99.999% 
   availability is only 100 Mbps, therefore the LSP path cannot be set 
   up. But in fact, video application doesn't need 99.999% availability; 
   99.99% availability is enough. In this case, the LSP could be set up 
   if availability is specified in the signaling message.    

   To fulfill LSP setup by signaling in these scenarios, this document 
   specifies an Availability TLV. The Availability TLV can be 
   applicable to any kind of physical links with variable discrete 
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   bandwidth, such as microwave or DSL. Multiple Availability TLVs 
   together with multiple Ethernet Bandwidth Profiles can be carried in 
   the Ethernet SENDER_TSPEC object. 

2. Overview 

   A PSN tunnel may span one or more links in a network. To setup a 
   Label Switched Path (LSP), a node may collect link information which 
   is spread in routing message, e.g., OSPF TE LSA message, by network 
   nodes to get to know about the network topology, and calculate out 
   an LSP route based on the network topology, and send the calculated 
   LSP route to signaling to initiate a PATH/RESV message for setting 
   up the LSP. 

   In case that there is(are) link(s) with variable discrete bandwidth 
   in a network, a <bandwidth, availability> requirement list should be 
   specified for an LSP. Each <bandwidth, availability> pair in the 
   list means that listed bandwidth with specified availability is 
   required. The list could be inherited from the results of service 
   planning for the LSP.  

   A node which has link(s) with variable discrete bandwidth attached 
   should contain a <bandwidth, availability> information list in its 
   OSPF TE LSA messages. The list provides the mapping between the link 
   nominal bandwidth and its availability level. This information is 
   used for path calculation by the node(s). The routing extension for 
   availability can be found in [ARTE]. 

   When a node initiates a PATH/RESV signaling to set up an LSP, the 
   PATH message should carry the <bandwidth, availability> requirement 
   list as bandwidth request.  Intermediate node(s) will allocate the 
   bandwidth resource for each availability requirement from the 
   remaining bandwidth with corresponding availability. An error 
   message may be returned if any <bandwidth, availability> request 
   cannot be satisfied. 

3. Extension to RSVP-TE Signaling 

3.1. Availability TLV 

   An Availability TLV is defined as a TLV of the Ethernet 
   SENDEDR_TSPEC object [RFC6003] in this document. The Ethernet 
   SENDER_TSPEC object MAY include more than one Availability TLV. The 
   Availability TLV has the following format: 

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       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 
      |    Index      |                 Reserved                      | 
      |                          Availability                         | 

                          Figure 1: Availability TLV 

      Index (1 octet):  

      The Availability TLV MUST come along with Ethernet Bandwidth 
      Profile TLV. If the bandwidth requirements in the multiple 
      Ethernet Bandwidth Profile TLVs have different Availability 
      requirements, multiple Availability TLVs SHOULD be carried. In 
      such a case, the Availability TLV has one to one correspondence 
      with Ethernet Bandwidth Profile TLV by having the same value of 
      Index field. If all the bandwidth requirements in the Ethernet 
      Bandwidth Profile have the same Availability requirement, one 
      Availability TLV SHOULD be carried. In this case, the Index field 
      is set to 0. 

      Reserved (3 octets): These bits SHOULD be set to zero when sent 
      and MUST be ignored when received.  

      Availability (4 octets): a 32-bit floating number describes the 
      decimal value of availability requirement for this bandwidth 
      request. The value MUST be less than 1and is usually expressed in 
      the value of 0.99/0.999/0.9999/0.99999. 

3.2. Signaling Process 

   The source node initiates PATH messages which carry a number of 
   bandwidth request information, including one or more Ethernet 
   Bandwidth Profile TLVs and one or more Availability TLVs. Each 
   Ethernet Bandwidth Profile TLV corresponds to an availability 
   parameter in the Availability TLV. 

   The intermediate and destination nodes check whether they can 
   satisfy the bandwidth requirements by comparing each bandwidth 
   requirement inside the SENDER_TSPEC objects with the remaining link 
   sub-bandwidth resource with respective availability guarantee on the 
   local link when received the PATH message.  

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     o   If all <bandwidth, availability> requirements can be 
        satisfied (the requested bandwidth under each availability 
        parameter is smaller than or equal to the remaining bandwidth 
        under the corresponding availability parameter on its local 
        link), it SHOULD reserve the bandwidth resource from each 
        remaining sub-bandwidth portion on its local link to set up 
        this LSP. Optionally, the higher availability bandwidth can be 
        allocated to lower availability request when the lower 
        availability bandwidth cannot satisfy the request. 

     o   If at least one <bandwidth, availability> requirement cannot 
        be satisfied, it SHOULD generate PathErr message with the error 
        code "Admission Control Error" and the error value "Requested 
        Bandwidth Unavailable" (see [RFC2205]). 

   If two LSPs request for the bandwidth with the same availability 
   requirement, a way to resolve the contention is comparing the node 
   ID, the node with the higher node ID will win the contention. More 
   details can be found in [RFC3473]. 

   If a node does not support Availability TLV, it SHOULD generate 
   PathErr message with the error code "Extended Class-Type Error" and 
   the error value "Class-Type mismatch" (see [RFC2205]).   

4. Security Considerations 

   This document does not introduce new security considerations to the    
   existing RSVP-TE signaling protocol. [RFC5920] provides an overview 
   of security vulnerabilities and protection mechanisms for the GMPLS 
   control plane. 

5. IANA Considerations 

   IANA maintains registries and sub-registries for RSVP-TE used by 
   GMPLS. IANA is requested to make allocations from these registries 
   as set out in the following sections.  

5.1 Ethernet Sender TSpec TLVs  

   IANA maintains a registry of GMPLS parameters called "Generalized 
   Multi-Protocol Label Switching (GMPLS) Signaling Parameters". 

   IANA has created a sub-registry called "Ethernet Sender TSpec TLVs / 
   Ethernet Flowspec TLVs" to contain the TLV type values for TLVs 
   carried in the Ethernet SENDER_TSPEC object. The sub-registry is 
   needed to be updated to include the Availability TLV which is 
   defined as follow. This document proposes a suggested value for the 
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   Availability sub-TLV; it is recommended that the suggested value be 
   granted by IANA. 


   Type       Description                            Reference 

   -----      -----------------------------------    --------- 

   0x04        Availability                           [This ID]          

   The registration procedure for this registry is Standards Action as 
   defined in [RFC8126]. 

6. References 

6.1. Normative References 

   [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and 
             S.Jamin, "Resource ReSerVation Protocol (RSVP) - Version 1 
             Functional Specification", RFC 2205, September 1997. 

   [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, 
             V.,and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 
             Tunnels", RFC 3209, December 2001. 

   [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching            
             (GMPLS) Signaling Resource ReserVation Protocol-Traffic            
             Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. 

   [RFC6003] Papadimitriou, D. "Ethernet Traffic Parameters", RFC 6003, 
             October 2010. 

6.2. Informative References 

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 
             Requirement Levels", RFC 2119, March 1997. 

   [RFC8126] Cotton,M. and Leiba,B., and Narten T., "Guidelines for 
             Writing an IANA Considerations Section in RFCs", 
             RFC 8126, June 2017. 

   [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS Networks", 
             RFC 5920, July 2010. 

   [G.827]  ITU-T Recommendation, "Availability performance parameters 
             and objectives for end-to-end international constant bit-
             rate digital paths", September, 2003. 
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   [F.1703]  ITU-R Recommendation, "Availability objectives for real 
             digital fixed wireless links used in 27 500 km 
             hypothetical reference paths and connections", January, 

   [P.530]   ITU-R Recommendation," Propagation data and prediction 
             methods required for the design of terrestrial line-of-
             sight systems", February, 2012 

   [EN 302 217] ETSI standard, "Fixed Radio Systems; Characteristics 
             and requirements for point-to-point equipment and 
             antennas", April, 2009 

   [ARTE]    H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H., 
             "OSPF Routing Extension for Links with Variable Discrete 
             Bandwidth", Work in Progress, October, 2016 

7. Appendix: Bandwidth Availability Example 

   In mobile backhaul network, microwave links are very popular for 
   providing connection of last hops. In case of heavy rain, to 
   maintain the link connectivity, the microwave link MAY lower the 
   modulation level since demodulating the lower modulation level needs 
   a lower Signal-to-Noise Ratio (SNR). This is called adaptive 
   modulation technology [EN 302 217]. However, a lower modulation 
   level also means lower link bandwidth. When link bandwidth is 
   reduced because of modulation down-shifting, high-priority traffic 
   can be maintained, while lower-priority traffic is dropped. 
   Similarly, the copper links MAY change their link bandwidth due to 
   external interference. 

   Presuming that a link has three discrete bandwidth levels:  

   The link bandwidth under modulation level 1, e.g., QPSK, is 100 Mbps; 

   The link bandwidth under modulation level 2, e.g., 16QAM, is 200 

   The link bandwidth under modulation level 3, e.g., 256QAM, is 400 

   In sunny day, the modulation level 3 can be used to achieve 400 Mbps 
   link bandwidth. 

   A light rain with X mm/h rate triggers the system to change the 
   modulation level from level 3 to level 2, with bandwidth changing 
   from 400 Mbps to 200 Mbps. The probability of X mm/h rain in the 
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   local area is 52 minutes in a year. Then the dropped 200 Mbps 
   bandwidth has 99.99% availability. 

   A heavy rain with Y(Y>X) mm/h rate triggers the system to change the 
   modulation level from level 2 to level 1, with bandwidth changing 
   from 200 Mbps to 100 Mbps. The probability of Y mm/h rain in the 
   local area is 26 minutes in a year. Then the dropped 100 Mbps 
   bandwidth has 99.995% availability. 

   For the 100M bandwidth of the modulation level 1, only the extreme 
   weather condition can cause the whole system unavailable, which only 
   happens for 5 minutes in a year. So the 100 Mbps bandwidth of the 
   modulation level 1 owns the availability of 99.999%. 

   In a word, the maximum bandwidth is 400 Mbps. According to the 
   weather condition, the sub-bandwidth and its availability are shown 
   as follows: 

   Sub-bandwidth(Mbps)    Availability                       

   ------------------     ------------          

   200                    99.99%                 

   100                    99.995%                

   100                    99.999%                

8. Acknowledgments 

   The authors would like to thank Khuzema Pithewan, Lou Berger, Yuji 
   Tochio, Dieter Beller, and Autumn Liu for their comments on the 




   Authors' Addresses 

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   Hao Long 
   Huawei Technologies Co., Ltd. 
   No.1899, Xiyuan Avenue, Hi-tech Western District 
   Chengdu 611731, P.R.China 
   Phone: +86-18615778750 
   Min Ye (editor) 
   Huawei Technologies Co., Ltd. 
   No.1899, Xiyuan Avenue, Hi-tech Western District 
   Chengdu 611731, P.R.China 
   Greg Mirsky (editor) 
   Alessandro D'Alessandro 
   Telecom Italia S.p.A 
   Himanshu Shah 
   Ciena Corp. 
   3939 North First Street 
   San Jose, CA 95134 


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