Network working group                                             X. Xu
Internet Draft                                                   Huawei
Category: Standard Track                                     M. Eubanks
                                                         AmericaFree.TV
                                                                L. Yong
                                                             Huawei USA

Expires: October 2012                                    April 28, 2012


                         Encapsulating MPLS in UDP

                          draft-xu-mpls-in-udp-00

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   carefully, as they describe your rights and restrictions with
   respect to this document.

Abstract

   This document specifies one additional IP-based encapsulation
   technology for MPLS packets referred to as MPLS-in-UDP, which is
   intended to facilitate load-balancing the traffic of various MPLS
   applications such as MPLS-based L2VPN and L3VPN in the core of IP-
   enabled packet switch networks.

Conventions used in this document

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

Table of Contents


   1. Introduction ................................................ 3
   2. Terminology ................................................. 3
   3. Encapsulation in UDP ........................................ 4
   4. Signaling for Encapsulation in UDP .......................... 4
   5. Processing Functions ........................................ 5
   6. Applicability ............................................... 5
   7. Security Considerations ..................................... 5
   8. IANA Considerations ......................................... 6
   9. Acknowledgements ............................................ 6
   10. References ................................................. 6
      10.1. Normative References .................................. 6
      10.2. Informative References ................................ 6
   Authors' Addresses ............................................. 7
















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1. Introduction

   Equal Cost Multi-Path (ECMP) and Link Aggregation Group (LAG) are
   widely used in the core of IP-enabled Packet Switch Networks (PSN)
   for load-balancing purposes. Most core routers (i.e., P routers) in
   the IP-enabled PSN are capable of load-balancing IP traffic flows
   across ECMP paths and/or LAG based on the hash of the five-tuple of
   UDP/TCP packets (i.e., source IP address, destination IP address,
   source port, destination port, and protocol) or some fields in the
   IP header of non-UDP/TCP packets (e.g., source IP address,
   destination IP address). However, with existing IP-based
   encapsulation methods as defined in [RFC4023] such as MPLS-in-IP and
   MPLS-in-GRE, distinct customer traffic flows of various MPLS
   applications (e.g., MPLS-based L2VPN or L3VPN) between a given PE
   pair would be encapsulated with the same IP or GRE tunnel header
   prior to traversing the core. Since the encapsulating traffic is
   neither TCP nor UDP traffic, core routers could only perform hash
   calculation on the fields in the IP header of IP or GRE tunnels. As
   a result, core routers could not achieve an effective load-balancing
   for these traffic flows in the network due to the lack of adequate
   entropy information.

   [RFC5640] describes a method for improving the load-balancing in
   Softwire mesh networks [RFC5565]. However, this method requires core
   routers to be able to perform hash calculation on the fields
   including the "load-balancing" field contained in the L2TPv3 or GRE
   tunnel header. [Entropy-Label] proposes to use the "entropy labels"
   for achieving a better load-balancing for MPLS traffic flows in the
   core of MPLS-enabled packet switching networks (PSN). Although the
   entropy label could be inserted in the "Key" field of the GRE header
   by ingress PE routers in the case where the PSN is IP enabled rather
   than MPLS enabled, it still requires core routers to be capable of
   performing hash calculation on the "entropy label" contained in the
   GRE tunnel header. Any of the above load-balancing methods requires
   a change to the date plane of core routers.

   This document describes a new IP-based encapsulation method for MPLS
   packets referred to as MPLS-in-UDP, which is intended to facilitate
   load-balancing the traffic of various MPLS applications such as
   MPLS-based L2VPN and L3VPN in the core of IP-enabled packet switch
   networks where the core routers could not be upgraded due to some
   reason.

2. Terminology

   This memo makes use of the terms defined in [RFC4364] and [RFC4664].



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3. Encapsulation in UDP

   MPLS-in-IP messages have the following format:

   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
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |    Source Port = entropy      |       Dest Port = MPLS        |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |           UDP Length          |        UDP Checksum           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |                                                               |
   ~                         MPLS Packet                           ~
   |                                                               |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

            Source Port of UDP

                This field contains an entropy value that is generated
                by the ingress PE router. For example, the entropy value
                can be generated by performing hash calculation on
                certain fields in the customer packets (e.g., the five
                tuple of UDP/TCP packets).

            Destination Port of UDP

                This field is set to a value (TBD) indicating the MPLS
                packet encapsulated in the UDP header is a MPLS unicast
                one or a MPLS multicast one.

            UDP Length

                The usage of this field is in accordance with the
                current UDP specification.

            UDP Checksum

                The usage of this field is in accordance with the
                current UDP specification. To simplify the operation on
                egress PE router, this field is recommended to be set to
                zero.

4. Signaling for Encapsulation in UDP

   PE routers could signal the UDP tunnel encapsulation information
   among them by some means.




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   In the case when BGP is used in the MPLS applications (e.g.,
   BGP/MPLS IP VPN [RFC4364]), the MPLS-in-UDP encapsulation
   information can be signaled by using the mechanism defined in [RFC
   5512]. In this case, a new Tunnel Type code for UDP tunnel
   technology needs to be assigned by IANA. If there is no explicit
   encapsulation information to signal using the Encapsulation SAFI for
   the UDP tunneling protocol, a BGP Encapsulation Extended Community
   with the Tunnel Type set to the value indicating UDP tunneling
   protocol would be enough. Otherwise, if more detailed information
   about the UDP tunnel technology (e.g., to specify what MPLS
   application is allowed to use this MPLS-in-UDP encapsulation) is
   needed for signaling, a new TLV and a set of sub-TLVs dedicated for
   UDP tunnel technology contained in the Tunnel Encapsulation
   attribute needs to be defined.

   More details about how to signal the MPLS-in-UDP encapsulation
   information will be described in a separate document.

5. Processing Functions

   This MPLS-in-UDP encapsulation causes MPLS packets to be forwarded
   through "IP UDP tunnels". When performing MPLS-in-UDP encapsulation
   by an ingress PE router, the entropy value would be generated by the
   ingress PE router and then be filled in the Source Port field of the
   UDP header. Then the ingress PE router inserts the remote PE's IP
   address in the destination IP field and its own IP address in the
   source IP field prior to forwarding the packet.

   P routers could perform load-balancing for these UDP packets based
   on the hash of the five-tuple.

   Upon receiving these UDP packets, egress PE routers would
   decapsulate them by removing the UDP headers and then process them
   accordingly.

6. Applicability

   Besides the MPLS-based L2VPN or L3VPN applications, MPLS-in-UDP
   encapsulation could also be used by other MPLS applications such as
   6PE [RFC4798].

7. Security Considerations

   TBD.






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8. IANA Considerations

   Two distinct UDP destination port numbers indicating MPLS unicast
   and MPLS multicast respectively need to be assigned by IANA.

9. Acknowledgements

   Thanks to Shane Amante and Dino Farinacci for their valuable
   comments on the idea of MPLS-in-UDP encapsulation.

10. References

   10.1. Normative References

   [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
             Requirement Levels", BCP 14, RFC 2119, March 1997.

   10.2. Informative References

   [RFC4364] Rosen. E and Y. Rekhter, "BGP/MPLS IP Virtual Private
             Networks (VPNs)", RFC 4364, February 2006.

   [RFC4664] Andersson, L. and Rosen, E. (Editors),"Framework for Layer
             2 Virtual Private Networks (L2VPNs)", RFC 4664, Sept 2006.

   [RFC4023] Worster, T., Rekhter, Y., and E. Rosen, "Encapsulating
             MPLS in IP or GRE", RFC4023, March 2005.

   [RFC5640] Filsfils, C., Mohapatra, P., and C. Pignataro, "Load-
             Balancing for Mesh Softwires", RFC 5640, August 2009.

   [RFC6391] Bryant, S., Filsfils, C., Drafz, U., Kompella, V., Regan,
             J., and S. Amante, "Flow Aware Transport of Pseudowires
             over an MPLS Packet Switched Network", RFC6391, November
             2011

   [Entropy-Label] Kompella, K., Drake, J., Amante, S., Henderickx, W.,
             and L. Yong, "The Use of Entropy Labels in MPLS
             Forwarding", draft-ietf-mpls-entropy-label-01, work in
             progress, October, 2011.

   [RFC5512] Mohapatra, P. and E. Rosen, "The BGP Encapsulation
             Subsequent Address Family Identifier (SAFI) and the
             BGP Tunnel Encapsulation Attribute", RFC 5512, April
             2009.





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   [RFC4798] J Declerq et al., "Connecting IPv6 Islands over IPv4 MPLS
             using IPv6 Provider Edge Routers (6PE)", RFC4798, February
             2007.

Authors' Addresses

   Xiaohu Xu
   Huawei Technologies,
   Beijing, China

   Phone: +86-10-60610041
   Email: xuxiaohu@huawei.com


   Marshall Eubanks
   AmericaFree.TV LLC
   P.O. Box 141
   Clifton, Virginia  20124
   USA

   Phone: +1-703-501-4376
   Fax:
   Email: marshall.eubanks@gmail.com


   Lucy Yong
   Huawei USA
   1700 Alma Dr. Suite 500
   Plano, TX  75075
   US

   Email: lucyyong@huawei.com

















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