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SFC Netmod                                                      R. Penno
Internet-Draft                                                  P. Quinn
Intended status: Standards Track                            C. Pignataro
Expires: April 2, 2016                                     Cisco Systems
                                                                 D. Zhou
                                                       Intel Corporation
                                                      September 30, 2015


                 Services Function Chaining Traceroute
                        draft-penno-sfc-trace-03

Abstract

   This document defines a protocol that checks the liveness and report
   the service-hops of a service path. .

Requirements Language

   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].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on April 2, 2016.

Copyright Notice

   Copyright (c) 2015 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of



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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Definitions and Acronyms  . . . . . . . . . . . . . . . . . .   2
   3.  SFC Trace . . . . . . . . . . . . . . . . . . . . . . . . . .   2
   4.  Service Function Behavior . . . . . . . . . . . . . . . . . .   6
   5.  Service Function Forwarder Behavior . . . . . . . . . . . . .   6
   6.  Implementation  . . . . . . . . . . . . . . . . . . . . . . .   7
   7.  SFC Reverse Trace . . . . . . . . . . . . . . . . . . . . . .   7
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   7
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .   7
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   11. Changes . . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   12. References  . . . . . . . . . . . . . . . . . . . . . . . . .   7
     12.1.  Normative References . . . . . . . . . . . . . . . . . .   7
     12.2.  Informative References . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   This document defines a protocol that allows a user to check liveness
   and get reports of the service-hops of a service path

2.  Definitions and Acronyms

   The reader should be familiar with the terms contained in
   [I-D.ietf-sfc-architecture], ,[I-D.ietf-sfc-architecture] and
   [I-D.quinn-vxlan-gpe]

3.  SFC Trace

   A trace packet uses the same NSH header as MD-type 1 with a few
   differences: OAM Bit and Next Protocol.











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   SFC Trace Request packet format

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\
    |Ver|1|C|R|R|R|R|R|R|   Length  |  MD-type=0x1  |  OAM Protocol | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |          Service Path ID                      | Service Index | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                Mandatory Context Header                       | |S
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |F
    |                Mandatory Context Header                       | |C
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                Mandatory Context Header                       | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                Mandatory Context Header                       | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <
    |Trace Msg Type |     SIL       |          Dest Port            | |O
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |A
    |                       Dest IP Address                         | |M
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                       Dest IP Address                         | |T
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R
    |                       Dest IP Address                         | |A
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |C
    |                       Dest IP Address                         | |E
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/

   (postamble)

   Ver:  1

   OAM Bit:  1

   Length:  6

   MD-Type:  1

   Next Protocol:  OAM Protocol

   Trace Msg Type:  1 for Trace Request and 2 for Trace Report

   SIL:  Service Index Limit: At least one less than the Starting Index

   Dest Port:  The trace report must be sent to this destination Port

   Dest IP:  the trace report must be sent to this destination IP
      address




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   For simplicity in building and parsing request and response packets,
   NSH Trace always uses fixed-size 128-bit IP address fields for both
   IPv6 addresses and IPv4 addresses.

   When the address field holds an IPv6 address, the fixed-size 128-bit
   IP address field holds the IPv6 address stored as is.

   When the address field holds an IPv4 address, an IPv4-mapped IPv6
   address [RFC4291] is used (::ffff:0:0/96).  This has the first 80
   bits set to zero and the next 16 set to one, while its last 32 bits
   are filled with the IPv4 address.  This is unambiguously
   distinguishable from a native IPv6 address, because an IPv4-mapped
   IPv6 address [RFC4291] would not be valid for a mapping.

   When checking for an IPv4-mapped IPv6 address, all of the first 96
   bits MUST be checked for the pattern -- it is not sufficient to check
   for ones in bits 81-96.

   The all-zeros IPv6 address MUST be expressed by filling the fixed-
   size 128-bit IP address field with all zeros (::).

   The all-zeros IPv4 address MUST be expressed by 80 bits of zeros, 16
   bits of ones, and 32 bits of zeros (::ffff:0:0).

   Allowing the client to insert the destination IP and port where it
   expects to receive reports in the NSH header allows for NAT
   traversal.  In other words, if the client is behind a NAT, it can
   acquire a stable external IP:port and put as the destnation IP and
   port in the NSH header.  This would allow NSH traceroute to function
   behind a NAT.





















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   SFC Trace Report

     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
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+\
    |Ver|1|C|R|R|R|R|R|R|   Length  |  MD-type=0x1  |  OAM Protocol | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |          Service Path ID                      | Service Index | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                Mandatory Context Header                       | |S
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |F
    |                Mandatory Context Header                       | |C
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                Mandatory Context Header                       | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                Mandatory Context Header                       | |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ <
    |Trace Msg Type |     SIL       |          Dest Port            | |O
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |A
    |                       Dest IP Address                         | |M
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
    |                       Dest IP Address                         | |T
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |R
    |                       Dest IP Address                         | |A
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |C
    |                       Dest IP Address                         | |E
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+/
    |   SF Type Len |        SF Type  ...                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    |   SF Name Len |        SF Name  ...                           |
    +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   (postamble)

   A trace report packet carries the identification of the Service
   Function that last processed the packet.  In all other aspects it is
   exactly the same as a trace request.

   SF Type Len:  The Type Length in 4-byte words.

   SF Type:  A string representing the SF type padded to a 4-byte
      boundary and encoded with UTF-8.  Service types can be found and
      registered in [I-D.penno-sfc-yang].

   SF Name Len:  The Name Length in 4-byte words.

   SF Name:  A string representing the Service Function padded to a
      4-byte boundary and encoded with UTF-8.  Service Function names
      and configuration can be found in [I-D.penno-sfc-yang].



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4.  Service Function Behavior

   When a Service Function receives a SFC Trace request packet it
   performs the following actions:

   1.  Decrement Service Index

   2.  If Service Index is equal to the Services Index Limit add its
       identifying information at the end of the existing headers

   3.  Send packet back to Service Function Forwarder

5.  Service Function Forwarder Behavior

   A SFF will route trace packets based on service path ID and services
   index just like any other NSH packet.  This guarantees that a trace
   packet follows the same path as data packets.  The SFF will drop it
   and generate a report only in the following conditions:

   o  If the SI is equal or less than SIL

   o  If it can not find the next service-hop.

   o  If a SFF receives a trace packet with SI = 0.

   In the cases enumerated above the SFF will proceed as following to
   build a trace report packet.

   1.  The SFF will use the same encapsulation as the received packet.

   2.  The destination IP:port will be the destination IP:port found in
       the OAM Trace NSH headers

   3.  The entire NSH +Trace Request headers + Report section will be
       copied from the received packet

   4.  The SFF will change the trace message type to trace report

   If a SFF can not find the next service-hop for a trace packet, it
   will drop the  packet and generate a report packet even if SIL is
   different from SI.  This guarantees that the trace ends at the end of
   the path irrespective if SI  has reached SIL or not.  More
   importantly, it allow users to perform a trace that   will traverse
   the entire path without having to know before hand the number  of
   service-hops in the path by setting SIL to zero.






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6.  Implementation

   SFC Trace was implemented in the Opendaylight projects and output of
   a 3 service-hop network can be found below.

sff_client.py --remote-sff-ip 10.0.1.41 --remote-sff-port 4789 --sfp-id 22 --sfp-index 255 --trace-req --num-trace-hops 3

Sending Trace packet to Service Path and Service Index: (22, 255)
Trace response...
Service-hop: 0. Service Type: dpi, Service Name: SF1, Address of Reporting SFF: ('10.0.1.41', 4789)
Service-hop: 1. Service Type: firewall, Service Name: SF4, Address of Reporting SFF: ('10.0.1.42', 4789)
Service-hop: 2. Service Type: napt44, Service Name: SF5, Address of Reporting SFF: ('10.0.1.43', 4789)
Trace end

   Implementation guideline for the client: If the trace request has a
   service index limit that would put the end of the trace beyond the
   service path, for example, starting Index=255, SIL=252 but only 2
   service-hops in the path, the last trace response will have no report
   information.  This is because no SF would detect that it is the end
   of the trace and include a report information

7.  SFC Reverse Trace

   Tracing a reverse path by sending a packet to the forward path is not
   always possible.  The reason is that the sets of SFFs used in the
   forward and reverse might not have common elements.

8.  IANA Considerations

   OAM Protocol Type and a OAM protocol Message type.

9.  Security Considerations

10.  Acknowledgements

11.  Changes

12.  References

12.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <http://www.rfc-editor.org/info/rfc2119>.






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   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
              Transfer Protocol -- HTTP/1.1", RFC 2616,
              DOI 10.17487/RFC2616, June 1999,
              <http://www.rfc-editor.org/info/rfc2616>.

12.2.  Informative References

   [I-D.ietf-sfc-architecture]
              Halpern, J. and C. Pignataro, "Service Function Chaining
              (SFC) Architecture", draft-ietf-sfc-architecture-11 (work
              in progress), July 2015.

   [I-D.penno-sfc-yang]
              Penno, R., Quinn, P., Zhou, D., and J. Li, "Yang Data
              Model for Service Function Chaining", draft-penno-sfc-
              yang-13 (work in progress), March 2015.

   [I-D.quinn-sfc-nsh]
              Quinn, P., Guichard, J., Surendra, S., Smith, M.,
              Henderickx, W., Nadeau, T., Agarwal, P., Manur, R.,
              Chauhan, A., Halpern, J., Majee, S., Elzur, U., Melman,
              D., Garg, P., McConnell, B., Wright, C., and K. Kevin,
              "Network Service Header", draft-quinn-sfc-nsh-07 (work in
              progress), February 2015.

   [I-D.quinn-vxlan-gpe]
              Quinn, P., Manur, R., Kreeger, L., Lewis, D., Maino, F.,
              Smith, M., Agarwal, P., Yong, L., Xu, X., Elzur, U., Garg,
              P., and D. Melman, "Generic Protocol Extension for VXLAN",
              draft-quinn-vxlan-gpe-04 (work in progress), February
              2015.

Authors' Addresses

   Reinaldo Penno
   Cisco Systems
   170 West Tasman Dr
   San Jose  CA
   USA

   Email: repenno@cisco.com









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   Paul Quinn
   Cisco Systems
   170 West Tasman Dr
   San Jose  CA
   USA

   Email: paulq@cisco.com


   Carlos Pignataro
   Cisco Systems
   170 West Tasman Dr
   San Jose  CA
   USA

   Email: cpignata@cisco.com


   Danny Zhou
   Intel Corporation
   2200 Mission College Blvd.
   Santa Clara  CA
   USA

   Email: danny.zhou@intel.com


























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