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Versions: (draft-joachimpillai-forces-interfelfb) 00 01 02 03 04 05 06 RFC 8013

Internet Engineering Task Force                         D. Joachimpillai
Internet-Draft                                                   Verizon
Intended status: Standards Track                           J. Hadi Salim
Expires: May 5, 2016                                   Mojatatu Networks
                                                        November 2, 2015


                          ForCES Inter-FE LFB
                    draft-ietf-forces-interfelfb-02

Abstract

   This document describes how to extend the ForCES LFB topology across
   FEs by defining the Inter-FE LFB Class.  The Inter-FE LFB Class
   provides the ability to pass data and metadata across FEs without
   needing any changes to the ForCES specification.  The document
   focuses on Ethernet transport.

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
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   This Internet-Draft will expire on May 5, 2016.

Copyright Notice

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












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   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
   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.  Terminology and Conventions . . . . . . . . . . . . . . . . .   3
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   3
     1.2.  Definitions . . . . . . . . . . . . . . . . . . . . . . .   3
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
   3.  Problem Scope And Use Cases . . . . . . . . . . . . . . . . .   4
     3.1.  Assumptions . . . . . . . . . . . . . . . . . . . . . . .   4
     3.2.  Sample Use Cases  . . . . . . . . . . . . . . . . . . . .   4
       3.2.1.  Basic IPv4 Router . . . . . . . . . . . . . . . . . .   4
         3.2.1.1.  Distributing The Basic IPv4 Router  . . . . . . .   6
       3.2.2.  Arbitrary Network Function  . . . . . . . . . . . . .   7
         3.2.2.1.  Distributing The Arbitrary Network Function . . .   7
   4.  Inter-FE LFB Overview . . . . . . . . . . . . . . . . . . . .   8
     4.1.  Inserting The Inter-FE LFB  . . . . . . . . . . . . . . .   8
   5.  Inter-FE Ethernet Connectivity  . . . . . . . . . . . . . . .  10
     5.1.  Inter-FE Ethernet Connectivity Issues . . . . . . . . . .  10
       5.1.1.  MTU Consideration . . . . . . . . . . . . . . . . . .  10
       5.1.2.  Quality Of Service Considerations . . . . . . . . . .  11
       5.1.3.  Congestion Considerations . . . . . . . . . . . . . .  11
       5.1.4.  Deployment Considerations . . . . . . . . . . . . . .  11
     5.2.  Inter-FE Ethernet Encapsulation . . . . . . . . . . . . .  12
   6.  Detailed Description of the Ethernet inter-FE LFB . . . . . .  13
     6.1.  Data Handling . . . . . . . . . . . . . . . . . . . . . .  13
       6.1.1.  Egress Processing . . . . . . . . . . . . . . . . . .  14
       6.1.2.  Ingress Processing  . . . . . . . . . . . . . . . . .  15
     6.2.  Components  . . . . . . . . . . . . . . . . . . . . . . .  16
     6.3.  Inter-FE LFB XML Model  . . . . . . . . . . . . . . . . .  16
   7.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  21
   8.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  21
   9.  IEEE Assignment Considerations  . . . . . . . . . . . . . . .  21
   10. Security Considerations . . . . . . . . . . . . . . . . . . .  21
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  22
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  22
     11.2.  Informative References . . . . . . . . . . . . . . . . .  23
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  24





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1.  Terminology and Conventions

1.1.  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 [RFC2119].

1.2.  Definitions

   This document reiterates the terminology defined in several ForCES
   documents [RFC3746], [RFC5810], [RFC5811], and [RFC5812] [RFC7391]
   [RFC7408] for the sake of contextual clarity.

      Control Engine (CE)

      Forwarding Engine (FE)

      FE Model

      LFB (Logical Functional Block) Class (or type)

      LFB Instance

      LFB Model

      LFB Metadata

      ForCES Component

      LFB Component

      ForCES Protocol Layer (ForCES PL)

      ForCES Protocol Transport Mapping Layer (ForCES TML)

2.  Introduction

   In the ForCES architecture, a packet service can be modelled by
   composing a graph of one or more LFB instances.  The reader is
   referred to the details in the ForCES Model [RFC5812].

   The current ForCES model describes the processing within a single
   Forwarding Element (FE) in terms of logical forwarding blocks (LFB),
   including provision for the Control Element (CE) to establish and
   modify that processing sequence, and the parameters of the individual
   LFBs.




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   Under some circumstance, it would be beneficial to be able to extend
   this view, and the resulting processing across more than one FE.
   This may be in order to achieve scale by splitting the processing
   across elements, or to utilize specialized hardware available on
   specific FEs.

   Given that the ForCES inter-LFB architecture calls out for the
   ability to pass metadata between LFBs, it is imperative therefore to
   define mechanisms to extend that existing feature and allow passing
   the metadata between LFBs across FEs.

   This document describes how to extend the LFB topology across FEs i.e
   inter-FE connectivity without needing any changes to the ForCES
   definitions.  It focuses on using Ethernet as the interconnection
   between FEs.

3.  Problem Scope And Use Cases

   The scope of this document is to solve the challenge of passing
   ForCES defined metadata alongside packet data across FEs (be they
   physical or virtual) for the purpose of distributing the LFB
   processing.

3.1.  Assumptions

   o  The FEs involved in the Inter-FE LFB belong to the same Network
      Element(NE) and are within a single administrative private network
      which is in close proximity.

   o  The FEs are already interconnected using Ethernet.  We focus on
      Ethernet because it is a very common setup as an FE interconnect.
      While other higher transports (such as UDP over IP) or lower
      transports could be defined to carry the data and metadata it is
      simpler to use Ethernet (for the functional scope of a single
      distributed device already interconnected with ethernet).

3.2.  Sample Use Cases

   To illustrate the problem scope we present two use cases where we
   start with a single FE running all the LFBs functionality then split
   it into multiple FEs achieving the same end goals.

3.2.1.  Basic IPv4 Router

   A sample LFB topology depicted in Figure 1 demonstrates a service
   graph for delivering basic IPV4 forwarding service within one FE.
   For the purpose of illustration, the diagram shows LFB classes as
   graph nodes instead of multiple LFB class instances.



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   Since the illustration on Figure 1 is meant only as an exercise to
   showcase how data and metadata are sent down or upstream on a graph
   of LFB instances, it abstracts out any ports in both directions and
   talks about a generic ingress and egress LFB.  Again, for
   illustration purposes, the diagram does not show exception or error
   paths.  Also left out are details on Reverse Path Filtering, ECMP,
   multicast handling etc.  In other words, this is not meant to be a
   complete description of an IPV4 forwarding application; for a more
   complete example, please refer the LFBlib document [RFC6956].

   The output of the ingress LFB(s) coming into the IPv4 Validator LFB
   will have both the IPV4 packets and, depending on the implementation,
   a variety of ingress metadata such as offsets into the different
   headers, any classification metadata, physical and virtual ports
   encountered, tunnelling information etc.  These metadata are lumped
   together as "ingress metadata".

   Once the IPV4 validator vets the packet (example ensures that no
   expired TTL etc), it feeds the packet and inherited metadata into the
   IPV4 unicast LPM LFB.


                      +----+
                      |    |
           IPV4 pkt   |    | IPV4 pkt     +-----+             +---+
       +------------->|    +------------->|     |             |   |
       |  + ingress   |    | + ingress    |IPv4 |   IPV4 pkt  |   |
       |   metadata   |    | metadata     |Ucast+------------>|   +--+
       |              +----+              |LPM  |  + ingress  |   |  |
     +-+-+             IPv4               +-----+  + NHinfo   +---+  |
     |   |             Validator                   metadata   IPv4   |
     |   |             LFB                                    NextHop|
     |   |                                                     LFB   |
     |   |                                                           |
     |   |                                                  IPV4 pkt |
     |   |                                               + {ingress  |
     +---+                                                  + NHdetails}
     Ingress                                                metadata |
      LFB                                +--------+                  |
                                         | Egress |                  |
                                      <--+        |<-----------------+
                                         |  LFB   |
                                         +--------+

             Figure 1: Basic IPV4 packet service LFB topology

   The IPV4 unicast LPM LFB does a longest prefix match lookup on the
   IPV4 FIB using the destination IP address as a search key.  The



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   result is typically a next hop selector which is passed downstream as
   metadata.

   The Nexthop LFB receives the IPv4 packet with an associated next hop
   info metadata.  The NextHop LFB consumes the NH info metadata and
   derives from it a table index to look up the next hop table in order
   to find the appropriate egress information.  The lookup result is
   used to build the next hop details to be used downstream on the
   egress.  This information may include any source and destination
   information (for our purposes, MAC addresses to use) as well as
   egress ports.  [Note: It is also at this LFB where typically the
   forwarding TTL decrementing and IP checksum recalculation occurs.]

   The details of the egress LFB are considered out of scope for this
   discussion.  Suffice it is to say that somewhere within or beyond the
   Egress LFB the IPV4 packet will be sent out a port (Ethernet, virtual
   or physical etc).

3.2.1.1.  Distributing The Basic IPv4 Router

   Figure 2 demonstrates one way the router LFB topology in Figure 1 may
   be split across two FEs (eg two ASICs).  Figure 2 shows the LFB
   topology split across FEs after the IPV4 unicast LPM LFB.

     FE1
   +-------------------------------------------------------------+
   |                            +----+                           |
   | +----------+               |    |                           |
   | | Ingress  |    IPV4 pkt   |    | IPV4 pkt     +-----+      |
   | |  LFB     +-------------->|    +------------->|     |      |
   | |          |  + ingress    |    | + ingress    |IPv4 |      |
   | +----------+    metadata   |    |   metadata   |Ucast|      |
   |      ^                     +----+              |LPM  |      |
   |      |                      IPv4               +--+--+      |
   |      |                     Validator              |         |
   |                             LFB                   |         |
   +---------------------------------------------------|---------+
                                                       |
                                                  IPv4 packet +
                                                {ingress + NHinfo}
                                                    metadata
     FE2                                               |
   +---------------------------------------------------|---------+
   |                                                   V         |
   |             +--------+                       +--------+     |
   |             | Egress |     IPV4 packet       | IPV4   |     |
   |       <-----+  LFB   |<----------------------+NextHop |     |
   |             |        |{ingress + NHdetails}  | LFB    |     |



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   |             +--------+      metadata         +--------+     |
   +-------------------------------------------------------------+

             Figure 2: Split IPV4 packet service LFB topology

   Some proprietary inter-connect (example Broadcom HiGig over XAUI
   [brcm-higig]) are known to exist to carry both the IPV4 packet and
   the related metadata between the IPV4 Unicast LFB and IPV4 NextHop
   LFB across the two FEs.

   This document defines the inter-FE LFB, a standard mechanism for
   encapsulating, generating, receiving and decapsulating packets and
   associated metadata FEs over Ethernet.

3.2.2.  Arbitrary Network Function

   In this section we show an example of an arbitrary Network Function
   which is more coarse grained in terms of functionality.  Each Network
   Function may constitute more than one LFB.

     FE1
   +-------------------------------------------------------------+
   |                            +----+                           |
   | +----------+               |    |                           |
   | | Network  |   pkt         |NF2 |    pkt       +-----+      |
   | | Function +-------------->|    +------------->|     |      |
   | |    1     |  + NF1        |    | + NF1/2      |NF3  |      |
   | +----------+    metadata   |    |   metadata   |     |      |
   |      ^                     +----+              |     |      |
   |      |                                         +--+--+      |
   |      |                                            |         |
   |                                                   |         |
   +---------------------------------------------------|---------+
                                                       V

         Figure 3: A Network Function Service Chain within one FE

   The setup in Figure 3 is a typical of most packet processing boxes
   where we have functions like DPI, NAT, Routing, etc connected in such
   a topology to deliver a packet processing service to flows.

3.2.2.1.  Distributing The Arbitrary Network Function









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   The setup in Figure 3 can be split out across 3 FEs instead of as
   demonstrated in Figure 4.  This could be motivated by scale out
   reasons or because different vendors provide different functionality
   which is plugged-in to provide such functionality.  The end result is
   to have the same packet service delivered to the different flows
   passing through.


      FE1                        FE2
      +----------+               +----+               FE3
      | Network  |   pkt         |NF2 |    pkt       +-----+
      | Function +-------------->|    +------------->|     |
      |    1     |  + NF1        |    | + NF1/2      |NF3  |
      +----------+    metadata   |    |   metadata   |     |
           ^                     +----+              |     |
           |                                         +--+--+
                                                        |
                                                        V

       Figure 4: A Network Function Service Chain Distributed Across
                               Multiple FEs

4.  Inter-FE LFB Overview

   We address the inter-FE connectivity requirements by defining the
   inter-FE LFB class.  Using a standard LFB class definition implies no
   change to the basic ForCES architecture in the form of the core LFBs
   (FE Protocol or Object LFBs).  This design choice was made after
   considering an alternative approach that would have required changes
   to both the FE Object capabilities (SupportedLFBs) as well
   LFBTopology component to describe the inter-FE connectivity
   capabilities as well as runtime topology of the LFB instances.

4.1.  Inserting The Inter-FE LFB

   The distributed LFB topology described in Figure 2 is re-illustrated
   in Figure 5 to show the topology location where the inter-FE LFB
   would fit in.

   As can be observed in Figure 5, the same details passed between IPV4
   unicast LPM LFB and the IPV4 NH LFB are passed to the egress side of
   the Inter-FE LFB.  This information is illustrated as multiplicity of
   inputs into the egress InterFE LFB instance.  Each input represents a
   unique set of selection information.

     FE1
   +-------------------------------------------------------------+
   | +----------+               +----+                           |



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   | | Ingress  |    IPV4 pkt   |    | IPV4 pkt     +-----+      |
   | |  LFB     +-------------->|    +------------->|     |      |
   | |          |  + ingress    |    | + ingress    |IPv4 |      |
   | +----------+    metadata   |    |   metadata   |Ucast|      |
   |      ^                     +----+              |LPM  |      |
   |      |                      IPv4               +--+--+      |
   |      |                     Validator              |         |
   |      |                      LFB                   |         |
   |      |                                  IPv4 pkt + metadata |
   |      |                                   {ingress + NHinfo} |
   |      |                                            |         |
   |      |                                       +..--+..+      |
   |      |                                       |..| |  |      |
   |                                            +-V--V-V--V-+    |
   |                                            |   Egress  |    |
   |                                            |  InterFE  |    |
   |                                            |   LFB     |    |
   |                                            +------+----+    |
   +---------------------------------------------------|---------+
                                                       |
                   Ethernet Frame with:    |
                    IPv4 packet data and metadata
                               {ingress + NHinfo + Inter FE info}
    FE2                                                |
   +---------------------------------------------------|---------+
   |                                                +..+.+..+    |
   |                                                |..|.|..|    |
   |                                              +-V--V-V--V-+  |
   |                                              | Ingress   |  |
   |                                              | InterFE   |  |
   |                                              |   LFB     |  |
   |                                              +----+------+  |
   |                                                   |         |
   |                                         IPv4 pkt + metadata |
   |                                          {ingress + NHinfo} |
   |                                                   |         |
   |             +--------+                       +----V---+     |
   |             | Egress |     IPV4 packet       | IPV4   |     |
   |       <-----+  LFB   |<----------------------+NextHop |     |
   |             |        |{ingress + NHdetails}  | LFB    |     |
   |             +--------+      metadata         +--------+     |
   +-------------------------------------------------------------+

         Figure 5: Split IPV4 forwarding service with Inter-FE LFB

   The egress of the inter-FE LFB uses the received packet and metadata
   to select details for encapsulation when sending messages towards the
   selected neighboring FE.  These details include what to communicate



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   as the source and destination FEs (abstracted as MAC addresses as
   described in Section 5.2); in addition the original metadata may be
   passed along with the original IPV4 packet.

   On the ingress side of the inter-FE LFB the received packet and its
   associated metadata are used to decide the packet graph continuation.
   This includes which of the original metadata and which next LFB class
   instance to continue processing on.  In the illustrated Figure 5, an
   IPV4 Nexthop LFB instance is selected and appropriate metadata is
   passed on to it.

   The ingress side of the inter-FE LFB consumes some of the information
   passed and passes on the IPV4 packet alongside with the ingress and
   NHinfo metadata to the IPV4 NextHop LFB as was done earlier in both
   Figure 1 and Figure 2.

5.  Inter-FE Ethernet Connectivity

   Section 5.1 describes some of the issues related to using Ethernet as
   the transport and how we mitigate them.

   Section 5.2 defines a payload format that is to be used over
   Ethernet.  An existing implementation of this specification on top of
   Linux Traffic Control [linux-tc] is described in [tc-ife].

5.1.  Inter-FE Ethernet Connectivity Issues

   There are several issues that may occur due to using direct Ethernet
   encapsulation that need consideration.

5.1.1.  MTU Consideration

   Because we are adding data to existing Ethernet frames, MTU issues
   may arise.  We recommend:

   o  To use large MTUs when possible (example with jumbo frames).

   o  Limit the amount of metadata that could be transmitted; our
      definition allows for filtering of select metadata to be
      encapsulated in the frame as described in Section 6.  We recommend
      sizing the egress port MTU so as to allow space for maximum size
      of the metadata total size to allow between FEs.  In such a setup,
      the port is configured to "lie" to the upper layers by claiming to
      have a lower MTU than it is capable of.  MTU setting can be
      achieved by ForCES control of the port LFB(or other config).  In
      essence, the control plane when explicitly making a decision for
      the MTU settings of the egress port is implicitly deciding how
      much metadata will be allowed.



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5.1.2.  Quality Of Service Considerations

   A raw packet arriving at the Inter-FE LFB (from upstream LFB Class
   instances) may have COS metadatum indicating how it should be treated
   from a Quality of Service perspective.

   The resulting Ethernet frame will be eventually (preferentially)
   treated by a downstream LFB(typically a port LFB instance) and their
   COS marks will be honored in terms of priority.  In other words the
   presence of the Inter-FE LFB does not change the COS semantics

5.1.3.  Congestion Considerations

   The addition of the Inter-FE encapsulation adds overhead to the
   packets and therefore bandwidth consumption on the wire.  In cases
   where Inter-FE encapsulated traffic shares wire resources with other
   traffic, the new dynamics could potentially lead to congestion.  In
   such a case, given that the Inter-FE LFB is deployed within a single
   administrative domain, the operator may need to enforce usage
   restrictions.  These restrictions may take the form of approriate
   provisioning; example by rate limiting at an upstream LFB all Inter-
   FE LFB traffic; or prioritizing non Inter-FE LFB traffic or other
   techniques such as managed circuit breaking[circuit-b].

   It is noted that a lot of the traffic passing through an FE that
   utilizes the Inter-FE LFB is expected to be IP based which is
   generally assumed to be congestion controlled and therefore does not
   need addtional congestion control mechanisms[RFC5405].

5.1.4.  Deployment Considerations

   While we expect to use a unique IEEE-issued ethertype for the inter-
   FE traffic, we use lessons learned from VXLAN deployment to be more
   flexible on the settings of the ethertype value used.  We make the
   ether type an LFB read-write component.  Linux VXLAN implementation
   uses UDP port 8472 because the deployment happened much earlier than
   the point of RFC publication where the IANA assigned udp port issued
   was 4789 [vxlan-udp].  For this reason we make it possible to define
   at control time what ethertype to use and default to the IEEE issued
   ethertype.  We justify this by assuming that a given ForCES NE is
   likely to be owned by a single organization and that the
   organization's CE(or CE cluster) could program all participating FEs
   via the inter-FE LFB (described in this document) to recognize a
   private Ethernet type used for inter-LFB traffic (possibly those
   defined as available for private use by the IEEE, namely: IDs 0x88B5
   and 0x88B6).





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5.2.  Inter-FE Ethernet Encapsulation

   The Ethernet wire encapsulation is illustrated in Figure 6.  The
   process that leads to this encapsulation is described in Section 6.
   The resulting frame is 32 bit aligned.


       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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Destination MAC Address                                       |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Destination MAC Address       |   Source MAC Address          |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Source MAC Address                                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Inter-FE ethertype            | Metadata length               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | TLV encoded Metadata ~~~..............~~                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | TLV encoded Metadata ~~~..............~~                      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Original packet data ~~................~~                     |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


                    Figure 6: Packet format suggestion

   The Ethernet header illustrated in Figure 6) has the following
   semantics:

   o  The Destination MAC Address is used to identify the Destination
      FEID by the CE policy (as described in Section 6).

   o  The Source MAC Address is used to identify the Source FEID by the
      CE policy (as described in Section 6).

   o  The Ethernet type is used to identify the frame as inter-FE LFB
      type.  Ethertype 0xFEFE is to be used (XXX: Note to editor, likely
      we wont get that value - update when available).

   o  The 16-bit metadata length is used to described the total encoded
      metadata length (including the 16 bits used to encode the metadata
      length).

   o  One or more 16-bit TLV encoded Metadatum follows the metadata
      length field.  The TLV type identifies the Metadata id.  ForCES
      IANA-defined Metadata ids will be used.  All TLVs will be 32 bit



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      aligned.  We recognize that using a 16 bit TLV restricts the
      metadata id to 16 bits instead of ForCES-defined component ID
      space of 32 bits.  However, at the time of publication we believe
      this is sufficient to carry all the info we need and approach
      taken would save us 4 bytes per Metadatum transferred.

   o  The original packet data payload is appended at the end of the
      metadata as shown.

6.  Detailed Description of the Ethernet inter-FE LFB

   The Ethernet inter-FE LFB has two LFB input port groups and three LFB
   output ports as shown in Figure 7.

   The inter-FE LFB defines two components used in aiding processing
   described in Section 6.2.

                    +-----------------+
     Inter-FE LFB   |                 |
     Encapsulated   |             OUT2+--> decapsulated Packet
     -------------->|IngressInGroup   |       + metadata
     Ethernet Frame |                 |
                    |                 |
     raw Packet +   |             OUT1+--> Encapsulated Ethernet
     -------------->|EgressInGroup    |           Frame
     Metadata       |                 |
                    |    EXCEPTIONOUT +--> ExceptionID, packet
                    |                 |           + metadata
                    +-----------------+


                          Figure 7: Inter-FE LFB

6.1.  Data Handling

   The Inter-FE LFB (instance) can be positioned at the egress of a
   source FE.  Figure 5 illustrates an example source FE in the form of
   FE1.  In such a case an Inter-FE LFB instance receives, via port
   group EgressInGroup, a raw packet and associated metadata from the
   preceding LFB instances.  The input information is used to produce a
   selection of how to generate and encapsulate the new frame.  The set
   of all selections is stored in the LFB component IFETable described
   further below.  The processed encapsulated Ethernet Frame will go out
   on OUT1 to a downstream LFB instance when processing succeeds or to
   the EXCEPTIONOUT port in the case of a failure.

   The Inter-FE LFB (instance) can be positioned at the ingress of a
   receiving FE.  Figure 5 illustrates an example destination FE in the



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   form of FE1.  In such a case an Inter-FE LFB receives, via an LFB
   port in the IngressInGroup, an encapsulated Ethernet frame.
   Successful processing of the packet will result in a raw packet with
   associated metadata IDs going downstream to an LFB connected on OUT2.
   On failure the data is sent out EXCEPTIONOUT.

6.1.1.  Egress Processing

   The egress Inter-FE LFB receives packet data and any accompanying
   Metadatum at an LFB port of the LFB instance's input port group
   labelled EgressInGroup.

   The LFB implementation may use the incoming LFB port (within LFB port
   group EgressInGroup) to map to a table index used to lookup the
   IFETable table.

   If lookup is successful, a matched table row which has the
   InterFEinfo details is retrieved with the tuple {optional IFEtype,
   optional StatId, Destination MAC address(DSTFE), Source MAC
   address(SRCFE), optional metafilters}.  The metafilters lists define
   a whitelist of which Metadatum are to be passed to the neighboring
   FE.  The inter-FE LFB will perform the following actions using the
   resulting tuple:

   o  Increment statistics for packet and byte count observed at
      corresponding IFEStats entry.

   o  When MetaFilterList is present, then walk each received Metadatum
      and apply against the MetaFilterList.  If no legitimate metadata
      is found that needs to be passed downstream then the processing
      stops and send the packet and metadata out the EXCEPTIONOUT port
      with exceptionID of EncapTableLookupFailed [RFC6956].

   o  Check that the additional overhead of the Ethernet header and
      encapsulated metadata will not exceed MTU.  If it does, increment
      the error packet count statistics and send the packet and metadata
      out the EXCEPTIONOUT port with exceptionID of FragRequired
      [RFC6956].

   o  Create the Ethernet header

   o  Set the Destination MAC address of the Ethernet header with value
      found in the DSTFE field.

   o  Set the Source MAC address of the Ethernet header with value found
      in the SRCFE field.





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   o  If the optional IFETYPE is present, set the Ethernet type to the
      value found in IFETYPE.  If IFETYPE is absent then the standard
      Inter-FE LFB Ethernet type is used (XXX: Note to editor, to be
      updated).

   o  Encapsulate each allowed Metadatum in a TLV.  Use the Metaid as
      the "type" field in the TLV header.  The TLV should be aligned to
      32 bits.  This means you may need to add padding of zeroes to
      ensure alignment.

   o  Update the Metadata length to the sum of each TLV's space plus 2
      bytes (for the Metadata length field 16 bit space).

   The resulting packet is sent to the next LFB instance connected to
   the OUT1 LFB-port; typically a port LFB.

   In the case of a failed lookup the original packet and associated
   metadata is sent out the EXCEPTIONOUT port with exceptionID of
   EncapTableLookupFailed [RFC6956].  Note that the EXCEPTIONOUT LFB
   port is merely an abstraction and implementation may in fact drop
   packets as described above.

6.1.2.  Ingress Processing

   An ingressing inter-FE LFB packet is recognized by inspecting the
   ethertype, and optionally the destination and source MAC addresses.
   A matching packet is mapped to an LFB instance port in the
   IngressInGroup.  The IFETable table row entry matching the LFB
   instance port may have optionally programmed metadata filters.  In
   such a case the ingress processing should use the metadata filters as
   a whitelist of what metadatum is to be allowed.

   o  Increment statistics for packet and byte count observed.

   o  Look at the metadata length field and walk the packet data
      extracting from the TLVs the metadata values.  For each Metadatum
      extracted, in the presence of metadata filters the metaid is
      compared against the relevant IFETable row metafilter list.  If
      the Metadatum is recognized, and is allowed by the filter the
      corresponding implementation Metadatum field is set.  If an
      unknown Metadatum id is encountered, or if the metaid is not in
      the allowed filter list the implementation is expected to ignore
      it, increment the packet error statistic and proceed processing
      other Metadatum.

   o  Upon completion of processing all the metadata, the inter-FE LFB
      instance resets the data point to the original payload i.e skips
      the IFE header information.  At this point the original packet



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      that was passed to the egress Inter-FE LFB at the source FE is
      reconstructed.  This data is then passed along with the
      reconstructed metadata downstream to the next LFB instance in the
      graph.

   In the case of processing failure of either ingress or egress
   positioning of the LFB, the packet and metadata are sent out the
   EXCEPTIONOUT LFB port with appropriate error id.  Note that the
   EXCEPTIONOUT LFB port is merely an abstraction and implementation may
   in fact drop packets as described above.

6.2.  Components

   There are two LFB components accessed by the CE.  The reader is asked
   to refer to the definitions in Figure 8.

   The first component, populated by the CE, is an array known as the
   IFETable table.  The array rows are made up of IFEInfo structure.
   The IFEInfo structure constitutes: optional IFETYPE, optionally
   present StatId, Destination MAC address(DSTFE), Source MAC
   address(SRCFE), optionally present array of allowed Metaids
   (MetaFilterList).

   The second component(ID 2), populated by the FE and read by the CE,
   is an indexed array known as the IFEStats table.  Each IFEStats row
   which carries statistics information in the structure bstats.

   A note about the StatId relationship between the IFETable table and
   IFEStats table: An implementation may choose to map between an
   IFETable row and IFEStats table row using the StatId entry in the
   matching IFETable row.  In that case the IFETable StatId must be
   present.  Alternative implementation may map at provisioning time an
   IFETable row to IFEStats table row.  Yet another alternative
   implementation may choose not to use the IFETable row StatId and
   instead use the IFETable row index as the IFEStats index.  For these
   reasons the StatId component is optional.

6.3.  Inter-FE LFB XML Model


   <LFBLibrary xmlns="urn:ietf:params:xml:ns:forces:lfbmodel:1.1"
        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
          provides="IFE">
     <frameDefs>

        <frameDef>
        <name>PacketAny</name>
         <synopsis>Arbitrary Packet</synopsis>



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        </frameDef>
        <frameDef>
        <name>InterFEFrame</name>
        <synopsis>
            Ethernet Frame with encapsulate IFE information
        </synopsis>
        </frameDef>

     </frameDefs>

     <dataTypeDefs>

       <dataTypeDef>
          <name>bstats</name>
          <synopsis>Basic stats</synopsis>
       <struct>
       <component componentID="1">
        <name>bytes</name>
        <synopsis>The total number of bytes seen</synopsis>
        <typeRef>uint64</typeRef>
       </component>

       <component componentID="2">
        <name>packets</name>
        <synopsis>The total number of packets seen</synopsis>
        <typeRef>uint32</typeRef>
       </component>

       <component componentID="3">
        <name>errors</name>
        <synopsis>The total number of packets with errors</synopsis>
        <typeRef>uint32</typeRef>
       </component>
       </struct>

      </dataTypeDef>

        <dataTypeDef>
           <name>IFEInfo</name>
       <synopsis>Describing IFE table row Information</synopsis>
           <struct>
              <component componentID="1">
                <name>IFETYPE</name>
            <synopsis>
            the ethernet type to be used for outgoing IFE frame
            </synopsis>
            <optional/>
                <typeRef>uint16</typeRef>



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              </component>
              <component componentID="2">
                <name>StatId</name>
            <synopsis>
            the Index into the stats table
            </synopsis>
            <optional/>
                <typeRef>uint32</typeRef>
              </component>
              <component componentID="3">
                <name>DSTFE</name>
            <synopsis>
                the destination MAC address of destination FE
            </synopsis>
                <typeRef>byte[6]</typeRef>
              </component>
              <component componentID="4">
                <name>SRCFE</name>
            <synopsis>
                the source MAC address used for the source FE
            </synopsis>
                <typeRef>byte[6]</typeRef>
              </component>
              <component componentID="5">
                <name>MetaFilterList</name>
            <synopsis>
                the allowed metadata filter table
            </synopsis>
            <optional/>
                <array type="variable-size">
                  <typeRef>uint32</typeRef>
                </array>
               </component>


           </struct>
        </dataTypeDef>

     </dataTypeDefs>

     <LFBClassDefs>
       <LFBClassDef LFBClassID="18">
         <name>IFE</name>
         <synopsis>
            This LFB describes IFE connectivity parameterization
         </synopsis>
         <version>1.0</version>




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       <inputPorts>

         <inputPort group="true">
          <name>EgressInGroup</name>
          <synopsis>
              The input port group of the egress side.
              It expects any type of Ethernet frame.
          </synopsis>
          <expectation>
           <frameExpected>
           <ref>PacketAny</ref>
           </frameExpected>
          </expectation>
         </inputPort>

         <inputPort  group="true">
          <name>IngressInGroup</name>
          <synopsis>
              The input port group of the ingress side.
              It expects an interFE encapsulated Ethernet frame.
           </synopsis>
          <expectation>
           <frameExpected>
           <ref>InterFEFrame</ref>
           </frameExpected>
          </expectation>
       </inputPort>

          </inputPorts>

          <outputPorts>

            <outputPort>
              <name>OUT1</name>
              <synopsis>
                   The output port of the egress side.
              </synopsis>
              <product>
                 <frameProduced>
                   <ref>InterFEFrame</ref>
                 </frameProduced>
              </product>
           </outputPort>

           <outputPort>
             <name>OUT2</name>
             <synopsis>
                 The output port of the Ingress side.



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             </synopsis>
             <product>
                <frameProduced>
                  <ref>PacketAny</ref>
                </frameProduced>
             </product>
          </outputPort>

          <outputPort>
            <name>EXCEPTIONOUT</name>
            <synopsis>
               The exception handling path
            </synopsis>
            <product>
               <frameProduced>
                 <ref>PacketAny</ref>
               </frameProduced>
               <metadataProduced>
                 <ref>ExceptionID</ref>
               </metadataProduced>
            </product>
         </outputPort>

      </outputPorts>

      <components>

         <component componentID="1" access="read-write">
            <name>IFETable</name>
            <synopsis>
               the table of all InterFE relations
            </synopsis>
            <array type="variable-size">
               <typeRef>IFEInfo</typeRef>
            </array>
         </component>

        <component componentID="2" access="read-only">
          <name>IFEStats</name>
          <synopsis>
           the stats corresponding to the IFETable table
          </synopsis>
          <typeRef>bstats</typeRef>
        </component>

     </components>

    </LFBClassDef>



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   </LFBClassDefs>

   </LFBLibrary>


                        Figure 8: Inter-FE LFB XML

7.  Acknowledgements

   The authors would like to thank Joel Halpern and Dave Hood for the
   stimulating discussions.  Evangelos Haleplidis shepherded and
   contributed to improving this document.  Alia Atlas was the AD
   sponsor of this document and did a tremendous job of critiquing it.
   The authors are grateful to Joel Halpern in his role as the Routing
   Area reviewer in shaping the content of this document.

8.  IANA Considerations

   This memo includes one IANA requests within the registry https://
   www.iana.org/assignments/forces

   The request is for the sub-registry "Logical Functional Block (LFB)
   Class Names and Class Identifiers" to request for the reservation of
   LFB class name IFE with LFB classid 18 with version 1.0.

   +--------------+---------+---------+-------------------+------------+
   |  LFB Class   |   LFB   |   LFB   |    Description    | Reference  |
   |  Identifier  |  Class  | Version |                   |            |
   |              |   Name  |         |                   |            |
   +--------------+---------+---------+-------------------+------------+
   |      18      |   IFE   |   1.0   |   An IFE LFB to   |    This    |
   |              |         |         |    standardize    |  document  |
   |              |         |         |  inter-FE LFB for |            |
   |              |         |         |   ForCES Network  |            |
   |              |         |         |      Elements     |            |
   +--------------+---------+---------+-------------------+------------+

     Logical Functional Block (LFB) Class Names and Class Identifiers

9.  IEEE Assignment Considerations

   This memo includes a request for a new ethernet protocol type as
   described in Section 5.2.

10.  Security Considerations

   The FEs involved in the Inter-FE LFB belong to the same Network
   Device (NE) and are within the scope of a single administrative



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   Ethernet LAN private network.  Trust of policy in the control and its
   treatment in the datapath exists already.

   This document does not alter [RFC5812] or the ForCES
   Protocol[RFC5810].  As such, it has no impact on their security
   considerations.  This document simply defines the operational
   parameters and capabilities of an LFB that performs LFB class
   instance extensions across nodes under a single administrative
   control.  This document does not attempt to analyze the presence or
   possibility of security interactions created by allowing LFB graph
   extension on packets.  Any such issues, if they exist should be
   resolved by the designers of the particular data path i.e they are
   not the responsibility of general mechanism outlined in this
   document; one such option for protecting Ethernet is the use of IEEE
   802.1AE Media Access Control Security [ieee8021ae] which provides
   encryption and authentication.

11.  References

11.1.  Normative References

   [RFC5810]  Doria, A., Ed., Hadi Salim, J., Ed., Haas, R., Ed.,
              Khosravi, H., Ed., Wang, W., Ed., Dong, L., Gopal, R., and
              J. Halpern, "Forwarding and Control Element Separation
              (ForCES) Protocol Specification", RFC 5810, DOI 10.17487/
              RFC5810, March 2010,
              <http://www.rfc-editor.org/info/rfc5810>.

   [RFC5811]  Hadi Salim, J. and K. Ogawa, "SCTP-Based Transport Mapping
              Layer (TML) for the Forwarding and Control Element
              Separation (ForCES) Protocol", RFC 5811, DOI 10.17487/
              RFC5811, March 2010,
              <http://www.rfc-editor.org/info/rfc5811>.

   [RFC5812]  Halpern, J. and J. Hadi Salim, "Forwarding and Control
              Element Separation (ForCES) Forwarding Element Model", RFC
              5812, DOI 10.17487/RFC5812, March 2010,
              <http://www.rfc-editor.org/info/rfc5812>.

   [RFC7391]  Hadi Salim, J., "Forwarding and Control Element Separation
              (ForCES) Protocol Extensions", RFC 7391, DOI 10.17487/
              RFC7391, October 2014,
              <http://www.rfc-editor.org/info/rfc7391>.

   [RFC7408]  Haleplidis, E., "Forwarding and Control Element Separation
              (ForCES) Model Extension", RFC 7408, DOI 10.17487/RFC7408,
              November 2014, <http://www.rfc-editor.org/info/rfc7408>.




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11.2.  Informative 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>.

   [RFC3746]  Yang, L., Dantu, R., Anderson, T., and R. Gopal,
              "Forwarding and Control Element Separation (ForCES)
              Framework", RFC 3746, DOI 10.17487/RFC3746, April 2004,
              <http://www.rfc-editor.org/info/rfc3746>.

   [RFC5405]  Eggert, L. and G. Fairhurst, "Unicast UDP Usage Guidelines
              for Application Designers", BCP 145, RFC 5405, DOI
              10.17487/RFC5405, November 2008,
              <http://www.rfc-editor.org/info/rfc5405>.

   [RFC6956]  Wang, W., Haleplidis, E., Ogawa, K., Li, C., and J.
              Halpern, "Forwarding and Control Element Separation
              (ForCES) Logical Function Block (LFB) Library", RFC 6956,
              DOI 10.17487/RFC6956, June 2013,
              <http://www.rfc-editor.org/info/rfc6956>.

   [brcm-higig]
              , "HiGig",
              <http://www.broadcom.com/products/brands/HiGig>.

   [circuit-b]
              Fairhurst, G., "Network Transport Circuit Breakers", Sep
              2015, <https://tools.ietf.org/html/draft-fairhurst-tsvwg-
              circuit-breaker-04>.

   [ieee8021ae]
              , "IEEE Standard for Local and metropolitan area networks
              Media Access Control (MAC) Security", IEEE 802.1AE-2006,
              Aug 2006.

   [linux-tc]
              Hadi Salim, J., "Linux Traffic Control Classifier-Action
              Subsystem Architecture", netdev 01, Feb 2015.

   [tc-ife]   Hadi Salim, J. and D. Joachimpillai, "Distributing Linux
              Traffic Control Classifier-Action Subsystem", netdev 01,
              Feb 2015.

   [vxlan-udp]
              , "iproute2 and kernel code (drivers/net/vxlan.c)",
              <https://www.kernel.org/pub/linux/utils/net/iproute2/>.



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Authors' Addresses

   Damascane M. Joachimpillai
   Verizon
   60 Sylvan Rd
   Waltham, Mass.  02451
   USA

   Email: damascene.joachimpillai@verizon.com


   Jamal Hadi Salim
   Mojatatu Networks
   Suite 200, 15 Fitzgerald Rd.
   Ottawa, Ontario  K2H 9G1
   Canada

   Email: hadi@mojatatu.com

































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