Internet DRAFT - draft-ietf-forces-interfelfb
draft-ietf-forces-interfelfb
Internet Engineering Task Force D. Joachimpillai
Internet-Draft Verizon
Intended status: Standards Track J. Hadi Salim
Expires: January 2, 2017 Mojatatu Networks
July 1, 2016
ForCES Inter-FE LFB
draft-ietf-forces-interfelfb-06
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.
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This Internet-Draft will expire on January 2, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Terminology and Conventions . . . . . . . . . . . . . . . . . 2
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 . . . 8
4. Inter-FE LFB Overview . . . . . . . . . . . . . . . . . . . . 8
4.1. Inserting The Inter-FE LFB . . . . . . . . . . . . . . . 9
5. Inter-FE Ethernet Connectivity . . . . . . . . . . . . . . . 10
5.1. Inter-FE Ethernet Connectivity Issues . . . . . . . . . . 10
5.1.1. MTU Consideration . . . . . . . . . . . . . . . . . . 11
5.1.2. Quality Of Service Considerations . . . . . . . . . . 11
5.1.3. Congestion Considerations . . . . . . . . . . . . . . 11
5.2. Inter-FE Ethernet Encapsulation . . . . . . . . . . . . . 12
6. Detailed Description of the Ethernet inter-FE LFB . . . . . . 13
6.1. Data Handling . . . . . . . . . . . . . . . . . . . . . . 14
6.1.1. Egress Processing . . . . . . . . . . . . . . . . . . 14
6.1.2. Ingress Processing . . . . . . . . . . . . . . . . . 15
6.2. Components . . . . . . . . . . . . . . . . . . . . . . . 16
6.3. Inter-FE LFB XML Model . . . . . . . . . . . . . . . . . 17
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 21
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 21
9. IEEE Assignment Considerations . . . . . . . . . . . . . . . 22
10. Security Considerations . . . . . . . . . . . . . . . . . . . 22
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
11.1. Normative References . . . . . . . . . . . . . . . . . . 23
11.2. Informative References . . . . . . . . . . . . . . . . . 24
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 25
1. Terminology and Conventions
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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 depends on 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 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.
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
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across elements, or to utilize specialized hardware available on
specific FEs.
Given that the ForCES inter-LFB architecture calls 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.
Other higher transports (such as UDP over IP) or lower transports
could be defined to carry the data and metadata, but these cases
are not addressed in this document.
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.
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
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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
result is typically a next hop selector which is passed downstream as
metadata.
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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.
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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 | |
| +--------+ 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
+-------------------------------------------------------------+
| +----+ |
| +----------+ | | |
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| | 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
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
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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
+-------------------------------------------------------------+
| +----------+ +----+ |
| | 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 | |
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| | 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
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.
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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. Caution needs to be exercised on
how low the resulting reported link MTU could be: For IPv4 packets
the minimum size is 64 octets [RFC 791] and for IPv6 the minimum
size is 1280 octets [RFC2460].
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
Most of the traffic passing through FEs that utilize the Inter-FE LFB
is expected to be IP based, which is generally assumed to be
congestion controlled [draft-ietf-tsvwg-rfc5405bis]. For example if
congestion causes a TCP packet annotated with additional ForCES
metadata to be dropped between FEs, the sending TCP can be expected
to react in the same fashion as if that packet had been dropped at a
different point on its path where ForCES is not involved. For this
reason, additional Inter-FE congestion control mechanisms are not
specified.
However, the increased packet size due to addition of ForCES metadata
is likely to require additional bandwidth on inter-FE links by
comparison to what would be required to carry the same traffic
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without ForCES metadata. Therefore, traffic engineering SHOULD be
done when deploying Inter-FE encapsulation.
Furthermore, the Inter-FE LFB MUST only be deployed within a single
network (with a single network operator) or networks of an adjacent
set of cooperating network operators where traffic is managed to
avoid congestion. These are Controlled Environments, as defined by
Section 3.6 of [draft-ietf-tsvwg-rfc5405bis]. Additional measures
SHOULD be imposed to restrict the impact of Inter-FE encapsulated
traffic on other traffic; example:
o rate limiting at an upstream LFB all Inter-FE LFB traffic
o managed circuit breaking[circuit-b].
o Isolating the Inter-FE traffic either via dedicated interfaces or
VLANs.
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 definition
The Ethernet header (illustrated in Figure 6) has the following
semantics:
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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 TBA1 is to be used (XXX: Note to RFC editor -
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
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 if an ILV is used. However, at the time of
publication we believe this is sufficient to carry all the info we
need; the TLV approach has been selected because it saves us 4
bytes per Metadatum transferred as compared to the ILV approach.
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
+-----------------+
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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
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.
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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.
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 TBA1 is used (XXX: Note to RFC editor -
update when available).
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 at the
end of the TLV 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
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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
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.
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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>
</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>
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<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>
</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>
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<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>
<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>
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</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.
</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">
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<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>
</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 and Sue Hares in their roles
as the Routing Area reviewers in shaping the content of this
document. David Black put a lot of effort in making sure congestion
control considerations are sane. Russ Housley did the Gen-ART review
and Joe Touch did the TSV area. Shucheng LIU (Will) did the OPS
review. Suresh Krishnan helped us provide clarity during the IESG
review. The authors are appreciative of the efforts Stephen Farrell
put in fixing the security section.
8. IANA Considerations
This memo includes one IANA request within the registry https://
www.iana.org/assignments/forces
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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
Ethernet LAN private network. While trust of policy in the control
and its treatment in the datapath exists already, an Inter-FE LFB
implementation SHOULD support security services provided by Media
Access Control Security(MACsec)[ieee8021ae]. MACsec is not currently
sufficiently widely deployed in traditional packet processing
hardware although present in newer versions of the Linux kernel
(which will be widely deployed) [linux-macsec]. Over time we would
expect that most FEs will be able to support MACsec.
MACsec provides security services such as message authentication
service and optional confidentiality service. The services can be
configured manually or automatically using MACsec Key Agreement(MKA)
over IEEE 802.1x [ieee8021x] Extensible Authentication Protocol (EAP)
framework. It is expected FE implementations are going to start with
shared keys configured from the control plane but progress to
automated key management.
The following are the MACsec security mechanisms that need to be in
place for the InterFE LFB:
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o Security mechanisms are NE-wide for all FEs. Once the security is
turned on depending upon the chosen security level
(Authentication, Confidentiality), it will be in effect for the
inter-FE LFB for the entire duration of the session.
o An operator SHOULD configure the same security policies for all
participating FEs in the NE cluster. This will ensure uniform
operations and avoid unnecessary complexity in policy
configuration. In other words, the Security Association
Keys(SAKs) should be pre-shared. When using MKA, FEs must
identify themselves with a shared Connectivity Association Key
(CAK) and Connectivity Association Key Name (CKN). EAP-TLS SHOULD
be used as the EAP method.
o An operator SHOULD configure the strict validation mode i.e all
non-protected, invalid or non-verifiable frames MUST be dropped.
It should be noted that given the above choices, if an FE is
compromised, an entity running on the FE would be able to fake inter-
FE or modify its content causing bad outcomes.
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>.
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[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>.
[draft-ietf-tsvwg-rfc5405bis]
Eggert, L., Fairhurst, G., and G. Shepherd, "UDP Usage
Guidelines", Nov 2015, <https://tools.ietf.org/html/draft-
ietf-tsvwg-rfc5405bis-07>.
[ieee8021ae]
, "IEEE Standard for Local and metropolitan area networks
Media Access Control (MAC) Security", IEEE 802.1AE-2006,
Aug 2006.
[ieee8021x]
, "IEEE standard for local and metropolitan area networks
- port-based network access control.", IEEE 802.1X-2010,
2010.
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>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[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>.
[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]
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Fairhurst, G., "Network Transport Circuit Breakers", Feb
2016, <https://tools.ietf.org/html/draft-fairhurst-tsvwg-
circuit-breaker-13>.
[linux-macsec]
Dubroca, S., "MACsec: Encryption for the wired LAN",
netdev 11, Feb 2016.
[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/>.
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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