Network Working Group H. Khosravi, Ed.
Request for Comments: 3654 T. Anderson, Ed.
Category: Informational Intel
November 2003
Requirements for Separation of IP Control and Forwarding
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard of any kind. Distribution of this
memo is unlimited.
Copyright Notice
Copyright (C) The Internet Society (2003). All Rights Reserved.
Abstract
This document introduces the Forwarding and Control Element
Separation (ForCES) architecture and defines a set of associated
terminology. This document also defines a set of architectural,
modeling, and protocol requirements to logically separate the control
and data forwarding planes of an IP (IPv4, IPv6, etc.) networking
device.
Table of Contents
1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Definitions . . . . . . . . . . . . . . . . . . . . . . . . . 2
3. Architecture. . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Architectural Requirements. . . . . . . . . . . . . . . . . . 5
5. FE Model Requirements . . . . . . . . . . . . . . . . . . . . 7
5.1. Types of Logical Functions. . . . . . . . . . . . . . . 8
5.2. Variations of Logical Functions . . . . . . . . . . . . 8
5.3. Ordering of Logical Functions . . . . . . . . . . . . . 8
5.4. Flexibility . . . . . . . . . . . . . . . . . . . . . . 8
5.5 Minimal Set of Logical Functions. . . . . . . . . . . . 9
6. ForCES Protocol Requirements. . . . . . . . . . . . . . . . . 10
7. References. . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Normative References. . . . . . . . . . . . . . . . . . 14
7.2. Informative References. . . . . . . . . . . . . . . . . 15
8. Security Considerations . . . . . . . . . . . . . . . . . . . 15
9. Authors' Addresses & Acknowledgments. . . . . . . . . . . . . 15
10. Editors' Contact Information. . . . . . . . . . . . . . . . . 17
11. Full Copyright Statement. . . . . . . . . . . . . . . . . . . 18
Khosravi & Anderson Informational [Page 1]
RFC 3654 ForCES Requirements November 2003
1. Introduction
An IP network element is composed of numerous logically separate
entities that cooperate to provide a given functionality (such as a
routing or IP switching) and yet appear as a normal integrated
network element to external entities. Two primary types of network
element components exist: control-plane components and forwarding-
plane components. In general, forwarding-plane components are ASIC,
network-processor, or general-purpose processor-based devices that
handle all data path operations. Conversely, control-plane
components are typically based on general-purpose processors that
provide control functionality such as the processing of routing or
signaling protocols. A standard set of mechanisms for connecting
these components provides increased scalability and allows the
control and forwarding planes to evolve independently, thus promoting
faster innovation.
For the purpose of illustration, let us consider the architecture of
a router to illustrate the concept of separate control and forwarding
planes. The architecture of a router is composed of two main parts.
These components, while inter-related, perform functions that are
largely independent of each other. At the bottom is the forwarding
path that operates in the data-forwarding plane and is responsible
for per-packet processing and forwarding. Above the forwarding plane
is the network operating system that is responsible for operations in
the control plane. In the case of a router or switch, the network
operating system runs routing, signaling and control protocols (e.g.,
RIP, OSPF and RSVP) and dictates the forwarding behavior by
manipulating forwarding tables, per-flow QoS tables and access
control lists. Typically, the architecture of these devices combines
all of this functionality into a single functional whole with respect
to external entities.
2. Definitions
Addressable Entity (AE) - A physical device that is directly
addressable given some interconnect technology. For example, on IP
networks, it is a device to which we can communicate using an IP
address; and on a switch fabric, it is a device to which we can
communicate using a switch fabric port number.
Physical Forwarding Element (PFE) - An AE that includes hardware used
to provide per-packet processing and handling. This hardware may
consist of (but is not limited to) network processors, ASIC's, line
cards with multiple chips or stand alone box with general-purpose
processors.
Khosravi & Anderson Informational [Page 2]
RFC 3654 ForCES Requirements November 2003
Physical Control Element (PCE) - An AE that includes hardware used to
provide control functionality. This hardware typically includes a
general-purpose processor.
Forwarding Element (FE) - A logical entity that implements the ForCES
protocol. FEs use the underlying hardware to provide per-packet
processing and handling as directed/controlled by a CE via the ForCES
protocol. FEs may happen to be a single blade(or PFE), a partition
of a PFE or multiple PFEs.
Control Element (CE) - A logical entity that implements the ForCES
protocol and uses it to instruct one or more FEs how to process
packets. CEs handle functionality such as the execution of control
and signaling protocols. CEs may consist of PCE partitions or whole
PCEs.
Pre-association Phase - The period of time during which a FE Manager
(see below) and a CE Manager (see below) are determining which FE and
CE should be part of the same network element. Any partitioning of
PFEs and PCEs occurs during this phase.
Post-association Phase - The period of time during which a FE does
know which CE is to control it and vice versa, including the time
during which the CE and FE are establishing communication with one
another.
ForCES Protocol - While there may be multiple protocols used within
the overall ForCES architecture, the term "ForCES protocol" refers
only to the ForCES post-association phase protocol (see below).
ForCES Post-Association Phase Protocol - The protocol used for post-
association phase communication between CEs and FEs. This protocol
does not apply to CE-to-CE communication, FE-to-FE communication, or
to communication between FE and CE managers. The ForCES protocol is
a master-slave protocol in which FEs are slaves and CEs are masters.
This protocol includes both the management of the communication
channel (e.g., connection establishment, heartbeats) and the control
messages themselves. This protocol could be a single protocol or
could consist of multiple protocols working together.
FE Model - A model that describes the logical processing functions of
a FE.
FE Manager - A logical entity that operates in the pre-association
phase and is responsible for determining to which CE(s) a FE should
communicate. This process is called CE discovery and may involve the
FE manager learning the capabilities of available CEs. A FE manager
may use anything from a static configuration to a pre-association
Khosravi & Anderson Informational [Page 3]
RFC 3654 ForCES Requirements November 2003
phase protocol (see below) to determine which CE to use. However,
this pre-association phase protocol is currently out of scope. Being
a logical entity, a FE manager might be physically combined with any
of the other logical entities mentioned in this section.
CE Manager - A logical entity that operates in the pre-association
phase and is responsible for determining to which FE(s) a CE should
communicate. This process is called FE discovery and may involve the
CE manager learning the capabilities of available FEs. A CE manager
may use anything from a static configuration to a pre-association
phase protocol (see below) to determine which FE to use. Again, this
pre-association phase protocol is currently out of scope. Being a
logical entity, a CE manager might be physically combined with any of
the other logical entities mentioned in this section.
Pre-association Phase Protocol - A protocol between FE managers and
CE managers that is used to determine which CEs or FEs to use. A
pre-association phase protocol may include a CE and/or FE capability
discovery mechanism. Note that this capability discovery process is
wholly separate from (and does not replace) what is used within the
ForCES protocol (see Section 6, requirement #1). However, the two
capability discovery mechanisms may utilize the same FE model (see
Section 5). Pre-association phase protocols are not discussed
further in this document.
ForCES Network Element (NE) - An entity composed of one or more CEs
and one or more FEs. To entities outside a NE, the NE represents a
single point of management. Similarly, a NE usually hides its
internal organization from external entities.
ForCES Protocol Element - A FE or CE.
High Touch Capability - This term will be used to apply to the
capabilities found in some forwarders to take action on the contents
or headers of a packet based on content other than what is found in
the IP header. Examples of these capabilities include NAT-PT,
firewall, and L7 content recognition.
3. Architecture
The chief components of a NE architecture are the CE, the FE, and the
interconnect protocol. The CE is responsible for operations such as
signaling and control protocol processing and the implementation of
management protocols. Based on the information acquired through
control processing, the CE(s) dictates the packet-forwarding behavior
of the FE(s) via the interconnect protocol. For example, the CE
might control a FE by manipulating its forwarding tables, the state
of its interfaces, or by adding or removing a NAT binding.
Khosravi & Anderson Informational [Page 4]
RFC 3654 ForCES Requirements November 2003
The FE operates in the forwarding plane and is responsible for per-
packet processing and handling. By allowing the control and
forwarding planes to evolve independently, different types of FEs can
be developed - some general purpose and others more specialized.
Some functions that FEs could perform include layer 3 forwarding,
metering, shaping, firewall, NAT, encapsulation (e.g., tunneling),
decapsulation, encryption, accounting, etc. Nearly all combinations
of these functions may be present in practical FEs.
Below is a diagram illustrating an example NE composed of a CE and
two FEs. Both FEs and CE require minimal configuration as part of
the pre-configuration process and this may be done by FE Manager and
CE Manager respectively. Apart from this, there is no defined role
for FE Manager and CE Manager. These components are out of scope of
the architecture and requirements for the ForCES protocol, which only
involves CEs and FEs.
--------------------------------
| NE |
| ------------- |
| | CE | |
| ------------- |
| / \ |
| / \ |
| / \ |
| / \ |
| ----------- ----------- |
| | FE | | FE | |
| ----------- ----------- |
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
| | | | | | | | | |
--------------------------------
| | | | | | | |
| | | | | | | |
4. Architectural Requirements
The following are the architectural requirements:
1) CEs and FEs MUST be able to connect by a variety of interconnect
technologies. Examples of interconnect technologies used in current
architectures include Ethernet, bus backplanes, and ATM (cell)
fabrics. FEs MAY be connected to each other via a different
technology than that used for CE/FE communication.
Khosravi & Anderson Informational [Page 5]
RFC 3654 ForCES Requirements November 2003
2) FEs MUST support a minimal set of capabilities necessary for
establishing network connectivity (e.g., interface discovery, port
up/down functions). Beyond this minimal set, the ForCES architecture
MUST NOT restrict the types or numbers of capabilities that FEs may
contain.
3) Packets MUST be able to arrive at the NE by one FE and leave the
NE via a different FE.
4) A NE MUST support the appearance of a single functional device.
For example, in a router, the TTL of the packet should be decremented
only once as it traverses the NE regardless of how many FEs through
which it passes. However, external entities (e.g., FE managers and
CE managers) MAY have direct access to individual ForCES protocol
elements for providing information to transition them from the pre-
association to post-association phase.
5) The architecture MUST provide a way to prevent unauthorized ForCES
protocol elements from joining a NE. (For more protocol details,
refer to section 6 requirement #2)
6) A FE MUST be able to asynchronously inform the CE of a failure or
increase/decrease in available resources or capabilities on the FE.
Thus, the FE MUST support error monitoring and reporting. (Since
there is not a strict 1-to-1 mapping between FEs and PFEs, it is
possible for the relationship between a FE and its physical resources
to change over time). For example, the number of physical ports or
the amount of memory allocated to a FE may vary over time. The CE
needs to be informed of such changes so that it can control the FE in
an accurate way.
7) The architecture MUST support mechanisms for CE redundancy or CE
failover. This includes the ability for CEs and FEs to determine
when there is a loss of association between them, ability to restore
association and efficient state (re)synchronization mechanisms. This
also includes the ability to preset the actions an FE will take in
reaction to loss of association to its CE e.g., whether the FE will
continue to forward packets or whether it will halt operations.
8) FEs MUST be able to redirect control packets (such as RIP, OSPF
messages) addressed to their interfaces to the CE. They MUST also
redirect other relevant packets (e.g., such as those with Router
Alert Option set) to their CE. The CEs MUST be able to configure the
packet redirection information/filters on the FEs. The CEs MUST also
be able to create packets and have its FEs deliver them.
Khosravi & Anderson Informational [Page 6]
RFC 3654 ForCES Requirements November 2003
9) Any proposed ForCES architectures MUST explain how that
architecture supports all of the router functions as defined in
[RFC1812]. IPv4 Forwarding functions such IP header validation,
performing longest prefix match algorithm, TTL decrement, Checksum
calculation, generation of ICMP error messages, etc defined in RFC
1812 should be explained.
10) In a ForCES NE, the CE(s) MUST be able to learn the topology by
which the FEs in the NE are connected.
11) The ForCES NE architecture MUST be capable of supporting (i.e.,
must scale to) at least hundreds of FEs and tens of thousands of
ports.
12) The ForCES architecture MUST allow FEs AND CEs to join and leave
NEs dynamically.
13) The ForCES NE architecture MUST support multiple CEs and FEs.
However, coordination between CEs is out of scope of ForCES.
14) For pre-association phase setup, monitoring, configuration
issues, it MAY be useful to use standard management mechanisms for
CEs and FEs. The ForCES architecture and requirements do not
preclude this. In general, for post-association phase, most
management tasks SHOULD be done through interaction with the CE. In
certain conditions (e.g., CE/FE disconnection), it may be useful to
allow management tools (e.g., SNMP) to be used to diagnose and repair
problems. The following guidelines MUST be observed:
1. The ability for a management tool (e.g., SNMP) to be used to read
(but not change) the state of FE SHOULD NOT be precluded.
2. It MUST NOT be possible for management tools (e.g., SNMP, etc) to
change the state of a FE in a manner that affects overall NE
behavior without the CE being notified.
5. FE Model Requirements
The variety of FE functionality that the ForCES architecture allows
poses a potential problem for CEs. In order for a CE to effectively
control a FE, the CE must understand how the FE processes packets. We
therefore REQUIRE that a FE model be created that can express the
logical packet processing capabilities of a FE. This model will be
used in the ForCES protocol to describe FE capabilities (see Section
6, requirement #1). The FE model MUST define both a capability model
and a state model, which expresses the current configuration of the
device. The FE model MUST also support multiple FEs in the NE
architecture.
Khosravi & Anderson Informational [Page 7]
RFC 3654 ForCES Requirements November 2003
5.1. Types of Logical Functions
The FE model MUST express what logical functions can be applied to
packets as they pass through a FE. Logical functions are the packet
processing functions that are applied to the packets as they are
forwarded through a FE. Examples of logical functions are layer 3
forwarding, firewall, NAT, and shaping. Section 5.5 defines the
minimal set of logical functions that the FE Model MUST support.
5.2. Variations of Logical Functions
The FE model MUST be capable of supporting/allowing variations in the
way logical functions are implemented on a FE. For example, on a
certain FE the forwarding logical function might have information
about both the next hop IP address and the next hop MAC address,
while on another FE these might be implemented as separate logical
functions. Another example would be NAT functionality that can have
several flavors such as Traditional/Outbound NAT, Bi-directional NAT,
Twice NAT, and Multihomed NAT [RFC2663]. The model must be flexible
enough to allow such variations in functions.
5.3. Ordering of Logical Functions
The model MUST be capable of describing the order in which these
logical functions are applied in a FE. The ordering of logical
functions is important in many cases. For example, a NAT function
may change a packet's source or destination IP address. Any number
of other logical functions (e.g., layer 3 forwarding, ingress/egress
firewall, shaping, and accounting) may make use of the source or
destination IP address when making decisions. The CE needs to know
whether to configure these logical functions with the pre-NAT or
post-NAT IP address. Furthermore, the model MUST be capable of
expressing multiple instances of the same logical function in a FE's
processing path. Using NAT again as an example, one NAT function is
typically performed before the forwarding decision (packets arriving
externally have their public addresses replaced with private
addresses) and one NAT function is performed after the forwarding
decision (for packets exiting the domain, their private addresses are
replaced by public ones).
5.4. Flexibility
Finally, the FE model SHOULD provide a flexible infrastructure in
which new logical functions and new classification, action, and
parameterization data can be easily added. In addition, the FE model
MUST be capable of describing the types of statistics gathered by
each logical function.
Khosravi & Anderson Informational [Page 8]
RFC 3654 ForCES Requirements November 2003
5.5. Minimal Set of Logical Functions
The rest of this section defines a minimal set of logical functions
that any FE model MUST support. This minimal set DOES NOT imply that
all FEs must provide this functionality. Instead, these requirements
only specify that the model must be capable of expressing the
capabilities that FEs may choose to provide.
1) Port Functions
The FE model MUST be capable of expressing the number of ports on the
device, the static attributes of each port (e.g., port type, link
speed), and the configurable attributes of each port (e.g., IP
address, administrative status).
2) Forwarding Functions
The FE model MUST be capable of expressing the data that can be used
by the forwarding function to make a forwarding decision. Support
for IPv4 and IPv6 unicast and multicast forwarding functions MUST be
provided by the model.
3) QoS Functions
The FE model MUST allow a FE to express its QoS capabilities in terms
of, e.g., metering, policing, shaping, and queuing functions. The FE
model MUST be capable of expressing the use of these functions to
provide IntServ or DiffServ functionality as described in [RFC2211],
[RFC2212], [RFC2215], [RFC2475], and [RFC3290].
4) Generic Filtering Functions
The FE model MUST be capable of expressing complex sets of filtering
functions. The model MUST be able to express the existence of these
functions at arbitrary points in the sequence of a FE's packet
processing functions. The FE model MUST be capable of expressing a
wide range of classification abilities from single fields (e.g.,
destination address) to arbitrary n-tuples. Similarly, the FE model
MUST be capable of expressing what actions these filtering functions
can perform on packets that the classifier matches.
5) Vendor-Specific Functions
The FE model SHOULD be extensible so that new, currently unknown FE
functionality can be expressed. The FE Model SHOULD NOT be extended
to express standard/common functions in a proprietary manner. This
would NOT be ForCES compliant.
6) High-Touch Functions
The FE model MUST be capable of expressing the encapsulation and
tunneling capabilities of a FE. The FE model MUST support functions
Khosravi & Anderson Informational [Page 9]
RFC 3654 ForCES Requirements November 2003
that mark the class of service that a packet should receive (i.e.,
IPv4 header TOS octet or the IPv6 Traffic Class octet). The FE model
MAY support other high touch functions (e.g., NAT, ALG).
7) Security Functions
The FE model MUST be capable of expressing the types of encryption
that may be applied to packets in the forwarding path.
8) Off-loaded Functions
Per-packet processing can leave state in the FE, so that logical
functions executed during packet processing can perform in a
consistent manner (for instance, each packet may update the state of
the token bucket occupancy of a give policer). In addition, the FE
Model MUST allow logical functions to execute asynchronously from
packet processing, according to a certain finite-state machine, in
order to perform functions that are, for instance, off-loaded from
the CE to the FE. The FE model MUST be capable of expressing these
asynchronous functions. Examples of such functions include the
finite-state machine execution required by TCP termination or OSPF
Hello processing, triggered not only by packet events, but by timer
events as well. This Does NOT mean off-loading of any piece of code
to an FE, just that the FE Model should be able to express existing
Off-loaded functions on an FE.
9) IPFLOW/PSAMP Functions
Several applications such as, Usage-based Accounting, Traffic
engineering, require flow-based IP traffic measurements from Network
Elements. [IPFLOW] defines architecture for IP traffic flow
monitoring, measuring and exporting. The FE model SHOULD be able to
express metering functions and flow accounting needed for exporting
IP traffic flow information. Similarly to support measurement-based
applications, [PSAMP] describes a framework to define a standard set
of capabilities for network elements to sample subsets of packets by
statistical and other methods. The FE model SHOULD be able to
express statistical packet filtering functions and packet information
needed for supporting packet sampling applications.
6. ForCES Protocol Requirements
This section specifies some of the requirements that the ForCES
protocol MUST meet.
1) Configuration of Modeled Elements
The ForCES protocol MUST allow the CEs to determine the capabilities
of each FE. These capabilities SHALL be expressed using the FE model
whose requirements are defined in Section 5. Furthermore, the
protocol MUST provide a means for the CEs to control all the FE
Khosravi & Anderson Informational [Page 10]
RFC 3654 ForCES Requirements November 2003
capabilities that are discovered through the FE model. The protocol
MUST be able to add/remove classification/action entries, set/delete
parameters, query statistics, and register for and receive events.
2) Support for Secure Communication
a) FE configuration will contain information critical to the
functioning of a network (e.g., IP Forwarding Tables). As
such, it MUST be possible to ensure the integrity of all ForCES
protocol messages and protect against man-in-the-middle
attacks.
b) FE configuration information may also contain information
derived from business relationships (e.g., service level
agreements). Because of the confidential nature of the
information, it MUST be possible to secure (make private) all
ForCES protocol messages.
c) In order to ensure that authorized CEs and FEs are
participating in a NE and defend against CE or FE impersonation
attacks, the ForCES architecture MUST select a means of
authentication for CEs and FEs.
d) In some deployments ForCES is expected to be deployed between
CEs and FEs connected to each other inside a box over a
backplane, where physical security of the box ensures that
man-in-the-middle, snooping, and impersonation attacks are not
possible. In such scenarios the ForCES architecture MAY rely
on the physical security of the box to defend against these
attacks and protocol mechanisms May be turned off.
e) In the case when CEs and FEs are connected over a network,
security mechanisms MUST be specified or selected that protect
the ForCES protocol against such attacks. Any security
solution used for ForCES MUST specify how it deals with such
attacks.
3) Scalability
The ForCES protocol MUST be capable of supporting (i.e., must scale
to) at least hundreds of FEs and tens of thousands of ports. For
example, the ForCES protocol field sizes corresponding to FE or port
numbers SHALL be large enough to support the minimum required
numbers. This requirement does not relate to the performance of a NE
as the number of FEs or ports in the NE grows.
4) Multihop
When the CEs and FEs are separated beyond a single L3 routing hop,
the ForCES protocol will make use of an existing RFC2914 compliant L4
protocol with adequate reliability, security and congestion control
(e.g., TCP, SCTP) for transport purposes.
Khosravi & Anderson Informational [Page 11]
RFC 3654 ForCES Requirements November 2003
5) Message Priority
The ForCES protocol MUST provide a means to express the protocol
message priorities.
6) Reliability
a) The ForCES protocol will be used to transport information that
requires varying levels of reliability. By strict or robust
reliability in this requirement we mean, no losses, no
corruption, no re-ordering of information being transported and
delivery in a timely fashion.
b) Some information or payloads, such as redirected packets or
packet sampling, may not require robust reliability (can
tolerate some degree of losses). For information of this sort,
ForCES MUST NOT be restricted to strict reliability.
c) Payloads such as configuration information, e.g., ACLs, FIB
entries, or FE capability information (described in section 6,
(1)) are mission critical and must be delivered in a robust
reliable fashion. Thus, for information of this sort, ForCES
MUST either provide built-in protocol mechanisms or use a
reliable transport protocol for achieving robust/strict
reliability.
d) Some information or payloads, such as heartbeat packets that
may be used to detect loss of association between CE and FEs
(see section 6, (8)), may prefer timeliness over reliable
delivery. For information of this sort, ForCES MUST NOT be
restricted to strict reliability.
e) When ForCES is carried over multi-hop IP networks, it is a
requirement that ForCES MUST use a [RFC2914]-compliant
transport protocol.
f) In cases where ForCES is not running over an IP network such as
an Ethernet or cell fabric between CE and FE, then reliability
still MUST be provided when carrying critical information of
the types specified in (c) above, either by the underlying
link/network/transport layers or by built-in protocol
mechanisms.
7) Interconnect Independence
The ForCES protocol MUST support a variety of interconnect
technologies. (refer to section 4, requirement #1)
8) CE redundancy or CE failover
The ForCES protocol MUST support mechanisms for CE redundancy or CE
failover. This includes the ability for CEs and FEs to determine
when there is a loss of association between them, ability to restore
association and efficient state (re)synchronization mechanisms. This
also includes the ability to preset the actions an FE will take in
Khosravi & Anderson Informational [Page 12]
RFC 3654 ForCES Requirements November 2003
reaction to loss of association to its CE, e.g., whether the FE will
continue to forward packets or whether it will halt operations.
(refer to section 4, requirement #7)
9) Packet Redirection/Mirroring
a) The ForCES protocol MUST define a way to redirect packets from
the FE to the CE and vice-versa. Packet redirection terminates
any further processing of the redirected packet at the FE.
b) The ForCES protocol MUST define a way to mirror packets from
the FE to the CE. Mirroring allows the packet duplicated by
the FE at the mirroring point to be sent to the CE while the
original packet continues to be processed by the FE.
Examples of packets that may be redirected or mirrored include
control packets (such as RIP, OSPF messages) addressed to the
interfaces or any other relevant packets (such as those with Router
Alert Option set). The ForCES protocol MUST also define a way for
the CE to configure the behavior of a) and b) (above), to specify
which packets are affected by each.
10) Topology Exchange
The ForCES protocol or information carried in the ForCES protocol
MUST allow those FEs which have inter-FE topology information to
provide that information to the CE(s).
11) Dynamic Association
The ForCES protocol MUST allow CEs and FEs to join and leave a NE
dynamically. (refer to section 4, requirement #12)
12) Command Bundling
The ForCES protocol MUST be able to group an ordered set of commands
to a FE. Each such group of commands SHOULD be sent to the FE in as
few messages as possible. Furthermore, the protocol MUST support the
ability to specify if a command group MUST have all-or-nothing
semantics.
13) Asynchronous Event Notification
The ForCES protocol MUST be able to asynchronously notify the CE of
events on the FE such as failures or change in available resources or
capabilities. (refer to section 4, requirement #6)
14) Query Statistics
The ForCES protocol MUST provide a means for the CE to be able to
query statistics (monitor performance) from the FE.
Khosravi & Anderson Informational [Page 13]
RFC 3654 ForCES Requirements November 2003
15) Protection against Denial of Service Attacks (based on CPU
overload or queue overflow)
Systems utilizing the ForCES protocol can be attacked using denial of
service attacks based on CPU overload or queue overflow. The ForCES
protocol could be exploited by such attacks to cause the CE to become
unable to control the FE or appropriately communicate with other
routers and systems. The ForCES protocol MUST therefore provide
mechanisms for controlling FE capabilities that can be used to
protect against such attacks. FE capabilities that MUST be
manipulated via ForCES include the ability to install classifiers and
filters to detect and drop attack packets, as well as to be able to
install rate limiters that limit the rate of packets which appear to
be valid but may be part of an attack (e.g., bogus BGP packets).
7. References
7.1. Normative References
[RFC3290] Bernet, Y., Blake, S., Grossman, D. and A. Smith, "An
Informal Management Model for DiffServ Routers", RFC 3290,
May 2002.
[RFC1812] Baker, F., "Requirements for IP Version 4 Routers", RFC
1812, June 1995.
[RFC2211] Wroclawski, J., "Specification of the Controlled-Load
Network Element Service", RFC 2211, September 1997.
[RFC2212] Shenker, S., Partridge, C. and R. Guerin, "Specification
of Guaranteed Quality of Service", RFC 2212, September
1997.
[RFC2215] Shenker, S. and J. Wroclawski, "General Characterization
Parameters for Integrated Service Network Elements", RFC
2215, September 1997.
[RFC2475] Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z.
and W. Weisss, "An Architecture for Differentiated
Service", RFC 2475, December 1998.
[RFC2914] Floyd, S., "Congestion Control Principles", BCP 14, RFC
2914, September 2000.
[RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address
Translator (NAT) Terminology and Considerations", RFC
2663, August 1999.
Khosravi & Anderson Informational [Page 14]
RFC 3654 ForCES Requirements November 2003
7.2. Informative References
[RFC3532] Anderson, T. and J. Buerkle, "Requirements for the Dynamic
Partitioning of Switching Elements", RFC 3532, May 2003.
[IPFLOW] Quittek, et al., "Requirements for IP Flow Information
Export", Work in Progress, February 2003.
[PSAMP] Duffield, et al., "A Framework for Passive Packet
Measurement ", Work in Progress, March 2003.
8. Security Considerations
See architecture requirement #5 and protocol requirement #2.
9. Authors' Addresses & Acknowledgments
This document was written by the ForCES Requirements design team:
Todd A. Anderson (Editor)
Ed Bowen
IBM Zurich Research Laboratory
Saumerstrasse 4
CH-8803 Rueschlikon Switzerland
Phone: +41 1 724 83 68
EMail: edbowen@us.ibm.com
Ram Dantu
Department of Computer Science
University of North Texas,
Denton, Texas, 76203
Phone: 940 565 2822
EMail: rdantu@unt.edu
Avri Doria
ETRI
161 Gajeong-dong, Yuseong-gu
Deajeon 305-350 Korea
EMail: avri@acm.org
Khosravi & Anderson Informational [Page 15]
RFC 3654 ForCES Requirements November 2003
Ram Gopal
Nokia Research Center
5, Wayside Road,
Burlington, MA 01803
Phone: 1-781-993-3685
EMail: ram.gopal@nokia.com
Jamal Hadi Salim
Znyx Networks
Ottawa, Ontario
Canada
EMail: hadi@znyx.com
Hormuzd Khosravi (Editor)
Muneyb Minhazuddin
Avaya Inc.
123, Epping road,
North Ryde, NSW 2113, Australia
Phone: +61 2 9352 8620
EMail: muneyb@avaya.com
Margaret Wasserman
Nokia Research Center
5 Wayside Road
Burlington, MA 01803
Phone: +1 781 993 3858
EMail: margaret.wasserman@nokia.com
The authors would like to thank Vip Sharma and Lily Yang for their
valuable contributions.
Khosravi & Anderson Informational [Page 16]
RFC 3654 ForCES Requirements November 2003
10. Editors' Contact Information
Hormuzd Khosravi
Intel
2111 NE 25th Avenue
Hillsboro, OR 97124 USA
Phone: +1 503 264 0334
EMail: hormuzd.m.khosravi@intel.com
Todd A. Anderson
Intel
2111 NE 25th Avenue
Hillsboro, OR 97124 USA
Phone: +1 503 712 1760
EMail: todd.a.anderson@intel.com
Khosravi & Anderson Informational [Page 17]
RFC 3654 ForCES Requirements November 2003
11. Full Copyright Statement
Copyright (C) The Internet Society (2003). All Rights Reserved.
This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it
or assist in its implementation may be prepared, copied, published
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of
developing Internet standards in which case the procedures for
copyrights defined in the Internet Standards process must be
followed, or as required to translate it into languages other than
English.
The limited permissions granted above are perpetual and will not be
revoked by the Internet Society or its successors or assignees.
This document and the information contained herein is provided on an
"AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Acknowledgement
Funding for the RFC Editor function is currently provided by the
Internet Society.
Khosravi & Anderson Informational [Page 18]