ICN Research Group J. Hong
Internet-Draft T. You
Intended status: Informational Y-G. Hong
Expires: January 9, 2020 ETRI
V. Kafle
NICT
B. Wissingh
TNO
July 08, 2019
Architectural Considerations of ICN using Name Resolution Service
draft-irtf-icnrg-nrsarch-considerations-02
Abstract
This document discusses architectural considerations and implications
of Information-Centric Networking (ICN) related to the usage of the
Name Resolution Service (NRS). It describes how ICN architectures
may change and what implications are introduced within the ICN
routing system when NRS is integrated into ICN.
Status of This Memo
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions and Terminology . . . . . . . . . . . . . . . . . 3
3. Background . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. Implications of NRS in ICN . . . . . . . . . . . . . . . . . 5
5. ICN Architectural Considerations for NRS . . . . . . . . . . 5
5.1. Name mapping records registration, resolution, and update 6
5.2. Protocols and Semantics . . . . . . . . . . . . . . . . . 7
5.3. Routing System . . . . . . . . . . . . . . . . . . . . . 7
6. Security Considerations . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction
Information-Centric Networking (ICN) is an approach to evolve the
Internet infrastructure to directly access Named Data Objects (NDOs)
by its name, i.e., the name of NDO is directly used to route the
request to the data object. Such name-based routing in ICN has
inherent challenges in supporting globally scalable routing system,
producer mobility, off-path caching, etc. In order to address these
challenges, the Name Resolution Service (NRS) has been integrated
into several ICN projects and literature
[Afanasyev][Zhang2][Ravindran][SAIL][MF][Bayhan].
This document describes how ICN architectures may change and what
implications are introduces within the ICN routing system when NRS is
integrated into ICN. It also discusses ICN architectural
considerations for an NRS. In other words, the scope of this
document includes considerations in the veiw of the ICN architecture
and routing system when integrating NRS into ICN. However, it does
not include the NRS discussion, itself, which is presented in
[NRSguidelines].
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2. Conventions and Terminology
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].
o Name Resolution Service (NRS): NRS in ICN is defined as the
service that provides the name resolution function for translating
an object name into some other information such as a locator and
another name that is used for forwarding the object request
[NRSguidelines].
o NRS server: The NRS is a service maintained by a distributed
mapping database system. The NRS consists of the distributed NRS
servers storing the mapping records in database. NRS servers
store and maintain the mapping records that keep the bindings of
name to other information that is used for forwarding content
request.
o NRS resolver: The client side of the NRS is called an NRS
resolver. The resolver is responsible for initiating and
sequencing the name resolution request queries that ultimately
lead to a name resolution of the data objects. NRS resolvers can
be located in the consumer (or client) nodes and ICN routers. NRS
resolver can also store the mapping records obtained through the
name for later usage.
o Name registration: In order to create the NRS, the content names
and their mapping records must be registered in NRS system by a
publisher who has at least one authoritative NRS server or by a
producer who generates named data objects. The mapping
information is the binding of a name to some information such as
another names and locators, which are used for forwarding the
content request. Thus, a publisher or producer creates an NRS
registration request and send to an NRS server. On registration,
the NRS server stores the mapping record in the database and sends
back an ACK as a response back to the producer or publisher.
o Name resolution: Name resolution is the main process of the NRS.
It is performed by an NRS resolver which can be deployed on a
consumer node or an ICN router. When the required name mapping
record has not been stored in the cache of a NRS resolver, it
sends a name resolution request toward the NRS server. The NRS
server searches the content name in its mapping record database,
retrieves and sends the mapping record in the name resolution
response message to the NRS resolver.
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3. Background
The name-based routing in ICN has inherent challenges in supporting
globally scalable routing system, producer mobility, off-path
caching, etc. In order to address these challenges, an NRS has been
integrated into several ICN projects and literature as follows:
o Routing scalability : In ICN, application names identifying
contents are used directly for packet delivery, so ICN routers run
a name-based routing protocol to build namebased routing and
forwarding tables. Similar to the scalability challenge of IP
routing, if non-aggregatable name prefixes are injected to the
Default Route Free Zone (DFZ) of ICN, they would be driving the
growth of the DFZ routing table size. Thus, integrating an NRS
with ICN can be a feasible solution to keep the routing table size
under control, where the NRS resolves name prefixes which do not
exist in the DFZ forwarding table into globally routable prefixes
such as one proposed in NDN [Afanasyev]. Another approach deal
with routing scalability is the Multi-level Distributed Hash
Table (MDHT) used in NetInf [Dannewitz]. It provides name-based
anycast routing that can support a non-hierarchical namespace can
be adopted on a global scale [Dannewitz2].
o Producer mobility : In ICN, if a producer moves into a different
authority domain or network location, the request for a content
produced by the moving producer with the origin name would be
hardly forwarded to the moving producer's new location.
Especially, in a hierarchical name scheme, producer mobility
support is much harder than in a flat name scheme since the
routing tables in broader area need to be updated according to the
producer movement. Therefore, various ICN architectures such as
NetInf [Dannewitz] and MobilityFirst [MF] have adopted NRS to
tackle the producer's location.
o Off-path caching : In-network caching is a feature of an ICN
architecture. Caching approaches can be categorized into on-path
caching and off-path caching according to the location of caches
in relation to the forwarding path from the original server to a
consumer. Off-path caching, also referred as content replication
or content storing, aims at replicating content in various
locations within a network in order to increase availability,
where the caching locations may not be lying along the content
forwarding path. Thus, finding off-path cached objects is not
trivial in name-based routing of ICN. In order to support off-
path caches, the locations of replicas are usually advertised into
a name-based routing system or into NRS such as in [Bayhan].
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This document discusses architectural considerations and implications
of ICN when NRS is integrated into ICN to solve such challenges due
to the name-based routing in ICN.
4. Implications of NRS in ICN
In general, NRS would not be mandatory in an ICN architecture if the
name-based routing system can be scalable enough to timely reflect
the optimal location of requested content in the routing table.
However, due to the unlimited size of content namespace, it is not
easy to achieve such a scalable routing system in near future.
Therefore, the adoption of an NRS is a design choice for making ICN
routing and forwarding scalable. Integration of NRS would change the
ICN architecture at least with respect to procedures, latency, and
security, as follows:
o Procedure : When NRS is adopted into an ICN architecture, the
procedure of the name resolution has to be integrated into ICN
overall procedures. For NRS integration, there are certain things
that have to be decided such as where and how the name resolution
task is performed.
o Latency : When NRS is adopted into an ICN architecture, the
additional latency of the resolution obviously occurs in the
routing and forwarding system. Although the latency of the
resolution is added, the total latency could be minimized if the
nearest copies or off-path caches can be located by the NRS lookup
procedure. Additionally, there might be a trade-off between the
resolution latency and inter-domain traffic reduction.
o Security : When NRS is adopted into an ICN architecture, security
threats may increase. Protection of the NRS system against
attacks such as Distributed Denial of Service (DDoS) and
authentication of name mapping records and related signaling
messages would be challenging.
5. ICN Architectural Considerations for NRS
This section discusses the various items that have to be considered
from the point of view of ICN architecture when ICN utilizes an NRS.
These items are related with the name mapping records registration,
resolution, and update, protocols and messages, and integration with
the routing system.
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5.1. Name mapping records registration, resolution, and update
When an NRS is integrated in an ICN architecture, the functions
related with the registration, resolution and update of name mapping
records have to be considered. The NRS nodes maintain the name
mapping records and may exist in an overlay network over the ICN
routers, that is, they communicate to each other through ICN routers.
The NRS nodes exist in a distributed manner so that an NRS node is
always available closer to an ICN node and communication latency for
the name registration and resolution performed by the ICN node
remains very low.
o Name registration: Name registration is performed by the producer
when it creates a new content and an ICN router when it stores the
content in its cache. When a producer creates a content and
assigns a name to it from the name prefix space assigned to it,
the producer performs the name registration in an NRS node. When
an ICN router caches the content in its content store, it performs
name registration with a nearby NRS node. As the content gets
cached in many ICN routers, all of them may register the same
content names in the same NRS node multiple times. In this case,
the NRS node adds the new location of the content to the name
record together with the previous locations. In this way, each of
the name records stored in the NRS node may contain multiple
locations of the content.
o Name resolution: Name resolution is performed to obtain the name
record from an NRS node by sending a name resolution request
message and getting the response containing the record. Regarding
the name-based ICN routing context, the name resolution will be
mostly performed by an ICN router that does not contain the name
in its FIB table. The name resolution may also be performed by
the consumer (in case the consumer is multihomed) to make decision
to forward the content request in a better direction so that it
obtains the content from the nearest cache. If the consumer is
single homed, it may not perform the name resolution. It creates
the content request packet containing the content name and
forwards to the nearest ICN router. The ICN router checks its FIB
table to know if the content name exists. If the content name
does not exist, it performs name resolution to obtain the name
mapping record and adds to FIB table. The ICN router may also
perform name resolution even before the arrival of the content
request time to time to use the name mapping record to configure
the FIB table.
o Name record update: Name record update is carried out when a
content name mapping record changes, e.g. the content is not
available in one or more of previous locations.
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5.2. Protocols and Semantics
In order to develop an NRS system within a local ICN network domain
or global ICN network domain, new protocols and semantics should be
designed to manage and resolve names between different name spaces.
One way of implementing an NRS is by extending the basic ICN TLV
format and semantics [CCNxMessages] [CCNxSemantics]. For instance,
name resolution and response messages can be implemented by defining
new type fields in the Interest and Content Object messages
[CCNxNRS]. Then it allows the ICN architecture to minimize
implication of ICN architectural changes. But NRS system cannot
support more flexible and scalable designs cause to restrict basic
ICN protocol and semantics.
On the other hand, an NRS system can be implemented by using its own
protocol and semantics like existing NRS systems, such as [Hong].
For instance, the NRS protocol and messages can be implemented by
using a RESTful API. Then an NRS as application protocol can be
operated independently from a basic ICN architecture, but an ICN
architecture cannot be assisted with the routing protocol itself
effectively.
5.3. Routing System
It has to be considered how to process the information resolved by an
NRS lookup. The results of an NRS operation can be intended to be
used just to construct tunnels resulting in NRS identifying tunnel
endpoints.
Another way to process the information resolved by an NRS lookup is
to use it as routing hints in request messages. In this case,
request message needs to be re-written with the resolved information
including the original name that was requested by a consumer to check
the data integrity.
6. Security Considerations
When NRS is integrated into an ICN architecture, security threats
will be increased in various aspects as follows:
o Name Space Separation: In order to deploy an NRS on ICN
architecture, ICN name spaces are separated into more than two
name spaces. Thus these name spaces should be mapped and managed
securely. According to the ICN research challenge [RFC7927], new
name space can also provide an integrity verification function to
authenticate its publishers. In addition to the verification,
binding two different name spaces should be securely required.
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o NRS System: NRS enables deployment of new entities to build
distributed and scalable NRS systems. Thus, the entities, e.g.,
mapping server that can be a mapping database, could be a single
point of failure receiving malicious requests from innumerable
adversaries like Denial of Service or Distributed Denial of
service attacks. Additionally, in order to communicate with the
entities to build a NRS system, an initiator should rely on other
NRS entities that are designed to be distributed deployed mapping
servers in each network domain. Because malicious entities should
be involved in this communication to impersonate control
functions. Thus, NRS entities should trust each other and
communications with them should be protected securely.
o NRS Protocols and Messages: Regarding NRS messages, such as
lookup, update, etc., if these messages are transported
unauthenticated, an adversary can manipulate them and hijack the
important communication to response or to store fake data. Thus,
the adversary can generate malicious traffic to be redirected to
victim hosts. Therefore, security requirements for NRS should be
considered to protect the ICN architecture as well as the NRS.
7. Acknowledgements
[TBD]
8. References
8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC7927] Kutscher, D., Ed., Eum, S., Pentikousis, K., Psaras, I.,
Corujo, D., Saucez, D., Schmidt, T., and M. Waehlisch,
"Information-Centric Networking (ICN) Research
Challenges", RFC 7927, DOI 10.17487/RFC7927, July 2016,
<https://www.rfc-editor.org/info/rfc7927>.
8.2. Informative References
[Afanasyev]
Afanasyev, A. et al., "SNAMP: Secure Namespace Mapping to
Scale NDN Forwarding", IEEE Global Internet Symposium ,
April 2015.
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[Zhang2] Zhang, Y., "A Survey of Mobility Support in Named Data
Networking", NAMED-ORIENTED MOBILITY: ARCHITECTURES,
ALGORITHMS, AND APPLICATIONS(NOM) , 2016.
[Ravindran]
Ravindran, R. et al., "Forwarding-Label support in CCN
Protocol", draft-ravi-icnrg-ccn-forwarding-label-01 , July
2017.
[SAIL] "FP7 SAIL project.", http://www.sail-project.eu/ .
[MF] "NSF Mobility First project.",
http://mobilityfirst.winlab.rutgers.edu/ .
[Bayhan] Bayhan, S. et al., "On Content Indexing for Off-Path
Caching in Information-Centric Networks", ACM ICN ,
September 2016.
[CCNxSemantics]
Mosko, M., Solis, I., and C. Wood, "CCNx Semantics",
draft-irtf-icnrg-ccnxsemantics-06 , October 2017.
[CCNxMessages]
Mosko, M., Solis, I., and C. Wood, "CCNx Messages in TLV
Format", draft-irtf-icnrg-ccnxmessages-06 , October 2017.
[CCNxNRS] Hong, J. et al., "CCNx Extension for Name Resolution
Service", draft-hong-icnrg-ccnx-nrs-02 , July 2018.
[Hong] Hong, J., Chun, W., and H. Jung, "Demonstrating a Scalable
Name Resolution System for Information-Centric
Networking", ACM ICN , September 2015.
[NRSguidelines]
Hong, J. et al., "Design Guidelines for Name Resolution
Service in ICN", draft-irtf-icnrg-nrs-guidelines-02 , July
2019.
[Dannewitz]
Dannewitz, C. et al., "Network of Information (NetInf)-An
information centric networking architecture", Computer
Communications vol. 36, no. 7, April 2013.
[Dannewitz2]
Dannewitz, C., DAmbrosio, M., and V. Vercellone,
"Hierarchical DHT-based name resolution for Information-
Centric Networks", Computer Communications vol. 36, no. 7,
April 2013.
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Authors' Addresses
Jungha Hong
ETRI
218 Gajeong-ro, Yuseung-Gu
Daejeon 34129
Korea
Email: jhong@etri.re.kr
Tae-Wan You
ETRI
218 Gajeong-ro, Yuseung-Gu
Daejeon 34129
Korea
Email: twyou@etri.re.kr
Yong-Geun Hong
ETRI
218 Gajeong-ro, Yuseung-Gu
Daejeon 34129
Korea
Email: yghong@etri.re.kr
Ved Kafle
NICT
4-2-1 Nukui-Kitamachi
Koganei, Tokyo 184-8795
Japan
Email: kafle@nict.go.jp
Bastiaan Wissingh
TNO
Email: bastiaan.wissingh@tno.nl
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