MAP-Me : Managing Anchorless Mobility in Content Centric Networking
draft-irtf-icnrg-mapme-01
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draft-irtf-icnrg-mapme-01
icnrg J. Auge
Internet-Draft G. Carofiglio
Intended status: Informational L. Muscariello
Expires: January 3, 2019 M. Papalini
Cisco Systems Inc.
July 02, 2018
MAP-Me : Managing Anchorless Mobility in Content Centric Networking
draft-irtf-icnrg-mapme-01
Abstract
Consumer mobility is supported in ICN by design, in virtue of its
connectionless pull-based communication model; producer mobility
through is not natively supported. This document describes MAP-Me,
an anchor-less solution to manage micro-mobility of content producers
in the CCN (Content Centric Networking) and NDN (Named Data
Networking) architectures, with support for latency-sensitive
applications. MAP-Me consists in the combination of two data plane
protocols, triggered by the producer movements, and leveraging ICN
named-based data plane. The main protocol consists in a lightweight
FIB update process, complemented by a mechanism of local notification
and scoped discovery suitable for low latency applications and fast
mobility.
Status of This Memo
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Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. MAP-Me overview . . . . . . . . . . . . . . . . . . . . . . . 4
2.1. Anchor-less mobility management . . . . . . . . . . . . . 4
2.2. Design principles . . . . . . . . . . . . . . . . . . . . 4
2.3. MAP-Me protocols . . . . . . . . . . . . . . . . . . . . 5
3. Update protocol . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Rationale . . . . . . . . . . . . . . . . . . . . . . . . 6
3.2. Update propagation . . . . . . . . . . . . . . . . . . . 6
3.3. Concurrent updates . . . . . . . . . . . . . . . . . . . 10
4. Notification protocol and scoped discovery . . . . . . . . . 11
4.1. Interest Notification . . . . . . . . . . . . . . . . . . 12
4.2. Scoped discovery . . . . . . . . . . . . . . . . . . . . 12
4.3. Full approach . . . . . . . . . . . . . . . . . . . . . . 13
5. Implementation . . . . . . . . . . . . . . . . . . . . . . . 13
5.1. MAP-Me messages . . . . . . . . . . . . . . . . . . . . . 13
5.2. Data structures and temporary state . . . . . . . . . . . 14
5.3. Algorithm description . . . . . . . . . . . . . . . . . . 14
5.3.1. Producer attachment and face creation . . . . . . . . 14
5.3.2. IU/IN transmission at producer . . . . . . . . . . . 14
5.3.3. IU/IN transmission at network routers . . . . . . . . 15
5.3.4. Consumer request forwarding in case of producer
discovery . . . . . . . . . . . . . . . . . . . . . . 16
5.3.5. Producer departure and face destruction . . . . . . . 18
6. Security considerations . . . . . . . . . . . . . . . . . . . 18
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 18
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 18
9.1. Normative References . . . . . . . . . . . . . . . . . . 18
9.2. Informative References . . . . . . . . . . . . . . . . . 18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 20
1. Introduction
With the phenomenal spread of portable user devices, mobility has
become a basic requirement for almost any communication network as
well as a compelling feature to integrate in the next generation
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networks (5G). The need for a mobility-management paradigm to apply
within IP networks has striven a lot of efforts in research and
standardization bodies (IETF, 3GPP among others), all resulting in a
complex access-dependent set of mechanisms implemented via a
dedicated control infrastructure. The complexity and lack of
flexibility of such approaches (e.g. Mobile IP) calls for a
radically new solution dismantling traditional assumptions like
tunneling and anchoring of all mobile communications into the network
core. This is particularly important with the increase in rates and
mobile nodes (IoT), a vast amount of which never moves.
The Information Centric Network (ICN) paradigm brings native support
for mobility, security, and storage within the network architecture,
hence emerging as a promising 5G technology candidate. Specifically
on mobility management, ICN has the potential to relieve limitations
of the existing approaches by leveraging its primary feature, the
redefinition of packet forwarding based on "names" rather than
"network addresses". Removing the dependence on location identifiers
is a first step in the direction of removing the need for any
anchoring of communications into fixed network nodes, which may
considerably simplify and improve mobility management. Within the
ICN paradigm, several architectures have been proposed, as reported
in [SURVEY12] and [SURVEY14].
As a direct result of CCN/NDN design principles, consumer mobility is
natively supported: a change in physical location for the consumer
does not translate into a change in the data plane like for IP. The
retransmission of requests for data not yet received by the consumer
takes place without involving any signaling to the network. Producer
mobility and realtime group communications present more challenges,
depending on the frequency of movements, latency requirements, and
content lifetime. The topology does not reflect the naming
structure, and the mobility management process has to preserve key
functionalities such as multipath, caching, etc. In all cases,
beyond providing connectivity guarantees, additional transport-level
mechanisms might be required to protect the flow performance (see
[WLDR] for instance).
MAP-Me aims at tackling such problems by exploiting key CCN/NDN
characteristics. Previous attempts have been made in CCN/NDN (and
ICN in general) literature to go beyond the traditional IP
approaches, by using the existing CCN/NDN request/data packet
structures to trace producer movements and to dynamically build a
reverse-forwarding path (see [SURVEY16b] for a survey). They still
rely on a stable home address to inform about producer movements or
on buffering of incoming requests at the producer's previous point of
attachment (PoA), which prevents support for latency-sensitive
streaming applications. The approach presented in this document
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focuses on this class of applications (e.g. live streaming or
videoconferencing) as they have the most stringent performance
requirements: negligible per-packet loss-rate and delays. In
addition, they typically originate from a single producer and don't
allow for the use of caching.
MAP-Me defines a name-based mechanism operating in the forwarding
plane and completely removing any anchoring, while aiming at latency
minimization. Its performance and guarantees of correctness,
stability and bounded stretch are analyzed in [MAPME].
2. MAP-Me overview
2.1. Anchor-less mobility management
Many efforts have been made to define mobility-management models for
IP networks in the last two decades, resulting in a variety of
complex, often not implemented, proposals. A survey of these
approaches is proposed in [RFC6301]. Likewise, within ICN, different
approaches to mobility management have been presented [SURVEY13].
Specifically for the CCN/NDN solutions, several surveys of mobility-
management approaches can be found [SURVEY16a] [SURVEY16b].
We follow here the classification presented in [MAPME] which
highlights their reliance on indirection/rendez-vous points. In
particular, a new class of anchor-less approaches is introduced, in
which the present proposal fits. Such solutions are less common and
have been introduced in ICN to remove the need for anchor points in
the data plane, but also in the control plane in the form of
resolution or mapping services. These solutions completely remove
the use of locators and extend the ICN forwarding mechanisms with
mobility support.
2.2. Design principles
o *Micro-Mobility* : MAP-Me addresses micro (e.g. intra Autonomous
Systems) producer mobility. Addressing macro-mobility is a non-
goal of the proposal. We are focusing here on complementary
mechanisms able to provide a fast and lightweight handover,
preserving the performance of flows in progress.
* *Control Plane Agnostic* : MAP-Me _is control-plane agnostic as
does not rely on routing updates or path computation_, which
would be too slow and too costly, but rather works at a faster
timescale propagating forwarding updates on a single path and
leveraging real-time notifications left as breadcrumbs by the
producer, to enable live tracking of its content prefixes and
avoid buffering at intermediate nodes. MAP-Me shares the use
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of data plane mechanisms for ensuring connectivity with
[DATAPLANE] which was originally proposed for link failures.
This enables the support of high-speed mobility and real-time
group applications. In addition, MAP-Me mobility updates are
issued at prefix granularity, rather than content or chunk/
packet granularity, to minimize signaling overhead and
temporary state kept by in-network nodes, and scale to large
and dynamic mobile networks.
o *Access-agnostic* : MAP-Me handles mobility at Layer 3 and is
designed to be access-agnostic, to cope with highly heterogeneous
wireless access and multi-homed/mobile users.
o *Decentralized and localized* : MAP-Me is designed to be fully
_decentralized_, to enhance robustness w.r.t. centralized mobility
management proposals subject to single point-of-passage problem.
MAP-Me updates are _localized_ and affect the minimum number of
routers at the edge of the network to restore connectivity. This
effectively realizes traffic off-load close to the end-users.
o *Transparent* : MAP-Me does not involve any name nor modifications
to basic request/reply operations to be compatible with standard
CCN/NDN design and to avoid issues caused by name modifications
like triangular routing, caching degradation, or security
vulnerabilities. It does not require consumers or producer to be
aware of the mobility of the remote endpoint, nor producers to
perform handover prediction.
o *Robust* : to network conditions (e.g. routing failure, wireless
or congestion losses, and delays), by leveraging hop-by-hop
retransmissions of mobility updates.
2.3. MAP-Me protocols
As a data plane protocol, MAP-Me handles producer mobility events by
means of dynamic FIB updates with the objective of minimizing
unreachability of the producer. It relies on the existence of a
routing protocol responsible for creating/updating the FIB of all
routers, possibly with multipath routes, and for managing network
failures [NLSR].
MAP-Me is composed of:
o an Update protocol, detailed in Section 3, which is the central
component of our proposal;
o a Notification/Discovery protocol, presented in Section 4, to be
coupled with the Update protocol to enhance reactivity in mobility
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management for realtime/latency-sensitive application, and lower
overhead during fast mobility events.
3. Update protocol
3.1. Rationale
The rationale behind MAP-Me is that the producer announces its
movements to the network by sending a special Interest Packet, named
Interest Update (IU) to "itself" after it reattaches to the network.
Such a message looks like a regular Interest packet named with the
prefix advertised by the producer. As such, it is forwarded
according to the information stored in the FIBs of traversed routers
towards previous locations of the producer known by router FIBs. A
special flag carried in the header of the IU enables all routers on
the path to identify the Interest as a mobility update and to process
it accordingly to update their FIBs (a detailed description of the IU
processing is provided in Section 5.3.
The key aspect of the proposal is that it removes the need for a
stable home address by directly leveraging name-based forwarding
state created by CCN/NDN routing protocols or left by previous
mobility updates. FIB updates are triggered by the reception of
mobility updates in a fully decentralized way and allow a
modification on-the-fly to point to the latest known location of the
producer.
3.2. Update propagation
The role of the update process is to quickly restore global
reachability of mobile prefixes with low signaling overhead, while
introducing a bounded maximum path stretch (i.e. ratio between the
selected and the shortest path in terms of hops).
Let us illustrate its behavior through an example where a single
producer serving prefix /p moves from position P0 to P1 and so on.
Figure 1 (a) shows the tree formed by the forwarding paths to the
name prefix /p where IU initiated by the producer propagates.
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+---+ +---+
| 0 | P0 | 0 | P0
+---+ +---+
^ ^ ^ ^
/ \ / \
+---+ +---+ +---+ +---+
| 0 | | 0 | | 0 | | 0 |
+---+ +---+ +---+ +---+
^ ^ ^ ^
/ \ / \
+---+ +---+ +---+ +---+
| 0 | | 0 | | 0 | | 0 |
+---+ +---+ A +---+ +---+
^ ^ IU1 / ^ ^
/ \ / / \
+---+ +---+ .... .+---+. +---+
| 0 | | 0 | . P1 | 1 | . | 0 |
+---+ +---+ . +---+ . +---+
^ ^ . ^ ^ .
/ \ . / \ .
+---+ +---+ . +---+ +---+ .
| 0 | | 0 | . | 0 | | 0 | .
+---+ +---+ . +---+ +---+ .
..................
(a) (b)
Figure 1: IU propagation example
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.................
+---+ ... +---+ ..
| 0 | P0 . | 1 | P0 .
+---+ . A +---+ .
^ ^ . IU(1) / / ^ .
/ \ . / V \ .
+---+ +---+ . +---+ +---+ .
| 0 | | 0 | . | 1 | | 0 | .
+---+ +---+ . A +---+ +---+ .
^ ^ . IU(1) / / ^ .
/ \ . / V \ .
........+---+. +---+ . +---+ +---+ .
. | 1 | . | 0 | . | 1 | | 0 | .
. FIB +---+ . +---+ . A +---+ +---+ .
. updated / ^ . . IU(1) / / ^ .
. V \ .... . / V \ .
. +---+ +---+ . . +---+ +---+ .
. P1 | 1 | | 0 | . . P1 | 1 | | 0 | .
. +---+ +---+ . . +---+ +---+ .
. ^ ^ . . ^ ^ .
. / \ . . / \ .
. +---+ +---+ . . +---+ +---+ .
. | 0 | | 0 | . . | 0 | | 0 | .
. +---+ +---+ . . +---+ +---+ .
.................. ..................
(a) (b)
Figure 2: IU propagation example
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+---+
| 1 | P1
+---+
^ A ^
/ | \
+---+ +---+ +---+
| 0 | | 0 | | 1 |
+---+ +---+ +---+
^ ^
/ \
+---+ +---+
| 0 | | 1 |
+---+ +---+
^ ^
/ \
+---+ +---+
P0 | 1 | | 0 |
+---+ +---+
^
/
+---+
| 0 |
+---+
Figure 3: IU propagation example
Network FIBs are assumed to be populated with routes toward P0 by a
name-based routing protocol. After the relocation of the producer
from P0 to P1, once the layer-2 attachment is completed, the producer
issues an IU carrying the prefix /p and this is forwarded by the
network toward P0 (in general, toward one of its previous locations
according to the FIB state of the traversed routers).
Figure 1 (b) shows the propagation of the IU. As the IU progresses,
FIBs at intermediate hops are updated with the ingress face of the IU
(Figure 2 (a) and (b)). IU propagation stops when the IU reaches P0
and there is no next hop to forward it. The result is that the
original tree rooted in P0 becomes re-rooted in P1 (Figure 3).
Looking at the different connected regions (represented with dotted
lines), we see that IU propagation and consequent FIB updates have
the effect of extending the newly connected subtree : at every step,
an additional router and its predecessors are included in the
connected subtree. The properties of the update propagation process
in terms of bounded length and stretch are studied in [MAPME].
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3.3. Concurrent updates
Frequent mobility of the producer may lead to the propagation of
concurrent updates. To prevent inconsistencies in FIB updates, MAP-
Me maintains a sequence number at the producer end that increases at
each handover and identifies every IU packet. Network routers also
keep track of such sequence number in FIB to verify IU freshness.
The modification of FIB entries is only triggered when the received
IU carries a higher sequence number than the one locally stored,
while the reception of a less recent update determines a propagation
of a more recent update through the not-yet-updated path.
An example of reconciliation of concurrent updates is illustrated in
Figure 4 (a), when the producer has moved successively to P1 and then
to P2 before the first update is completed.
+---+ +---+
| 0 | P0 | 2 | P0
+---+ A +---+
^ ^ IU(2) / / ^
/ \ / V \
+---+ +---+ +---+ +---+
| 0 | | 0 | <!> | 2 | | 0 |
+---+ A +---+ A +---+ A +---+
^ ^ \ IU(1) / ^ \ \
/ \ \ IU(2) / / V \ IU(2)
+---+ +---+ +---+ +---+
| 0 | | 2 | P2 | 1 | | 2 |
A +---+ +---+ A +---+ +---+
IU(1) / ^ ^ IU1 / / ^
/ / \ / V \
+---+ +---+ +---+ +---+
P1 | 1 | | 0 | P1 | 1 | | 0 |
+---+ +---+ +---+ +---+
^ ^ ^ ^
/ \ / \
+---+ +---+ +---+ +---+
| 0 | | 0 | | 0 | | 0 |
+---+ +---+ +---+ +---+
(a) (b)
Figure 4
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+---+ +---+
| 2 | P0 | 2 | P2
+---+ +---+
/ ^ ^
V \ |
+---+ +---+ +---+
<!> | 2 | | 2 | | 2 |
IU(2) / +---+ +---+ +---+
/ ^ \ ^ ^
V / V / \
+---+ +---+ +---+ +---+
| 2 | | 2 | P2 P0 | 2 | | 2 |
IU(2) / +---+ +---+ +---+ +---+
/ / ^ ^ ^ ^
V V \ / P1 / \
+---+ +---+ +---+ +---+ +---+
P1 | 1 | | 0 | | 0 | | 2 | | 0 |
+---+ +---+ +---+ +---+ +---+
^ ^ ^ ^
/ \ / \
+---+ +---+ +---+ +---+
| 0 | | 0 | | 0 | | 0 |
+---+ +---+ +---+ +---+
(a) (b)
Figure 5
Both updates propagate concurrently until the update with sequence
number 1 (IU(1)) crosses a router that has been updated with fresher
information - that has received IU with higher sequence number
(IU(2)) as in Figure 4 (b). In this case, the router stops the
propagation of IU(1) and sends back along its path a new IU with an
updated sequence number (Figure 5 (a)). The update proceeds until
ultimately the whole network has converged towards P2 (Figure 5 (b)).
MAP-Me protocol reacts at a faster timescale than routing - allowing
more frequent and numerous mobility events - and over a localized
portion of the network edge between current and previous producer
locations. This allows to minimize disconnectivity time and reduce
link load, which are the main factors affecting user flow
performance, as show in [MAPME] evaluations.
4. Notification protocol and scoped discovery
IU propagation in the data plane accelerates forwarding state re-
convergence w.r.t. routing or resolution-based approaches operating
at control plane, and w.r.t. anchor-based approaches requiring
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traffic tunneling through an anchor. Still, network latency makes IU
completion not instantaneous and before an update completes, it may
happen that a portion of the traffic is forwarded to the previous PoA
and dropped because of the absence of a valid output face leading to
the producer.
Previous work in the Anchor-Less category has suggested the buffering
of Interests at previous producer location to prevent such losses by
increasing network reactivity. However, such a solution is not
suitable for applications with stringent latency requirements (e.g.
real-time) and may be incompatible with IU completion times.
Moreover, the negative effects on latency performance might be
further exacerbated by IU losses and consequent retransmissions in
case of wireless medium. To alleviate such issues, we introduce two
enhancements to the previously described behavior, namely (i) an
"Interest Notification" mechanism for frequent, yet lightweight,
signaling of producer movements to the network and (ii) a scoped
"Producer Discovery" mechanism for consumer requests to proactively
search for the producer's recently visited locations.
4.1. Interest Notification
An Interest Notification (IN) is a breadcrumb left by producers at
every encountered PoA. It looks like a normal Interest packet
carrying a special identification flag and a sequence number, like
IUs. Both IU and IN share the same sequence number (producers
indistinctly increase it for every sent message) and follow the same
FIB lookup and update processes. However, unlike IU packets, the
trace left by INs at the first hop router does not propagate further.
It is rather used by the discovery process to route consumer requests
to the producer even before an update process is completed.
It is worth observing that updates and notifications serve the same
purpose of informing the network of a producer movement. The IU
process restores connectivity and as such has higher latency/
signaling cost than the IN process, due to message propagation. The
IN process provides information to track producer movements before
update completion when coupled with a scoped discovery. The
combination of both IU and IN allows to control the trade-off between
protocol reactivity and stability of forwarding re-convergence.
4.2. Scoped discovery
The extension of MAP-Me with notifications relies on a local
discovery phase: when a consumer Interest reaches a PoA with no valid
output face in the corresponding entry, the Interest is tagged with a
"discovery" flag and labeled with the latest sequence number stored
in FIB (to avoid loops). From that point on, it is broadcasted with
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hop limit equal to one to all neighbors and discarded unless it finds
the breadcrumbs left by the producer to track him (notifications).
The notifications can either allow to forward consumer Interests
directly to the producer or give rise to a repeated broadcast in case
of no valid output face. The latter is the case of a breadcrumb left
by the producer with no associated forwarding information because the
producer has already left that PoA as well. A detailed description
of the process is reported in Section 5.3.
The notification/discovery mechanism proves important to preserve the
performance of flows in progress, especially when latency-sensitive.
4.3. Full approach
The full MAP-Me approach consists in the combination of Updates and
Notifications through a heuristic allowing the producer or its PoA to
select which type of packet to send. One such heuristic consist in
sending a IN immediately after an attachment and a IU at most every
Tu seconds, which allows to reduce signaling overhead during periods
of high-mobility. The Tu parameter allows to tune the timescale at
which Updates occur, and leads to a trade-off between signaling and
discovery overhead [MAPME]. The definition of more advanced
heuristics is out of scope for the present draft.
5. Implementation
In this section we describe the changes to a regular CCN/NDN
architecture required to implement MAP-ME and detail the above-
described algorithms. This requires to specify a special Interest
message, additional temporary information associated to the FIB entry
and additional operations to update such entry.
5.1. MAP-Me messages
MAP-Me signaling messages are carried within user plane as special
Interest messages corresponding to "update" and "notification", and
their corresponding acknowledgements.
Two new optional fields are introduced in a CCN/NDN Interest header:
o an "Interest Type" (T) used to specify one of the four types of
messages: Interest Update (IU), Interest Notification (IN), and as
well as their associated acknowledgment (Ack) messages (IU_Ack and
IN_Ack). Those flags are recognized by the forwarding pipeline to
trigger special treatment;
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o a "sequence number" to handle concurrent updates and prevent
forwarding loops during signaling, and to control discovery
Interests' propagation;
5.2. Data structures and temporary state
FIB entries are augmented with information required for mobility
management:
o a "sequence number" which is incremented upon reception of IU/IN
messages. It can be assumed this counter is set to 0 by the
routing protocol.
o a buffer storing data about not-yet-acknowledged messages for
ensuring reliability of the update process, which we refer to as
"Temporary FIB buffer", or "TFIB". As sketched in Figure 6, each
TFIB entry is composed of an associative array (F -> T) mapping a
face F on which IU has been sent with the associated
retransmission timer T (possibly Null). TFIB entries are removed
upon reception of the corresponding acknowledgement.
IU (IN) input face(s) IU (IN) output face
+-----------+-------------------+.......+.......................+
| /prefix | { next hop(s) } | seq | { face : rx_timer } |
+-----------+-------------------+.......+.......................+
\_____________ _______________/ \______________ ______________/
V V
original FIB TFIB section
Figure 6: MAP-Me FIB/TFIB description
5.3. Algorithm description
5.3.1. Producer attachment and face creation
MAP-Me operations are triggered by producer mobility/handover events.
At the producer end, a mobility event is followed by a layer-2
attachment and, at network layer, a change in the FIB. More
precisely, a new face is created and activated upon attachment to a
new PoA.
5.3.2. IU/IN transmission at producer
The creation of a new face on the producer triggers the increase of
MAP-Me sequence number and the transmission of an IU or IN for every
served prefix carrying the updated sequence number.
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To ensure reliable delivery of IUs, a timer is setup in the temporary
section of the FIB entry (TFIB). If an acknowledgement of the IU/IN
reception is not received within t seconds since the packet
transmission, IU is retransmitted.
We define the following function for sending Special Interests of a
given type on faces F based on FIB entry E.
SendReliably(F, type, E)
It schedules their retransmission through a timer T stored in TFIB,
and removed upon reception of the corresponding Ack.
E.TFIB = E.TFIB U (F -> T)
5.3.3. IU/IN transmission at network routers
At the reception of IU/IN packets, each router performs a name-based
Longest Prefix Match lookup in FIB to compare sequence number from
IU/IN and from FIB. According to that comparison:
o if the IU/IN packet carries a higher sequence number, the existing
next hops associated to the lower sequence number in FIB are used
to forward further the IU (INs are not propagated) and temporarily
copied into TFIB to avoid loss of such information before
completion of the IU/IN acknowledgement process (in case of IN,
such entries in TFIB are set with a Null timer to maintain a trace
of the producer recent attachment). Also, the originating face of
the IU/IN is added to FIB to route consumer requests to the latest
known location of the producer.
o If the IU/IN packet carries the same sequence number as in the
FIB, the originating face of the IU/IN is added to the existing
ones in FIB without additional packet processing or propagation.
This may occur in presence of multiple forwarding paths.
o If the IU/IN packet carries a lower sequence number than the one
in the FIB, FIB entry is not updated as it already stores 'fresher
information'. To advertise the latest update through the path
followed by the IU/IN packet, this one is re-sent through the
originating face after having updated its sequence number with the
value stored in FIB.
The operations in the forwarding pipeline for IU/IN processing are
reported in Figure 7.
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| Algorithm 1:ForwardSpecialInterest(SpecialInterest SI,IngressFace F)
|
| CheckValidity()
| // Retrieve the FIB entry associated to the prefix
| e, T <- FIB.LongestPrefixMatch(SI.name)
| if SI.seq >= e.seq then
| . // Acknowledge reception
| . s <- e.seq
| . e.seq <- SI.seq
| . SendReliably(F, SI.type + Ack, e)
| . //Process special interest
| . if F in e.TFIB then
| . . // Remove outdated TFIB entry (eventually cancelling timer)
| . . e.TFIB = e.TFIB \ F
| . if SI.seq > s then
| . . if SI.type == IU then
| . . . // Forward the IU following the FIB entry
| . . . SendReliably(e.NextHops, SI.type, e
| . . else
| . . . // Create breadcrumb and preserve forwarding structure
| . . . e.TFIB = e.TFIB U {(f -> NULL):for all f in e.NextHops}
| . . e.NextHops = {}
| . e.NextHops = e.NextHops U { F }
| else
| . // Send updated IU backwards
| . SI.seq = e.seq
| . SendReliably(F, SI.type, e)
Figure 7
5.3.4. Consumer request forwarding in case of producer discovery
The forwarding of regular Interests is mostly unaffected in MAP-Me,
except in the case of discovery Interests that we detail in Figure 8.
The function SendToNeighbors(I) is responsible for broadcasting the
Interest I to all neighboring PoAs.
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| Algorithm 2: InterestForward(Interest I, Origin face F)
|
| // Regular PIT and CS lookup
| e <- FIB.LongestPrefixMatch(I.name)
| if e = 0 then
| . return
| if I.seq = 0 then
| . // Regular interest
| . if hasValidFace(e.NextHops) or DiscoveryDisabled then
| . . ForwardingStrategy.process(I, e)
| . else
| . . // Enter discovery mode
| . . I.seq <- e.seq
| . . SendToNeighbors(I)
| else
| . // Discovery interest: forward if producer is connnected
| . if hasProducerFace(e.NextHops) then
| . . ForwardingStrategy.process(I, e)
| . // Otherwise iterate iif higher seq and breadcrumb
| . else if e.seq >= I.seq and EXISTS f |(f -> NULL) in e.TFIB then
| . . I.seq <- e.seq
| . . SendToNeighbors(I)
Figure 8
When an Interest arrives to a PoA which has no valid next hop for it
(because the producer left and the face got destroyed), it enters a
discovery phase where the Interest is flagged as a Discovery Interest
and with the local sequence number, then broadcasted to neighboring
PoAs.
Upon reception of a Discovery Interest, the PoA forwards it directly
to the producer if still attached, otherwise it repeats the one-hop
brodcast discovery to neighboring PoAs if it stores a recent
notification of the producer presence, i.e. an entry in TFIB having
higher sequence number than the one in the Discovery Interest.
Otherwise, the Discovery Interest is discarded.
It is worth observing that the discovery process is initiated only in
the case of no valid next hop, and not every time a notification is
found in a router. This is important to guarantee that the
notification/discovery process does not affect IU propagation and
completion.
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5.3.5. Producer departure and face destruction
Upon producer departures from a PoA, the corresponding face is
destroyed. If this leads to the removal of the last next hop, then
faces in TFIB with Null timer (entries generated by notifications)
are restored in FIB to preserve the original forwarding tree and thus
global connectivity.
6. Security considerations
All mobility management protocols share the same critical need for
securing their control messages which have a direct impact on the
forwarding of users' traffic. [SEC] reviews standard approaches from
the literature and proposes a fast, lightweight and decentralized
approach based on hash chains that can be applied to MAP-Me and fits
its design principles.
7. Acknowledgements
The authors would like to thank Giulio Grassi (UPMC/UCLA), Giovanni
Pau (UPMC/UCLA) and Xuan Zeng (Cisco Systems) for their contribution
to the work that has led to this document.
8. IANA Considerations
This memo includes no request to IANA.
9. References
9.1. Normative References
[RFC6301] Zhu, Z., Wakikawa, R., and L. Zhang, "A Survey of Mobility
Support in the Internet", RFC 6301, DOI 10.17487/RFC6301,
July 2011, <https://www.rfc-editor.org/info/rfc6301>.
9.2. Informative References
[DATAPLANE]
J, ., A, ., A, ., B, ., M, ., and . S, "Ensuring
connectivity via data plane mechanisms.", 2013.
[KITE] Zhang, Y., Zhang, H., and L. Zhang, "Kite", Proceedings of
the 1st international conference on Information-centric
networking - INC '14, DOI 10.1145/2660129.2660159, 2014.
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[MAPME] Auge, J., Carofiglio, G., Grassi, G., Muscariello, L.,
Pau, G., and X. Zeng, "MAP-Me: Managing Anchor-Less
Producer Mobility in Content-Centric Networks", IEEE
Transactions on Network and Service Management Vol. 15,
pp. 596-610, DOI 10.1109/tnsm.2018.2796720, June 2018.
[NLSR] Hoque, A., Amin, S., Alyyan, A., Zhang, B., Zhang, L., and
L. Wang, "NISR", Proceedings of the 3rd ACM SIGCOMM
workshop on Information-centric networking - ICN '13,
DOI 10.1145/2491224.2491231, 2013.
[SEC] Compagno, A., Zeng, X., Muscariello, L., Carofiglio, G.,
and J. Auge, "Secure producer mobility in information-
centric network", Proceedings of the 4th ACM Conference on
Information-Centric Networking - ICN '17,
DOI 10.1145/3125719.3125725, 2017.
[SURVEY12]
Ahlgren, B., Dannewitz, C., Imbrenda, C., Kutscher, D.,
and B. Ohlman, "A survey of information-centric
networking", IEEE Communications Magazine Vol. 50, pp.
26-36, DOI 10.1109/mcom.2012.6231276, July 2012.
[SURVEY13]
Tyson, G., Sastry, N., Rimac, I., Cuevas, R., and A.
Mauthe, "A survey of mobility in information-centric
networks", Proceedings of the 1st ACM workshop on Emerging
Name-Oriented Mobile Networking Design - Architecture,
Algorithms, and Applications - NoM '12,
DOI 10.1145/2248361.2248363, 2012.
[SURVEY14]
Xylomenos, G., Ververidis, C., Siris, V., Fotiou, N.,
Tsilopoulos, C., Vasilakos, X., Katsaros, K., and G.
Polyzos, "A Survey of Information-Centric Networking
Research", IEEE Communications Surveys & Tutorials Vol.
16, pp. 1024-1049, DOI 10.1109/surv.2013.070813.00063,
2014.
[SURVEY16a]
Feng, B., Zhou, H., and Q. Xu, "Mobility support in Named
Data Networking: a survey", EURASIP Journal on Wireless
Communications and Networking Vol. 2016,
DOI 10.1186/s13638-016-0715-0, September 2016.
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[SURVEY16b]
Zhang, Y., Afanasyev, A., Burke, J., and L. Zhang, "A
survey of mobility support in Named Data Networking", 2016
IEEE Conference on Computer Communications Workshops
(INFOCOM WKSHPS), DOI 10.1109/infcomw.2016.7562050, April
2016.
[WLDR] Carofiglio, G., Muscariello, L., Papalini, M., Rozhnova,
N., and X. Zeng, "Leveraging ICN In-network Control for
Loss Detection and Recovery in Wireless Mobile networks",
Proceedings of the 2016 conference on 3rd ACM Conference
on Information-Centric Networking - ACM-ICN '16,
DOI 10.1145/2984356.2984361, 2016.
Authors' Addresses
Jordan Auge
Cisco Systems Inc.
Email: augjorda@cisco.com
Giovanna Carofiglio
Cisco Systems Inc.
Email: gcarofig@cisco.com
Luca Muscariello
Cisco Systems Inc.
Email: lumuscar@cisco.com
Michele Papalini
Cisco Systems Inc.
Email: micpapal@cisco.com
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