Internet DRAFT - draft-previdi-spring-problem-statement
draft-previdi-spring-problem-statement
Network Working Group S. Previdi, Ed.
Internet-Draft C. Filsfils, Ed.
Intended status: Standards Track Cisco Systems, Inc.
Expires: October 26, 2014 B. Decraene
S. Litkowski
Orange
M. Horneffer
R. Geib
Deutsche Telekom
R. Shakir
British Telecom
R. Raszuk
Individual
April 24, 2014
SPRING Problem Statement and Requirements
draft-previdi-spring-problem-statement-04
Abstract
The ability for a node to specify a forwarding path, other than the
normal shortest path, that a particular packet will traverse,
benefits a number of network functions. Source-based routing
mechanisms have previously been specified for network protocols, but
have not seen widespread adoption. In this context, the term
'source' means 'the point at which the explicit route is imposed'.
This document outlines various use cases, with their requirements,
that need to be taken into account by the Source Packet Routing in
Networking (SPRING) architecture for unicast traffic. Multicast use-
cases and requirements are out of scope of this document.
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 RFC 2119 [RFC2119].
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on October 26, 2014.
Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Dataplanes . . . . . . . . . . . . . . . . . . . . . . . . . 4
3. IGP-based MPLS Tunneling . . . . . . . . . . . . . . . . . . 4
3.1. Example of IGP-based MPLS Tunnels . . . . . . . . . . . . 4
4. Fast Reroute . . . . . . . . . . . . . . . . . . . . . . . . 5
5. Traffic Engineering . . . . . . . . . . . . . . . . . . . . . 5
5.1. Examples of Traffic Engineering Use Cases . . . . . . . . 6
5.1.1. Traffic Engineering without Bandwidth Admission
Control . . . . . . . . . . . . . . . . . . . . . . . 6
5.1.2. Traffic Engineering with Bandwidth Admission Control 10
6. Interoperability with non-SPRING nodes . . . . . . . . . . . 14
7. OAM . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8. Security . . . . . . . . . . . . . . . . . . . . . . . . . . 14
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
10. Manageability Considerations . . . . . . . . . . . . . . . . 15
11. Security Considerations . . . . . . . . . . . . . . . . . . . 15
12. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 15
13. References . . . . . . . . . . . . . . . . . . . . . . . . . 15
13.1. Normative References . . . . . . . . . . . . . . . . . . 15
13.2. Informative References . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
The ability for a node to specify a unicast forwarding path, other
than the normal shortest path, that a particular packet will
traverse, benefits a number of network functions, for example:
Some types of network virtualization, including multi-topology
networks and the partitioning of network resources for VPNs
Network, link, path and node protection such as fast re-route
Network programmability
OAM techniques
Simplification and reduction of network signaling components
Load balancing and traffic engineering
Source-based routing mechanisms have previously been specified for
network protocols, but have not seen widespread adoption other than
in MPLS traffic engineering.
These network functions may require greater flexibility and per
packet source imposed routing than can be achieved through the use of
the previously defined methods. In the context of this charter,
'source' means 'the point at which the explicit route is imposed'.
In this context, Source Packet Routing in Networking (SPRING)
architecture is being defined in order to address the use cases and
requirements described in this document.
SPRING architecture should allow incremental and selective deployment
without any requirement of flag day or massive upgrade of all network
elements.
SPRING architecture should allow optimal virtualization: put policy
state in the packet header and not in the intermediate nodes along
the path. Hence, the policy is completely virtualized away from
midpoints and tail-ends.
SPRING architecture objective is not to replace existing source
routing and traffic engineering mechanisms but rather complement them
and address use cases where removal of signaling and path state in
the core is a requirement.
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2. Dataplanes
The SPRING architecture should be general in order to ease its
applicability to different dataplanes.
MPLS dataplane doesn't require any modification in order to apply a
source-based routed model (e.g.:
[I-D.filsfils-spring-segment-routing-mpls]).
IPv6 specification [RFC2460], amended by [RFC6564] and [RFC7045],
defines the Routing Extension Header which provides IPv6 source-based
routing capabilities.
The SPRING architecture should leverage existing MPLS dataplane
without any modification and leverage IPv6 dataplane with a new IPv6
Routing Header Type (IPv6 Routing Header is defined in [RFC2460]).
3. IGP-based MPLS Tunneling
The source-based routing model, applied to the MPLS dataplane, offers
the ability to tunnel services (VPN, VPLS, VPWS) from an ingress PE
to an egress PE, with or without the expression of an explicit path
and without requiring forwarding plane or control plane state in
intermediate nodes.
The source-based routing model, applied to the MPLS dataplane, offers
the ability to tunnel unicast services (VPN, VPLS, VPWS) from an
ingress PE to an egress PE, with or without the expression of an
explicit path and without requiring forwarding plane or control plane
state in intermediate nodes. p2mp and mp2mp tunnels are out of the
scope of this document.
3.1. Example of IGP-based MPLS Tunnels
This section illustrates an example use-case taken from
[I-D.filsfils-spring-segment-routing-use-cases].
P1---P2
/ \
A---CE1---PE1 PE2---CE2---Z
\ /
P3---P4
Figure 1: IGP-based MPLS Tunneling
In Figure 1 above, the four nodes A, CE1, CE2 and Z are part of the
same VPN. CE2 advertises to PE2 a route to Z. PE2 binds a local
label LZ to that route and propagates the route and its label via
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MPBGP to PE1 with nhop 192.168.0.2. PE1 installs the VPN prefix Z in
the appropriate VRF and resolves the next-hop onto the node segment
associated with PE2.
In order to cope with the reality of current deployments, the SPRING
architecture should allow PE to PE forwarding according to the IGP
shortest path without the addition of any other signaling protocol.
The packet each PE forwards across the network will contain (within
their label stack) the necessary information derived from the
topology database in order to deliver the packet to the remote PE.
4. Fast Reroute
FRR technologies have been deployed by network operators in order to
cope with link or node failures through pre-computation of backup
paths.
The SPRING architecture should address following requirements:
o support of FRR on any topology
o pre-computation and setup of backup path without any additional
signaling (other than the regular IGP/BGP protocols)
o support of shared risk constraints
o support of node and link protection
o support of microloop avoidance
Further illustrations of the problem statement for FRR are to be
found in [I-D.francois-spring-resiliency-use-case].
5. Traffic Engineering
Traffic Engineering has been addressed using IGP protocol extensions
(for resources information propagation) and RSVP-TE for signaling
explicit paths. Different contexts and modes have been defined
(single vs. multiple domains, with or without bandwidth admission
control, centralized vs. distributed path computation, etc).
In all cases, one of the major components of the TE architecture is
the soft state based signaling protocol (RSVP-TE) which is used in
order to signal and establish the explicit path. Each path, once
computed, need to be signaled and state for each path must be present
in each node traversed by the path. This incurs a scalability
problem especially in the context of SDN where traffic
differentiation may be done at a finer granularity (e.g.: application
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specific). Also the amount of state needed to be maintained and
periodically refreshed in all involved nodes contributes
significantly to complexity and the number of failures cases, and
thus increases operational effort while decreasing overall network
reliability.
The source-based routing model allows traffic engineering to be
implemented without the need of a signaling component.
The SPRING architecture should support traffic engineering,
including:
o loose or strict options
o bandwidth admission control
o distributed vs. centralized model (PCE, SDN Controller)
o disjointness in dual-plane networks
o egress peering traffic engineering
o load-balancing among non-parallel links
o Limiting (scalable, preferably zero) per-service state and
signaling on midpoint and tail-end routers.
o ECMP-awareness
o node resiliency property (i.e.: the traffic-engineering policy is
not anchored to a specific core node whose failure could impact
the service.
5.1. Examples of Traffic Engineering Use Cases
As documented in [I-D.filsfils-spring-segment-routing-use-cases] here
follows the description of two sets of use cases:
o Traffic Engineering without Admission Control
o Traffic Engineering with Admission Control
5.1.1. Traffic Engineering without Bandwidth Admission Control
In this section, we describe Traffic Engineering use-cases without
bandwidth admission control.
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5.1.1.1. Disjointness in dual-plane networks
Many networks are built according to the dual-plane design, as
illustrated in Figure 2:
Each access region k is connected to the core by two C routers
(C(1,k) and C(2,k)).
C(1,k) is part of plane 1 and aggregation region K
C(2,k) is part of plane 2 and aggregation region K
C(1,k) has a link to C(2, j) iff k = j.
The core nodes of a given region are directly connected.
Inter-region links only connect core nodes of the same plane.
{C(1,k) has a link to C(1, j)} iff {C(2,k) has a link to C(2, j)}.
The distribution of these links depends on the topological
properties of the core of the AS. The design rule presented
above specifies that these links appear in both core planes.
We assume a common design rule found in such deployments: the inter-
plane link costs (Cik-Cjk where i<>j) are set such that the route to
an edge destination from a given plane stays within the plane unless
the plane is partitioned.
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Edge Router A
/ \
/ \
/ \ Agg Region A
/ \
/ \
C1A----------C2A
| \ | \
| \ | \
| C1B----------C2B
Plane1 | | | | Plane2
| | | |
C1C--|-----C2C |
\ | \ |
\ | \ |
C1Z----------C2Z
\ /
\ / Agg Region Z
\ /
\ /
Edge Router Z
Figure 2: Dual-Plane Network and Disjointness
In this scenario, the operator requires the ability to deploy
different strategies. For example, A should be able to use the three
following options:
o the traffic is load-balanced across any ECMP path through the
network
o the traffic is load-balanced across any ECMP path within the
Plane1 of the network
o the traffic is load-balanced across any ECMP path within the
Plane2 of the network
Most of the data traffic from A to Z would use the first option, such
as to exploit the capacity efficiently. The operator would use the
two other choices for specific premium traffic that has requested
disjoint transport.
The SPRING architecture should support this use case with the
following requirements:
o Zero per-service state and signaling on midpoint and tail-end
routers.
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o ECMP-awareness.
o Node resiliency property: the traffic-engineering policy is not
anchored to a specific core node whose failure could impact the
service.
5.1.1.2. Egress Peering Traffic Engineering
+------+
| |
+---D F
+---------+ / | AS 2 |\ +------+
| |/ +------+ \| Z |
A C | |
| |\ +------+ /| AS 4 |
B AS1 | \ | |/ +------+
| | +---E G
+---------+ | AS 3 |
+------+\
Figure 3: Egress peering traffic engineering
Let us assume, in the network depicted in Figure 3, that:
C in AS1 learns about destination Z of AS 4 via two BGP paths
(AS2, AS4) and (AS3, AS4).
C may or may not be configured so to enforce next-hop-self
behavior before propagating the paths within AS1.
C may propagate all the paths to Z within AS1 (add-path).
C may install in its FIB only the route via AS2, or only the route
via AS3, or both.
In that context, SPRING should allow the operator of AS1 to apply the
following traffic-engineering policy, regardless the configured
behavior of next-hop-self:
Steer 60% of the Z-destined traffic received at A via AS2 and 40%
via AS3.
Steer 80% of the Z-destined traffic received at B via AS2 and 20%
via AS3.
While egress routers are known in the routing domain (generally
through their loopback address), the SPRING architecture should
enable following:
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o identify the egress interfaces of an egress node
o identify the peering neighbors of an egress node
o identify the peering ASes of an egress node
With these identifiers known in the domain, the SPRING architecture
should allow an ingress node to select the exit point of a packet as
any combination of an egress node, an egress interface, a peering
neighbor, and a peering AS.
5.1.1.3. Load-balancing among non-parallel links
The SPRING architecture should allow a given node should be able to
load share traffic across multiple non parallel links even if these
ones lead to different neighbors. This may be useful to support
traffic engineering policies.
+---C---D---+
| |
PE1---A---B-----F-----E---PE2
Figure 4: Multiple (non-parallel) Adjacencies
In the above example, the operator requires PE1 to load-balance its
PE2-destined traffic between the ABCDE and ABFE paths.
5.1.2. Traffic Engineering with Bandwidth Admission Control
The implementation of bandwidth admission control within a network
(and its possible routing consequence which consists in routing along
explicit paths where the bandwidth is available) requires a capacity
planning process.
The spreading of load among ECMP paths is a key attribute of the
capacity planning processes applied to packet-based networks.
5.1.2.1. Capacity Planning Process
Capacity Planning anticipates the routing of the traffic matrix onto
the network topology, for a set of expected traffic and topology
variations. The heart of the process consists in simulating the
placement of the traffic along ECMP-aware shortest-paths and
accounting for the resulting bandwidth usage.
The bandwidth accounting of a demand along its shortest-path is a
basic capability of any planning tool or PCE server.
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For example, in the network topology described below, and assuming a
default IGP metric of 1 and IGP metric of 2 for link GF, a 1600Mbps
A-to-Z flow is accounted as consuming 1600Mbps on links AB and FZ,
800Mbps on links BC, BG and GF, and 400Mbps on links CD, DF, CE and
EF.
C-----D
/ \ \
A---B +--E--F--Z
\ /
G------+
Figure 5: Capacity Planning an ECMP-based demand
ECMP is extremely frequent in SP, Enterprise and DC architectures and
it is not rare to see as much as 128 different ECMP paths between a
source and a destination within a single network domain. It is a key
efficiency objective to spread the traffic among as many ECMP paths
as possible.
This is illustrated in the below network diagram which consists of a
subset of a network where already 5 ECMP paths are observed from A to
M.
C
/ \
B-D-L--
/ \ / \
A E \
\ M
\ G /
\ / \ /
F K
\ /
I
Figure 6: ECMP Topology Example
When the capacity planning process detects that a traffic growth
scenario and topology variation would lead to congestion, a capacity
increase is triggered and if it cannot be deployed in due time, a
traffic engineering solution is activated within the network.
A basic traffic engineering objective consists of finding the
smallest set of demands that need to be routed off their shortest
path to eliminate the congestion, then to compute an explicit path
for each of them and instantiating these traffic-engineered policies
in the network.
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SPRING architecture should offer a simple support for ECMP-based
shortest path placement as well as for explicit path policy without
incurring additional signaling in the domain. This includes:
o the ability to steer a packet across a set of ECMP paths
o the ability to diverge from a set of ECMP shortest paths to one or
more paths not in the set of shortest paths
5.1.2.2. SDN/SR use-case
The SDN use-case lies in the SDN controller, (e.g.: Stateful PCE as
described in [I-D.ietf-pce-stateful-pce].
The SDN controller is responsible to control the evolution of the
traffic matrix and topology. It accepts or denies the addition of
new traffic into the network. It decides how to route the accepted
traffic. It monitors the topology and upon topological change,
determines the minimum traffic that should be rerouted on an
alternate path to alleviate a bandwidth congestion issue.
The algorithms supporting this behavior are a local matter of the SDN
controller and are outside the scope of this document.
The means of collecting traffic and topology information are the same
as what would be used with other SDN-based traffic-engineering
solutions (e.g. [RFC7011] and [I-D.ietf-idr-ls-distribution].
The means of instantiating policy information at a traffic-
engineering head-end are the same as what would be used with other
SDN-based traffic-engineering solutions (e.g.:
[I-D.ietf-i2rs-architecture], [I-D.crabbe-pce-pce-initiated-lsp] and
[I-D.sivabalan-pce-segment-routing]).
In the context of Centralized-Based Optimization and the SDN use-
case, here are the benefits that the SPRING architecture should
deliver:
Explicit routing capability with or without ECMP-awareness.
No signaling hop-by-hop through the network.
State is only maintained at the policy head-end. No state is
maintained at mid-points and tail-ends.
Automated guaranteed FRR for any topology.
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Optimum virtualization: the policy state is in the packet header
and not in the intermediate nodes along the path. The policy is
completely virtualized away from midpoints and tail-ends.
Highly responsive to change: the SDN Controller only needs to
apply a policy change at the head-end. No delay is introduced due
to programming the midpoints and tail-end along the path.
5.1.2.2.1. SDN Example
The data-set consists in a full-mesh of 12000 explicitly-routed
tunnels observed on a real network. These tunnels resulted from
distributed headend-based CSPF computation.
We measured that only 65% of the traffic is forwarded over its
shortest path.
Three well-known defects are illustrated in this data set:
The lack of ECMP support in explicitly routed tunnels: ATM-alike
traffic-steering mechanisms steer the traffic along a non-ECMP
path.
The increase of the number of explicitly-routed non-ECMP tunnels
to enumerate all the ECMP options.
The inefficiency of distributed optimization: too much traffic is
forwarded off its shortest path.
We applied the SDN use-case to this dataset implying a source route
model where the path of the packet is encoded within the packet
itself. This means that:
The distributed CSPF computation is replaced by centralized
optimization and BW admission control, supported by the SDN
Controller.
As part of the optimization, we also optimized the IGP-metrics
such as to get a maximum of traffic load-spread among ECMP
paths by default.
The traffic-engineering policies are supported by a source route
model (e.g.: [I-D.filsfils-rtgwg-segment-routing]).
As a result, we measured that 98% of the traffic would be kept on its
normal policy (over the shortest-path) and only 2% of the traffic
requires a path away from the shortest-path.
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Let us highlight a few benefits:
98% of the traffic-engineering head-end policies are eliminated.
Indeed, by default, an ingress edge node capable of injecting
source routed packets steers the traffic to the egress edge
node. No configuration or policy needs to be maintained at the
ingress edge node to realize this.
100% of the states at mid/tail nodes are eliminated.
6. Interoperability with non-SPRING nodes
SPRING must inter-operate with non-SPRING nodes.
An illustration of interoperability between SPRING and other MPLS
Signalling Protocols (LDP) is described here in
[I-D.filsfils-spring-segment-routing-ldp-interop].
Interoperability with IPv6 non-SPRING nodes will be described in a
future document.
7. OAM
The SPRING WG should provide OAM and the management needed to manage
SPRING enabled networks. The SPRING procedures may also be used as a
tool for OAM in SPRING enabled networks.
OAM use cases and requirements are described in
[I-D.geib-spring-oam-usecase] and
[I-D.kumar-spring-sr-oam-requirement].
8. Security
There is an assumed trust model such that any node imposing an
explicit route on a packet is assumed to be allowed to do so. In
such context trust boundaries should strip explicit routes from a
packet.
For each data plane technology that SPRING specifies, a security
analysis must be provided showing how protection is provided against
an attacker disrupting the network by for example, maliciously
injecting SPRING packets.
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9. IANA Considerations
TBD
10. Manageability Considerations
TBD
11. Security Considerations
TBD
12. Acknowledgements
The authors would like to thank Yakov Rekhter for his contribution to
this document.
13. References
13.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, December 1998.
[RFC6564] Krishnan, S., Woodyatt, J., Kline, E., Hoagland, J., and
M. Bhatia, "A Uniform Format for IPv6 Extension Headers",
RFC 6564, April 2012.
[RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of
the IP Flow Information Export (IPFIX) Protocol for the
Exchange of Flow Information", STD 77, RFC 7011, September
2013.
[RFC7045] Carpenter, B. and S. Jiang, "Transmission and Processing
of IPv6 Extension Headers", RFC 7045, December 2013.
13.2. Informative References
[I-D.crabbe-pce-pce-initiated-lsp]
Crabbe, E., Minei, I., Sivabalan, S., and R. Varga, "PCEP
Extensions for PCE-initiated LSP Setup in a Stateful PCE
Model", draft-crabbe-pce-pce-initiated-lsp-03 (work in
progress), October 2013.
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[I-D.filsfils-rtgwg-segment-routing]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
"Segment Routing Architecture", draft-filsfils-rtgwg-
segment-routing-01 (work in progress), October 2013.
[I-D.filsfils-spring-segment-routing-ldp-interop]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
"Segment Routing interoperability with LDP", draft-
filsfils-spring-segment-routing-ldp-interop-01 (work in
progress), April 2014.
[I-D.filsfils-spring-segment-routing-mpls]
Filsfils, C., Previdi, S., Bashandy, A., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., and E. Crabbe,
"Segment Routing with MPLS data plane", draft-filsfils-
spring-segment-routing-mpls-01 (work in progress), April
2014.
[I-D.filsfils-spring-segment-routing-use-cases]
Filsfils, C., Francois, P., Previdi, S., Decraene, B.,
Litkowski, S., Horneffer, M., Milojevic, I., Shakir, R.,
Ytti, S., Henderickx, W., Tantsura, J., Kini, S., and E.
Crabbe, "Segment Routing Use Cases", draft-filsfils-
spring-segment-routing-use-cases-00 (work in progress),
March 2014.
[I-D.francois-spring-resiliency-use-case]
Francois, P., Filsfils, C., Decraene, B., and R. Shakir,
"Use-cases for Resiliency in SPRING", draft-francois-
spring-resiliency-use-case-02 (work in progress), April
2014.
[I-D.geib-spring-oam-usecase]
Geib, R. and C. Filsfils, "Use case for a scalable and
topology aware MPLS data plane monitoring system", draft-
geib-spring-oam-usecase-01 (work in progress), February
2014.
[I-D.ietf-i2rs-architecture]
Atlas, A., Halpern, J., Hares, S., Ward, D., and T.
Nadeau, "An Architecture for the Interface to the Routing
System", draft-ietf-i2rs-architecture-02 (work in
progress), February 2014.
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[I-D.ietf-idr-ls-distribution]
Gredler, H., Medved, J., Previdi, S., Farrel, A., and S.
Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", draft-ietf-idr-ls-distribution-04
(work in progress), November 2013.
[I-D.ietf-pce-stateful-pce]
Crabbe, E., Medved, J., Minei, I., and R. Varga, "PCEP
Extensions for Stateful PCE", draft-ietf-pce-stateful-
pce-08 (work in progress), February 2014.
[I-D.kumar-spring-sr-oam-requirement]
Kumar, N., Pignataro, C., Akiya, N., Geib, R., and G.
Mirsky, "OAM Requirements for Segment Routing Network",
draft-kumar-spring-sr-oam-requirement-00 (work in
progress), February 2014.
[I-D.sivabalan-pce-segment-routing]
Sivabalan, S., Medved, J., Filsfils, C., Crabbe, E., and
R. Raszuk, "PCEP Extensions for Segment Routing", draft-
sivabalan-pce-segment-routing-02 (work in progress),
October 2013.
Authors' Addresses
Stefano Previdi (editor)
Cisco Systems, Inc.
Via Del Serafico, 200
Rome 00142
Italy
Email: sprevidi@cisco.com
Clarence Filsfils (editor)
Cisco Systems, Inc.
Brussels
BE
Email: cfilsfil@cisco.com
Bruno Decraene
Orange
FR
Email: bruno.decraene@orange.com
Previdi, et al. Expires October 26, 2014 [Page 17]
Internet-Draft SPRING Problem Statement April 2014
Stephane Litkowski
Orange
FR
Email: stephane.litkowski@orange.com
Martin Horneffer
Deutsche Telekom
Hammer Str. 216-226
Muenster 48153
DE
Email: Martin.Horneffer@telekom.de
Ruediger Geib
Deutsche Telekom
Heinrich Hertz Str. 3-7
Darmstadt 64295
DE
Email: Ruediger.Geib@telekom.de
Rob Shakir
British Telecom
London
UK
Email: rob.shakir@bt.com
Robert Raszuk
Individual
Email: robert@raszuk.net
Previdi, et al. Expires October 26, 2014 [Page 18]
