DetNet Working Group G. Mirsky
Internet-Draft Ericsson
Intended status: Standards Track M. Chen
Expires: 13 June 2022 Huawei
B. Varga
J. Farkas
Ericsson
10 December 2021
Operations, Administration and Maintenance (OAM) for Deterministic
Networks (DetNet) with MPLS Data Plane
draft-ietf-detnet-mpls-oam-06
Abstract
This document defines format and use principals of the Deterministic
Network (DetNet) service Associated Channel (ACH) over a DetNet
network with the MPLS data plane. The DetNet service ACH can be used
to carry test packets of active Operations, Administration, and
Maintenance protocols that are used to detect DetNet failures and
measure performance metrics.
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 https://datatracker.ietf.org/drafts/current/.
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 13 June 2022.
Copyright Notice
Copyright (c) 2021 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Mirsky, et al. Expires 13 June 2022 [Page 1]
Internet-Draft OAM for DetNet over MPLS December 2021
Please review these documents carefully, as they describe your rights
and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Conventions used in this document . . . . . . . . . . . . . . 3
2.1. Terminology and Acronyms . . . . . . . . . . . . . . . . 3
2.2. Keywords . . . . . . . . . . . . . . . . . . . . . . . . 4
3. Active OAM for DetNet Networks with MPLS Data Plane . . . . . 4
3.1. DetNet Active OAM Encapsulation . . . . . . . . . . . . . 5
3.2. DetNet Packet Replication, Elimination, and Ordering
Functions Interaction with Active OAM . . . . . . . . . . 7
4. Use of Hybrid OAM in DetNet . . . . . . . . . . . . . . . . . 7
5. OAM Interworking Models . . . . . . . . . . . . . . . . . . . 8
5.1. OAM of DetNet MPLS Interworking with OAM of TSN . . . . . 8
5.2. OAM of DetNet MPLS Interworking with OAM of DetNet IP . . 9
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
6.1. DetNet MPLS OAM Flags Registry . . . . . . . . . . . . . 9
7. Security Considerations . . . . . . . . . . . . . . . . . . . 9
8. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 10
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
9.1. Normative References . . . . . . . . . . . . . . . . . . 10
9.2. Informational References . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12
1. Introduction
[RFC8655] introduces and explains Deterministic Networks (DetNet)
architecture and how the Packet Replication, Elimination, and
Ordering functions (PREOF) can be used to ensure low packet drop
ratio in DetNet domain.
Operations, Administration and Maintenance (OAM) protocols are used
to detect, localize defects in the network, and monitor network
performance. Some OAM functions, e.g., failure detection, work in
the network proactively, while others, e.g., defect localization,
usually performed on-demand. These tasks achieved by a combination
of active and hybrid, as defined in [RFC7799], OAM methods.
Also, this document defines format and use principals of the DetNet
service Associated Channel over a DetNet network with the MPLS data
plane [RFC8964].
Mirsky, et al. Expires 13 June 2022 [Page 2]
Internet-Draft OAM for DetNet over MPLS December 2021
2. Conventions used in this document
2.1. Terminology and Acronyms
The term "DetNet OAM" used in this document interchangeably with
longer version "set of OAM protocols, methods and tools for
Deterministic Networks".
CW Control Word
DetNet Deterministic Networks
d-ACH DetNet Associated Channel Header
d-CW DetNet Control Word
DNH DetNet Header
GAL Generic Associated Channel Label
G-ACh Generic Associated Channel
OAM: Operations, Administration and Maintenance
PREOF Packet Replication, Elimination, and Ordering Functions
PW Pseudowire
RDI Remote Defect Indication
E2E End-to-end
CFM Connectivity Fault Management
BFD Bidirectional Forwarding Detection
TSN Time-Sensitive Network
F-Label A Detnet "forwarding" label that identifies the LSP used to
forward a DetNet flow across an MPLS PSN, e.g., a hop-by-hop label
used between label switching routers (LSR).
S-Label A DetNet "service" label that is used between DetNet nodes
that implement also the DetNet service sub-layer functions. An
S-Label is also used to identify a DetNet flow at DetNet service sub-
layer.
Mirsky, et al. Expires 13 June 2022 [Page 3]
Internet-Draft OAM for DetNet over MPLS December 2021
Underlay Network or Underlay Layer: The network that provides
connectivity between the DetNet nodes. MPLS network providing LSP
connectivity between DetNet nodes is an example of the underlay
layer.
DetNet Node - a node that is an actor in the DetNet domain. DetNet
domain edge node and node that performs PREOF within the domain are
examples of DetNet node.
2.2. Keywords
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Active OAM for DetNet Networks with MPLS Data Plane
OAM protocols and mechanisms act within the data plane of the
particular networking layer. And thus it is critical that the data
plane encapsulation supports OAM mechanisms in such a way to comply
with the OAM requirements listed in [I-D.tpmb-detnet-oam-framework].
One of such examples that require special consideration is
requirement #5:
DetNet OAM packets MUST be in-band, i.e., follow precisely the
same path as DetNet data plane traffic both for unidirectional and
bi-directional DetNet paths.
The Det Net data plane encapsulation in transport network with MPLS
encapsulation specified in [RFC8964]. For the MPLS underlay network,
DetNet flows to be encapsulated analogous to pseudowires (PW) over
MPLS packet switched network, as described in [RFC3985], [RFC4385].
Generic PW MPLS Control Word (CW), defined in [RFC4385], for DetNet
displayed in Figure 1.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 0| Sequence Number |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: DetNet Control Word Format
Mirsky, et al. Expires 13 June 2022 [Page 4]
Internet-Draft OAM for DetNet over MPLS December 2021
PREOF in the DetNet domain composed by a combination of nodes that
perform replication and elimination functions. The elimination
function always uses the S-Label and packet sequencing information,
e.g., the value in the Sequence Number field of DetNet CW (d-CW).
The replication sub-function uses the S-Label information only. For
data packets Figure 2 presents an example of PREOF in DetNet domain.
1111 11111111 111111 112212 112212 132213
CE1----EN1--------R1-------R2-------R3--------EN2----CE2
\2 22222/ 3 /
\2222222 /----+ 3 /
+------R4------------------------+
333333333333333333333333
Figure 2: DetNet Data Plane Based on PW
3.1. DetNet Active OAM Encapsulation
DetNet OAM, like PW OAM, uses PW Associated Channel Header defined in
[RFC4385]. Figure 3 displays the encapsulation of a DetNet MPLS
[RFC8964] active OAM packet.
+---------------------------------+
| |
| DetNet OAM Packet |
| |
+---------------------------------+ <--\
| DetNet Associated Channel Header| |
+---------------------------------+ +--> DetNet active OAM
| S-Label | | MPLS encapsulation
+---------------------------------+ |
| [ F-Label(s) ] | |
+---------------------------------+ <--/
| Data-Link |
+---------------------------------+
| Physical |
+---------------------------------+
Figure 3: DetNet Active OAM Packet Encapsulation in MPLS Data Plane
Figure 4 displays encapsulation of a test packet of an active DetNet
OAM protocol in case of MPLS-over-UDP/IP [RFC9025].
Mirsky, et al. Expires 13 June 2022 [Page 5]
Internet-Draft OAM for DetNet over MPLS December 2021
+---------------------------------+
| |
| DetNet OAM Packet |
| |
+---------------------------------+ <--\
| DetNet Associated Channel Header| |
+---------------------------------+ +--> DetNet active OAM
| S-Label | | MPLS encapsulation
+---------------------------------+ |
| [ F-label(s) ] | |
+---------------------------------+ <--+
| UDP Header | |
+---------------------------------+ +--> DetNet data plane
| IP Header | | IP encapsulation
+---------------------------------+ <--/
| Data-Link |
+---------------------------------+
| Physical |
+---------------------------------+
Figure 4: DetNet Active OAM Packet Encapsulation in MPLS-over-UDP/IP
Figure 5 displays the format of the DetNet Associated Channel Header
(d-ACH).
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0 0 0 1|Version|Sequence Number| Channel Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Node ID |Level| Flags |Session|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: DetNet Associated Channel Header Format
The d-ACH encodes the following fields:
Bits 0..3 MUST be 0b0001. This value of the first nibble allows
the packet to be distinguished from an IP packet [RFC4928] and a
DetNet data packet [RFC8964].
Version - is a four-bits field, and the value is the version
number of the d-ACH. This specification defines version 0x1.
Mirsky, et al. Expires 13 June 2022 [Page 6]
Internet-Draft OAM for DetNet over MPLS December 2021
Sequence Number - is an unsigned eight-bit field. The sequence
number space is circular with no restriction on the initial value.
The originator DetNet node MUST set the value of the Sequence
Number field before the transmission of a packet. The originator
node MUST increase the value of the Sequence Number field by 1 for
each active OAM packet.
Channel Type - contains the value of DetNet Associated Channel
Type. It is one of the values defined in the IANA PW Associated
Channel Type registry.
Node ID - is an unsigned 20 bits-long field. The value of the
Node ID field identifies the DetNet node that originated the
packet. Methods of distributing Node ID are outside the scope of
this specification.
Level - is a three-bits field.
Flags - is a five-bits field. Flags field contains five one-bit
flags. Section 6.1 creates an IANA registry for new flags to be
defined.
Session ID is a four-bits field.
The DetNet flow, according to [RFC8964], is identified by the S-label
that MUST be at the bottom of the stack. Active OAM packet MUST
include d-ACH immediately following the S-label.
3.2. DetNet Packet Replication, Elimination, and Ordering Functions
Interaction with Active OAM
At the DetNet service sub-layer, special functions MAY be applied to
the particular DetNet flow, PREOF, to potentially lower packet loss,
improve the probability of on-time packet delivery and ensure in-
order packet delivery. PREOF rely on sequencing information in the
DetNet service sub-layer. For a DetNet active OAM packet, 28 MSBs of
the d-ACH MUST be used as the source of the sequencing information by
PREOF.
4. Use of Hybrid OAM in DetNet
Hybrid OAM methods are used in performance monitoring and defined in
[RFC7799] as:
Hybrid Methods are Methods of Measurement that use a combination
of Active Methods and Passive Methods.
Mirsky, et al. Expires 13 June 2022 [Page 7]
Internet-Draft OAM for DetNet over MPLS December 2021
A hybrid measurement method may produce metrics as close to passive,
but it still alters something in a data packet even if that is the
value of a designated field in the packet encapsulation. One example
of such a hybrid measurement method is the Alternate Marking method
described in [RFC8321]. Reserving the field for the Alternate
Marking method in the DetNet Header will enhance available to an
operator set of DetNet OAM tools.
5. OAM Interworking Models
Interworking of two OAM domains that utilize different networking
technology can be realized either by a peering or a tunneling model.
In a peering model, OAM domains are within the corresponding network
domain. When using the peering model, state changes that are
detected by a Fault Management OAM protocol can be mapped from one
OAM domain into another or a notification, e.g., an alarm, can be
sent to a central controller. In the tunneling model of OAM
interworking, usually, only one active OAM protocol is used. Its
test packets are tunneled through another domain along with the data
flow, thus ensuring the fate sharing among test and data packets.
5.1. OAM of DetNet MPLS Interworking with OAM of TSN
Active DetNet OAM is required to provide the E2E fault management and
performance monitoring for a DetNet flow. Interworking of DetNet
active OAM with MPLS data plane with the IEEE 802.1 Time-Sensitive
Networking (TSN) domain based on [RFC9037].
In the case of the peering model is used in the fault management OAM,
then the node that borders both TSN and DetNet MPLS domains MUST
support [RFC7023]. [RFC7023] specified the mapping of defect states
between Ethernet Attachment Circuits (ACs) and associated Ethernet
PWs that are part of an end-to-end (E2E) emulated Ethernet service.
Requirements and mechanisms described in [RFC7023] are equally
applicable to using the peering model to achieve E2E FM OAM over
DetNet MPLS and TSN domains. The Connectivity Fault Management (CFM)
protocol [IEEE.CFM] or in [ITU.Y1731] can provide fast detection of a
failure in the TSN segment of the DetNet service. In the DetNet MPLS
domain BFD (Bidirectional Forwarding Detection), specified in
[RFC5880] and [RFC5885], can be used. To provide E2E failure
detection, the TSN segment might be presented as a concatenated with
the DetNet MPLS and the Section 6.8.17 [RFC5880] MAY be used to
inform the upstream DetNet MPLS node of a failure of the TSN segment.
Performance monitoring can be supported by [RFC6374] in the DetNet
MPLS and [ITU.Y1731] in the TSN domains, respectively. Performance
objectives for each domain should refer to metrics that additive or
be defined for each domain separately.
Mirsky, et al. Expires 13 June 2022 [Page 8]
Internet-Draft OAM for DetNet over MPLS December 2021
The following considerations are to be realized when using the
tunneling model of OAM interworking between DetNet MPLS and TSN
domains:
* Active OAM test packet MUST be mapped to the same TSN Stream ID as
the monitored DetNet flow.
* Active OAM test packets MUST be treated in the TSN domain based on
its S-label and CoS marking (TC field value).
Note that the tunneling model of the OAM interworking requires that
the remote peer of the E2E OAM domain supports the active OAM
protocol selected on the ingress endpoint. For example, if BFD is
used for proactive path continuity monitoring in the DetNet MPLS
domain, a TSN endpoint of the DetNet service has also support BFD as
defined in [RFC5885].
5.2. OAM of DetNet MPLS Interworking with OAM of DetNet IP
Interworking between active OAM segments in DetNet MPLS and DetNet IP
domains can also be realized using either the peering or the
tunneling model, as discussed in Section 5.1. Using the same
protocol, e.g., BFD, over both segments, simplifies the mapping of
errors in the peering model. To provide the performance monitoring
over a DetNet IP domain STAMP [RFC8762] and its extensions [RFC8972]
can be used.
6. IANA Considerations
6.1. DetNet MPLS OAM Flags Registry
This document describes a new IANA-managed registry to identify
DetNet MPLS OAM Flags Bits. The registration procedure is "IETF
Review" [RFC8126]. The registry name is "DetNet MPLS OAM Flags".
There are five flags in the five-bit Flags field.
7. Security Considerations
Additionally, security considerations discussed in DetNet
specifications: [RFC8655], [RFC9055], [RFC8964] are applicable to
this document. Security concerns and issues related to MPLS OAM
tools like LSP Ping [RFC8029], BFD over PW [RFC5885] also apply to
this specification.
Mirsky, et al. Expires 13 June 2022 [Page 9]
Internet-Draft OAM for DetNet over MPLS December 2021
8. Acknowledgment
Authors extend their appreciation to Pascal Thubert for his
insightful comments and productive discussion that helped to improve
the document.
9. References
9.1. 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>.
[RFC7023] Mohan, D., Ed., Bitar, N., Ed., Sajassi, A., Ed., DeLord,
S., Niger, P., and R. Qiu, "MPLS and Ethernet Operations,
Administration, and Maintenance (OAM) Interworking",
RFC 7023, DOI 10.17487/RFC7023, October 2013,
<https://www.rfc-editor.org/info/rfc7023>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8655] Finn, N., Thubert, P., Varga, B., and J. Farkas,
"Deterministic Networking Architecture", RFC 8655,
DOI 10.17487/RFC8655, October 2019,
<https://www.rfc-editor.org/info/rfc8655>.
[RFC8964] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., Bryant,
S., and J. Korhonen, "Deterministic Networking (DetNet)
Data Plane: MPLS", RFC 8964, DOI 10.17487/RFC8964, January
2021, <https://www.rfc-editor.org/info/rfc8964>.
[RFC9025] Varga, B., Ed., Farkas, J., Berger, L., Malis, A., and S.
Bryant, "Deterministic Networking (DetNet) Data Plane:
MPLS over UDP/IP", RFC 9025, DOI 10.17487/RFC9025, April
2021, <https://www.rfc-editor.org/info/rfc9025>.
9.2. Informational References
Mirsky, et al. Expires 13 June 2022 [Page 10]
Internet-Draft OAM for DetNet over MPLS December 2021
[I-D.tpmb-detnet-oam-framework]
Mirsky, G., Theoleyre, F., Papadopoulos, G. Z., and C. J.
Bernardos, "Framework of Operations, Administration and
Maintenance (OAM) for Deterministic Networking (DetNet)",
Work in Progress, Internet-Draft, draft-tpmb-detnet-oam-
framework-01, 30 March 2021,
<https://datatracker.ietf.org/doc/html/draft-tpmb-detnet-
oam-framework-01>.
[IEEE.CFM] IEEE, "Connectivity Fault Management clause of IEEE
802.1Q", IEEE 802.1Q, 2013.
[ITU.Y1731]
ITU-T, "OAM functions and mechanisms for Ethernet based
Networks", ITU-T Recommendation G.8013/Y.1731, November
2013.
[RFC3985] Bryant, S., Ed. and P. Pate, Ed., "Pseudo Wire Emulation
Edge-to-Edge (PWE3) Architecture", RFC 3985,
DOI 10.17487/RFC3985, March 2005,
<https://www.rfc-editor.org/info/rfc3985>.
[RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson,
"Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for
Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385,
February 2006, <https://www.rfc-editor.org/info/rfc4385>.
[RFC4928] Swallow, G., Bryant, S., and L. Andersson, "Avoiding Equal
Cost Multipath Treatment in MPLS Networks", BCP 128,
RFC 4928, DOI 10.17487/RFC4928, June 2007,
<https://www.rfc-editor.org/info/rfc4928>.
[RFC5880] Katz, D. and D. Ward, "Bidirectional Forwarding Detection
(BFD)", RFC 5880, DOI 10.17487/RFC5880, June 2010,
<https://www.rfc-editor.org/info/rfc5880>.
[RFC5885] Nadeau, T., Ed. and C. Pignataro, Ed., "Bidirectional
Forwarding Detection (BFD) for the Pseudowire Virtual
Circuit Connectivity Verification (VCCV)", RFC 5885,
DOI 10.17487/RFC5885, June 2010,
<https://www.rfc-editor.org/info/rfc5885>.
[RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay
Measurement for MPLS Networks", RFC 6374,
DOI 10.17487/RFC6374, September 2011,
<https://www.rfc-editor.org/info/rfc6374>.
Mirsky, et al. Expires 13 June 2022 [Page 11]
Internet-Draft OAM for DetNet over MPLS December 2021
[RFC7799] Morton, A., "Active and Passive Metrics and Methods (with
Hybrid Types In-Between)", RFC 7799, DOI 10.17487/RFC7799,
May 2016, <https://www.rfc-editor.org/info/rfc7799>.
[RFC8029] Kompella, K., Swallow, G., Pignataro, C., Ed., Kumar, N.,
Aldrin, S., and M. Chen, "Detecting Multiprotocol Label
Switched (MPLS) Data-Plane Failures", RFC 8029,
DOI 10.17487/RFC8029, March 2017,
<https://www.rfc-editor.org/info/rfc8029>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8321] Fioccola, G., Ed., Capello, A., Cociglio, M., Castaldelli,
L., Chen, M., Zheng, L., Mirsky, G., and T. Mizrahi,
"Alternate-Marking Method for Passive and Hybrid
Performance Monitoring", RFC 8321, DOI 10.17487/RFC8321,
January 2018, <https://www.rfc-editor.org/info/rfc8321>.
[RFC8762] Mirsky, G., Jun, G., Nydell, H., and R. Foote, "Simple
Two-Way Active Measurement Protocol", RFC 8762,
DOI 10.17487/RFC8762, March 2020,
<https://www.rfc-editor.org/info/rfc8762>.
[RFC8972] Mirsky, G., Min, X., Nydell, H., Foote, R., Masputra, A.,
and E. Ruffini, "Simple Two-Way Active Measurement
Protocol Optional Extensions", RFC 8972,
DOI 10.17487/RFC8972, January 2021,
<https://www.rfc-editor.org/info/rfc8972>.
[RFC9037] Varga, B., Ed., Farkas, J., Malis, A., and S. Bryant,
"Deterministic Networking (DetNet) Data Plane: MPLS over
IEEE 802.1 Time-Sensitive Networking (TSN)", RFC 9037,
DOI 10.17487/RFC9037, June 2021,
<https://www.rfc-editor.org/info/rfc9037>.
[RFC9055] Grossman, E., Ed., Mizrahi, T., and A. Hacker,
"Deterministic Networking (DetNet) Security
Considerations", RFC 9055, DOI 10.17487/RFC9055, June
2021, <https://www.rfc-editor.org/info/rfc9055>.
Authors' Addresses
Greg Mirsky
Ericsson
Mirsky, et al. Expires 13 June 2022 [Page 12]
Internet-Draft OAM for DetNet over MPLS December 2021
Email: gregimirsky@gmail.com
Mach(Guoyi) Chen
Huawei
Email: mach.chen@huawei.com
Balazs Varga
Ericsson
Budapest
Magyar Tudosok krt. 11.
1117
Hungary
Email: balazs.a.varga@ericsson.com
Janos Farkas
Ericsson
Budapest
Magyar Tudosok krt. 11.
1117
Hungary
Email: janos.farkas@ericsson.com
Mirsky, et al. Expires 13 June 2022 [Page 13]