draft-ietf-ccamp-rsvp-te-bandwidth-availability-12.txt   draft-ietf-ccamp-rsvp-te-bandwidth-availability-13.txt 
Network Working Group H. Long, M. Ye Network Working Group H. Long, M. Ye
Internet Draft Huawei Technologies Co., Ltd Internet Draft Huawei Technologies Co., Ltd
Intended status: Standards Track G. Mirsky Intended status: Standards Track G. Mirsky
ZTE ZTE
A.D'Alessandro A.D'Alessandro
Telecom Italia S.p.A Telecom Italia S.p.A
H. Shah H. Shah
Ciena Ciena
Expires: July 2019 January 2, 2019 Expires: July 2019 January 17, 2019
Ethernet Traffic Parameters with Availability Information Ethernet Traffic Parameters with Availability Information
draft-ietf-ccamp-rsvp-te-bandwidth-availability-12.txt draft-ietf-ccamp-rsvp-te-bandwidth-availability-13.txt
Abstract Abstract
A packet switching network may contain links with variable bandwidth, A packet switching network may contain links with variable
e.g., copper, radio, etc. The bandwidth of such links is sensitive bandwidth, e.g., copper, radio, etc. The bandwidth of such links is
to external environment. Availability is typically used for sensitive to external environment (e.g., climate). Availability is
describing the link during network planning. This document typically used for describing these links when during network
introduces an optional Availability TLV in Resource ReSerVation planning. This document introduces an optional Availability TLV in
Protocol - Traffic Engineer (RSVP-TE) signaling. This extension can Resource ReSerVation Protocol - Traffic Engineer (RSVP-TE)
be used to set up a Generalized Multi-Protocol Label Switching signaling. This extension can be used to set up a Generalized Multi-
(GMPLS) Label Switched Path (LSP) using the Ethernet SENDER_TSPEC Protocol Label Switching (GMPLS) Label Switched Path (LSP) using the
object. Ethernet SENDER_TSPEC object.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 2, line 4 skipping to change at page 2, line 4
Internet-Drafts are draft documents valid for a maximum of six Internet-Drafts are draft documents valid for a maximum of six
months and may be updated, replaced, or obsoleted by other documents months and may be updated, replaced, or obsoleted by other documents
at any time. It is inappropriate to use Internet-Drafts as at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress." reference material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt http://www.ietf.org/ietf/1id-abstracts.txt
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html http://www.ietf.org/shadow.html
This Internet-Draft will expire on July 2, 2019. This Internet-Draft will expire on July 17, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with carefully, as they describe your rights and restrictions with
respect to this document. Code Components extracted from this respect to this document. Code Components extracted from this
document must include Simplified BSD License text as described in document must include Simplified BSD License text as described in
Section 4.e of the Trust Legal Provisions and are provided without Section 4.e of the Trust Legal Provisions and are provided without
warranty as described in the Simplified BSD License. warranty as described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction ................................................ 3 1. Introduction ................................................ 3
2. Overview .................................................... 4 2. Overview .................................................... 4
3. Extension to RSVP-TE Signaling............................... 4 3. Extension to RSVP-TE Signaling............................... 5
3.1. Availability TLV........................................ 4 3.1. Availability TLV........................................ 5
3.2. Signaling Process....................................... 5 3.2. Signaling Process....................................... 5
4. Security Considerations...................................... 6 4. Security Considerations...................................... 6
5. IANA Considerations ......................................... 6 5. IANA Considerations ......................................... 6
5.1 Ethernet Sender TSpec TLVs ............................. 6 5.1 Ethernet Sender TSpec TLVs ............................. 7
6. References .................................................. 7 6. References .................................................. 7
6.1. Normative References.................................... 7 6.1. Normative References.................................... 7
6.2. Informative References.................................. 7 6.2. Informative References.................................. 8
7. Appendix: Bandwidth Availability Example..................... 8 7. Appendix: Bandwidth Availability Example..................... 8
8. Acknowledgments ............................................. 9 8. Acknowledgments ............................................ 10
Conventions used in this document Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in RFC-2119 [RFC2119]. "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.
The following acronyms are used in this draft: The following acronyms are used in this draft:
RSVP-TE Resource Reservation Protocol-Traffic Engineering RSVP-TE Resource Reservation Protocol-Traffic Engineering
LSP Label Switched Path LSP Label Switched Path
SNR Signal-to-noise Ratio SNR Signal-to-noise Ratio
TLV Type Length Value TLV Type Length Value
LSA Link State Advertisement LSA Link State Advertisement
1. Introduction 1. Introduction
The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473] The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473]
specify the signaling message including the bandwidth request for specify the signaling message including the bandwidth request for
setting up a Label Switched Path in a packet switching network. setting up a Label Switched Path in a packet switching network.
skipping to change at page 3, line 18 skipping to change at page 3, line 20
1. Introduction 1. Introduction
The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473] The RSVP-TE specification [RFC3209] and GMPLS extensions [RFC3473]
specify the signaling message including the bandwidth request for specify the signaling message including the bandwidth request for
setting up a Label Switched Path in a packet switching network. setting up a Label Switched Path in a packet switching network.
Some data communication technologies allow seamless change of Some data communication technologies allow seamless change of
maximum physical bandwidth through a set of known discrete values. maximum physical bandwidth through a set of known discrete values.
The parameter availability [G.827], [F.1703], [P.530] is often used The parameter availability [G.827], [F.1703], [P.530] is often used
to describe the link capacity during network planning. The to describe the link capacity during network planning. The
availability is a time scale, which is a proportion of the operating availability is based on a time scale, which is a proportion of the
time that the requested bandwidth is ensured. A more detailed operating time that the requested bandwidth is ensured. A more
example on the bandwidth availability can be found in Appendix A. detailed example on the bandwidth availability can be found in
Assigning different bandwidth availability classes to different Appendix A. Assigning different bandwidth availability classes to
types of service over such kind of links provides more efficient different types of services over such kind of links provides for a
planning of link capacity. To set up an LSP across these links, more efficient planning of link capacity. To set up an LSP across
bandwidth availability information is required for the nodes to these links, bandwidth availability information is required for the
verify bandwidth satisfaction and make bandwidth reservation. The nodes to verify bandwidth satisfaction and make bandwidth
bandwidth availability information should be inherited from the reservation. The bandwidth availability information should be
bandwidth availability requirements of the services expected to be inherited from the bandwidth availability requirements of the
carried on the LSP. For example, voice service usually needs "five services expected to be carried on the LSP. For example, voice
nines" bandwidth availability, while non-real time services may service usually needs "five nines" bandwidth availability, while
adequately perform at four or three nines bandwidth availability. non-real time services may adequately perform at four or three nines
Since different service types may need different availabilities bandwidth availability. Since different service types may need
guarantees, multiple <availability, bandwidth> pairs may be required different availabilities guarantees, multiple <availability,
when signaling. bandwidth> pairs may be required when signaling.
If the bandwidth availability requirement is not specified in the If the bandwidth availability requirement is not specified in the
signaling message, the bandwidth will be reserved as the highest signaling message, the bandwidth will be reserved as the highest
bandwidth availability. For example, the bandwidth with 99.999% bandwidth availability. For example, the bandwidth with 99.999%
availability of a link is 100 Mbps; the bandwidth with 99.99% availability of a link is 100 Mbps; the bandwidth with 99.99%
availability is 200 Mbps. When a video application requests for 120 availability is 200 Mbps. When a video application requests for 120
Mbps without bandwidth availability requirement, the system will Mbps without bandwidth availability requirement, the system will
consider the request as 120 Mbps with 99.999% bandwidth availability, consider the request as 120 Mbps with 99.999% bandwidth
while the available bandwidth with 99.999% bandwidth availability is availability, while the available bandwidth with 99.999% bandwidth
only 100 Mbps, therefore the LSP path cannot be set up. But in fact, availability is only 100 Mbps, therefore the LSP path cannot be set
video application doesn't need 99.999% bandwidth availability; 99.99% up. But, in fact, the video application doesn't need 99.999%
bandwidth availability is enough. In this case, the LSP could be set bandwidth availability; 99.99% bandwidth availability is enough. In
up if bandwidth availability is specified in the signaling message. this case, the LSP could be set up if bandwidth availability is also
specified in the signaling message.
To fulfill LSP setup by signaling in these scenarios, this document To fulfill LSP setup by signaling in these scenarios, this document
specifies an Availability TLV. The Availability TLV can be specifies an Availability TLV. The Availability TLV can be
applicable to any kind of physical links with variable discrete applicable to any kind of physical links with variable discrete
bandwidth, such as microwave or DSL. Multiple Availability TLVs bandwidth, such as microwave or DSL. Multiple Availability TLVs
together with multiple Ethernet Bandwidth Profiles can be carried by together with multiple Ethernet Bandwidth Profiles can be carried by
the Ethernet SENDER_TSPEC object [RFC6003]. Since the Ethernet the Ethernet SENDER_TSPEC object [RFC6003]. Since the Ethernet
FLOWSPEC object has the same format as the Ethernet SENDER_TSPEC FLOWSPEC object has the same format as the Ethernet SENDER_TSPEC
object [RFC6003], the Availability TLV can also be carried by the object [RFC6003], the Availability TLV can also be carried by the
Ethernet FLOWSPEC object. Ethernet FLOWSPEC object.
2. Overview 2. Overview
A tunnel in a packet switching network may span one or more links in A tunnel in a packet switching network may span one or more links in
a network. To setup a Label Switched Path (LSP), a node may collect a network. To setup a Label Switched Path (LSP), a node may collect
link information which is spread in routing message, e.g., OSPF TE link information which is advertised in a routing message, e.g.,
LSA message, by network nodes to get to know about the network OSPF TE LSA message, by network nodes to obtain network topology
topology, and calculate out an LSP route based on the network information, and then calculate an LSP route based on the network
topology, and send the calculated LSP route to signaling to initiate topology. The calculated LSP route is signaled using a PATH/RESV
a PATH/RESV message for setting up the LSP. message for setting up the LSP.
In case that there is (are) link(s) with variable discrete bandwidth In case that there is (are) link(s) with variable discrete bandwidth
in a network, a <bandwidth, availability> requirement list should be in a network, a <bandwidth, availability> requirement list should be
specified for an LSP. Each <bandwidth, availability> pair in the specified for an LSP at setup. Each <bandwidth, availability> pair
list means that listed bandwidth with specified availability is in the list means the listed bandwidth with specified availability
required. The list could be inherited from the results of service is required. The list could be derived from the results of service
planning for the LSP. planning for the LSP.
A node which has link(s) with variable discrete bandwidth attached A node which has link(s) with variable discrete bandwidth attached
should contain a <bandwidth, availability> information list in its should contain a <bandwidth, availability> information list in its
OSPF TE LSA messages. The list provides the mapping between the link OSPF TE LSA messages. The list provides the mapping between the link
nominal bandwidth and its availability level. This information is nominal bandwidth and its availability level. This information can
used for path calculation by the node(s). The routing extension for then be used for path calculation by the node(s). The routing
availability can be found in [RFC8330]. extension for availability can be found in [RFC8330].
When a node initiates a PATH/RESV signaling to set up an LSP, the When a node initiates a PATH/RESV signaling to set up an LSP, the
PATH message should carry the <bandwidth, availability> requirement PATH message should carry the <bandwidth, availability> requirement
list as bandwidth request. Intermediate node(s) will allocate the list as a bandwidth request. Intermediate node(s) will allocate the
bandwidth resource for each availability requirement from the bandwidth resource for each availability requirement from the
remaining bandwidth with corresponding availability. An error remaining bandwidth with corresponding availability. An error
message may be returned if any <bandwidth, availability> request message may be returned if any <bandwidth, availability> request
cannot be satisfied. cannot be satisfied.
3. Extension to RSVP-TE Signaling 3. Extension to RSVP-TE Signaling
3.1. Availability TLV 3.1. Availability TLV
An Availability TLV is defined as a TLV of the Ethernet SENDER_TSPEC An Availability TLV is defined as a TLV of the Ethernet SENDER_TSPEC
skipping to change at page 5, line 21 skipping to change at page 5, line 30
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Availability TLV Figure 1: Availability TLV
Index (1 octet): Index (1 octet):
When the Availability TLV is included, it MUST be present along When the Availability TLV is included, it MUST be present along
with the Ethernet Bandwidth Profile TLV. If the bandwidth with the Ethernet Bandwidth Profile TLV. If the bandwidth
requirements in the multiple Ethernet Bandwidth Profile TLVs have requirements in the multiple Ethernet Bandwidth Profile TLVs have
different Availability requirements, multiple Availability TLVs different Availability requirements, multiple Availability TLVs
SHOULD be carried. In such a case, the Availability TLV has one to SHOULD be carried. In such a case, the Availability TLV has a one
one correspondence with Ethernet Bandwidth Profile TLV by having to one correspondence with the Ethernet Bandwidth Profile TLV by
the same value of Index field. If all the bandwidth requirements having the same value of Index field. If all the bandwidth
in the Ethernet Bandwidth Profile have the same Availability requirements in the Ethernet Bandwidth Profile have the same
requirement, one Availability TLV SHOULD be carried. In this case, Availability requirement, one Availability TLV SHOULD be carried.
the Index field is set to 0. In this case, the Index field is set to 0.
Reserved (3 octets): These bits SHOULD be set to zero when sent Reserved (3 octets): These bits SHOULD be set to zero when sent
and MUST be ignored when received. and MUST be ignored when received.
Availability (4 octets): a 32-bit floating number describes the Availability (4 octets): a 32-bit floating number describes the
decimal value of availability requirement for this bandwidth decimal value of availability requirement for this bandwidth
request. The value MUST be less than 1and is usually expressed in request. The value MUST be less than 1and is usually expressed in
the value of 0.99/0.999/0.9999/0.99999. the value of 0.99/0.999/0.9999/0.99999.
3.2. Signaling Process 3.2. Signaling Process
The source node initiates a PATH message which may carry a number of The source node initiates a PATH message which may carry a number of
bandwidth request information, including one or more Ethernet bandwidth requests, including one or more Ethernet Bandwidth Profile
Bandwidth Profile TLVs and one or more Availability TLVs. Each TLVs and one or more Availability TLVs. Each Ethernet Bandwidth
Ethernet Bandwidth Profile TLV corresponds to an availability Profile TLV corresponds to an availability parameter in the
parameter in the Availability TLV. Availability TLV.
The intermediate and destination nodes check whether they can The intermediate and destination nodes check whether they can
satisfy the bandwidth requirements by comparing each bandwidth satisfy the bandwidth requirements by comparing each bandwidth
requirement inside the SENDER_TSPEC objects with the remaining link request inside the SENDER_TSPEC objects with the remaining link sub-
sub-bandwidth resource with respective availability guarantee on the bandwidth resource with respective availability guarantee on the
local link when the PATH message is received. local link when the PATH message is received.
o When all <bandwidth, availability> requirements can be o When all <bandwidth, availability> requirement requests can
satisfied (the requested bandwidth under each availability be satisfied (the requested bandwidth under each availability
parameter is smaller than or equal to the remaining bandwidth parameter is smaller than or equal to the remaining bandwidth
under the corresponding availability parameter on its local under the corresponding availability parameter on its local
link), it SHOULD reserve the bandwidth resource from each link), it SHOULD reserve the bandwidth resource from each
remaining sub-bandwidth portion on its local link to set up remaining sub-bandwidth portion on its local link to set up
this LSP. Optionally, the higher availability bandwidth can be this LSP. Optionally, the higher availability bandwidth can be
allocated to lower availability request when the lower allocated to lower availability request when the lower
availability bandwidth cannot satisfy the request. availability bandwidth cannot satisfy the request.
o When at least one <bandwidth, availability> requirement o When at least one <bandwidth, availability> requirement
cannot be satisfied, it SHOULD generate PathErr message with request cannot be satisfied, it SHOULD generate PathErr message
the error code "Admission Control Error" and the error value with the error code "Admission Control Error" and the error
"Requested Bandwidth Unavailable" (see [RFC2205]). value "Requested Bandwidth Unavailable" (see [RFC2205]).
When two LSPs request bandwidth with the same availability When two LSPs request bandwidth with the same availability
requirement, contention MUST be resolved by comparing the node IDs, requirement, contention MUST be resolved by comparing the node IDs,
with the LSP with the higher node ID being assigned the reservation. with the LSP with the higher node ID being assigned the reservation.
This is consistent with general contention resolution mechanism This is consistent with general contention resolution mechanism
provided in section 3.2 of [RFC3473]. provided in section 3.2 of [RFC3473].
When a node does not support Availability TLV, it SHOULD generate When a node does not support the Availability TLV, it SHOULD
PathErr message with the error code "Extended Class-Type Error" and generate PathErr message with the error code "Extended Class-Type
the error value "Class-Type mismatch" (see [RFC2205]). Error" and the error value "Class-Type mismatch" (see [RFC2205]).
4. Security Considerations 4. Security Considerations
This document does not introduce new security considerations to the This document does not introduce any new security considerations to
existing RSVP-TE signaling protocol. [RFC5920] provides an overview the existing RSVP-TE signaling protocol. [RFC5920] provides an
of security vulnerabilities and protection mechanisms for the GMPLS overview of security vulnerabilities and protection mechanisms for
control plane. the GMPLS control plane.
5. IANA Considerations 5. IANA Considerations
IANA maintains registries and sub-registries for RSVP-TE used by IANA maintains registries and sub-registries for RSVP-TE used by
GMPLS. IANA is requested to make allocations from these registries GMPLS. IANA is requested to make allocations from these registries
as set out in the following sections. as set out in the following sections.
5.1 Ethernet Sender TSpec TLVs 5.1 Ethernet Sender TSpec TLVs
IANA maintains a registry of GMPLS parameters called "Generalized IANA maintains a registry of GMPLS parameters called "Generalized
Multi-Protocol Label Switching (GMPLS) Signaling Parameters". Multi-Protocol Label Switching (GMPLS) Signaling Parameters".
IANA has created a sub-registry called "Ethernet Sender TSpec TLVs / IANA has created a sub-registry called "Ethernet Sender TSpec TLVs /
Ethernet Flowspec TLVs" to contain the TLV type values for TLVs Ethernet Flowspec TLVs" to contain the TLV type values for TLVs
carried in the Ethernet SENDER_TSPEC object. The sub-registry is carried in the Ethernet SENDER_TSPEC object. The sub-registry needs
needed to be updated to include the Availability TLV which is to be updated to include the Availability TLV which is defined as
defined as follow. This document proposes a suggested value for the follow. This document proposes a suggested value for the
Availability sub-TLV; it is recommended that the suggested value be Availability sub-TLV; it is requested that the suggested value be
granted by IANA. granted by IANA.
Type Description Reference Type Description Reference
----- ----------------------------------- --------- ----- ----------------------------------- ---------
0x04 Availability [This ID] 0x04 Availability [This ID]
The registration procedure for this registry is Standards Action as The registration procedure for this registry is Standards Action as
defined in [RFC8126]. defined in [RFC8126].
skipping to change at page 7, line 36 skipping to change at page 7, line 46
V.,and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP V.,and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001. Tunnels", RFC 3209, December 2001.
[RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching [RFC3473] Berger, L., "Generalized Multi-Protocol Label Switching
(GMPLS) Signaling Resource ReserVation Protocol-Traffic (GMPLS) Signaling Resource ReserVation Protocol-Traffic
Engineering (RSVP-TE) Extensions", RFC 3473, January 2003. Engineering (RSVP-TE) Extensions", RFC 3473, January 2003.
[RFC6003] Papadimitriou, D. "Ethernet Traffic Parameters", RFC 6003, [RFC6003] Papadimitriou, D. "Ethernet Traffic Parameters", RFC 6003,
October 2010. October 2010.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, May 2017.
6.2. Informative References 6.2. Informative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", RFC 2119, March 1997. Requirement Levels", RFC 2119, March 1997.
[RFC8126] Cotton,M. and Leiba,B., and Narten T., "Guidelines for [RFC8126] Cotton,M. and Leiba,B., and Narten T., "Guidelines for
Writing an IANA Considerations Section in RFCs", RFC 8126, Writing an IANA Considerations Section in RFCs", RFC 8126,
June 2017. June 2017.
[RFC5920] Fang, L., "Security Framework for MPLS and GMPLS Networks", [RFC5920] Fang, L., "Security Framework for MPLS and GMPLS
RFC 5920, July 2010. Networks", RFC 5920, July 2010.
[G.827] ITU-T Recommendation, "Availability performance parameters [G.827] ITU-T Recommendation, "Availability performance parameters
and objectives for end-to-end international constant bit- and objectives for end-to-end international constant bit-
rate digital paths", September, 2003. rate digital paths", September, 2003.
[F.1703] ITU-R Recommendation, "Availability objectives for real [F.1703] ITU-R Recommendation, "Availability objectives for real
digital fixed wireless links used in 27 500 km digital fixed wireless links used in 27 500 km
hypothetical reference paths and connections", January, hypothetical reference paths and connections", January,
2005. 2005.
skipping to change at page 8, line 29 skipping to change at page 8, line 41
and requirements for point-to-point equipment and and requirements for point-to-point equipment and
antennas", April, 2009 antennas", April, 2009
[RFC8330] H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H., [RFC8330] H., Long, M., Ye, Mirsky, G., Alessandro, A., Shah, H.,
"OSPF Traffic Engineering (OSPF-TE) Link Availability "OSPF Traffic Engineering (OSPF-TE) Link Availability
Extension for Links with Variable Discrete Bandwidth", Extension for Links with Variable Discrete Bandwidth",
RFC8330, February, 2018 RFC8330, February, 2018
7. Appendix: Bandwidth Availability Example 7. Appendix: Bandwidth Availability Example
In mobile backhaul network, microwave links are very popular for In a mobile backhaul network, microwave links are very popular for
providing connection of last hops. In case of heavy rain, to providing connections of last hops. In case of heavy rain
maintain the link connectivity, the microwave link MAY lower the conditions, to maintain the link connectivity, the microwave link
modulation level since demodulating the lower modulation level needs MAY lower the modulation level since demodulating to a lower
a lower Signal-to-Noise Ratio (SNR). This is called adaptive modulation level provides for a lower Signal-to-Noise Ratio (SNR)
modulation technology [EN 302 217]. However, a lower modulation requirement. This is called adaptive modulation technology [EN 302
level also means lower link bandwidth. When link bandwidth is 217]. However, a lower modulation level also means lower link
reduced because of modulation down-shifting, high-priority traffic bandwidth. When link bandwidth is reduced because of modulation
can be maintained, while lower-priority traffic is dropped. down-shifting, high-priority traffic can be maintained, while lower-
Similarly, the copper links MAY change their link bandwidth due to priority traffic is dropped. Similarly, copper links may change
external interference. their link bandwidth due to external interference.
Presuming that a link has three discrete bandwidth levels: Presuming that a link has three discrete bandwidth levels:
The link bandwidth under modulation level 1, e.g., QPSK, is 100 Mbps; The link bandwidth under modulation level 1, e.g., QPSK, is 100
Mbps;
The link bandwidth under modulation level 2, e.g., 16QAM, is 200 The link bandwidth under modulation level 2, e.g., 16QAM, is 200
Mbps; Mbps;
The link bandwidth under modulation level 3, e.g., 256QAM, is 400 The link bandwidth under modulation level 3, e.g., 256QAM, is 400
Mbps. Mbps.
In sunny day, the modulation level 3 can be used to achieve 400 Mbps On a sunny day, the modulation level 3 can be used to achieve 400
link bandwidth. Mbps link bandwidth.
A light rain with X mm/h rate triggers the system to change the A light rain with X mm/h rate triggers the system to change the
modulation level from level 3 to level 2, with bandwidth changing modulation level from level 3 to level 2, with bandwidth changing
from 400 Mbps to 200 Mbps. The probability of X mm/h rain in the from 400 Mbps to 200 Mbps. The probability of X mm/h rain in the
local area is 52 minutes in a year. Then the dropped 200 Mbps local area is 52 minutes in a year. Then the dropped 200 Mbps
bandwidth has 99.99% availability. bandwidth has 99.99% availability.
A heavy rain with Y(Y>X) mm/h rate triggers the system to change the A heavy rain with Y(Y>X) mm/h rate triggers the system to change the
modulation level from level 2 to level 1, with bandwidth changing modulation level from level 2 to level 1, with bandwidth changing
from 200 Mbps to 100 Mbps. The probability of Y mm/h rain in the from 200 Mbps to 100 Mbps. The probability of Y mm/h rain in the
local area is 26 minutes in a year. Then the dropped 100 Mbps local area is 26 minutes in a year. Then the dropped 100 Mbps
bandwidth has 99.995% availability. bandwidth has 99.995% availability.
For the 100M bandwidth of the modulation level 1, only the extreme For the 100M bandwidth of the modulation level 1, only the extreme
weather condition can cause the whole system unavailable, which only weather condition can cause the whole system to be unavailable,
happens for 5 minutes in a year. So the 100 Mbps bandwidth of the which only happens for 5 minutes in a year. So the 100 Mbps
modulation level 1 owns the availability of 99.999%. bandwidth of the modulation level 1 owns the availability of
99.999%.
In a word, the maximum bandwidth is 400 Mbps. According to the Therefore, the maximum bandwidth is 400 Mbps. According to the
weather condition, the sub-bandwidth and its availability are shown weather condition, the sub-bandwidth and its availability are shown
as follows: as follows:
Sub-bandwidth (Mbps) Availability Sub-bandwidth (Mbps) Availability
------------------ ------------ ------------------ ------------
200 99.99% 200 99.99%
100 99.995% 100 99.995%
100 99.999% 100 99.999%
8. Acknowledgments 8. Acknowledgments
The authors would like to thank Khuzema Pithewan, Lou Berger, Yuji The authors would like to thank Deborah Brungard, Khuzema Pithewan,
Tochio, Dieter Beller, and Autumn Liu for their comments on the Lou Berger, Yuji Tochio, Dieter Beller, and Autumn Liu for their
document. comments and contributions on the document.
Authors' Addresses Authors' Addresses
Hao Long Hao Long
Huawei Technologies Co., Ltd. Huawei Technologies Co., Ltd.
No.1899, Xiyuan Avenue, Hi-tech Western District No.1899, Xiyuan Avenue, Hi-tech Western District
Chengdu 611731, P.R.China Chengdu 611731, P.R.China
Phone: +86-18615778750 Phone: +86-18615778750
Email: longhao@huawei.com Email: longhao@huawei.com
 End of changes. 33 change blocks. 
105 lines changed or deleted 113 lines changed or added

This html diff was produced by rfcdiff 1.47. The latest version is available from http://tools.ietf.org/tools/rfcdiff/