No relevant resource is found in the selected language.

This site uses cookies. By continuing to browse the site you are agreeing to our use of cookies. Read our privacy policy>Search

Reminder

To have a better experience, please upgrade your IE browser.

upgrade

NE20E-S V800R010C10SPC500 Feature Description - QoS 01

This is NE20E-S V800R010C10SPC500 Feature Description - QoS
Rate and give feedback:
Huawei uses machine translation combined with human proofreading to translate this document to different languages in order to help you better understand the content of this document. Note: Even the most advanced machine translation cannot match the quality of professional translators. Huawei shall not bear any responsibility for translation accuracy and it is recommended that you refer to the English document (a link for which has been provided).
QoS Priority Mapping

QoS Priority Mapping

The priority field in a packet varies with network type. For example, a packet carries the 802.1p field on a VLAN, the DSCP field on an IP network, and the EXP field on an MPLS network. To provide differentiated services for different packets, the device maps the QoS priority of incoming packets to the scheduling precedence (also called service-class) and drop precedence (also called color), and then performs congestion management based on the service-class and congestion avoidance based on the color. Before forwarding packets out, the device maps the service-class and color of the packets back to the QoS priority, which provides a basis for other devices to process the packets.

A device maps the QoS priority to the service-class and color for incoming packets and maps the service-class and color back to the QoS priority for outgoing packets, as shown in the following figure.

Figure 6-5 QoS priority mapping

Service-class

Service-class refers to the internal service class of packets. Eight service-class values are available: class selector 7 (CS7), CS6, expedited forwarding (EF), assured forwarding 4 (AF4), AF3, AF2, AF1, and best effort (BE). Service-class determines the type of queues to which packets belong.

The priority of queues with a specific service-class is calculated based on scheduling algorithms.

  • If queues with eight service-class all use priority queuing (PQ) scheduling, the queues are displayed in descending order of priorities: CS7 > CS6 > EF > AF4 > AF3 > AF2 > AF1 > BE.
  • If the BE queue uses PQ scheduling (rarely on live networks) but all the other seven queues use weighted fair queuing (WFQ) scheduling, the BE queue is of the highest priority.
  • If queues with eight service-class all use WFQ scheduling, the priority is irrelevant to WFQ scheduling.
NOTE:
More details about queue scheduling are provided later in this document.

Color

Color, referring to the drop precedence of packets on a device, determines the order in which packets in one queue are dropped when traffic congestion occurs. As defined by the Institute of Electrical and Electronics Engineers (IEEE), the color of a packet can be green, yellow, or red.

Drop precedences are compared based on the configured parameters. For example, if a maximum of 50% of the buffer area is configured to store packets colored Green, whereas a maximum of 100% of the buffer area is configured to store packets colored Red, the drop precedence of packets colored Green is higher than that of packets colored Red.

Trusting the Priority of Received Packets

As described in section Traffic Classifiers and Traffic Behaviors, after packets are classified on the DiffServ domain edge, internal nodes provide differentiated services for the packets that are classified. A downstream node can resume the classification result calculated on an upstream node or perform another traffic classification based on its own criteria. If the downstream node resumes the classification result calculated on an upstream node, the downstream node trusts the QoS priority (DSCP, IP precedence, 802.1p, or EXP) of packets that the interface connecting to the upstream node receives. This is called the mode of trusting the interface.

A NE20E does not trust the interface by default. After receiving a packet, a NE20E re-marks the service-class of the packet as BE and the color of the packet as Green, regardless of what QoS priority the packet carries.

DS Domain and Priority Mapping Table

A NE20E can perform QoS priority mapping based on the priority mapping table. Different DiffServ (DS) domains can have their own mapping tables. Administrators of a device can define DS domains and specify differentiated mappings for the DS domains.

A NE20E allows administrators to define a DS domain and has predefined the following domains:

  • Default domain: describes the default mappings between the external priority, service-class, and color of IP, VLAN, and MPLS packets.
  • 5p3d domain: describes the mappings between the 802.1p value, service-class, and color of VLAN packets. This domain applies to the 802.1ad-compliant local area network (LAN) that supports five scheduling precedence and three drop precedences.
    NOTE:

    IEEE defines eight PHBs (CS7, CS6, EF, AF4, AF3, AF2, AF1, and BE) and further defines four PHBs for three drop precedences. Therefore, the total number of PHBs is 16 (4 + 4 x 3 = 16).

    There are 64 DSCP values, allowing each PHB to correspond to a DSCP value. However, there are only eight 802.1p values, causing some PHBs not to have corresponding 802.1p values. Generally the eight 802.1p values correspond to the eight scheduling precedence. IEEE 802.1ad defines STAG and CTAG formats, with the STAG supporting Drop Eligible Indicator (DEI) whereas the CTAG does not. IEEE 802.1ad provides a 3-bit Priority Code Point (PCP) field that applies to both the CTAG and STAG to specify the scheduling and drop precedence. PCP allows an 802.1p value to indicate both the scheduling and drop precedences, and also brings the concepts of 8p0d, 7p1d, 6p2d, and 5p3d. The letter p indicates the scheduling precedence, and the letter d indicates the drop precedence. For example, 5p3d supports five scheduling precedences and three drop precedences.

The default and 5p3d domains exist by default and cannot be deleted, and only the default domain can be modified.

Priority Mapping Table for the Default Domain

The mapping between the external priority, service-class, and color on a NE20E is described as follows:

Table 6-4 Default mapping from the DSCP value to the service-class and color
DSCP Service-class Color DSCP Service-class Color
0~7 BE Green 28 AF3 Yellow
8 AF1 29 BE Green
9 BE 30 AF3 Red
10 AF1 31 BE Green
11 BE 32 AF4
12 AF1 Yellow 33 BE
13 BE Green 34 AF4
14 AF1 Red 35 BE
15 BE Green 36 AF4 Yellow
16 AF2 37 BE Green
17 BE 38 AF4 Red
18 AF2 39 BE Green
19 BE 40 EF
20 AF2 Yellow 41~45 BE
21 BE Green 46 EF
22 AF2 Red 47 BE
23 BE Green 48 CS6
24 AF3 49~55 BE
25 BE 56 CS7
26 AF3 57~63 BE
27 BE
Table 6-5 Default mapping from the service-class and color to the DSCP value
Service-class Color DSCP
BE Green 0
AF1 Green 10
AF1 Yellow 12
AF1 Red 14
AF2 Green 18
AF2 Yellow 20
AF2 Red 22
AF3 Green 26
AF3 Yellow 28
AF3 Red 30
AF4 Green 34
AF4 Yellow 36
AF4 Red 38
EF Green 46
CS6 Green 48
CS7 Green 56
Table 6-6 Default mapping from the IP Precedence/MPLS EXP/802.1p to the service-class and color
IP Precedence/MPLS EXP/802.1p Service-class Color
0 BE Green
1 AF1 Green
2 AF2 Green
3 AF3 Green
4 AF4 Green
5 EF Green
6 CS6 Green
7 CS7 Green
Table 6-7 Default mapping from the service-class and color to IP Precedence/MPLS EXP/802.1p
Service-class Color IP Precedence/MPLS EXP/802.1p
BE Green, Yellow, Red 0
AF1 Green, Yellow, Red 1
AF2 Green, Yellow, Red 2
AF3 Green, Yellow, Red 3
AF4 Green, Yellow, Red 4
EF Green, Yellow, Red 5
CS6 Green, Yellow, Red 6
CS7 Green, Yellow, Red 7

Priority Mapping Table for the 5p3d Domain

IEEE 802.1ad provided the PCP definition, as shown in the following figure.

Figure 6-6 PCP encoding/decoding

As shown in Figure 6-6, the number that ranges from 0 to 7 indicates the 802.1p value. The value in the format of number x+letter DE indicates that the 802.1p priority is x and the drop_eligible value is true. If the drop_eligible value is false, the drop precedence can be ignored. If the drop_eligible value is true, the drop precedence cannot be ignored.

The 5p3d domain on a NE20E uses an IEEE 802.1ad-compliant priority mapping table by default. Table 1-9 shows the mapping table that is designed to match the IEEE 802.1ad.

Table 6-8 IEEE802.1ad-compliant mapping table for the 5p3d domain
802.1p Value to Color Color to 802.1p Value
Drop_eligible defined in IEEE 802.1ad Color defined in a NE20E Color defined in a NE20E Drop_eligible defined in IEEE 802.1ad
false Green Green false
true Yellow Yellow, Red true

The default mapping between the 802.1p value, service-class, and color for the 5p3d domain on a NE20E is shown in Table 6-9 and Table 6-10.

Table 6-9 Mapping from the 802.1p value to the service-class and color
802.1p Service-class Color
0 BE Yellow
1 BE Green
2 AF2 Yellow
3 AF2 Green
4 AF4 Yellow
5 AF4 Green
6 CS6 Green
7 CS7 Green
NOTE:

The mapping from the 802.1p value to the service-class may apply to an inbound interface that belongs to a non-5p3d domain, leading to eight 802.1p values in Table 6-9. The outbound interface belongs to a 5p3d domain, leading to five service-classes in Table 1-10: BE, AF2, AF4, CS6, and CS7.

Table 6-10 Mapping from the service-class and color to the 802.1p value
Service-class Color 802.1p
BE Green 1
BE Yellow 0
BE Red 0
AF1 Green 1
AF1 Yellow 0
AF1 Red 0
AF2 Green 3
AF2 Yellow 2
AF2 Red 2
AF3 Green 3
AF3 Yellow 2
AF3 Red 2
AF4 Green 5
AF4 Yellow 4
AF4 Red 4
EF Green 5
EF Yellow 4
EF Red 4
CS6 Green/Yellow/Red 6
CS7 Green/Yellow/Red 7
NOTE:

In Table 6-10, the mapping from the service-class and color to the 802.1p value may apply to an inbound interface that uses a 5p3d domain or DSCP, EXP, or IP precedence as a basis for mapping, leading to eight service-classes. The outbound interface may use a non-5p3d domain, leading to eight 802.1p values.

IETF RFC Recommendation

IETF relevant standards classify services into 12 types (Table 6-11) based on service attributes and service quality requirements and provides recommendation on DSCP mappings (Table 6-12).

Table 6-11 Recommendation for traffic classification (Figure 2 in RFC)
Service Category Service Characteristics QoS Counters
Delay Tolerance Jitter Tolerance Packet Loss Rate Tolerance
Network Control Network control plane service flow, such as a routing protocol, VRRP, and RSVP-TE Low Low Yes
Telephony VoIP services (such as G.711 and G.729) Very Low Very Low Very Low
Signaling VoIP and video service signaling, such as SIP, SIP-T, H.323, and H.248 Low Low Yes
Multimedia Conferencing Desktop multimedia conference (including only voice and video. Data is classified as Low-Latency Data)

Low

-

Medium

Very Low Low
Real-Time Interactive Video conference (including only voice and video. Data is classified as Low-Latency Data), HD video, interactive game (using RTP/UDP) Low Very Low Low
Multimedia Streaming VoD

Low

-

Medium

Medium Yes
Broadcast Video Broadcast television, real-time video surveillance service Very Low Medium Low
Low-Latency Data Interactive important data services requiring quick response, such as VCX IP messaging, ERP, CRM, and DB. Low

Low

-

Medium

Yes
OAM Network O&M, maintenance, and management services, such as SNMP, Syslog, and SSH Low Medium Yes
High-Throughput Data Non-interactive background service, not requiring quick response, such as E-mail and FTP Low

Medium

-

High

Yes
Standard Default Internet services (best effort services). Services that are not marked with priorities can be classified into this category. Not Specified
Low-Priority Data Non-real-time elastic services, such as entertainment video traffic. If network congestion occurs, services of this category are dropped first. High High Yes
Table 6-12 Mappings from service types to DSCP values (Figure 3 in RFC)
Service Type DSCP Name DSCP Value Application Examples
Network Control CS6 110000(48) Network routing
Telephony EF 101110(46) IP Telephony bearer
Signaling CS5 101000(40) IP Telephony signaling
Multimedia Conferencing

AF41

AF42

AF43

100010(34)

100100(36)

100110(38)

H.323/V2 video conferencing (adaptive)
Real-Time Interactive CS4 100000(32) Video conferencing and Interactive gaming
Multimedia Streaming

AF31

AF32

AF33

011010(26)

011100(28)

011110(30)

Streaming video and audio on demand
Broadcast Video CS3 011000(24) Broadcast TV & live events
Low-Latency Data

AF21

AF22

AF23

010010(18)

010100(20)

010110(22)

Client/server transactions Web-based ordering
OAM CS2 010000(16) OAM & P
High-Throughput Data

AF11

AF12

AF13

001010(10)

001100(12)

001110(14)

Store and forward applications
Standard CS0 000000(0) Undifferentiated applications
Low-Priority Data CS1 001000(8) Any flow that has no BW assurance

Traffic Classification Recommendations from the 3GPP

As defined in TS23.203 by the 3GPP, wireless services are classified as nine classes with specific QoS class identifiers (QCIs). Each QCI indicates the QoS requirements of one class, including the resource type, priority, delay, and packet loss rate. QCIs standardize the QoS requirements. The EPS controls QoS based on QCIs. QCIs are transmitted between NEs so that QoS parameters do not have to be negotiated or transmitted. QCIs are applied only to wireless NEs but are invisible at the bearer layer.

3GPP recommendations
Table 6-13 Traffic classification recommendations from the 3GPP (Table 6.1.7 in 3GPP TS23.203)
QCI Resource Type Priority Data Packet Delay Packet Error Rate and Loss Rate Typical Service
1 GBR 2 100 ms 10-2 Conversational voice
2 4 150 ms 10-3 Conversational video (real-time)
3 3 50 ms 10-3 Online games
4 5 300 ms 10-6 Non-conversational video (buffered streaming media)
5 Non-GBR 1 100 ms 10-6 IMS signaling
6 6 300 ms 10-6 Video (buffered streaming) and TCP-based applications such as WWW, emails, chat, FTP, p2p file sharing, and progressive scanning video)
7 7 100 ms 10-3 Voice, video (live streaming), and interactive game
8 8 300 ms 10-6 Video (buffered streaming) and TCP-based applications such as the WWW Internet access, email, chat, FTP, p2p file sharing, progressive scanning video)
9 9

The 3GPP does not provide any recommendations on mappings between QCIs and DSCP values. For Huawei's recommendations, see Table 6-14.

Table 6-14 Recommended priority mappings for LTE services
Service Type QCI Resource Type Typical Service DSCP 802.1p/MPLS EXP PHB
User Plane 1 GBR Conversational voice 0x2E(46) 5 EF
2 Conversational video 0x1A(26) 3 AF31
3 Online games 0x22(34) 4 AF41
4 Non-conversational video 0x1A(26) 3 AF31
5 non-GBR IMS signaling 0x30(48) 5 EF
6 Video (buffered streaming) and TCP-based applications such as WWW, email, chat, FTP, p2p file sharing, and progressive scanning video) 0x12(18) 2 AF21
7 Voice, video (live streaming), and interactive game 0x12(18) 2 AF21
8 Video (buffered streaming) and TCP-based applications such as WWW, email, chat, FTP, p2p file sharing, and progressive scanning video) 0x0A(10) 1 AF11
9 0x00(00) 0 BE
Control Plane - SCTP 0x2E(46) 5 EF
OM - Man-machine language (MML) 0x2E(46) 5 EF
- FTP 0x0E(14) 1 AF11
IP Clock - 0x2E(46) 5 EF

Traffic Classification Recommendations from the GSMA

The GSMA classifies traffic as four types: conversational, streaming, interactive, and background traffic. The GSMA recommends that the four traffic types be mapped to six DSCP values recommended by the IETF. For details, see Table 6-15 and Table 6-16.

Table 6-15 Mappings between traffic types and DSCP values (Table 6 in GSMA IR34)
Traffic Type QoS Information
THP(Traffic Handing Priority) PHB DSCP
Conversational N/A EF 101110 (46)
Streaming media N/A AF41 100010 (34)
Interactive 1 AF31 011010 (26)
2 AF21 010010 (18)
3 AF11 001010 (10)
Background N/A BE 000000 (0)
Table 6-16 Mappings between service applications and DSCP values (Table 7 in GSMA IR34)
Service Application Diffserv PHB Traffic Type
Video sharing EF Conversational
VoIP EF Conversational
Push-to-Talk AF4 Streaming media
Video streaming AF4 Streaming media
GTP traffic that cannot be identified AF3 Interactive
DNS AF3 Interactive
Online games AF3 Interactive
Webpage browsing AF2 Interactive
Instant messaging (IM) AF1 Interactive
Remote connection AF1 Interactive
Email, MMS BE Background

Traffic Classification Recommendations from the IEEE 802.1

As defined in the IEEE 802.1 standard (including the 802.1D, 802.1Q, and 802.1ad), services are classified as eight classes based on the PCP field (3 bits) in the VLAN tag.

Table 6-17 Traffic classification recommendations from the IEEE 802.1
Traffic Type Priority Example Protocol Service Characteristics
Network Control 7 BGP, PIM, SNMP Network maintenance and management packets that must be transmitted in a reliable manner, with a low packet loss rate
Internet Work Control 6 STP, OSPF, RIP Network protocol control packets that are differentiated from common packets on large-scale networks
Voice 5 SIP, MGCP Voice services that generally require delay of less than 10 ms
Video 4 RTP Video services that generally require delay of less than 100 ms
Critical Applications 3 NFS, SMB, RPC Services that require the minimum bandwidth to be guaranteed
Excellent Effort 2 SQL Used for an information organization to send messages to the most important customers.
Best Effort 0(default) HTTP, IM, X11 Default service types, requiring only best-effort service quality
Background 1 FTP, SMTP Batch transmission services that do not affect users or key applications

Traffic Classification Recommendations from the MEF

The MEF 23.1 standard classifies services as high-priority (H), medium-priority (M), and low-priority (L) services and uses CoS labels and drop eligibility identifiers (DEIs). For details, see Table 6-18.

The MEF 23.1 standard also provides recommended mappings between CoS labels and DSCP values. For details, see Table 6-19 and Table 6-20.

Table 6-18 Service prioritizing (Table 36 in MEF 23.1)
Service Type COS Label
VoIP H
VoIP & videoconf signaling M
Videoconf data M
IPTV data M
IPTV control M
Streaming media L
Interactive gaming H/M
SANs synch replication M
SANs asynch replication M
Network attached storage L
Text & graphics terminals L
T.38 fax over IP M
Database hot standby M
Database WAN replication M
Database client/server L
Financial/Trading H
CCTV H
Telepresence H
Circuit Emulation H
Mobile BH H H
Mobile BH M M
Mobile BH L L
Table 6-19 Color IDs when the CoS ID type is only EVC or OVC EP (Table 3 in MEF 23.1)
CoS Label CoS ID Type Color ID
C-Tag PCP PHB (DSCP)
Color Green Color Yellow Color Green Color Yellow
H EVC or OVC EP 5, 3 or 1 N/S in Phase 2 EF or AF (10, 26 or 46) N/S in Phase 2
M EVC or OVC EP 5, 3 or 1 2 or 0 EF or AF (10, 26 or 46) AF (0, 12, 14, 28 or 30)
L EVC or OVC EP 5, 3 or 1 2 or 0 EF or AF (10, 26 or 46) AF (0, 12, 14, 28 or 30)
Table 6-20 CoS and Color ID (Table 4 in MEF 23.1)
CoS Label CoS and Color ID
C-Tag PCP PHB (DSCP) S-Tag PCP (DEI not supported) S-Tag PCP
Color Green Color Yellow Color Green Color Yellow Color Green Color Yellow DEI supported
H 5 N/S in phase 2 EF(46) N/S in phase 2 5 N/S in phase 2 5
M 3 2 AF31(26) AF32(28) 3 2 3
AF33(30)
L 1 0 AF11(10) AF12(12) 1 0 1
AF13(14)
DF(0)

Recommendations from the ITU-T

As defined in Y.1541 by the ITU-T, services can be classified as six classes numbered 0 to 5 (see Table 6-21) based on the four parameters: IPTD, IPDV, IPLR, and IPER. For details about IP QoS guidance, see Table 6-22 and Figure 6-7.

Table 6-21 IP network QoS type definitions and network performance counters (Table 1 in ITU-T Y.1541)
Network Performance Parameter Network Performance Target QoS Type
Class 0 Class 1 Class 2 Class 3 Class 4 Class 5 Unspecified
IPTD Upper limit for the average IPTD 100 ms 400 ms 100 ms 400 ms 1 s Not required
IPDV Minimum value of IPTDx(1-10-3)-IPTD 50 ms 50 ms Not required Not required Not required Not required
IPLR Upper limit for IPLR 1 x 10–3 1 x 10–3 1 x 10–3 1 x 10–3 1 x 10–3 Not required
IPER Upper limit for IPER 1 x 10–4 Not required
Table 6-22 IP QoS classification guide (Table 2 in ITU-T Y.1541)
QoS Class Application Network Node Mechanism Technology
0 Real-time, jitter-sensitive, and highly interactive services, such as VoIP and VTC Independent queues, high service priority, and traffic grooming Restrictions
1 Real-time, jitter-sensitive, and highly interactive services, such as VoIP and VTC Constraint route and distance
2 The transaction (handling) data, and highly interactive services (such as the signaling) Independent queues, and low packet loss rate Constraint route and distance
3 Transaction data and interactive service Constraint route and distance
4 Services that require only low packet loss rates, such as short transaction data, batch data, and video streams Long queue, low packet loss rate Any route/path
5 Default traditional applications on IP networks Independent queue (lowest service priority) Any route/path
Figure 6-7 Multi-service classification based on a few QoS types (Figure 2 in ITU-T Y.1541)

MPLS DiffSev

On an MPLS network, EXP values are used to identify a maximum of eight service priorities. If there are more than eight types of services, multiple types must be aggregated to one PHB.

Relevant standards reclassify services as four types and provides recommended DSCP and EXP values. For details, see Table 6-23.

Table 6-23 Treatment Aggregate and MPLS EXP Field Usage (Figure 2 and Figure 3 in RFC)
Service Type PHB DSCP Four-Type QoS Counter Exp
Binary (Decimal Notation) Delay Tolerance Jitter Tolerance Packet Loss Rate Tolerance Binary (Decimal Notation)
Network Control CS6 110000(48) Network Control Low Low Yes 110(6)
Telephony EF 101110(46) Real-Time Very Low Very Low Very Low 100(4)
CS5 101000(40)
AF41 100010(34)
Signaling AF42 100100(36)
Multimedia Conferencing AF43 100110(38)
Real-Time Interactive CS4 100000(32)
Broadcast Video CS3 011000(24)
Multimedia Streaming CS2 010000(16) Assured Elastic Low Low – Medium Yes 010(2)
AF31 011010(26)
AF21 010010(18)
Low-Latency Data AF11 001010(10)
OAM AF32 011100(28) 011(3)
AF22 010100(20)
AF12 001100(12)
AF33 011110(30)
AF23 010110(22)
High-Throughput Data AF13 010110(14)
Standard Default (CS0) 000000(0) Elastic Not Specified 000(0)
Low-Priority Data CS1 001000(8) 001(1)
Translation
Download
Updated: 2019-01-03

Document ID: EDOC1100055126

Views: 7271

Downloads: 17

Average rating:
This Document Applies to these Products
Related Documents
Related Version
Share
Previous Next