TP ON BU CHNH VIN THNG VIT NAM HC VIN CNG NGH BU CHNH VIN THNG

VIN KHOA HC K THUT BU IN

BO CO CHUYN 5.1

Thuc nhim v: 003-2006-T-VT

Tn chuyn :

XY DNG TIU CHUN K THUT CHO DCH V ETHERNET L2VPN TRN MNG MAN ETHERNET

MPLS + yu cu v cu trc phn lp

Nhng ngi thc hin chnh: Hong Vn Bnh CV Ban Vin thng

H ni 2007

MC LC 1. Ti liu trch dn v tham kho ............................................................................3 2. Cc nh ngha v khi nim ................................................................................3 3. Cc thut ng vit tt............................................................................................4 4. Ethernet-MPLS interworking ...............................................................................4 5. Cc yu cu...........................................................................................................5 5.1. Cc yu cu v User plane ...................................................................................5 5.2. Cc yu cu v Control plane...............................................................................6 5.3. Cc yu cu v Management plane ......................................................................6 5.4. Cc yu cu v Traffic Management....................................................................7 6. Cc th tc............................................................................................................9 6.1. ng gi ...............................................................................................................9 6.2. X l cc khung Ethernet ti ingress IWF .........................................................10 6.3. X l gi MPLS ti egress IWF.........................................................................10

1. Ti liu trch dn v tham kho [2] IEEE 802.3-2002, IEEE Standard for Information technology Telecommunications and Information Exchange between Systems Local and Metropolitan Area Networks Specific Requirements Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications. [3] ITU-T Recommendation G.809 (2003), Functional architecture of connectionless layer networks. [4] ITU-T Recommendation Y.1411 (2003), ATM-MPLS network interworking Cell mode user plane interworking. [5] IEEE 802.1Q-2003, IEEE standards for local and metropolitan area networks: Virtual bridged local area networks. [6] IETF RFC 3031 (2001), Multiprotocol label switching architecture. [7] ITU-T Recommendation G.8012/Y.1308 (2004), Ethernet UNI and Ethernet NNI. [8] ITU-T Recommendation G.805 (2000), Generic functional architecture of transport networks. [9] IEEE 802.1D-2004, IEEE standard for local and metropolitan area networks: Media Access Control (MAC) Bridges. [10] ITU-T Recommendation Y.1710 (2002), Requirements for Operation & Maintenance functionality in MPLS networks. [11] ITU-T Recommendation Y.1711 (2004), Operation & Maintenance mechanism for MPLS networks. [12] ITU-T Recommendation Y.1730 (2004), Requirements for OAM functions in Ethernet-based networks and Ethernet services. [13] IETF RFC 3032 (2001), MPLS Label Stack Encoding. [14] ITU-T Recommendation G.8011.1/Y.1307.1 (2004), Ethernet private line service.

2. Cc nh ngha v khi nim Trong tiu chun ny c s dng mt s khi nim sau: 1 egress IWF: L IWF trong Ethernet frames c trch ra t MPLS packets (Hng MPLS-to-Ethernet). 2 flow: Xem trong tiu chun ITU-T Rec. G.809 [2]. 3 ingress IWF: L IWF trong Ethernet frames c ng gi vo MPLS packets (Hng Ethernet-to-MPLS). 4 interworking: Xem trong tiu chun ITU-T Rec. Y.1411 [3]. 5 Interworking Function (IWF): Xem trong tiu chun ITU-T Rec. Y.1411 [3].

3. Cc thut ng vit tt

AP Access Point ATM Asynchronous Transfer Mode DIX DEC/Intel/Xerox ETH Ethernet EXP Experimental Bits FCS Frame Check Sequence FIFO First-In First-Out IWF Interworking Function LSP Label Switched Path LSR Label Switching Router MAC Medium (Media) Access Control MPLS Multi-Protocol Label Switching MTU Maximum Transport Unit OAM Operation and Maintenance PDU Protocol Data Unit QoS Quality of Service RFC Request For Comments S-bit Stack bit STP Spanning Tree Protocol TCP Termination Connection Point TDM Time Division Multiplexing TTL Time To Live

4. Ethernet-MPLS interworking Cng ngh chuyn mch nhn a giao thc (MPLS) [5] cho php nhiu cng ngh nh IP, ATM, frame relay, TDM v Ethernet c th c h tr trn cng mt h tng mng. Tiu chun ny dnh ring cho mng interworking ca MPLS vi Ethernet. Hnh 1 trnh by cu trc chung ca mt mng Ethernet-MPLS interworking trong Ethernet c kt ni xuyn qua mng MPLS. i vi hng Ethernet-to-MPLS. Cc Ethernet frame c ng gi vo mt MPLS packet thng qua chc nng interworking (IWF). i vi hng MPLS-to-Ethernet, cc Ethernet frame c cu trc li t cc MPLS packet thng qua IWF. V mt kin trc, chc nng Ethernet-to-MPLS IWF c t ti mt im tham chiu Network-Network Interface (NNI) [6]. Hnh 2 m t cu trc chc nng ca mng Ethernet-MPLS interworking s dng k thut m t bng biu ca ITU-T Rec. G.805 [7]. Hnh 3 m t m hnh tham chiu v phn lp chc nng ca mt phng ngi s dng Ethernet-MPLS interworking.

Hnh 1 Cu trc chun ca mng Ethernet-MPLS interworking

Hnh 2 Cu trc chc nng ca mng Ethernet-MPLS interworking m t theo

cc quy c biu ITU-T Rec.G.805

Hnh 3 M hnh tham chiu mng v phn lp th tc cho Ethernet-MPLS

user plane interworking

5. Cc yu cu

5.1. Cc yu cu v User plane truyn cc Ethernet frame trong user plane, yu cu h thng phi c cc chc nng sau:

a) Kh nng truyn ti nhiu Ethernet flow trong cng mt Interworking LSP b) Kh nng truyn ti cc khung Ethernet c hoc khng c FCS (Frame Check Sequence) c) Duy tr nguyn vn Ethernet frame sequence d) H tr cc traffic contract v QoS commitment c thit lp bi cc kt ni Ethernet e) H tr cc kt ni point-to-point theo hai hng gia hai IWF vi bng thng i xng hoc khng i xng

5.2. Cc yu cu v Control plane truyn cc Ethernet frame, cc chc nng sau cn c cung cp:

a) Chuyn i mt hoc nhiu Interworking label gia cc IWF b) S tng quan ca Interworking label i vi mt kt ni hai hng cho mi Interworking LSP. Cc c ch phi c nh ngha c) S lin kt ca mi Interworking LSP label vi mt Transport LSP label; d) Kh nng ca hai IWF c th chuyn i MTU size c th c cung cp e) Kh nng biu th nu FCS c gi li nh mt phn ca payload ca Interworking LSP f) C cc hin th v tnh trng v s dng ca Common interworking g) Kh nng ca IWF ngu nhin kim tra user priority field ca tagged Ethernet frame [8] quyt nh yu cu QoS v nh du MPLS packet thch hp

5.3. Cc yu cu v Management plane Chc nng interworking h tr truyn thng tin v s c t server mng MPLS n client mng Ethernet. Chc nng OAM trong cc mng MPLS v cc c ch OAM cho cc mng MPLS c quy nh trong tiu chun ITU-T Recs Y.1710 v Y.1711. Vic truyn dn thng tin s c khng nn trong ni dung tiu chun ny. Cc yu cu i vi cc chc nng OAM trong mng nn Ethernet v mng dch v Ethernet c quy nh trong ITU-T Rec. Y.1730. Cc thng tin user-to-user OAM v provider OAM c truyn trong sut khi c mt trong mt khung Ethernet.. thc hin truyn thng sut thng tin lin quan n Ethernet trong mt phng qun l, chc nng interworking cn h tr truyn dn hoc ghp cc thng s hiu sut QoS gia mng Ethernet v mng MPLS. Kiu ghp nh vy c th da trn vic la chn mt LSP truyn dn vi QoS tng ng ca dch v Ethernet.

5.4. Cc yu cu v Traffic Management Ethernet client layer ch truyn traffic n IWF tun theo traffic contract. Nu Ethernet client vt qu traffic contract v IWF tr nn nghn, data c th b loi b. Hnh 4 cung cp mt th d minh ha ca functional grouping cho mng Ethernet-MPLS interworking.

Hnh 4 Ethernet-MPLS interworking functional groups

Transport label 4-octet trong Transport label nhn din mt LSP c s dng truyn traffic gia hai IWF. Transport label l mt shim header MPLS tiu chun, c quy nh trong IETF RFC 3032 [12], v c x l bi LSR c trnh by trong IETF RFC 3032 [12]. S bit c t l "0" biu th y khng phi l cui ca label stack. Vic thit lp ca EXP fields khng nm trong gii hn ca khuyn ngh ny. Vic thit lp ca TTL fields khng nm trong gii hn ca khuyn ngh ny. Cc th tc thit lp Transport LSP khng nm trong gii hn ca khuyn ngh ny. Khi cc LSP l n hng v Ethernet l song hng, yu cu phi c hai Transport LSP, theo tng ng phi c hai Transport label cho mng Ethernet-MPLS interworking. Interworking label Interworking function lin kt vi mt Interworking LSP label vi mi Ethernet connection. 4-octet Interworking label nhn din n nht mt Interworking LSP c truyn ti bn trong mt Transport LSP. The Interworking label l mt shim header MPLS tiu chn, theo IETF RFC 3032 [12]. Nhiu Interworking LSP c th c cung cp bi mt Transport LSP. Interworking label c x l ch ti ingress hoc egress IWF. S bit c t l "1" biu th y ca label stack. Thit lp EXP field cn ang c nghin cu tip. TTL field khng c t thp hn 2. Cc th tc thit lp Interworking LSP khng nm trong gii hn ca khuyn ngh ny. Khi cc LSP n hng v Ethernet hai hng, yu cu hai Interworking LSP, tng ng vi n l hai Interworking label cho mng Ethernet-MPLS interworking. Cc biu th Common interworking

Cc chc nng biu th Common interworking lin quan n Interworking LSP. Ni chung trong mng interworking MPLS, Cc chc nng Common interworking indicators bao gm Control field, Fragmentation, Length field v Sequence number field. Vic s dng Common interworking indicators ty chn, c th s dng tt c cc fields. Hnh 5 trnh by cu trc ca Common interworking indicators.

Hnh 5 Common interworking indicators theo nhm chc nng

Control field Field ny khng c dng trong khuyn ngh ny. Fragmentation and Length fields Field ny khng c dng trong khuyn ngh ny. Fragmentation field 2-bit ca Fragmentation field biu th nu bt k fragmentation ca original frame c hon thnh p ng cc yu cu ca MTU. Field ny khng c dng trong khuyn ngh ny. Length field 6-bit ca Length field biu th di ca payload so snh v m cho MPLS packet. Field ny khng c dng trong khuyn ngh ny. Sequence number field Sequence number field c s dng kim tra sequence integrity ca MPLS packets gi t ingress IWF n egress IWF. Khi Ethernet services c truyn trn nn mng MPLS based, yu cu mng MPLS duy tr sequence integrity ca Ethernet frames encapsulated trong MPLS packets. Mc d s dng phng thc "first in first out" (FIFO), vn c kh nng xut hin s mt trt t. Sequence number field c th c thit lp ti IWF theo hng Ethernet-to-MPLS. Sequence number gm 2-octet field s dng 16-bit, unsigned circular space. Gi tr sequence number "0" c s dng biu th thut ton kim tra sequence number khng c s dng. Thit lp sequence numbers Nu sequence number field c s dng, cc th tc sau c thit lp theo hng Ethernet-to-MPLS: sequence number c t l 1 cho MPLS packet u tin c truyn trong Interworking LSP. vi mi subsequent MPLS packet, sequence number tng ln 1. Nu gi tr sequence number l 65535 i vi MPLS packet hin ti, sequence number s c t l 1 vi MPLS packet tip theo. Nu ingress IWF khng s dng sequence number, sequence number field s c t l 0. X l sequence numbers

Mc ch ca x l sequence number pht hin cc packet li v tr. Nu IWF c kh nng qun l sequence integrity, th cc th tc sau s c thc hin. Khi mt Interworking LSP c thit lp ban u, "expected sequence number" tng ng vi n l 1. Nu sequence number l "0", sequence integrity ca packets khng th c xc nh bi IWF. Trong trng hp ny, packet nhn c c xem l theo ng trt t. Trng hp nu sequence number = the expected sequence number v sequence number the expected sequence number < 32768, packet nhn c c xem l theo ng trt t. Trng hp sequence number < the expected sequence number v expected sequence number the sequence number = 32768, packet nhn c c xem l theo ng trt t. Trng hp khc, packet nhn c c xem l sai trt t. Nu packet nhn c c xem l theo ng trt t, expected sequence number = the sequence number +1 mod 2 . Nu expected sequence number = 0, th expected sequence number = 1. Nu mt IWF khng h tr receive sequence number processing, sequence number field c th b qua.

6. Cc th tc Phn ny cung cp cc th tc cho encapsulating Ethernet frames vo MPLS packets ti ingress IWF v retrieving Ethernet frames t MPLS packets ti egress IWF.

6.1. ng gi Ingress IWF c chc nng to cc MPLS packet theo nh dng sau. Hnh 6 v 7 trnh by khun dng MPLS packet cho Ethernet frame encapsulation c v khng s dng Common interworking indicators.

Hnh 6 Ethernet frame encapsulation c Common interworking indicators

Hnh 7 Ethernet frame encapsulation khng Common interworking indicators

Transport label Ingress IWF s dng Transport label. Interworking label Ingress IWF s dng Interworking label Common interworking indicators Khi Common interworking indicators c s dng, cc th tc sau c thc hin. Control field Control field cho mng ETH-MPLS interworking t l "0" bi ingress IWF v c b qua ti egress IWF. Fragmentation and Length fields Cc fields ny khng c s dng trong khuyn ngh ny. Chng c t l "0" bi ingress IWF v b qua ti egress IWF. Sequence number field Cc th tc thit lp v x l c trnh by trn.

6.2. X l cc khung Ethernet ti ingress IWF Khi Ethernet frames ti ingress IWF chng c kim tra framing v FCS errors. Nu c li c pht hin, frame s b loi. Preamble b loi b v ty chn FCS b loi b. Tip theo n xc nh resulting frame c phi l IEEE 802.3 control protocol PDU. Trong trng hp ng, tin trnh x l tun theo layer 2 control processing trong ITU-T Rec. G.8011.1/Y.1307.1 [13].

6.3. X l gi MPLS ti egress IWF Khi mt gi MPLS ti egress IWF, labels v Common interworking indicators c x l nh trnh by cc mc trn v c loi b. Nu FCS c duy tr bi ingress IWF th FCS c kim tra v nu c pht hin li th chm dt qu trnh x l. Nu khng c li th qu trnh kim tra resulting frame c phi IEEE 802.3 control protocol PDU hay khng. Nu ng th qu trnh tip theo tun theo layer 2 control processing trong ITU-T Rec. G.8011.1/Y.1307.1 [13]. Nu FCS b loi b, qu trnh m li v sp xp vo frame. Ethernet frame c ti thit lp truyn trong mng Ethernet