1999.12.9
손장우
son@netmanias.com
www.netmanias.com
Netmanias Confidential
Internet backbone에선...
.순수라우터기반인터넷구조
.IP over ATM overlay 구조
.고속라우터기반인터넷구조
.MPLS
.Gigabit Router Vendors 현황분석
.Terabit Router Vendors 현황분석
.국내ISP 및Vendor 현황분석
Netmanias Confidential
순수라우터기반인터넷백본구조
액세스네트워크
(PSTN, ADSL)
LAN/Campus/Enterprise네트워크
백본라우터
에지라우터
L3
L3
L3
L3
L3
.순수라우터기반인터넷백본구조: 1996년정도까지는이구조가주류
.Problem
.인터넷사용자증가.전송링크용량증가, 전송링크및라우터증설
.Low performance router가네트워크성능에병목이됨.(low forwarding rate, Low switching capacity)   L3 processing
.최단경로를선호하는IGP .Traffic engineering(트래픽분산) 문제발생
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
Netmanias Confidential
IP over ATM overlay architecture
액세스네트워크(PSTN, ADSL)
LAN/Campus/
Enterprise
네트워크
ATM PVCs
IP over ATM overlay model: 1997-98년경에도입
각라우터를PVC로
full mesh 연결
ATM core
L2 ATM switching:
암것두안하니까빨라!
L3
L3
(1) 네트워크의Edge에라우터를두고Core에ATM 스위치를둠.(2) 각라우터를ATM PVC로full mesh 연결(3) ATM 네트워크는라우터에게고속연결성을제공
Overlay 구조의장점(1) Edge의라우터에서만Layer 3 IP forwarding 수행하고core에서는H/W기반ATM 스위칭만수행(one-hop으로각라우터연결)(2) PVC 설정시, 트래픽부하가ATM 네트워크에균등히분산되도록설정.Traffic engineering !(3) ATM의BW 할당능력: 1.5Mbps ~ 622Mbps
IP Forwarding
IP Forwarding
Netmanias Confidential
IP over ATM overlay architecture
.IP/AAL5/ATM/SONET 구조:
.IP network / ATM network / SONET 전송망: 관리의어려움, 중복투자
.PVC full-mesh로각라우터를연결.VC 확장성문제, 라우터가N개면O(N2)개의VC이필요.
.Routing adjacency문제로에지라우터가단일홉으로다른모든에지라우터와ATM PVC를통해연결되어있으므로하나의라우터에라우팅정보가갱신되면다른모든라우터의라우팅정보가갱신되어야하는데여기에소요되는route update complexity가O(N3)으로매우복잡하고라우팅테이블이안정화되는데긴시갂이소요
.ATM cell tax .25% of SONET bandwidth, waste
.AAL SAR chip 구현이OC-48급, OC-192급의link를지원하기어렵다.
.more: see http://aims.iae.re.kr/~jwson/bb.htm
FR/ATM/
Leased line
FR/ATM/Leased line
Router
ATM교환기
SONET
or DWDM
ADM
SONET링
or DWDM링
ISP POP/CO(혜화전화국)
CO
(남수원
전화국)
CO
ISP POP/CO
ISP POP
Enterprise
Campus
VoIP GW
RAS/RADIUS
ADSL
RAS
Dialupmodem
VoIP GW
RAS/RADIUS
Access
VoIP GW
RAS/RADIUS
ISP POP
VoIP GW
RAS/RADIUS
CO
ADSL
Campus
Edge
Core
FR/ATM/Leased line
DSLAM
RAS
DSLAM
DSLAM
ADSL
RAS
DSLAM
Dialup
modem
ADSL
Netmanias Confidential
IP over ATM overlay architecture
Packet-size distribution in the Internet backbone
IP packet size[Byte]     Total packets [%]      Total bytes [%]
40                          38.9                           4.4
1,500                          11.5                         48.7
552                          10.1                         15.8
44                            6.1                           0.8
576                            4.9                           7.9
Percentage of PPP/HDLC and ATM overhead
IP packet size[Byte] IP over SONET overhead [%]  ATM overhead [%]
40                                 20.0                                   165.0
1,500                                   0.5                                     13.1
552                                   1.4                                     15.2
44                                 18.2                                   140.9
576                                   1.4                                     19.6
25%
2%
IP over ATM overlay
IP over SONET/SDH
즉, 2.5 Gbps의OC-48 링크중ATM cell tax로낭비되는대역폭은625 Mbps로OC-12 링크하나분에해당하며PPP/HDLC tax로
낭비되는대역폭은50 Mbps로DS-3 링크하나분에해당한다. 이와같은관측에서보면현재와같이실인터넷트래픽이
기가급에이른상황에서인터넷백본에서ATM을사용하는경우대단히비효율적임을알수있다.
Netmanias Confidential
Gigabit/Terabit Router-based IP backbone
고속라우터(스위칭라우터)의등장: 1998-1999
액세스네트워크
(PSTN, ADSL)
LAN/Campus/Enterprise네트워크
백본라우터
에지라우터
할것다하는데빨라!
L3
L3
L3
L3
L3
액세스네트워크(PSTN, ADSL)
LAN/Campus/
Enterprise
네트워크
백본라우터
에지라우터
L3
L3
L3
L3
L3
라우터내의Data-path (forwarding engine, Switching fabric, QoS scheduling engine)을H/W화
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
IP Forwarding
Netmanias Confidential
Gigabit/Terabit Router-based IP backbone
FR/ATM/Leased line
FR/ATM/
Leased line
SONET링or DWDM링
ISP POP/CO
(혜화전화국)
CO
(남수원
전화국)
CO
ISP POP/CO
ISP POP
Enterprise
Campus
VoIP GW
RAS/RADIUS
ADSL
RAS
Dialup
modem
VoIP GW
RAS/RADIUS
Access
VoIP GW
RAS/RADIUS
RAS/RADIUS
CO
ADSL
Campus
Edge
Core
FR/ATM/
Leased line
DSLAM
RAS
DSLAM
DSLAM
ADSL
RAS
DSLAM
Dialupmodem
ADSL
ISP POP
VoIP GW
Router
SONETor DWDMADM
기가/테라
라우터
.고속라우터(IP/SONET) 구조는
.기존의라우터기반구조에비해,
.S/W 기반포워딩.1Mpps이상의고속포워딩제공(ASIC, Dedicated processor,...)
.공유버스(shared backplane) .Switching fabric 사용(CXB,...), 수십Gbps~Terabit/sec의스위칭용량제공.
.더이상라우터가인터넷의병목이아니다. 즉, 빨라졌다. (Routing protocol은그대로)
.IP over ATM overlay 구조에비해,
.IP network / ATM network / SONET 전송망: 관리의어려움, 중복투자.ATM 생략!
.PVC full-mesh로각라우터를연결로인한VC 확장성문제: .X
.Routing adjacency : adjacency 수대폭감소
.ATM cell tax 문제(25% of SONET bandwidth): .POS (Packet-over SONET) 2% overhead
Netmanias Confidential
MPLS-based IP backbone
FR/ATM/
Leased line
FR/ATM/
Leased line
MPLS
SONETor DWDMADM
SONET링
or DWDM링
ISP POP/CO(혜화전화국)
CO
(남수원
전화국)
CO
ISP POP/CO
ISP POP
Enterprise
Campus
VoIP GW
RAS/RADIUS
ADSL
RAS
Dialup
modem
VoIP GW
RAS/RADIUS
Access
VoIP GW
RAS/RADIUS
ISP POP
CO
ADSL
Campus
Edge
Core
FR/ATM/Leased line
DSLAM
RAS
DSLAM
DSLAM
ADSL
RAS
DSLAM
Dialup
modem
ADSL
VoIP GW
RAS/RADIUS
.IP/MPLS/ATM or SONET or DWDM 구조:
.탁월한확장성.
.Explicit routing  .Traffic engineering, VPN, QoS 제공
MPLSLSR
Netmanias Confidential
In my opinion, ...
.Core
.IP/(MPLS)/ATM/SONET(Past) .IP/(MPLS)/SONET(Current)  .IP/(MPLS)/DWDM .(Future)
.Access
.FR or ATM .ATM  (ADSL)
.Enterprise/Campus
.ATM(MPOA) or Layer 3 Switch + Gigabit Ethernet .~