Cristina Vistoli12 Maggio 19981 APPLICAZIONI TECNOLOGIA ATM zATM su LAN -- Classical IP e LANE...

Cristina Vistoli 12 Maggio 1998 1

APPLICAZIONI TECNOLOGIA ATM

ATM su LAN -- Classical IP e LANE

Cristina VistoliINFN-CNAF

[email protected]



RFC 1577

Router

ATM Network circondata la dispositivi di livello 3 : Router

Classical IP

ATM Network come una IP Subnetwork

ATM su LAN



Classical IP:RFC 1577 considera l’uso di ATM come una sostituzione dei "wires”(fili) e considera le LAN come un insieme di segmenti che connettono le IP end-stations ed i router.

L’indirizzo IP e’ utilizzato per definire la sottorete (LIS) a cui appartiene la workstation. Le end-stations nella stessa rete (LIS) possono comunicare direttamente, due end-stations in due diverse sottoreti (LIS) hanno bisogno di un router per comunicare.Si chiama Classical IP perche’ ha lo stesso comportamento di una normale rete IP.



Classical IP:Il classical IP puo’ essere configurato sia in presenza di ATM-SVC che ATM-PVC.Nel caso di ATM-SVC, un end-station deve essere configurato come ARP server mentre tutte le stazioni devono essere configurate come client di tale server.ARP: Address Resolution Protocol : indirizzo IP - ATM(MAC) Address



Classical IP:

+Vantaggio: Poco overhead di servizi, Possibilita’ MTU grandi in modo da ridurre l’overhead di protocollo ed ottenere prestazioni prossime al valore teorico

-Svantaggio:Limitato alle end-station con interfacce ATM appartenenti ad una unica sottorete



Phy Phy Phy Phy

SSCOPSSCOP

Q.2931Q.2931

NNI Convg

P-NNI

TCP

IP

SSCOPSSCOP

Q.2931Q.2931

SSCOP

Q.2931

NNINNI Convg Convg

P-NNIP-NNI

SSCOPSSCOP

Q.2931Q.2931

ATM Switch ATM Switch ATM Host/Router

AAL 5 AAL 5

RFC 1483 Encapsulation

AAL 5

ATM ATM ATM

Phy

ATM

Phy

ATMPhy

UNISignal-

ing

ATM Routing (P-NNI Protocol)

Virtual LANs (LAN Emulation)

Native Mode Routing Protocols

NNISignal-

ing

UNISignal-

ing

ATM Host/Router

TCP

IP

RFC 1483 Encapsulation

AAL 5

ATM

Phy

MACMAC



LAN Emulation Clients (LEC)

LAN Emulation ServiceLANE Configuration Server (LECS)

Initialization

LAN Emulation Server (LES)

Address Resolution

Broadcast and Unknown Server (BUS)

Data Flooding



LAN Switch

ATM circondata da dispositivi di Livello 2: Switching (tutti i protocolli)Adatto per desktop, edifici e campus (via LANE Version 1)

LANE

ATM Network as a Layer 2

LAN

Lan switch: E’ un dispositivo che assegna ad ogni utente dello switch una connessione di rete dedicata e ad alta velocita’. E’ diverso da un HUB in cui le risorse di rete sono “shared”.



LANE

LAN Switch

Ethernet Ethernet

LAN Switch

Router

ATMNetwork

Connettivita’:Connettivita’: Ethernet to Ethernet attraverso ATMEthernet to ATMATM to ATM

LAN Emulation e’ una possibile opzione per realizzare la seguente connettivita’:



LAN Switch LAN Switch

ATMNetwork Ethernet

Goal:Goal: Fare in modo che la rete ATM si comporti come una rete Ethernet (an Emulated LAN)Fare in modo che la rete ATM si comporti come una rete Ethernet (an Emulated LAN) LAN Emulation lavora a livello 2 della pila OSILAN Emulation lavora a livello 2 della pila OSI

La rete ATM puo’ supportare Emulated LANs multiple



LAN emulation servicesLEC: LAN Emulation Client

Fornisce address resolution service e data forwarding. Ci possono essere piu’ istanze LEC su un ATM adapter.

LES: Assign individual LEC to different Emulated LANsBUS: Handle data sent by LEC to:

Broadcast MAC address Multicast dataInitial Unicast dataRiceve tutti i pacchetti multicast e broadcast e li inoltra a tutti i membri della LAN Emulata

LECS:Control and coordination functionRegistering and resolving MAC addresses

LEC

ATM Switches

LEC

LECS LES BUS

EnterpriseWAN

LEC



LEC

ATM Switches

LEC

LECS LES BUS

EnterpriseWAN

LEC

Il protocollo di LAN Emulation fornisce i servizi richiesti dal livello 3 di una rete broadcast e connectionless facendo le conversioni necessarie tra pacchetti della LAN e celle ATM e traducendo indirizzi MAC in indirizzi ATM



End goal—communication between LECs

LANE Servers Provide Mechanismsthat Enable LEC-to-LECCommunications

LECEthernet

LEC

Data Direct VCC

LECS LES BUS



LEC

Ethernet

LEC

SVC are required to make this a viable technology

Setup of all VCC are automaticautomatic

LECS LES BUS


In a typical LANE operation, the LEC must first find the LECS to discover which ELAN it should join. Specifically, the LEC is looking for the ATM address of the LECS that serves the desired ELAN.

Contacting the LECS

The LEC creates a signaling packet with the ATM address of the LECS. It signals a Configure Direct VCC and then issues an LE_CONFIGURE_REQUEST on that VCC. The information in this request is compared with the data in the LECS database. The source ATM address is most commonly used to place a LEC into a specific ELAN.


Joining the LES

After the LEC has discovered the ATM address of the desired LES, it drops the connection to the LECS, creates a signaling packet with the ATM address of the LES, and signals a Control Direct VCC. Upon successful VCC setup, the LES sends an LE_JOIN_REQUEST. This request contains the LEC ATM address as well as a MAC address that the LEC wants to register with the ELAN. This information is maintained so that no two LECs can register the same MAC or ATM addresses.

Upon receipt of the LE_JOIN_REQUEST, the LES checks with the LECS via its own open connection with the LECS and verifies the request, thus confirming the client's membership. Upon successful verification, the LES adds the LEC as a leaf of its point-to-multipoint Control Distribute VCC. Finally, the LES issues the LEC a successful LE_JOIN_RESPONSE that contains a LANE client ID (LECID), which is an identifier that is unique to the new client. This ID is used by the LEC to filter its own broadcasts from the BUS.


Finding the BUS

After the LEC has successfully joined the LES, its first task is to find the ATM address of the BUS and join the broadcast group. The LEC creates an LE_ARP_REQUEST packet with the MAC address 0xFFFFFFFF. This special LE_ARP packet is sent on the Control Direct VCC to the LES. The LES recognizes that the LEC is looking for the BUS, responds with the ATM address of the BUS, and forwards that response on the Control Distribute VCC.

Joining the BUS

When the LEC has the ATM address of the BUS, its next action is to create a signaling packet with that address and signal a Multicast Send VCC. Upon receipt of the signaling request, the BUS adds the LEC as a leaf on its point-to-multipoint Multicast Forward VCC. At this time, the LEC has become a member of the ELAN.



ATM-AttachedServers

CampusATM

Network

Ethernet Switch w/LANE Module

EnterpriseWAN

OC-12

OC-12

OC-12

Ethernet Switch w/LANE

module

Local SwitchedEthernet Servers

Dispositivi critici per il buon funzionamneto

della rete



Constant Bit Rate Circuit Emulation, Voice

VBR

CBR

UBR

ABR

GuaranteedService Variable Bit Rate

Full Traffic CharacterizationReal-Time VBR and Non Real-Time VBR

Unspecified Bit RateNo Guarantees, Adequate Buffering Needed

Available Bit RateNo Quantitative Guarantees, but Congestion Control Feedback Assures No/Low Cell Loss



Switched

Traditional CollapsedBackbone

ATM Internetworking

Software

LAN Switch(Layer 2)

ATM Workgroup Switch

Multilayer Switch (Layer 2 and 3) The

NewWiringCloset

VLANSystem

ATMCampus

SwitchHub

The New Switched Internetwork Backbone

SharedSiSi



ProsScalable backbone BWHigh speed server farmsLoad sharing uplinksNo disruption of current applicationsStandards-based VLANsMultiservice capable infrastructure

ConsCostComplexityManagementInefficient transportNo ATM QoSEtherchannel and GE competition



Prospettive:LAN Emulation v2.0

LAN Emulation UNI (LUNI) v2.0LAN Emulation NNI (LNNI)



LUNI v2.0 Goals

Migliore efficienzaRiduce l’uso di VC via optional LCC multiplexingdistribuzione dei multicast piu’ efficente

Migliore uso di ATM QOSABR e signaling 4.0 Supporto IEEE 802.1q/p Class of Service (CoS)



LUNI v2.0 GoalsImprove robustness of LANE servers

Allow LES/BUS function to be distributed in a tree architectureUp to (20) LES/BUS pairs can support one ELAN (all LES/BUS’s must forward all broadcast packets, etc.)No longer a LES/BUS single point failure LECS redundancy

Support LUNI v1.0 or LUNI v2.0 clients simultaneously—backwards compatible

Cristina Vistoli12 Maggio 19981 APPLICAZIONI TECNOLOGIA ATM zATM su LAN -- Classical IP e LANE...

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Transcript of Cristina Vistoli12 Maggio 19981 APPLICAZIONI TECNOLOGIA ATM zATM su LAN -- Classical IP e LANE...