APPLICAZIONI TECNOLOGIA ATM

APPLICAZIONI TECNOLOGIA ATM
ATM su LAN -- Classical IP e LANE Cristina Vistoli INFN-CNAF Cristina Vistoli 12 Maggio 1998

ATM su LAN Classical IP ATM Network come una IP Subnetwork Router ATM Network circondata la dispositivi di livello 3 : Router RFC 1577 Cristina Vistoli 12 Maggio 1998

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. Cristina Vistoli 12 Maggio 1998

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 Cristina Vistoli 12 Maggio 1998

Cristina Vistoli 12 Maggio 1998

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 Cristina Vistoli 12 Maggio 1998

TCP TCP Native Mode Routing Protocols IP IP Virtual LANs (LAN Emulation) MAC MAC RFC Encapsulation ATM Routing (P-NNI Protocol) RFC Encapsulation Q.2931 Q.2931 P-NNI P-NNI Q.2931 Q.2931 UNI Signal- ing NNI Signal- ing UNI Signal- ing SSCOP NNI Convg NNI Convg SSCOP SSCOP SSCOP AAL 5 AAL 5 AAL 5 AAL 5 ATM ATM ATM ATM ATM ATM Phy Phy Phy Phy Phy Phy Phy Phy ATM Host/Router ATM Switch ATM Switch ATM Host/Router Cristina Vistoli 12 Maggio 1998

LAN Emulation Service LANE Configuration Server (LECS) Initialization LAN Emulation Server (LES) Address Resolution Broadcast and Unknown Server (BUS) Data Flooding LAN Emulation Clients (LEC) Cristina Vistoli 12 Maggio 1998

LANE ATM Network as a Layer 2 LAN LAN Switch ATM circondata da dispositivi di Livello 2: Switching (tutti i protocolli) Adatto per desktop, edifici e campus (via LANE Version 1) 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”. Cristina Vistoli 12 Maggio 1998

LAN Emulation e’ una possibile opzione per realizzare la seguente connettivita’: LAN Switch LAN Switch Ethernet Ethernet ATM Network LANE Router Connettivita’: Ethernet to Ethernet attraverso ATM Ethernet to ATM ATM to ATM Cristina Vistoli 12 Maggio 1998

LAN Switch LAN Switch ATM Network Ethernet Goal: Fare in modo che la rete ATM si comporti come una rete Ethernet (an Emulated LAN) LAN Emulation lavora a livello 2 della pila OSI La rete ATM puo’ supportare Emulated LANs multiple Cristina Vistoli 12 Maggio 1998

LECS LES BUS LAN emulation services LEC: 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 LANs BUS: Handle data sent by LEC to: Broadcast MAC address Multicast data Initial Unicast data Riceve tutti i pacchetti multicast e broadcast e li inoltra a tutti i membri della LAN Emulata LECS: Control and coordination function Registering and resolving MAC addresses ATM Switches LEC LEC LEC Enterprise WAN Cristina Vistoli 12 Maggio 1998

LECS LES BUS 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 ATM Switches LEC LEC LEC Enterprise WAN Cristina Vistoli 12 Maggio 1998

End goal—communication between LECs LECS LES BUS LANE Servers Provide Mechanisms that Enable LEC-to-LEC Communications Data Direct VCC LEC LEC Ethernet Cristina Vistoli 12 Maggio 1998

SVC are required to make this a viable technology Setup of all VCC are automatic LECS LES BUS LEC LEC Ethernet Cristina Vistoli 12 Maggio 1998

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. Cristina Vistoli 12 Maggio 1998

that no two LECs can register the same MAC or ATM addresses.
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. Cristina Vistoli 12 Maggio 1998

VCC. At this time, the LEC has become a member of the ELAN.
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. Cristina Vistoli 12 Maggio 1998

Dispositivi critici per il buon funzionamneto della rete Ethernet Switch w/LANE Module Enterprise WAN OC-12 Campus ATM Network Local Switched Ethernet Servers OC-12 OC-12 Ethernet Switch w/LANE module ATM-Attached Servers Cristina Vistoli 12 Maggio 1998

Constant Bit Rate Circuit Emulation, Voice CBR Guaranteed Service Variable Bit Rate Full Traffic Characterization Real-Time VBR and Non Real-Time VBR VBR Unspecified Bit Rate No Guarantees, Adequate Buffering Needed UBR Available Bit Rate No Quantitative Guarantees, but Congestion Control Feedback Assures No/Low Cell Loss ABR Cristina Vistoli 12 Maggio 1998

ATM Workgroup Switch Multilayer Switch (Layer 2 and 3) Shared Switched The New Wiring Closet VLAN System LAN Switch (Layer 2) ATM Campus Switch Hub ATM Internetworking Software Traditional Collapsed Backbone The New Switched Internetwork Backbone Cristina Vistoli 12 Maggio 1998

Pros Scalable backbone BW High speed server farms Load sharing uplinks No disruption of current applications Standards-based VLANs Multiservice capable infrastructure Cons Cost Complexity Management Inefficient transport No ATM QoS Etherchannel and GE competition Cristina Vistoli 12 Maggio 1998

Prospettive: LAN Emulation v2.0 LAN Emulation UNI (LUNI) v2.0 LAN Emulation NNI (LNNI) Cristina Vistoli 12 Maggio 1998

LUNI v2.0 Goals Migliore efficienza Riduce l’uso di VC via optional LCC multiplexing distribuzione dei multicast piu’ efficente Migliore uso di ATM QOS ABR e signaling 4.0 Supporto IEEE 802.1q/p Class of Service (CoS) Cristina Vistoli 12 Maggio 1998

LUNI v2.0 Goals Improve robustness of LANE servers Allow LES/BUS function to be distributed in a tree architecture Up 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 Vistoli 12 Maggio 1998

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APPLICAZIONI TECNOLOGIA ATM

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