8 Routing

La gestione del routing ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Routing Unicast ,[object Object],[object Object],A B

Routing Unicast ,[object Object],[object Object],Entità A deve instradare Entità C Entità B

Protocolli di Routing ,[object Object],[object Object],[object Object],[object Object],[object Object]

Politiche di Routing ,[object Object],[object Object],[object Object]

Routing e capacità ,[object Object],[object Object],[object Object],[object Object]

Routing e capacità: concetti intuitivi (1) ,[object Object],[object Object],S 1 D 1 S 2 D 2 Capacità di tutti i link = C Traffico massimo = C

Routing e capacità: concetti intuitivi (2) ,[object Object],S 1 D 1 S 2 D 2 Capacità di tutti i link = C Traffico massimo = 3C

Politiche di routing per Internet ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],R D

Politiche di routing per Internet ,[object Object],[object Object],[object Object],S5 D S1 S2 S3 S4 S6

Routing a cammini minimi ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Algoritmi di routing Grafi Algoritmo di Bellman-Ford Algoritmo di Dyikstra

Richiami sui Grafi ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Problema del cammino minimo ,[object Object],Dato un digrafo G(N,A) e due nodi i e j , trovare il cammino di lunghezza minima tra tutti quelli che consentono di andare i a j Proprietà: se il nodo k è attraversato dal cammino minimo da i a j, il sotto-cammino fino a k è anch’esso minimo

Algoritmo di Bellman-Ford ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Algoritmo di Bellman-Ford ,[object Object],[object Object],[object Object],[object Object],[object Object]

Algoritmo di Bellman-Ford in forma distribuita ,[object Object],[object Object],D j

Algoritmo di Bellman-Ford in pratica ,[object Object],[object Object],[object Object],[object Object]

Esempio: Bellman-Ford 2 2 1 5 3 1 1 2 4 (-,  ) (-,  ) (-,  ) (-,  ) (-,  ) (1, 0) 1 2 3 6 4 5 (1, 2) (1, 5) (1, 1) (-,  ) (-,  ) (1, 0) (3, 9) (4, 2) (1, 5) (1, 2) (1, 0) (1, 1) (5, 4) (5, 3) (1, 2) (4, 2) (1, 1) (1, 0)

Algoritmi di Dijkstra ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Algoritmi: complessità ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Algoritmi di Dijkstra in pratica ,[object Object],[object Object],[object Object],[object Object]

Esempio: Dijkstra 2 2 1 5 3 1 1 2 4 (-,  ) (-,  ) (-,  ) (-,  ) (-,  ) (1, 0) 1 2 3 6 4 5 (1, 2) (1, 5) (1, 1) (-,  ) (-,  ) (1, 0) (3, 9) (4, 2) (1, 5) (1, 2) (1, 0) (1, 1) (5, 4) (5, 3) (1, 2) (4, 2) (1, 1) (1, 0)

Tabelle di Routing IP ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Routing IP ,[object Object],[object Object],[object Object],[object Object],[object Object]

Protocolli di Routing ,[object Object],[object Object],[object Object],[object Object]

I protocolli di routing di tipo Distance Vector

I protocolli Distance Vector ,[object Object],[object Object],[object Object],[object Object]

Distance Vector: Algoritmo ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Distance Vector ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Ricalcolo: D j ’ = min k [ D k + d kj ] K, D k J, D j d kj

Modifica delle tabelle di routing

Esempio: Distance Vector (1) ,[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Esempio: Distance Vector (2) ,[object Object],[object Object],[object Object],[object Object]

Esempio: Distance Vector (4) ,[object Object],[object Object]

Esempio: Distance Vector (5) ,[object Object],[object Object],[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Esempio: Distance Vector (6) ,[object Object],[object Object],[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Esempio: Distance Vector (8) ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Esempio: Distance Vector (9) ,[object Object],[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Esempio: Distance Vector (10) ,[object Object],[object Object],[object Object],A: A=0, B=1, D=1 C: C=0, B=1, A=2 E: E=0, B=1, A=2, D=1 A: A=0, B=1, D=1 E: E=0, B=1, A=2, D=1 C: C=0, B=1, A=2 1 1 A 0 local B 1 3 A 0 local D 1 4 B 2 4 A 1 6 D 0 Local E

Esempio: Distance Vector (11) ,[object Object],[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Esempio: Distance Vector (12) ,[object Object],[object Object],[object Object],B=0, A=1, D=2, C=1, E=1 D: D=0, A=1, B=2, E=1 B=0, A=1, D=2, C=1, E=1 D=0, A=1, B=2, E=1 E=0, B=1, A=2, D=1, C=1 E=0, B=1, A=2, D=1, C=1 1 1 B 1 3 D 0 local A 1 2 B 2 2 A 0 local C 1 3 A 2 3 B 1 6 E 0 Local D

Esempio: Distance Vector (13) ,[object Object],A B E D C 1 2 3 6 5 4

Distance Vector: rottura del link 1 ,[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Distance Vector: rottura del link 1 ,[object Object],[object Object],[object Object]

[object Object],[object Object],Distance Vector: rottura link 1 A B E D C 1 2 3 6 5 4

[object Object],Distance Vector: rottura link 1

[object Object],[object Object],[object Object],[object Object],Distance Vector: rottura link 1 A B E D C 1 2 3 6 5 4

Distance Vector: rottura link 1 ,[object Object]

Distance Vector: rottura link 1 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Distance Vector: caratteristiche ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Velocità di convergenza ,[object Object]

Distance Vector: counting to infinity ,[object Object],A B E D C 2 3 6 5 4

Distance Vector: counting to infinity ,[object Object],[object Object]

Distance Vector: counting to infinity ,[object Object],[object Object],[object Object],[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Counting to infinity: rimedi

Counting to infinity: rimedi ,[object Object],[object Object],[object Object],A D X

Distance Vector: Split Horizon ,[object Object],[object Object],[object Object],[object Object],[object Object]

Distance Vector: Split Horizon ,[object Object],A B E D C 2 3 6 5 4

Distance Vector: Split Horizon ,[object Object],[object Object]

Distance Vector: Split Horizon ,[object Object],[object Object],[object Object],[object Object],[object Object],A B E D C 2 3 6 5 4

Distance Vector: Split Horizon ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Counting to infinity: rimedi ,[object Object],[object Object],[object Object],[object Object]

Counting to infinity: rimedi ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

I protocolli di routing di tipo Link State

[object Object],[object Object],[object Object],[object Object],Protocolli di routing Link State

Vantaggi protocolli Link State ,[object Object],[object Object],[object Object]

Svantaggi protocolli Link State ,[object Object],[object Object],[object Object],[object Object]

Link State: esempio R1 R2 R4 R5 R3 a b c a 1 b 1 c 1 R2 0 R1 2 R3 4 2 4 1 LSP generato da R2

Flooding ,[object Object],[object Object],[object Object],[object Object]

Esempio: Link State ,[object Object],A B E D C 1 2 3 6 5 4

Esempio: Link State ,[object Object],[object Object]

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],All’arrivo di un LSP

Esempio: Link State ,[object Object],[object Object],[object Object],[object Object],A B E D C 1 2 3 6 5 4

Routing in Internet ,[object Object],backbone AS AS AS Autonomous System Exterior Gateway Interior Gateway ,[object Object],[object Object]

Domini di Routing ,[object Object],[object Object],AS RD RD RD

Ridistribuzione ,[object Object],[object Object],[object Object],RD RD Prot. A Prot. B

I Protocolli di Routing più usati ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Link State Distance Vector Path Vector

[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],RIP Version 1

RIP v1: formato dei messaggi ,[object Object],[object Object],[object Object],Source: TCP/IP Protocol Suite, B. Forouzan

Messaggi di richiesta ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Source: TCP/IP Protocol Suite, B. Forouzan

Messaggi di risposta Contengono il DV Source: TCP/IP Protocol Suite, B. Forouzan

RIP v1: tempistica dei messaggi ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

RIP Version 2 ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],Source: TCP/IP Protocol Suite, B. Forouzan

RIPv2: Autenticazione Source: TCP/IP Protocol Suite, B. Forouzan

OSPF ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

OSPF: gerarchia e classificazione dei router Source: Computer Networking, J. Kurose

Tipi di collegamenti in OSPF Source: TCP/IP Protocol Suite, B. Forouzan

Rappresentazione della topologia ,[object Object],[object Object],Rete reale Source: TCP/IP Protocol Suite, B. Forouzan

OSPF: i pacchetti scambiati ,[object Object],Source: TCP/IP Protocol Suite, B. Forouzan

OSFP: Header comune Version (1) Type Message Length Source Gateway IP address Checksum Authentication 1 4 8 16 19 32 Area ID Authentication type Authentication

OSFP: Open Shortest Path First ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

OSPF: Tipi di LSA ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

OSPF ,[object Object],[object Object],Visto nella area 2

[object Object],[object Object],[object Object],OSFP: Open Shortest Path First

I pacchetti di Hello ,[object Object],[object Object],[object Object],Common Header 24 bytes Type:1 Settato a 1 quando la rete è una foglia Settato a 1 se il router mittente usa metriche multiple Network Mask Dead Interval Backup Designated Router IP Hello Interval All 0’s E T Priority Neighbor IP address Designated Router IP

I pacchetti LSU ,[object Object]

Router Link LSA ,[object Object],[object Object]

Esempio di Router Link LSA 10.24.7.14 10.24.7.15 10.24.7.16 10.24.7.0/24 Metrica:4 Metrica:6 Metrica:2 10.24.7.14 1 4 1 OSPF Header Type: 4 LSA Header Type:1 10.24.7.15 2 6 1 10.24.7.0 255.255.255.0 2 3

Network Link LSA ,[object Object],[object Object]

Esempio: Network Link LSA ,[object Object],[object Object],10.24.7.14 10.24.7.15 10.24.7.16 OSPF Header Type:4 255.255.255.0 10.24.7.15 LSA Header Type:2 10.24.7.16 10.24.7.14

Summary Link Network LSA ,[object Object],[object Object]

Summary Link to AS Boundary Router LSA ,[object Object]

External Link LSA ,[object Object],[object Object]

BGP ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

BGP: Path vector ,[object Object],… … … AS11,AS12,AS8,AS6 R09 N03 AS4,AS13,AS6,AS9 R07 N02 AS2,AS5,AS7,AS12 R01 N01 Percorso Router successivo Rete

BGP: scambio dei messaggi ,[object Object],[object Object],[object Object],[object Object]

BGP: Path Vector ,[object Object],[object Object]

Policy based routing ,[object Object],[object Object],[object Object],[object Object]

Policy based routing: esempio 1 ,[object Object],A B D C N01, RD, D N01, RA, A-D Non inoltrare pacchetti attraverso A D RD N01 Percorso Router successivo Rete

Policy based routing: esempio 2 ,[object Object],A B D N01, D, RD N1, B-A-D, RB N01, A-D, RA D RD N01 Percorso Router successivo Rete A-D RA N01 Percorso Router successivo Rete

BGP: Path vector ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

I messaggi BGP ,[object Object]

Messaggi di Open ,[object Object],[object Object],Versione di BGP (4) Tempo di attesa per un messaggio di keepalive Identificativo dell’autonomous system Identificativo del trasmettitore Ad oggi definita solo l’opzione di autenticazione

Messaggi di Update ,[object Object],[object Object]

Messaggio di Notification ,[object Object]

Multicasting ,[object Object],[object Object],[object Object],[object Object]

Multicasting ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Gruppi ed indirizzi ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object],11110 multicast addresses da 224.0.0.0 a 239.255.255.255

Internet Group Management Protocol (IGMP) ,[object Object],[object Object],[object Object]

Gestione dei gruppi ,[object Object],[object Object],Source: Computer Networking, J. Kurose

Multicast routing ,[object Object],[object Object],[object Object],[object Object]

Quali alberi ,[object Object],[object Object],Group-shared tree Source-based trees

Group-Shared Tree ,[object Object],[object Object],[object Object],[object Object],[object Object],[object Object]

Source-based Trees ,[object Object],[object Object],[object Object],[object Object],[object Object],i pacchetti giungono anche a nodi senza host associati

Source-based Trees: pruning ,[object Object],[object Object],[object Object],[object Object],[object Object]

Distance Vector Multicast Routing Protocol (DVMRP) – RFC 1075 ,[object Object],[object Object],[object Object],[object Object],[object Object]

Multicast in Internet ,[object Object],[object Object],[object Object]

8 Routing

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