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Computer Networks Lecture 9 By: Dr. Dina Fawzy Introduction transport segment from sending to receiving host on sending side encapsulates segments into ______ on receiving side, delivers segments to transport layer
datagrams
Network layer protocols in every host and router router examines header fields in all IP ______ passing through it
datagrams
Application transport network data link physical ______
network
Network Layer Functions Forwarding: move packets from router’s input to appropriate router output using ______ plan
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Routing: determine route taken by packets from source to destination using ______ plan
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Data Plan vs Control Plan Control plane Data plane Local function determines how ______ arriving on router input port is forwarded to router output port values forwarding function in arriving packet header
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Two control-plane approaches: ______ control plane
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Control plane Individual routing algorithm components in each and every router interact in the ______
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Routing Algorithm control plane data plane values in arriving packet ______
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Router architecture overview high-level view of generic router architecture: routing processor Routing control plane (software) operates in millisecond time frame forwarding data plane (hardware) operates in nanosecond timeframe high-seed switching fabric router input ports router output ports Input port functions line termination link layer protocol (receive ) lookup, forwarding switch fabric Input buffer physical layer: bit-level reception data link layer
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Ethernet decentralized ______: Input buffer (queueing): if ______ arrive faster than ______ ______ into switch fabric Input port functions ______ termination physical layer: bit-level reception data link layer: e.g., Ethernet link layer protocol (receive ) lookup, ______ switch fabric Input buffer decentralized ______: using header field values, lookup output port using ______ table in input port memory: ______-based ______: forward based only on ______ IP ______ (traditional) generalized ______: forward based on any set of header field values Destination-based ______ ______ table Destination Address Range Link Interface 11001000 00010111 00010000 00000000 through 11001000 00010111 00010111 11111111 0 11001000 00010111 00011000 00000000 through 11001000 00010111 00011000 11111111 1 11001000 00010111 00011001 00000000 through 11001000 00010111 00011111 11111111 2 otherwise 3 Q: but what happens if ranges don’t divide up so nicely. Longest ______ matching longest ______ matching when looking for ______ table entry for given ______ ______, use longest ______ ______ that matches ______ ______. Destination Address Range Link ______ 11001000 00010111 00010*** ********* 0 11001000 00010111 00011000 ********* 1 11001000 00010111 00011*** ********* 2 otherwise 3 examples: DA: 11001000 00010111 00010110 10100001 DA: 11001000 00010111 00011000 10101010 which ______. which . Switching fabrics ▪transfers ______ from input buffer to appropriate output buffer ▪ ______: ______ at which ______s can be transfer from inputs to outputs often measured as multiple of input/output ______ ______ N inputs: ______ ______ N times ______ ______ desirable ▪thr.
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Ethernet decentralized switching: Input buffer (queueing): if ______ arrive faster than forwarding rate into switch fabric Input port functions line termination physical layer: bit-level reception data link layer: e.g., Ethernet link layer protocol (receive ) lookup, forwarding switch fabric Input buffer decentralized switching: using header field values, lookup output port using forwarding table in input port memory: destination-based forwarding: forward based only on destination IP address (traditional) generalized forwarding: forward based on any set of header field values Destination-based forwarding forwarding table Destination Address Range Link Interface 11001000 00010111 00010000 00000000 through 11001000 00010111 00010111 11111111 0 11001000 00010111 00011000 00000000 through 11001000 00010111 00011000 11111111 1 11001000 00010111 00011001 00000000 through 11001000 00010111 00011111 11111111 2 otherwise 3 Q: but what happens if ranges don’t divide up so nicely. Longest prefix matching longest prefix matching when looking for forwarding table entry for given destination address, use longest address prefix that matches destination address. Destination Address Range Link interface 11001000 00010111 00010*** ********* 0 11001000 00010111 00011000 ********* 1 11001000 00010111 00011*** ********* 2 otherwise 3 examples: DA: 11001000 00010111 00010110 10100001 DA: 11001000 00010111 00011000 10101010 which interface. which interface. Switching fabrics ▪transfers packet from input buffer to appropriate output buffer ▪switching rate: rate at which packets can be transfer from inputs to outputs often measured as multiple of input/output line rate N inputs: switching rate N times line rate desirable ▪thr.
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Switching fabrics â–ª______s packet from input buffer to appropriate output buffer â–ªswitching rate: rate at which packets can be ______ from inputs to outputs often measured as multiple of input/output line rate N inputs: switching rate N times line rate desirable â–ªthr.
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Router architecture overview high-level view of generic router architecture: routing processor Routing control plane (software) operates in millisecond time frame forwarding data plane (hardware) operates in nanosecond timeframe high-seed switching fabric router input ports router output ports Input port functions line termination link layer protocol (receive ) lookup, forwarding switch fabric Input buffer physical layer: bit-level reception data link layer
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Data Plan vs Control Plan Control plane Data plane Local function determines how ______ arriving on router input port is forwarded to router output port values forwarding function in arriving packet header
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Network Layer Functions Forwarding: move packets from router’s input to appropriate router output using ______ plan
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Ethernet decentralized switching: Input buffer (queueing): if ______ arrive faster than forwarding rate into switch fabric Input port functions line termination physical layer: bit-level reception data link layer: e.g., Ethernet link layer protocol (receive ) lookup, forwarding switch fabric Input buffer decentralized switching: using header field values, lookup output port using forwarding table in input port memory: destination-based forwarding: forward based only on destination IP address (traditional) generalized forwarding: forward based on any set of header field values
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Destination-based forwarding forwarding table Destination Address Range Link Interface 11001000 00010111 00010000 00000000 through 11001000 00010111 00010111 11111111 0 11001000 00010111 00011000 00000000 through 11001000 00010111 00011000 11111111 1 11001000 00010111 00011001 00000000 through 11001000 00010111 00011111 11111111 2 otherwise 3 Q: but what happens if ranges don’t divide up so nicely. Longest ______ matching longest ______ matching when looking for forwarding table entry for given destination address, use longest address prefix that matches destination address. Destination Address Range Link interface 11001000 00010111 00010*** ********* 0 11001000 00010111 00011000 ********* 1 11001000 00010111 00011*** ********* 2 otherwise 3 examples: DA: 11001000 00010111 00010110 10100001 DA: 11001000 00010111 00011000 10101010 which interface. which interface.
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Destination-based forwarding forwarding table Destination Address Range Link Interface 11001000 00010111 00010000 00000000 through 11001000 00010111 00010111 11111111 0 11001000 00010111 00011000 00000000 through 11001000 00010111 00011000 11111111 1 11001000 00010111 00011001 00000000 through 11001000 00010111 00011111 11111111 2 otherwise 3 examples: DA: 11001000 00010111 00010110 10100001 DA: 11001000 00010111 00011000 10101010 which ______. which ______.
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Existing questions. Do NOT ask these: Routing Algorithm control plane data plane values in arriving packet ______ Computer Networks Lecture 9 By: Dr. Dina Fawzy Introduction transport segment from sending to receiving host on sending side encapsulates segments into ______ on receiving side, delivers segments to transport layer Network layer protocols in every host and router router examines header fields in all IP ______ passing through it Two control-plane approaches: ______ control plane Application transport network data link physical ______ Control plane Individual routing algorithm components in each and every router interact in the ______ Routing: determine route taken by packets from source to destination using ______ plan
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Application transport network data link physical ______ Control plane Individual routing algorithm components in each and every router interact in the ______ Routing: determine route taken by packets from source to destination using ______ plan
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