网络2
Chapter 5 the Network Layer Routing Algorithm Basics Routing Algorithms
Adaptive Algorithm: Distance Vector Routing
《Computer Network v4》cs.sjtu DVR Example
(a)A subnet. (b)Input from A, I, H, K, and the new routing table for J.z Delay is used as a metric z Once every T msec each router sends to each neighbor a list of its
estimated delays to each destination.
Adaptive Algorithm: Link State Routing
Chord –Key Location: for a shared resource, first builds a tuple 使用
Chord Leave How Networks Can Be Connected
Comparting VLANs
《Computer Network v4》cs.sjtu2009-12-11
Tunneling Congestion Control Quality of Service (QoS)
Overprovisioning Buffering
Traffic Shaping
The Leaky Bucket Algorithm z Resource
Reservation
z Admission Control
z Proportional Routing
《Computer Network v4》cs.sjtu2009-12-11
A leaky bucket with water. (b)a leaky bucket with packets.
《Computer Network v4》cs.sjtu 2009-12-11
The Token Bucket Algorithm
(a)Before. (b)After.
5-34
bursts of input.
《Computer Network v4》cs.sjtu 2009-12-11
The Internet Protocol (IP)
network layer protocol, IP (Internet Protocol).
《Computer Network v4》cs.sjtu 2009-12-11
IP Protocol Family
OSPF
HTTP
SNMP
《Computer Network v4The IPv4 Header
padding
Assign 35: IP packets whose total length is 1024 bytes. Assuming that packets
《Computer Network v4》cs.sjtu 2009-12-11Fragmentation
z
Fragmentation:we may have to split a packet into smaller ones when forwarding it through a network whose maximum packet size is too small z
Where to reassemble the fragments?
z Gateway: Transparent fragmentation
z
The destination host: Nontransparent （IP mode ）
《Computer Network v4》cs.sjtu 2009-12-11
IP Addresses
Special IP addresses
10.0.0.0 -10.255.255.255A Address
Class IANA （Internet Assigned Number Variable Length Subnet Mask （network + subnet id bits, 0 for host id bits)
A class
B network subnetted into 64 subnets
如何分段的，要掌握
《Computer Network v4》cs.sjtu 2009-12-11
mask
addresses IP ID subnet network ∧=+CIDR Routing
NAT—Network Address Translation
NAT
《Computer Network v4》cs.sjtu 2009-12-11
The IPv6 Header
The IPv6 fixed header (required).
《Computer Network v4OSPF –z z
z
z
The relation between ASes, backbones, and areas in OSPF.
ICMP-Message Protocol
ARP Resolution Protocol
Computer Network v4》cs.sjtu 2009-12-11
ARP
z
and so, Y sends a reply back with its datalink address.
message, and (generally) caches the address. to the correct host, encapsulating them Packet Chapter 6 The Transport Layer
《Computer Network v4》cs.sjtu 2009-12-11
Transport Protocol
Environment of the data link layer. (b)Environment of the transport layer.
《Computer Network v4》cs.sjtu 2009-12-11
Transport Service Interface Berkeley Sockets
The socket primitives for TCP.
Addressing -z
establish a connection to a remote TSAP
Both UDP and TCP use port numbers to identify the destination entity
when delivering a message. Give two reasons for why these protocols invented a new abstract ID (port numbers), instead of using process IDs, which already
《Computer Network v4》cs.sjtu 2009-12-11
UDP(The UDP header.
The TCP Service Model (RFC793)
《Computer Network v4》cs.sjtu 2009-12-11
The TCP Header
Assign 33. The entire TCP segment must fit in the 65,515-byte payload field of an IP packet. Since the TCP header is a minimum of 20 bytes, only 65,495 bytes are left for TCP data?
+1. What maximum packet lifetime is required to make sure that future 75 Tbps
networks do not have wraparound problems even with 64-bit sequence numbers?
《Computer Network v4》cs.sjtu 2009-12-11
Reliable Establishment
TCP connection establishment in the normal case. (b)Call collision.
的使用
Graceful Release
Computer Network v4》cs.sjtu 2009-12-11
TCP Flow Management
the buffering from the acknowledgements.
acknowledgment and the normally send segments, Computer Network v4》cs.sjtu 2009-12-11granted by the receiver. The actual window size is the Suppose that the TCP congestion window is set to 18 KB and a
timeout occurs. How big will the window be if the next four transmission bursts
are all successful? Assume that the maximum segment size is 1 KB.
《Computer Network v4》TCP Timer Management
Probability density of ACK arrival times in
(a)the data link layer (b)TCP.
αis a smoothing factor that
determines how much weight
Application Layer
Cryptography
《Computer Network v4》cs.sjtu 2009-12-11
Public-Key Signatures
knowing that it came fro Alice.
Digital signatures using public-key cryptography.
《Computer Network v4》cs.sjtu 2009-12-11
Digital signatures using message digests.
《Computer Network v4》cs.sjtu 2009-12-11
Establishing a Shared Key:
The Diffie-Hellman Key Exchange
does the same, say y .
The Diffie-Hellman key exchange.
《Computer Network v4》cs.sjtu 2009-12-11
Establishing a Shared Key Public-Key Cryptography
but now encrypted with the session key K S .