FLOW CONTROL QuickTime™ and a GIF decompressor are needed to see this picture. QuickTime™ and a Photo - JPEG decompressor are needed to see this picture. LIDS Flow control: end-to-end mechanism for regulating traffic between source and destination

Optimal Routing View routing as a “global” optimization problem Assumptions: – The cost of using a link is a function of the flow on that link

Outline Network Layer and Internetworking The TCP/IP protocol suit ATM MPLS

一、设计应掌握的基础资料 进行活性污泥系统的工艺计算和设计时，首先应比较充分地掌握与废水、污泥有关的原始资料并确定 设计的基础数据，主要有： ①废水的水量、水质及其变化规律； ②对处理后出水的水质要求； ③对处理中产生的污泥的处理要求； ⎯⎯以上属于设计所需要的原始资料

Routing Must choose routes for various origin destination pairs (O/D pairs) or for various sessions – Datagram routing: route chosen on a packet by packet basis Using datagram routing is an easy way to split paths – Virtual circuit routing: route chosen a session by session basis

Broadcast Routing Route a packet from a source to all nodes in the network Possible solutions: – Flooding: Each node sends packet on all outgoing links Discard packets received a second time – Spanning Tree Routing: Send packet along a tree that includes all of the nodes in the network

DestinationAddress Output port number or VC number A packet switch consists of a routing engine (table look-up), a switch scheduler, and a switch fabric

RESERVATION SYSTEMS Single channel shared by multiple users Only one user can use t he channel at a time

Multiple Access Shared Transmission Medium a receiver can hear multiple transmitters a transmitter can be heard by multiple receivers the major problem with multi-access is allocating the channel between the users; the nodes do not know when the other nodes

Responsible for reliable transmission of packets over a link – Framing: Determine t he star t and end of packets (sec 2.5) – Error Detection: Determine w hen a packet contains errors (sec 2.3) – Error recovery: Retransmissio n of packets containing errors (sec 2..4)