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

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

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

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

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

Service times M/G/1 General independent Poisson arrivals at rate λ Service time has arbitrary distribution with given E[X] and E[X2] – Service times are independent and identically

Carrier Sense Multiple Access (CSMA) In certain situations nodes can hear each other by listening to the channel “Carrier Sensing” CSMA: Polite version of Aloha

An interesting property of an M/M/1 queue, which greatly simplifies combining these queues into a network, is the surprising fact that the output of an M/M/1 queue with arrival rate λ is a Poisson process of rate

When the receiver detects errors in a packet, how does it let the transmitter know to re-send the corresponding packet? Systems which automatically request the retransmission of missing

Queueing Systems Used for analyzing network performance In packet networks, events are random Random packet arrivals