CSCI 373 Computer Networking — Comments on IP

The PowerPoint


Slide 64

In the Internet model (TCP/IP), this is the network layer. The Internet model pre-dates bridges which are covered at the beginning of this chapter.

You can purchase wireless routers for $25. The first router was the Internet Message Processor (IMP). Those cost about $100,000.

Slide 65

PPP is the Point-to-Point Protocol. Usually it is a point-to-point serial connection between two routers, though sometimes a host computer may be directly connected to a router (or another host) via PPP. PPPoE is used in many DSL connections.

Slide 67

Slide 70

It’s all done with linked lists.

Slide 71

This is the old way.

Slide 73

Slide 74

The Computer Science department computers operate within a subnet (152.18.69/24) of the UNC Asheville network (

Slide 78

This is how it is done today.

Slide 80

AS is Autonomous System.

Try out

Before slide 86

Address allocation is handled by iana and its registries, such as ARIN. Use WHOIS IP search to look up assigned network numbers.

Slide 88

Slide 89

Slide 90

Try out a MAC manufacturer look up.

Slide 91

Slide 93

Technically, ICMP is part of IP. However, it does have its own specification.

Here are some useful common ICMP message types:

Many routers are configured so that they will not pass ICMP packages. Also access to ICMP is restricted to a handful of system utilities. See Intrusion Detection FAQ: How can attacker use ICMP for reconnaissance? for examples of why this is the case.

After slide 94

Slide 98 and on

It’s pretty much all CSCI 331 from now on. Keep in mind that these functions are often performed by expensive specific-purpose routers.

Extending the textbook

Unfortunately, the textbook does not cover Network Address Translation (NAT), which is widely use in home, business, and (of course) dormitory networks. The textbook also does not cover IP6, which is supposed to replace IP4 some day.