From jacobson@math-cs.cns.uni.edu Thu Jan 15 13:51:49 2004 Date: Thu, 15 Jan 2004 13:49:52 -0600 (CST) From: Mark Jacobson To: 810-023-01@uni.edu Subject: [810-023-01] Chapter 11 slides work okay with Internet Explorer... Hi 023 students, The chapter 11 slides that we could not show today in class using the Konqueror web browser on the Linux machines works fine from our class web page with the Explorer Windows web browser, and is probably okay with Netscape too. I forgot the publish the powerpoint slides for the older versions of web browsers, but won't make that mistake again! Chapter 11 pages 524-528 talk about subnetting and subnets. The Figure 11-2 IP addresses before and after subnets Figure 11-3 A subnetted IP address and its subnet mask Figure 11-4 A subnetted network connected to the Internet Figure 11-5 A network with several subnets Figure 11-6 Data travelling over subnets diagrams on pages 525, 526, 527 and 528 of your textbook are part of the published powerpoint presentation located on our web page. http://www.cns.uni.edu/~jacobson/c023.html UNI's subnet mask is currently: 255.255.128.0 C:\> ipconfig N Network A Adapter Windows NT IP Configuration C Card Ethernet adapter E100B2: <---------- NIC or NAC IP Address. . . . . . . . . : 134.161.243.4 N Network Subnet Mask . . . . . . . . : 255.255.128.0 I Interface Default Gateway . . . . . . : 134.161.128.1 C Card Up until about 4 years ago, UNI's subnet mask was 255.255.252.0 252 = 11111100 128 = 10000000 Here is what the current UNI subnet mask looks like as 32 bits, instead of being shown in dotted decimal. 11111111.11111111.10000000.00000000 = 255.255.128.0 11111111.11111111.11111100.00000000 = 255.255.252.0 UNI consists of only 2 subnets with 255.255.128.0 as the mask. UNI used to allow up to 64 different subnets when the mask was 255.255.252.0 See today's handout (or the web page links) to review the information about subnet masks, and all of the possible values that UNI could use for its y octet of the subnet mask (w.x.y.z dotted decimal format). 255, 11111111 The y component (3rd octet of w.x.y.z) 254, 11111110 - 252, 11111100 could be any one of these 8 different 248, 11111000 values. 240, 11110000 224, 11100000 255.255.128.0 Currently at UNI its this. 192 11000000 --- or 128 10000000 or 0 00000000 255.255.252.0 It used to be this at UNI --- until late 99 or early 2000. We will discuss chapter one and chapter two basics more after the Martin Luther King holiday next week. We will also look at the Chapter 11 pages 519-528 pages and slides again in class on Tuesday, so go ahead and read or reread those pages and look at the Figures and Tables on those pages. You do NOT need to look at anything except the first ten pages of ------ chapter eleven. I know from past experience that it will take a month or two before the IP number addressing and subnet masking makes sense, so do not worry if it is difficult or confusing right now. Mark