Our entire address space is 192.188.58.64/26
192.188.58.64 = 11000000 10111100 00111010 01000000 Prefix /26 +++++++++++++++++++++++++++++ Host part xxxxxx Total number of IPs = 2^6 = 64 (000000 - 111111) Lowest IP: 11000000 10111100 00111010 01000000 = 192.188.58.64 Highest IP: 11000000 10111100 00111010 01111111 = 192.188.58.127 We have previously subdivided it like this: 192.188.58.64/26 split into 192.188.58.64/27 192.188.58.96/27 +-------------------------------+-------------------------------+ | 64 - 95 | 96 - 127 | +-------------------------------+-------------------------------+ for classroom for instructors Note that 192.188.58.64 = network address 192.188.58.95 = broadcast address 192.188.58.xx = host address (65-94) /27 = netmask 255.255.255.224 For this exercise, we will divide this up even more. +---------------+---+---+---+---+---+---+---+---+---+---+---+---+ | 64 - 79 |80 |84 |88 |92 |96 |100|104|108|112|116|120|124| | |83 |87 |91 |95 |99 |103|107|111|115|119|123|127| +---------------+---+---+---+---+---+---+---+---+---+---+---+---+ backbone separate subnet for each desk TABLE ONE 192.188.58.64/28 Classroom backbone ---------------- ------------------ 192.188.58.65 router 192.188.58.66 PC15 eth0 192.188.58.67 PC29 eth0 192.188.58.68 PC5 eth0 192.188.58.69 PC23 eth0 192.188.58.70 PC9 eth0 192.188.58.71 PC7 eth0 192.188.58.72 PC13 eth0 192.188.58.73 PC17 eth0 192.188.58.74 PC3 eth0 192.188.58.75 PC27 eth0 192.188.58.76 PC21 eth0 192.188.58.77 PC11 eth0 192.188.58.78 PC25 eth0 Q. What is the netmask for a /28 network? ______________________ (PC19 is not used in this exercise; unplug eth0 and join another group) There are separate /30 networks for the *private* links between machines on each desktop TABLE TWO 192.188.58.80/30 PC3 (eth1), PC4 (eth0) 192.188.58.84/30 PC5, PC6 192.188.58.88/30 PC7, PC8 192.188.58.92/30 PC9, PC10 192.188.58.96/30 PC11, PC12 192.188.58.100/30 PC13, PC14 192.188.58.104/30 PC15, PC16 192.188.58.108/30 PC17, PC18 192.188.58.112/30 PC21, PC22 192.188.58.116/30 PC23, PC24 192.188.58.120/30 PC25, PC26 192.188.58.124/30 For instructor use 192.168.0.0/30 PC27, PC28 (these are private IPs because we 192.168.0.4/30 PC29, PC30 do not have enough real IPs) Q. What is the netmask for a /30 network? ______________________
Each desk has one machine which will be the ROUTER, another machine which is a CLIENT, and a private ethernet link (crossover cable) between the two.
+-------+ +-------+ 192.188.58.___ | PC __ | | PC __ |------------------> to backbone +-------+ +-------+ eth0 | eth0 | eth1 | ___.___.___.___ | ___.___.___.___ | | +----------------------+ crossover cable
Don't change /etc/sysconfig/ifcfg-eth0, because we don't want these changes to be permanent. The commands you will need are:
/sbin/ifconfig # show interfaces /sbin/ifconfig eth0 x.x.x.x netmask y.y.y.y # configure interface /sbin/route -n # show routes /sbin/route add -net x.x.x.x netmask y.y.y.y gw z.z.z.z # add a route /sbin/route del -net x.x.x.x netmask y.y.y.y # delete a route /sbin/route del default # delete defaultroute ping x.x.x.x # send test packets /usr/sbin/traceroute -n x.x.x.x # show route to destination
Remember that the next hop gateway (z.z.z.z) must be an address on one of the networks which you are DIRECTLY connected to.
Can you ping other routers on the backbone? Can you ping other workstations? Debug the problems.