Options
Route Summarization
fluk3d
Member Posts: 141 ■■■□□□□□□□
in CCNA & CCENT
How would you know if route summarization is used if you were given the subnet aka 192.168.156.0/22? maybe I'm drawing a blank here...
Logically I look at this and it's a class c and by default class C only has 254 usable IPs is that the only way to figure this puzzle out?
Logically I look at this and it's a class c and by default class C only has 254 usable IPs is that the only way to figure this puzzle out?
"Imagination is more important than knowledge." - Albert Einstein
Comments
-
OptionsLtat42a Member Posts: 587 ■■■□□□□□□□Use the "show ip route" command....it should show what routes are within that subnet.
-
Optionsfluk3d Member Posts: 141 ■■■□□□□□□□Thanks.. But what if you wanted to work this out via pen and paper no equipment used"Imagination is more important than knowledge." - Albert Einstein
-
OptionsDANMOH009 Member Posts: 241Have you been given a question or a scenario?
Im sure i'll get confirmation of this but i was led to believe that 192.168.156.0/22 is just like any other IP and Subnet, a Subnet with 1022 Hosts 36 Subnets. Just because its /22 doesnt really mean that it is a summary address. -
Optionsfluk3d Member Posts: 141 ■■■□□□□□□□Have you been given a question or a scenario?
Im sure i'll get confirmation of this but i was led to believe that 192.168.156.0/22 is just like any other IP and Subnet, a Subnet with 1022 Hosts 36 Subnets. Just because its /22 doesnt really mean that it is a summary address.
No just curious using the techexams subnet calculator whenever I input that information I can see that it's a supernet addresses so I want to know the logic behind how it determined it was a supernet and not a regular subnet"Imagination is more important than knowledge." - Albert Einstein -
OptionsCodeBlox Member Posts: 1,363 ■■■■□□□□□□Supernets can have a shorter prefix length than the default classful network masks. If you look in the routing table at routes that have been summarized however (NOT supernets), they'd show with just the summary and anything that falls in that range uses that route.Currently reading: Network Warrior, Unix Network Programming by Richard Stevens
-
Optionsfluk3d Member Posts: 141 ■■■□□□□□□□Supernets can have a shorter prefix length than the default classful network masks. If you look in the routing table at routes that have been summarized however (NOT supernets), they'd show with just the summary and anything that falls in that range uses that route.
Definitly however; this is what I'm talking about how did this utility determine this was a supernetted address; what is the math behind it ?
"Imagination is more important than knowledge." - Albert Einstein -
Optionsnetworker050184 Mod Posts: 11,962 ModNo math involved. As CodeBlox pointed out if the mask is shorter than the default classfull mask then its a supernet.An expert is a man who has made all the mistakes which can be made.
-
Optionsmella060 Member Posts: 198 ■■■□□□□□□□Thanks.. But what if you wanted to work this out via pen and paper no equipment used
What is the range of 192.168.156.0/22 ?
From my understanding, the range would be 192.168.156.1 - 192.168.159.255
Next network is 192.168.160.0/22 and so on. The number just increments/goes up by 4 in the 3rd octet.
Looking at the summary address, i would assume that this summary is for the class c networks...
192.168.156.0/24
192.168.157.0/24
192.168.158.0/24
192.168.159.0/24
Since all of those subnets fall in the range of the summary address. -
Optionszrockstar Member Posts: 378To summarize with pen and paper, write out your subnets you want to summarize in binary. What ever the last common bit across all IPs is, draw a dividing line between that bit and the next. Everything to the left of the line = your summary IP address, and however many bits are common is your subnet mask.
Maybe this will help:
STEP ONE: WRITE IN BINARY
192.168.XOOXXXOO.0
192.168.XOOXXXOX.0
192.168.XOOXXXXO.0
192.198.XOOXXXXX.0
STEP TWO: DRAW A LINE
192.168.XOOXXX|OO.0
192.168.XOOXXX|OX.0
192.168.XOOXXX|XO.0
192.168.XOOXXX|XX.0
<<<<<KEEP>>>>|<<CONVERT TO ALL 0s>>
STEP THREE: CONVERT IP
192.168.156.0
STEP FOUR: COUNT SUBNET MASK BITS
192.168.XOOXXX
12345678.12345678.123456 = 22
SUMMARY IP = 192.168.156.0/22 -
Optionszrockstar Member Posts: 378Sorry. After reading the thread again, I realize you weren't asking how to summarize, but as previously stated, a supernet is just a mask that is less than the classful address. I'll leave my previous comment up in case it does help you or someone else understand it a little better.
-
Optionsfluk3d Member Posts: 141 ■■■□□□□□□□Thanks that's what I was looking for the mask is "smaller" then it's default mask"Imagination is more important than knowledge." - Albert Einstein