Need reasurance with VLSM
Dan-Humphreys
Member Posts: 20 ■□□□□□□□□□
in CCNA & CCENT
I have the use of 172.20.0.0/22 and 172.20.4.0/22 I must subnet these addresses down and this is the table I have created. Can anybody reasure me that it is correct?
Network Area
No. Users / IPs
VLSM block size / No. of IPs (powers of 2)
HQ Network
112
172.20.4.0 255.255.255.128
RO1 Network
200
172.20.3.0 255.255.255.0
RO2 Network / VLANs
VLAN 1 (Server Farm)
18 users
172.20.2.64 255.255.255.224
VLAN 2 (Native/mgmt -IP)
9 users
172.20.2.96 255.255.255.240
VLAN 11 (Dept 1)
75 users
172.20.1.128 255.255.255.128
VLAN 12 (Dept 2)
112 users
172.20.1.0 255.255.255.128
VLAN 13 (Dept 3)
38 users
172.20.2.0 255.255.255.192
VLAN 101 (wireless)
52 users
172.20.1.192 255.255.255.192
WAN link (RO2 to HQ)
2
172.20.2.112 255.255.255.252
Total users and block sizes for RO2
306
172.20.0.0 255.255.254.0
RO2 block size to subdivide
N/A
Total users and all VLSM blocks
618
Network Area
No. Users / IPs
VLSM block size / No. of IPs (powers of 2)
HQ Network
112
172.20.4.0 255.255.255.128
RO1 Network
200
172.20.3.0 255.255.255.0
RO2 Network / VLANs
VLAN 1 (Server Farm)
18 users
172.20.2.64 255.255.255.224
VLAN 2 (Native/mgmt -IP)
9 users
172.20.2.96 255.255.255.240
VLAN 11 (Dept 1)
75 users
172.20.1.128 255.255.255.128
VLAN 12 (Dept 2)
112 users
172.20.1.0 255.255.255.128
VLAN 13 (Dept 3)
38 users
172.20.2.0 255.255.255.192
VLAN 101 (wireless)
52 users
172.20.1.192 255.255.255.192
WAN link (RO2 to HQ)
2
172.20.2.112 255.255.255.252
Total users and block sizes for RO2
306
172.20.0.0 255.255.254.0
RO2 block size to subdivide
N/A
Total users and all VLSM blocks
618
Comments
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jukem
Member Posts: 33 ■■□□□□□□□□
Looks correct to me.“You got a dream, you gotta protect it. People can’t do something themselves, they wanna tell you, you can’t do it. If you want something, go get it. Period.”--Will Smith in the Movie: Pursuit of Happyness
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pheobo
Registered Users Posts: 2 ■□□□□□□□□□
At first glance looks like the block for RO2 is the right size, but there is an error.
172.20.0.0 255.255.254.0 = 172.20.0.0/23
You usable range for this mask is:
172.20.0.0 - 172.20.1.255
You have several addresses from 172.20.2.X in your R02 block. They don't fit the address allocation you gave that area.
I have not checked any further. -
jukem
Member Posts: 33 ■■□□□□□□□□
Oops phoebo is correct. Your mask for the RO2 network must be 255.255.252.0 for a usable range of 172.20.0.0 - 172.20.3.255 unless the zero subnet is usable.“You got a dream, you gotta protect it. People can’t do something themselves, they wanna tell you, you can’t do it. If you want something, go get it. Period.”--Will Smith in the Movie: Pursuit of Happyness
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inscom.brigade
Member Posts: 400 ■■■□□□□□□□
172.20.0.0/22 has 1022 host, 1020 usable, and 64 subnets available.
I am re doing my math
edit:
dang it, to bad, i should not have had that drink, haha.
now i have dirt on my face.
Oh well it is Friday night and I worked hard this week, I am going to play a video game F, VLSM tonight!
Edit
172.20.0.0...... 172.20.0.3/30 2 user
172.20.0.4...... 172.20.0.15/28 10 user
172.20.0.16......172.20.0.31/27
172.20.0.32 .....172.20.0.127/25
172.20.0.128....172.20.0.191/26
172.20.0.192....172.20.0.255/25
172.20.1.0........172.20.0.127/25
172.20.1.128.....172.20.1.255/25
172.20.2.0....... 172.20.2.255/24
172.20.3.0....... 172.20.3.255/23
I am thinking that this could work, as you see from above it is friday night after a couple.
I might be eating Crow in the Morning -
Dan-Humphreys
Member Posts: 20 ■□□□□□□□□□
Thanks to everyone for the advise, I see my mistake was calculating the RO2 address before the VLAN's. What I had done was calculated the RO2 network with the consideration for 306 users that led me to the mask of /23. After realising my mistake I see why it would not work, as there are over used host bits on every vlan which leads to the requirement of over 510.