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tp chia mng con (Phn 2)

Posted by Hong V on May 20, 2011

1/ Chia mng con lm g?


- d qun l v qun l mt cch khoa hc
- tit kim a ch IP
- p ng nhu cu ca con ngi
- .
2/ Cch chia mng con.
- a ch IP c 2 phn NET ID v HOST ID. Chng ta s mn vi bit trong HOST ID chia mng con theo
yu cu.
3/ Mt s lu khi chia mng con

Gi s bn gp mng 192.168.1.1/24 iu ny tng ng vi IP 192.168.1.1 v subnet mask


255.255.255.0
/23 /24 /25 . Tng ng vi subnet mask. Nhn vo n ta c th bit c bao nhiu bit lm Net ID.
Nh v d trn l mng dung 24 bit lm Net ID.
Mt mng thng thng lun c 3 loi a ch
a ch mng (a ch u mi mng, i din cho mng)
a ch broadcast (a ch cui mi mng, l a ch m s pht tt tt c cc thng tin n mng ).
Vng a ch IP xi c (nm gia a ch Mng v a ch Broadcast).
4/ Mn bit chia mng con.(Nn nm k phn ny)
Gi s mun chia mt mng bt k thuc lp C 194.23.12.0/24 (Net ID 24 bit, Host ID 8bit)

S bit
mn

S bit cn S mng con chia c


li

S hosts trong mt mng Khong cch gia 2


mng lin tip

2^1 =2

2^7 -2 = 126

128 (2^7)

2^2 =4

2^6 -2 = 62

64 (2^6)

2^5 -2 = 30

32 (2^5)

16

2^4 -2 = 14

16 (2^4)

32

2^3 -2 = 6

8 (2^3)

64

2^2 -2 = 2

4 (2^2)

Tng t nh vy i vi cc lp A,B
Vd mun chia mng 194.23.12.0/24 ra lm 4 mng con
- Ta cn phi mn 2 bit.
- Khi Sub net l 255.255.255.192.
- S host trong mt mng l 64-2 =62 (Tr a ch mng v a ch Broadcast)
- Mi mng cch nhau 64 n v
(cc mng s l 194.23.12.0, 192.23.12.64, 192.23.12.128, 192.23.12.192)
5/ Bi tp Trc Nghim
1. Mt mng con lp C mn 2 bit chia Subnet th Subnet Mask s l:
a. 255.255.224.0 b. 255.255.255.192 c. 255.255.255.240 d. 255.255.255.128
Lp C th Subnet Mask mc nh l 255.255.255.0
Mn thm 2 bit chia sub net Mask th ta phi bt 2 bit 1 tip theo my tnh bit ti khc l Net ID.
iu c ngha l
Subnet Mask : 11111111.11111111.11111111.11000000 => 255.255.255.192
Cc bn nn thuc lng cch xc nh Subnet Mask (i vi Mng con lp C)

S bit mn chia
mng

Subnet Mask

255.255.255.128

255.255.255.192

255.255.255.224

255.255.255.240

255.255.255.248

2. Mt mng con lp C mn 5 bit chia Subnet th Subnet Mask s l:


a. 255.255.224.0 b. 255.255.255.1 c. 255.255.255.248 d. 255.255.255.128
Mn 4 bit th Subnet Mask s l 240 -> Mn 5 bit s l 248. Vic nh gip cc bn lm bi nhanh hn ^^
3. Mt mng con lp A mn 21 bit chia Subnet th Subnet Mask s l:
a. 255.255.224.0 b. 255..255.192.0 c. 255.255.248.0 d. 255.255.255.248
Ch : Lp A c 8 bit u lm Net ID mn 21 bit => c 29 bit lm Host ID
29> 24 nn 3 octet u ta bt bit 1 ln ht -> n l 255.255.255.0
Cn 5 bit cn li ta cng bt ln nt. Vy cui cng ta c Subnet Mask l 255.255.255.248
4. Trong mng my tnh dng giao thc TCP/IP v Subnet Mask l 255.255.255.224, hy xc nh a ch
broadcast ca mng nu bit rng mt my tnh trong mng c a ch 192.168.1.1:
a. 192.168.1.31 b. 192.168.1.255 c. 192.168.1.15 d. 192.168.1.96
Hng dn gii:
- Khi c Subnet Mask Ta d dng suy ra c Phn Net ID v Host ID ( trong bt ny th Phn Net l 27 bit
v host l 5 bit).
- Da vo a ch ca my tnh, ta bit c a ch lp no (trong bt ny l lp C)
T suy ra Net ny mn 3 bit chia Subnet -> Do ta cn li 5 bit host.
- 3 bit chia c 8 Subnet, mi Subnet cch nhau 32 n v. v s host trong mi Net l 32-2 =30

- Ta tm c Mng u tin 192.168.1.0


- Mng th 2 192.168.1.32..
- T suy ra Broadcast ca Mng u tin cha a ch 192.168.1.1 l 192.168.1.31
6 Trong mng my tnh dng Subnet Mask l 255.255.255.0 th cp my tnh no sau y lin thng:
a. 192.168.1.3 v 192.168.100.1 b. 192.168.15.1 v 192.168.15.254
c. 192.168.100.15 v 192.186.100.16 d. 172.25.11.1 v 172.26.11.2
Ci ny Subnet Mc nh lp C. Nn NET ID c 24 bit u, v Host ID l 8 bit 6.
Ta i chiu cc NET ID vi nhau th s bit c cp no cng mng. p n B
y l mt vi bi tp c bn. Mnh s post cc bi tp c Lin quan v p n ca mnh trong mt part
khc. Cc bn nu c thc mc g c li Comment cho mnh nh
Posted under Network
Comments (5)

5 Responses to Bi tp chia mng con (Phn 2)

1.

May 24 2011

nhan
Cu 6 bn b sai ri phi l B mi ng.

2.

May 30 2011

hung
em co bai tap nay mong anh huong dan chi tiet gium em voi.
cho: ip 192.168.1.0,subnetmak 255255.92.0
cau hoi? mang tren co chia mang con hay khong neu ro tung truong hop?,
cho biet dia chi mang

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