diff --git a/00. Jeremy's IT LAB CCNA course.md b/00. Jeremy's IT LAB CCNA course.md index 13e3986..ac42e22 100644 --- a/00. Jeremy's IT LAB CCNA course.md +++ b/00. Jeremy's IT LAB CCNA course.md @@ -22,3 +22,4 @@ tags: [[Routing Fundamentals]] [[Static Routing]] [[The Life of a Packet]] +[[Subnetting (Part 1)]] diff --git a/07. IPv4 Addressing (Part 1).md b/07. IPv4 Addressing (Part 1).md index c03ee61..2d3be97 100644 --- a/07. IPv4 Addressing (Part 1).md +++ b/07. IPv4 Addressing (Part 1).md @@ -1,8 +1,8 @@ --- id: 07. IPv4 Addressing (Part 1) aliases: [] -tags: - - CCNA +tags: + - CCNA --- # IPv4 Addressing (Part 1) @@ -37,13 +37,13 @@ Class C ## [[IPV4]] address classes -| Class |First octet | numeric range| Prefix Length | -| ----- | ---------- | --------------| /8 | -| A |0xxxxxxxx | 0-127 | /16 | -| B |10xxxxxxx | 128-191 | /24 | -| C |110xxxxxx | 192-223 | | -| D |1110xxxxx | 224-239 | | -| E |1111xxxxx | 240-255 | | +| Class |First octet | numeric range | Prefix Length | +| ----- | ---------- | ------------- |------------- | +| A |0xxxxxxxx | 0-127 | /8 | +| B |10xxxxxxx | 128-191 | /16 | +| C |110xxxxxx | 192-223 | /24 | +| D |1110xxxxx | 224-239 | | +| E |1111xxxxx | 240-255 | | class D are reserverd for Multicast addresses diff --git a/13. Subnetting (Part 1).md b/13. Subnetting (Part 1).md new file mode 100644 index 0000000..90de4e7 --- /dev/null +++ b/13. Subnetting (Part 1).md @@ -0,0 +1,194 @@ +--- +id: 1777840095-WYOD +aliases: + - Subnetting (Part 1) +tags: + - CCNA +--- + +# Subnetting (Part 1) + +## IPV4 Address Classes + +| Class |First octet | numeric range | Prefix Length | +| ----- | ---------- | ------------- |------------- | +| A |0xxxxxxxx | 0-127 | /8 | +| B |10xxxxxxx | 128-191 | /16 | +| C |110xxxxxx | 192-223 | /24 | +| D |1110xxxxx | 224-239 | | +| E |1111xxxxx | 240-255 | | + + +### Maximum Hosts per Network + +Host portion all 0s = Network address (network ID) +Host portion all 1s = broadcast address + +192.168.1.0/24 -> 192.168.1.255/24 +Host portion = 8 bits = 2^8 = 256 +Maximum hosts per network = 2^8-2 = 254 + + +172.16.0.0/16 -> 172.16.255.255/16 +Host portion = 16 bits = 2^16 = 65,536 +Maximum hosts per network = 2^16 -2 = 254 + +10.0.0.0/8 -> 10.255.255.255/8 +Host portion = 24 bits = 2^24 = 16,777,216 +Maximum hosts per network = 2^24 -2 = 16,777,214 + +### How IP addresses are distrubuted + +- The [[IANA]] (Internet Assigned Numbers Authority) assigns IPV4 addresses/networks to +companies based on their size +- For example, a very large company might receive a class A or class B network, while a small +company might receive a ckass C network. +- However, this led to many wasted IP addresses. + +#### Example 1 + ++----+ +----+ +| R1 |<----->| R2 | ++----+ ^ +----+ + Point to Point network + - 256 addresses + - 1 network address (203.0.113.0) + - 1 broadcast address (203.0.113.255) + - 1 R1 address (203.0.113.1) + - 1 R2 address (203.0.113.2) + - **252 addresses Wasted** + + +#### Example 2 + +Company X needs IP addressing for 5000 end hosts. +- A class C network does not provide enough addresses, so a class B network must be assigned +- This will result in about 6000 addresses being wasted. + +## CIDR + +- When the internet was first created, the creators did not predict that the internet +would become as large as it is today +- This resulted in wasted address space like the examples. +- The [[IETF]] introduced [[CIDR]] in 1993 to replace the 'classful' addressing system. +- With CIDR, the requirement of ... + - Class A = /8 + - Class B = /16 + - Class C = /24 +were removed +- This allowed larger networks to be split into smaller networks, allowing greater efficiency +- These smaller networks are called 'subnetworks' or [[subnetting]] + ++----+ +----+ +| R1 |<----->| R2 | ++----+ ^ +----+ + 203.0.113.0/24 + +Network address +11001011.00000000.01110001.*00000000* + 203 . 0 . 113 . 0 + +Subnet Mask +11111111.11111111.11111111.*00000000* + 255 . 255 . 255 . 0 + +2^8 - 2 = 254 usable addresses. + +How many usable addreses are there in each network? + +#### CIDR /25 +**203.0.113.0/25** +Network address: +11001011.00000000.01110001.0*0000000* + 203 . 0 . 113 . 0 +Subnet Mask +11111111.11111111.11111111.1*0000000* + 255 . 255 . 255 . 128 +*2^7 - 2 = 126 usable addresses* + +#### CIDR /26 +**203.0.113.0/26** +Network address +11001011.00000000.01110001.00*000000* + 203 . 0 . 113 . 0 +Subnet Mask +11111111.11111111.11111111.11*000000* + 255 . 255 . 255 . 192 +*2^6 - 2 = 62 usable addresses* + +#### CIDR /27 +**203.0.113.0/27** +Network address +11001011.00000000.01110001.00*000000* + 203 . 0 . 113 . 0 +Subnet Mask +11111111.11111111.11111111.111*00000* + 255 . 255 . 255 . 224 +*2^5 - 2 = 30 usable addresses* + +#### CIDR /28 +**203.0.113.0/28** +Network address +11001011.00000000.01110001.00*000000* + 203 . 0 . 113 . 0 +Subnet Mask +11111111.11111111.11111111.1111*0000* + 255 . 255 . 255 . 240 +*2^4 - 2 = 14 usable addresses* + +#### CIDR /29 +*203.0.113.0/29* +Network address +11001011.00000000.01110001.00000*000* + 203 . 0 . 113 . 0 +Subnet Mask +11111111.11111111.11111111.11111*000* + 255 . 255 . 255 . 248 +*2^4 - 2 = 6 usable addresses* + +#### CIDR /30 +**203.0.113.0/30** +Network address +11001011.00000000.01110001.000000*00* + 203 . 0 . 113 . 0 +Subnet Mask +11111111.11111111.11111111.111111*00* + 255 . 255 . 255 . 252 +*2^4 - 2 = 6 usable addresses* + +This is the perfect CIDR for our 2 router + +The remaining addresses in the 20 203.0.113.0/24 address block (20 203.0.113.4 - 20 203.0.113.255) +are now available to be used in other subnets! + +#### CIDR /31 +*203.0.113.0/31* + +2^1 -2= 0 usable addresses + +but for our point to point connection we can utilisize it +no need for broadcast or network address +In cisco device however you get a systeme warning + +```cisco +Router(config-if)# ip address 203.0.113.0 255.255.255.254 +Warning use /31 mask on non point-to-pint interface cautiously +``` + +The remaining addresses in the 20 203.0.113.0/24 address block (20 203.0.113.2 - 203.0.113.255) +are now available to be used in other network! + + +#### CIDR /32 +*203.0.113.0/32* + +2^1 -2= -1 usable addresses + +can be used in static routes +don't worry about them now + +## Review + +- [[CIDR]] (Classless Inter-Domain Routing) +- The process of subnetting +