Free Network Tutorials Posts

It is good to know these types of power cables/plug in case you need to bring up servers from external parties. Normally servers are C13 plug but the other end can be different depending on the rack you have, (country specific). These are the common types that you need to be familiar with if you work in a datacenter or somewhere you do server hosting.   C14 NEMA5-15 – Type B NEMA6-15 BS1316 – (UK 3 pin) CEE7/7 – Type…

Datacenter

As mentioned from the previous post, Bogon prefixes or routes should never appear in the Internet routing table. Network Engineers should implement “Best Practices” in their network, that includes filtering of bogons as it maybe used in DDoS attacks or Spams. Refer to https://freenetworktutorials.com/ipv4-and-ipv6-bogon-address-list  for more info. “Martians” bogons may changed occasionally so at least make sure private address mentioned in https://freenetworktutorials.com/ipv4-classful-and-reserved-addresses are filtered so it wont leak out into the Internet. Here is sample steps and configuration. (This is the equivalent configuration…

Juniper

As mentioned from the previous post, Bogon prefixes or routes should never appear in the Internet routing table. Network Engineers should implement “Best Practices” in their network, that includes filtering of bogons as it maybe used in DDoS attacks or Spams. Refer to https://freenetworktutorials.com/ipv4-and-ipv6-bogon-address-list  for more info. “Martians” bogons may changed occasionally so at least make sure private address mentioned in https://freenetworktutorials.com/ipv4-classful-and-reserved-addresses are filtered so it wont leak out into the Internet. Here is sample steps and configuration. 1. Create the Ingress…

Cisco

In routing world, Administrative Distance refers to the reliability of the routing protocol. It is equivalent to Juniper’s Route Preference and Huawei’s Preference. It is important to consider these values as in the scenario that there are multiple routes to a destination (with same prefix length), the route (learned via the routing protocol) with the lowest value is preferred. Table below will show the values for respective platform.   Routing Protocol Cisco(AD) Juniper (RP) Huawei(P) Connected Interface 0 0 0…

Networking

Dynamic Host Configuration Protocol, or DHCP, is a network protocol used (via DHCP server) to dynamically or automatically assign IP address and other info (e.g.Gateway,DNS) to each hosts in the network. Here’s a sample configuration of running DHCP server in a Layer 3 switch. Host Setup: Gateway: 192.168.10.1 Netmask: 255.255.255.0 DNS Server: 192.168.20.254, 8.8.8.8 Layer 3 Switch(tested in Cisco 49xx) VLAN ID: 888 IP Block: 192.168.10.0/24   Fig.A. Hosts connected to switch Configure respective interfaces for access vlan L3-Switch#conf t…

Cisco

UTP or Unshielded Twisted Pair is a type of copper cabling used in LANs and has several categories based on the TIA/EIA 568 standard namely as CAT3,CAT4,CAT5,CAT5E and CAT6. Common connector used with these UTP cables are RJ-45. Most common used now are CAT5e as it supports up to 1Gbps for 100 meters, and now CAT6 is becoming popular to LAN and datacenter networks as it supports 1Gbps for 100 meters and up to 10Gbps for 50 meters. As of…

Networking

“Bogon” or coined from the word “bogus”, In computer world,  these are IP addresses that have not been officially assigned to an entity such as IANA or Internet Assigned Number Authority which is an organization who managed allocation of globally unique IPs. Bogon IP adddress/ranges should not appear on the public Internet so network engineers should filter these as they are meant for use only in private networks  and considered reserved for special purposes. You can refer to Team Cymru website…

Networking

This is very useful for IP address planning and management especially for network engineers as part of designing their network. This is one of the consideration in proper assignment of IPs to the network devices and hosts.    IPv4 Address Classes Classes IP Address Range A 0.0.0.0 – 127.255.255.255 B 128.0.0.0 – 191.255.255.255 C 192.0.0.0 – 223.255.255.255 D 224.0.0.0 – 239.255.255.255 E 240.0.0.0 – 255.255.255.255 Reserved (Private) IPv4 Classes IP Address Range A 10.0.0.0 – 10.255.255.255 B 172.16.0.0 – 172.31.255.255…

Networking

For number of addresses, I always used this formula:32 – (cidr) = Xthen 2^x = number of addressesTo get the number of hosts, subtract with 2 (network and subnet mask) Example: (to get # of addresses and hosts of /24)32 – 24 = 82^8 = 256 (total number of addresses)256 -2 = 254 (total number of hosts) CIDR Addresses Netmask Wildcard /32 1 255.255.255.255 0.0.0.0 /31 2 255.255.255.254 0.0.0.1 /30 4 255.255.255.252 0.0.0.3 /29 8 255.255.255.248 0.0.0.7 /28 16 255.255.255.240…

Cisco

Here’s the Cisco IOS-XR commands vs Huawei OS commands Cisco IOS-XR Huawei BASIC show display     | include | include ..formal |   configure system-view shutdown shutdown  no shutdown undo shutdown     no undo  clear  reset show running-config display current-configuration show version display version    show tech-support display diagnostic-information show configuration (after change)   clear counters <interface> reset counters <int> clear line <line><line number>       terminal length <num>   screen-length disable terminal width <num>   terminal…

Networking