Free Network Tutorials Posts

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

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

“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

Here’s the Cisco IOS-XR commands vs Juniper OS commands Cisco IOS-XR Juniper OS BASIC show show     | include | match ..formal |       display set    configure        configure/edit shutdown      disable   no shutdown  delete interface <interface> disable     no        delete   clear  clear show running-config show configuration  show version show version    show tech-support request support information  show configuration (after change) show | compare (after change) clear counters <interface>  clear interface…

Cisco Juniper Networking

An Access List or ACL is set of rules to filter network traffic that can be applied to router or switches. In some large networks where it requires like hundreds of lines, it’s a bit a pain in the ass to manage and configure this. Another thing if user keeps on requesting for changes like adding and removing rules, then using object-group can be the answer. Object-groupgs can be implemented in extended ACLs, both numbered and named, and can be…

Cisco

Static Route Configuration Examples in Juniper for BGP aggregated prefix advertisements In order to advertise the aggregated routes (and default routes) via BGP, it should exists in the routing table, that’s the #1 rule. If these summarized routes (/16) are not existing and only smaller subnets are learned via the IGP(e.g. OSPF,IS-IS), then configure static route and next hop e.g. Null0. Configuration: routing-options { graceful-restart; rib inet6.0 { static { route fd41:c8be:2153:f400::/64 discard; route ::0/0 { discard; no-install; static {…

Juniper