COS2626 is a practical, heavy-hitting module. Unlike the first-year networks module, which was mostly vocabulary (“What is an IP address?”), this module requires you to be a Network Administrator.
You aren’t just learning definitions; you are learning to configure Routers and Switches. You need to understand how to segment traffic, secure the network, and make different protocols talk to each other. If you cannot look at a Routing Table and visualize the network topology in your head, you will struggle.
This guide breaks down the curriculum based on the Cisco (CCNA) concepts covered in the module.
1. Routing Protocols (The Brain of the Network)
This is the core of the module. You need to understand how routers make decisions.
Static Routing
You manually tell the router where to go.
- Exam Skill: You must be able to write the command:
ip route [destination_network] [mask] [next_hop_address] - Concept: It is secure but doesn’t scale. If a cable breaks, the static route is dead.
Dynamic Routing
The routers talk to each other to find the best path. You need to master:
- Distance Vector (RIP): Counts “hops.” Simple but slow.
- Link State (OSPF): Checks the “speed/cost” of the link. Complex but fast.
- Tutor Tip: Be able to explain the “Administrative Distance.” Why does a router trust a Static Route (AD=1) more than OSPF (AD=110)?
2. Switching & VLANs (The Backbone)
Switches are usually plug-and-play, but not in this module. You need to configure them to separate traffic.
- VLANs (Virtual LANs): This splits one physical switch into multiple virtual switches.
- Why? Security and Performance. Marketing can’t see Engineering’s traffic.
- Trunking (802.1Q): How do we carry multiple VLANs over a single cable between switches? We “tag” the frames.
- Inter-VLAN Routing: A switch cannot route traffic between VLAN 10 and VLAN 20. You need a “Router on a Stick” to do this.
3. Network Security & Services (The Guard)
This section is about controlling who gets in and out.
ACLs (Access Control Lists)
This is the network’s “Bouncer.”
- Standard ACL: Filters based on Source IP only. (1-99).
- Extended ACL: Filters based on Source, Destination, Protocol, and Port. (100-199).
- The Trap: There is an invisible “Implicit Deny” at the bottom of every list. If you don’t explicitly “Permit” traffic, everything else is blocked!
Services
- NAT (Network Address Translation): This is how your entire house uses one Public IP address to talk to the internet.
- DHCP: Automatically assigning IP addresses. Know the “DORA” process (Discover, Offer, Request, Acknowledge).
4. Network Management
- SNMP (Simple Network Management Protocol): Used to monitor the health of network devices.
- Syslog: Where routers send their error messages. You need to know the severity levels (0 is Emergency, 7 is Debug).
Decksh’s Top 3 Tips for a Distinction
Tip 1: Think in “CLI” (Command Line Interface)
In the exam, you might be asked to “configure OSPF.” You can’t click buttons. You need to write the commands:
Router(config)# router ospf 1
Router(config-router)# network 192.168.10.0 0.0.0.255 area 0Memorize the basic configuration blocks for OSPF, VLANs, and ACLs.
Tip 2: Master Subnetting (Again)
You cannot pass COS2626 if you are slow at subnetting.
- VLSM (Variable Length Subnet Masking) is crucial. You need to take a
/24network and chop it into a/26,/27, and/30for different departments. - If you assign the wrong Gateway IP because you miscalculated the range, your routing will fail.
Tip 3: Read the Routing Table
Learn to interpret the output of show ip route.
- C: Connected (Directly attached).
- S: Static (Manually added).
- O: OSPF (Learned dynamically).
- If a route is missing from the table, the router cannot send data there. This is always the first step in troubleshooting.
Conclusion
COS2626 is about logical flow. Can you trace a packet from PC A, through a switch (VLAN 10), up a Trunk, into a Router, through an ACL, and out to the Server? If you can visualize that path, you will ace this module.
Good luck!