| EtherChannel Configuration
EtherChannel is a channel aggregation technology developed by Cisco Systems. The technology allows the combination of multiple Ethernet physical channels into one logical channel to increase bandwidth and enhance connection reliability. |
Cisco Discovery Protocol — A Spy’s Find
The Cisco Discovery Protocol (CDP) is a proprietary protocol of Cisco, using the SNAP frame at the data link layer to collect information about neighboring Cisco devices, such as routers and switches. |
Real Throughput of Network Devices
When selecting network devices for infrastructure, network engineers and system administrators face the question of the real capability of network devices to transmit data through themselves. Many mistakenly believe that a router with two 1Gb/s ports can guarantee traffic transmission at the speed of these ports — but in reality, it’s far from the case. |
Configuring Cisco + HWIC-3G-HSPA
Lately, the technologies of cellular data transmission 3G/4G have become widely spread, and naturally, businesses have armed themselves with these technologies, and engineers are increasingly faced with the need to configure various 3G modules and modems. |
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| Configuring Cisco ASA with FirePOWER Services
The next-generation firewall has acquired new and very serious network protection functions. Such innovations cost Cisco 2.7 billion dollars. Let’s understand what prompted Cisco to take such a step and try these functions in action. |
How to Build a Career in IT?
The complexity of modern technologies reveals the helplessness of HR specialists in the task of searching for IT personnel. The fact is that a recruitment specialist is not able to verify the technical knowledge of a candidate for a position because they themselves cannot possess the necessary knowledge. Documentary work experience, in turn, does not guarantee a quality knowledge of technologies by the specialist applying for a position in the IT sector, and competence in this area is a leading asset. |
Feasible Successor in EIGRP and Routing Loops
An important advantage of the EIGRP protocol is the presence of backup routes that can be instantly placed in the routing table in case of the primary route failure. Such a mechanism ensures the fastest possible network convergence in the event of a failure, but at the same time, it harbors some problems… |
Configuring Port Security
Port security is a traffic control technology at the second layer of the OSI model used in Cisco Catalyst switches. This technology allows only frames with specific source MAC addresses to pass through the ports on which it is configured. The main purpose of this technology is… |
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| Configuring OSPF Virtual Links
Virtual links in OSPF help solve the problem of divided areas, this article introduces the basic principles of its configuration. |
SVI or Routed Interface
There are two ways to organize L3 connectivity between two L3 switches. The first method involves creating a VLAN for L3 connectivity along with SVI interfaces (Interface VLAN) on both devices. The configuration looks something like this: |
What are IPv6 Link-Local Addresses?
The block of IPv6 link-local addresses is specifically allocated for use within a single L2 domain, i.e., for organizing interaction in a local network segment. Packets, where the source or destination address is a link-local address, are not forwarded by routers from one L2 segment to another, i.e., these packets are not routed. These addresses … |
Path MTU Discovery
When a device needs to transmit information through an interface into the network, it first refers to the Maximum Transmission Unit (MTU) parameter of that interface to … |
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| What is Remotely-Triggered Black Hole (RTBH) Routing?
The Remotely-Triggered Black Hole (RTBH) routing mechanism is one of the interesting applications of the BGP protocol as a protective mechanism in the networks of communication operators… |
Disabling Dynamic Trunking Protocol (DTP)
The Dynamic Trunking Protocol helps to automatically create a trunk between two Cisco devices. If DTP is enabled on two ports, and at least one of them is set to desirable mode, the two switches will negotiate the establishment of a trunk on this communication line. DTP and VLAN Trunking Protocol (VTP) should not be confused, although the VTP domain indeed plays a role for DTP. |
Unidirectional Link Detection (UDLD)
Unidirectional Link Detection (UDLD) is a proprietary Cisco second-level protocol created for automatic detection of loss of bidirectional communication on communication lines. It is usually mentioned in discussions about the spanning tree… |
Routing or Switching at the Access Level
The main discussion in the process of network design focuses on whether traffic from the access level will be switched or routed to the aggregation level. |
OSPF Design
OSPF is a well-scalable protocol, if its features are considered during network design. |
Installing Equipment in a 19″ Rack
The terms rack, telecommunications cabinet, or «rack» usually refer to a standard metal cabinet, or frame 19 inches (~48 cm) wide between the bolt holes. |
Types of OSPF Areas (OSPF area types)
Understanding the principles of OSPF operation is based on concepts such as LSA and Area Type. Often the multitude of their types leads to misunderstandings… |