Port Aggregation

Port aggregation is a technique to bind more than one physical port and create a bigger virtual port. It is done for multiple purposes. The biggest advantage of this technique is increasing the bandwidth of a port. If you have two 100Mb ports and you need a port that can support 200Mb bandwidth then you just have to merge two ports and you will get the 200Mb bandwidth. Another reason is redundancy if we want to provide resources with zero second downtime we can use this technique Read more [...]

Layer 2 Threat Mitigation Part 2

VLAN Hopping An attack in which an attacker jumps from one VLAN to another VLAN by tagging targeted VLAN number to frame. For example I am an attacker and I am connected to VLAN 10 but I want to get access to VLAN 1 so what I do that I grab the packet before it leaves my NIC and I tag it with VLAN ID 1 so now when it gets to the switch it will tag another VLAN ID which is 10 because I am connected to VLAN 10 but when this frame gets to another switch then the switch will open the first tag VLAN ID Read more [...]

Layer 2 Threat Mitigation

Layer 2 threat mitigation is important, it is defense from an insider who aims to damage the network. There are security devices such as firewall, IDS/IPS, and other systems to protect the network but these technologies do not work at layer 2.There are many threat that can be initiated by an insider in a local network, such as insider could leak or grab information, he/she can cause a denial of service condition to switch or servers. MAC Flooding It is the attack against switches that feeds Read more [...]

Quality of Service

QoS is an umbrella term that includes many tools and techniques to improve the performance of network, it is very complex topic as well. QoS is intended to prioritize the traffic on the basis of protocols. For example, the VoIP traffic take 64Kb bandwidth for entire session the call is up and if there is quite a much other traffic in your service then it could affect the VoIP call and there could be dozens of glitters in call. The sole purpose of this technology is Read more [...]

Spanning Tree Protocol Part 3

Spanning tree (802.1d) also known as common spanning tree (CST) which means only one big spanning tree for all VLANs.Where Cisco uses per vlan spanning tree (PVST+) which means running individuals spanning tree for each VLAN. Rapid Spanning Tree Protocol It is 802.1w which does not takes 30 seconds to shutdown or turn on loop protocol. This protocol looks for alternate port or back-over port to turn on when primary ports gets fail. Note: Cisco highly recommends Read more [...]

Quality of Service Part – 2

Random Early Detection – RED Random Early Detection (RED) is the mechanism that detects the memory buffer size before it gets full. It looks for the hosts that are sending more data and it drops the packet of host that is transmitting more data and it lets go the host who is sending low data. For example, Host – A is sending 100Mb traffic and Host – B is sending 100Kb traffic now when RED detects the buffer is getting full it will start dropping the Host Read more [...]