Month: April 2015

PPP Authentication

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In this article I want to discuss PPP authentivation methods. You can use simple authentication method or use a server (RADIUS or TACACS+) to authenticate and authorize users.
The topology is so simple: just 2 routers with a serial connection and I am not using an actual RADIUS server but I will provide a non-existing address so that you can get the idea.ppp Read the rest of this entry »

Weighted Fair Queueing (WFQ)

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In this section I discuss Waighted Fair Queueing (WFQ) and before starting I would like to define the terminology.WFQ

Flow:A flow is a sequence of packets with a particular protocol type (e.g. TCP), source IP address and port (R1’s Lopback 0, port 55656), destination IP address and port (R4’s Loopback 0, port 110) and ToS value.

ToS Bits: 3 Bits in the IEEE Ethernet frame that define a value between 0-7 and we can use it to define the importance of that data frame.

Adaptive Flow: A flow that slows down when drop rate for that flow increases. This process uses multiple operators and I will discuss it later.

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Quality of Service: Interface Queues

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I want to start a series of discussions about QoS (although discontiguous!) and I will dive deep into that so that you can grab the idea and be quite comfortable with it.
I will start with the easiest examples and then discuss more advanced methods and finally I will wrap up all methods and will talk about pros and cons and application of each method.
Note that in each scenario I may change the topology a little bit.

Hardware Queueing

QoS-1 Read the rest of this entry »

Policy-Based Routing

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In this article I am going to examine a simple scenario for PBR. This is the phyical topology and it roughly corresponds to its logical topology:

Policy-Based Routing Topology

EIGRP AS 1 is running on all routers. You may run OSPF as well and you will get the same result.
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