Archive for September, 2012

Basic QoS part 1 – Traffic Policing and Shaping on Cisco IOS Router

September 19, 2012 14 comments

In this post I will talk about Cisco Router QoS and more particularly Traffic Shaping and Traffic Policing. I will describe and show how to configure Traffic Shaping and Traffic Policing using the legacy methods but also using the new methods. In this post I will neither talk about Frame Relay Traffic Shaping nor Frame Relay Traffic Policing which I will try to cover in another post. For now on I will use TS for Traffic Shaping and TP for Traffic Policing.

 To illustrate the different examples in this post I will use the following topology:


 Platform/IOS: Cisco 2691/12.4(15)T11 Adv IP services.

 Side note: Please note that I am using IOS version older than 12.4(20)T so I will not talk about the new QoS model of Cisco which is called Hierarchical QoS (HFQ). I will only be using CBWFQ (Class-Based Weighed Fair Queuing) which is the previous version of MQC (Modular Quality of Service Command Line Interface) used by Cisco Router up to 12.4(20)T. Note that in the current CCIE R&S LAB v4.0 Cisco is using IOS image 12.4(15)T which uses CBWFQ as QoS model. Also in IOS version from 12.4(20)T and above as IOS image is using HFQ, many features differ from CBWFQ such as the queuing mechanisms, show outputs, etc.

 Addressing: All the IP addresses are configured as shown on the diagram.

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Basic Multicast part 4 – PIM Sparse Mode – BSR and Multicast Security

September 11, 2012 4 comments

Continuing with Multicast topic I will talk this time about PIM BSR (Bootstrap Router) which is an alternative way to advertise dynamic RP information. We saw in the previous posts on Multicast that the RP information could be configured statically or dynamically with Auto-RP. Auto-RP is a legacy mechanism which is neither part of the PIMv2 standard nor used in IPv6 Multicast. The issue with Auto-RP is that it uses specific multicast groups to propagate the RP information which gives some challenge in NBMA partially meshed networks and some methods are needed in order to allow the Multicast Auto-RP control plane traffic to be propagate everywhere.

BSR (Bootstrap Router) which is part of PIMv2 standard and used in IPv6 Multicast is similar to Auto-RP but the RP information is not disseminate using Multicast group but instead this information is encapsulated in PIM packets.

 I will also talk about some Multicast security features that can be used in order to protect the Multicast domain.

 Before reading further I invite you to read my previous post on Multicast PIM Sparse Mode if you are not familiar with PIM SM.

 I will use the same network topology as I did in my previous posts on Multicast. Let´s consider the following topology:

Source: The multicast source will be sending to multicast group which is part of the administratively scoped addresses assigned by IANA which is for use in private multicast domains, much like the IP unicast range defined in RFC 1918.

RP: The RP is R4 with IP:

BSR: The Bootstrap router is R3 with IP

IGP: The IGP used is EIGRP

Platform/IOS: Cisco 2691/12.4(15)T11 Adv IP services

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MPLS Layer 3 VPNs

September 10, 2012 21 comments

This post is the continuation of the previous post I made on Basic MPLS. In this post, I will talk about the different steps in order to configure MPLS Layer 3 VPNs which include the PE-CE routing protocols configuration with RIP, EIGRP and OSPF. I will also talk about the different loop prevention rules used when using OSPF as a PE-CE routing protocol. Finally I will conclude this post by talking about OSPF Sham-link.

 In this topic, I will use the following topology:

Platform/IOS: Cisco 2691/12.4(15)T11 Adv IP services


  • Customer A: VRF A | IGP: RIP
  • Customer B: VRF B | IGP: EIGRP
  • Customer C: VRF C | IGP: OSPF 2 Area 0
  • ISP: Core IGP: OSPF 1 Area 0 | MP-BGP AS 200

 Addressing: See topology. All the routers are configured with a Loopback IP and the format X.X.X.X /32 where X is the router number.

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