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Cisco Packet Tracer 8.x tutorials

What is Netflow?

Netflow is a network analysis protocol that was initially created by Cisco to give the ability to collect detailled informations about network traffic as it flows through a router interface.

The data processed by Netflow collectors provides the network administrator with detailled traffic informations such as the source and destination of the traffic, class of service, .... Netflow version 9 was standardized in 2008 as IPFIX by the IETF organization. This feature is used by network operators for billing network users.

NetFlow records are exported to a Netflow collector using User Datagram Protocol (UDP). The IP address and the destination UDP port of the NetFlow collector have to be configured on the sending device (router or l3 switch). The standard value is UDP port 2055, but other values like 9555 or 9995 can also be used.

Cisco Wireless concepts

The Cisco Wireless Controller (WLC) devices is the Cisco solution to centrally configure, manage enterprise wireless networks, regardless of the number of access points deployed and thei location. Wireless controllers have become very popular as companies move from standalone Access Point (AP) wireless designs, complicated to configure and to secure properly, to centralized controller-based designs, reaping the enhanced visibility, functionality and redundancy benefits that come with those modern designs.

The following youtube video presents the basic concepts of how Wireless Controllers work and interact with Lightweight access points using CAPWAP protocol. A good understanding of the concepts presented in this video is mandatory before starting this Packet Tracer 8.2 wireless tutorial.

 

Introduction - IPSEC VPN on ISR routers

Cisco Packet Tracer allows IPSEC VPN configuration between routers. The example below presents a basic VPN configuration over a Frame Relay between Paris and New-York using Cisco 2811 routers.

IPSEC Tunneling allows network adminisrators to use the Internet to create secure connections between networks (teleworkers, remote sites, ...). Cisco 2811 routers use the ISAKMP and IPsec tunneling standards to crete and manage tunnels. IPsec provides authentication (AH) and encryption (ESP) services to prevent unauthorized data access or modification. ISAKMP is the negotiation protocol that makes peers negociate on how to build the IPsec security association.

A major problem with IPSec sessions is that they do not support multicast or broadcast traffic. Enabling dynamic routing protocols such as OSPF or EIGRP requires multicast or brodcast support to allow hellos and updates traffic between routers.

Solution : Build another generic tunnel over IPSEC. Three options available in Cisco routers :

  • Virtual Tunnel Interface (VTI)
  • Generic Routing Encapsulation (GRE)
  • DMVPN and GET VPN

GRE over IPSEC has been working in Cisco Packet Tracer since at least version 6.0.1 . This tunnel design allows OSPF dynamic routing over the tunnel

Access point overview

The Cisco 819 ISR supports built-in enterprise class WLAN capability with an embedded Cisco 3500 Access Point featuring 802.11a/b/g/n and 2X3 MIMO antenna diversity (2 transmitting antennas and 3 receiving antennas).  With the dual 802.11 radio capability, the integrated AP can serve both as an access point and as a client to another wireless network for backbone/internet connectivity. This provides another source for WAN diversity along with Gigabit Ethernet, serial, and 3G/4G capabilities.

The Cisco 819 ISR router wireless access-point is a service module connected to the router with the following interfaces :

  • wlan-ap0 for access point management
  • Wlan-GigabitEthernet0 for production traffic between the router and the AP. This interface can be configured as a trunk to allow the AP to link multiple SSID to different vlans

  

Router#show ip interface brief 
Interface              IP-Address      OK? Method Status                Protocol
 
GigabitEthernet0       unassigned      YES NVRAM  administratively down down
 
FastEthernet0          unassigned      YES unset  up                    down
 
FastEthernet1          unassigned      YES unset  up                    down
 
FastEthernet2          unassigned      YES unset  up                    down
 
FastEthernet3          unassigned      YES unset  up                    down
 
Serial0                unassigned      YES NVRAM  administratively down down
 
Wlan-GigabitEthernet0  unassigned      YES unset  up                    up
 
wlan-ap0               10.10.10.1      YES TFTP   up                    up
 
Cellular0              unassigned      YES unset  administratively down down
 
Vlan1                  10.10.10.1      YES NVRAM  up                    up

 

BGP in Packet Tracer

BGP (Border Gateway Protocol) is the core routing protocol of the Internet. It is described as a path vector protocol, as BGP does not use traditional IGP (OSPF, EIGRP, RIP) metrics, but makes routing decisions based on paths, network policies, and/or rulesets. It maintains a table of IP networks or 'prefixes' which designate network reachability among autonomous systems (AS).

BGP protocol support in Packet Tracer allows Cisco CCNP Route students to better understand this complex routing protocol and to be prepared for the simulation questions in the exam.

 

Internal BGP (iBGP) is currently not supported in Packet Tracer (see screenshot below). iBGP support has still not been added in the new Packet Tracer 8.2.2 version

Packet Tracer 8.2.2 - iBGP support in a Cisco ISR 2811 router

 

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