Routing & Switching

The video picks up where we left off on the Basic NAT video. The more advanced NAT functionalities on Cisco router are demonstrated.

The video demonstrates various Network Address Translation (NAT) functionalities on Cisco router. We look at  scenarios when the NAT IP is assigned from the router interface subnet, where proxy-arp is utilized, and the IP is assigned from a completely different subnet.

Topic includes

The video walks you through DHCP configuration on Cisco router and switch for both server and client roles, how to exclude blocks of IP from a pool, and reserve IPs for certain hosts. We then look at DHCP relay (UDP unicast forwarding) used when the DHCP server is not situated on the same client subnet, and the significant of DHCP Option 82. Wireshark captures of DHCP packets are reviewed throughout the video.

The video demonstrates GLBP configuration on two routers providing an IP gateway. We review the roles of Active Virtual Gateway (AVG) and Active Virtual Forwarder (AVF), and how load balancing is achieved, and perform various failover test scenarios. GLBP main distinction from HSRP and VRRP is its ability to natively provide gateway load balancing to end devices, hence increase in protocol complexity.

The video demonstrates VRRP configuration on two routers providing an IP gateway. Failover behavior caused by interface object tracking is observed. We also review VRRP packet captured on Wireshark. VRRP serves the same purpose as HSRP with minor differences: one being a standard protocol, hence it would be a protocol of choice for inter-operability with other vendors.

The video demonstrates HSRPv2 configuration on two routers providing an IP gateway. Failover behavior caused by interface object tracking is observed. We look into the HSRP packet and identify differences between having MD5 authentication enabled and disabled. HSRP provides redundancy at the first-hop gateway to end devices. Although load balancing is possible, multiple HSRP group and virtual IPs are needed.

The video walks you through SNMPv2 configurations on a Cisco router with most commands being applicable to a Catalyst switch. SNMP Poll and Trap are demonstrated through SNMPB tool and by analyzing packets captured on Wireshark. SNMP is a widely-used protocol for monitoring the health of network devices, and collecting performance statistics.

The video walks you through Syslog configurations on a Cisco router with most commands being applicable to a Catalyst switch. Testing is performed by sending log messages to an external Syslog server. Syslog packets captured on Wireshark are also reviewed. It is recommended to your Syslog messages sent and retained on an external server, whether it is for forensic or regulatory compliance.

Topic includes

• Logging to Console/Buffer/Server
• Syslog Packet Analysis

Quick Facts:

• Syslog uses UDP 514

The video provides recommended router startup configurations (majority also applies to a Catalyst switch) that will tighten your device security and improve your console experience. It is always recommended to disable any unused services on network devices and enforce access-control for administration. 

Topic includes

• Router/Switch Services Disabling
• Password Encryption
• Console Access Management
• Administrative Access-Control

The video explains the benefit of configuration archive and configuration replace used for router configuration management over the 'copy flash: running-config'. This is a convenient way to revert your device configuration to a previously saved copy without having to reload the device.

Topic includes

• Configuration Archive
• Configuration Replace