PODCAST

Cisco Hands On Training Podcast

Darrell Root

A video podcast showing Cisco hands-on training exercises.

technology software how-to

All Episodes

IPv6 RIPng dynamic routing

Cisco Hands On Training Podcast ·

2010/03/14

The linked video demonstrates RIPng, our first dynamic routing protocol for IPv6. This is a simple but inefficient routing protocol. The metric is based on number of router hops, with no provision for differentiating between links with drastically different bandwidth (a frame-relay hop has the same cost as a 10-gig-ethernet in RIPng). Each router multicasts its entire routing protocol out each interface every 30 seconds, which wastes router CPU. RIPng routinely takes minutes to reroute around

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IPv6 Static Routing

Cisco Hands On Training Podcast ·

2009/11/02

In this hands-on exercise, we configure IPv6 addresses on 3 routers in a triangle. Then we configure IPv6 static routes to allow the 6 IPv6 subnets (3 loopback, 3 P2P links) to be accessible on all 3 routers.Static routes are easy to understand. At first glance they appear simple. You just manually configure which next-hop to go to for each subnet destination. But in actual use they are very complex. In our example with 3 routers and 6 subnets, we end up using 12 static route commands to

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The need for QOS versus Net Neutrality

Cisco Hands On Training Podcast ·

2009/09/27

In 2003, I made a VOIP call from home while downloading a large email attachment. The DSL line saturated and my audio quality became horrible while VOIP packets (and email packets) were being dropped. Doubling the bandwidth to my home would not have solved this problem. The email download would simply have been faster, but the VOIP call would still have suffered packet loss.The solution to this problem is 'quality of service' (QOS). Some applications, particularly realtime interactive

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IPv6 theory

Cisco Hands On Training Podcast ·

2009/09/20

The linked video introduces IPv6 theory. IPv6 is the 128-bit address replacement for IPv4. The Internet is expected to run out of it's 4-billion IPv4 addresses in 2012. IPv6 will replace IPv4 at the network-layer of the OSI stack. By replacing one layer in the stack, most applications and most layer-2 network devices will continue to function.IPv6 includes several technical improvements over IPv4. IPv6 uses optional extension headers, so only packets requiring special options will have those

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IOS Version Selection Tactics

Cisco Hands On Training Podcast ·

2009/05/31

The linked video provides guidance for optimal IOS version selection.The large number of IOS versions makes choosing the best version for your router or switch difficult. You must pick the most reliable version which includes the features you need. Different IOS "packages" have different features. For example, the "LAN base" package includes basic switching code. "IP base" adds access-layer routing features (RIP and EIGRP-stub). "IP services" adds most layer-3 routing protocols (OSPF, EIGRP,

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IOS Access Control Lists

Cisco Hands On Training Podcast ·

2009/03/24

In this video demonstration, we show an example of writing IOS Access Control Lists (ACL's) on a home router. We use the revision control system (RCS) to maintain the master ACL file and push the ACL's to the router via TFTP. This is similar to many production networks, where maintaing comments and old revisions of ACL's is a requirement. We also show examples explaining the "don't care bit" format of IOS ACLs. Many network engineers mistakenly refer to the format as inverse-netmask, but that is

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IOS DHCP and NAT

Cisco Hands On Training Podcast ·

2009/03/23

IOS routers can act as DHCP clients and DHCP servers. They can also function as Network Address Translation (NAT) devices. In this video we show a demonstration using a 2621 as a DHCP client, server, and NAT translation device for my home network.It's important to understand that most IOS routers have relatively slow CPU's. An IOS router is fine as a DHCP server for a few dozen clients. But if you try to serve thousands of DHCP clients you are likely to fail and suffer an outage.IOS routers can

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Hot Standby Router Protocol

Cisco Hands On Training Podcast ·

2009/03/22

In this episode we show a video demonstration of the hot standby router protocol. This is a Cisco proprietary redundancy protocol. The purpose is to allow two routers to share one virtual IP address on an access subnet/vlan. Hosts on the subnet can use the virtual IP for their default route. This way if one router goes down the redundant router will assume the virtual IP address, preventing a loss of connectivity to the hosts on the net.HSRP is configured with the "standby ip" group of commands

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Rapid Spanning Tree 802.1w

Cisco Hands On Training Podcast ·

2009/03/08

This video demonstrates layer-2 convergence in less than 2 seconds thanks to rapid spanning-tree.Rapid per-vlan spanning-tree is configured with "spanning-tree mode rapid-pvst".The rapid spanning tree protocol, 802.1w, is the answer to the slow convergence time of the historic 802.1d spanning-tree protocol. Rapid spanning tree replaces timers with triggered updates. Switches almost never wait for a timer to expire. When converging on a new switch-to-switch link they will start with the port in

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Etherchannels and the port aggregation protocol

Cisco Hands On Training Podcast ·

2009/03/03

When you have two different links between the same two switches, normally spanning tree will forward on one and block on the other. This means half of your bandwidth is sitting idle. An etherchannel is a way to bind two links into one logical link with twice the bandwidth. In addition to increased bandwidth, etherchannels fail over in a fraction of a second. So the failure of one physical link in a multi-link etherchannel will not result in a significant outage.The port aggregation protocol

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VTP Vlan Trunking Protocol

Cisco Hands On Training Podcast ·

2009/03/01

VTP is the VLAN trunking protocol. It's used to disseminate uniform vlan information between switches over 802.1q or ISL trunks. It can also "prune" vlans, dynamically removing unneeded VLANs from trunks. This decreases unneeded frame flooding.VTP can eliminate outages thanks to the uniform VLAN configuration. But it can also cause outages if incorrect VLAN information is uniformly distributed.We also attempt a loopguard demonstration, but it doesn't work out well. We'll have to revisit the

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802.1q and ISL trunks

Cisco Hands On Training Podcast ·

2009/02/24

Switches can have multiple vlans. When we connect switches together we use 802.1q trunks (or older ISL trunks) to run multiple vlans over one physical link. With either trunking protocol, a tag is added to the ethernet frame with the vlan information. ISL is an older Cisco-proprietary trunking protocol. Newer switches do not even support ISL. Newer switches use the 802.1q vendor-indepentend trunking protocol. Cisco switches also speak the dynamic trunk protocol (DTP) to dynamically negotiate

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Intermediate spanning tree

Cisco Hands On Training Podcast ·

2009/02/23

We cover intermediate spanning tree concepts. The importance of specifying your root bridge and backup root bridge with spanning-tree priority. Using portfast to allow host ports to start forwarding without waiting for 30 seconds. Using bpduguard to disable portfast-enabled ports where someone erroneously plugs in a switch. Using errdisable timeout to automatically reenable those ports after 15 minutes. Using rootguard to prevent improper switches from becoming your spanning-tree root. The

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VLANs and spanning tree

Cisco Hands On Training Podcast ·

2009/01/31

VLANs are a feature of ethernet switches which makes them act like multiple "virtual switches". Each VLAN is a separate broadcast domain and could be configured with a separate subnet. That way could could have separate subnets for separate purposes (IT, accounting, network management) on one physical switch. This saves money and cabling while decreasing complexity.Spanning tree is a protocol which allows you to build redundant loops out of ethernet switches without suffering a bandwidth outage

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How ARP and Ethernet Work

Cisco Hands On Training Podcast ·

2009/01/25

So far we've talked about how IPv4 encodes data into a packet, and how routers learn which direction to forward those IPv4 packets based on the destination IP address and the route table.But in the end, routers and hosts need to encode the IPv4 packet onto a physical medium. Examples of physical mediums include fiber, twisted pair, coax, radio waves, lasers, and microwaves. Each encoding rate and medium requires a specification or protocol definition.Ethernet is a family of similar encoding

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BGP route selection with MEDs

Cisco Hands On Training Podcast ·

2008/05/29

In BGP, MED stands for Multi Exit Discriminator. It is a well-known optional attribute which allows one autonomous system to inject it's IGP route metrics into its BGP advertisements to another BGP autonomous system. This allows the second autonomous system to make intelligent routing decisions regarding which of multiple paths to take to send traffic to a particular destination in the first autonomous system.Because different AS's use different IGP's and can calculate metrics in different ways,

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BGP route filtering

Cisco Hands On Training Podcast ·

2008/04/11

We filter BGP routes in 4 different ways.

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eBGP and iBGP

Cisco Hands On Training Podcast ·

2008/03/22

We put together what we learned about eBGP, iBGP, and OSPF.

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iBGP

Cisco Hands On Training Podcast ·

2008/03/20

An iBGP example with 1 autonomous system with 3 routers.

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eBGP

Cisco Hands On Training Podcast ·

2008/03/19

An eBGP example with 3 autonomous systems with 1 router each.

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Cisco Hands On Training Podcast

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