Cisco Hands On Training Podcast
41 episodes - English - Latest episode: over 14 years ago - ★★★★ - 72 ratingsA video podcast showing Cisco hands-on training exercises.
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Episodes
IPv6 RIPng dynamic routing
March 14, 2010 04:22 VideoThe 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 ar...
IPv6 Static Routing
November 02, 2009 01:44 VideoIn 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 t...
The need for QOS versus Net Neutrality
September 27, 2009 03:19 VideoIn 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 ap...
IPv6 theory
September 20, 2009 05:42 VideoThe 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...
IOS Version Selection Tactics
May 31, 2009 04:11 VideoThe 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, E...
IOS Access Control Lists
March 24, 2009 04:47 VideoIn 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 ...
IOS DHCP and NAT
March 23, 2009 04:42 VideoIOS 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 ro...
Hot Standby Router Protocol
March 22, 2009 04:36 VideoIn 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 c...
Rapid Spanning Tree 802.1w
March 08, 2009 04:57 VideoThis 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 p...
Etherchannels and the port aggregation protocol
March 03, 2009 05:35 VideoWhen 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 proto...
VTP Vlan Trunking Protocol
March 01, 2009 23:14 VideoVTP 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 revis...
802.1q and ISL trunks
February 24, 2009 02:17 VideoSwitches 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 nego...
Intermediate spanning tree
February 23, 2009 03:49 VideoWe 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. ...
VLANs and spanning tree
January 31, 2009 17:33 VideoVLANs 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...
How ARP and Ethernet Work
January 25, 2009 05:22 VideoSo 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 enco...
BGP route selection with MEDs
May 29, 2008 05:42 VideoIn 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 differen...
eBGP and iBGP
March 22, 2008 05:51 VideoWe put together what we learned about eBGP, iBGP, and OSPF.
OSPF route filtering and area border routers
October 21, 2007 05:45 VideoOSPF routes should be filtered or summarized at area border routers.
OSPF distribute-list problems
October 07, 2007 05:41 VideoOSPF's fundamental design is that all routers in an area have the same exact view of the network topology. This is fundamentally incompatible with filtering routes within an area. As a result OSPF distribute lists do not have the same effect as RIP distribute lists. In fact, using distribute-lists within an OSPF area is dangerous.
Totally stubby and not-so-stubby OSPF areas
September 30, 2007 05:39 VideoOSPF totally stubby areas and not-so-stubby areas are ways to improve OSPF scalability. But they can be very confusing.
OSPF stub areas and neighbor synchronization
September 23, 2007 05:35 VideoWe cover OSPF stub areas and neighbor synchronization.
OSPF Redistribution
July 31, 2007 05:33 VideoWe redistribute from RIPv2 into OSPF and introduce autonomous system boundry summary LSAs and external summary LSAs.
OSPF Areas and Network Summary LSA's
July 16, 2007 05:31 VideoWe introduce multiple OSPF areas and network summary LSA's.
Introduction to OSPF
July 01, 2007 05:29 VideoWe show a single area OSPF network and go into router and network link state advertisements (LSA's) in detail.
Shortest Path First Algorithm
June 04, 2007 05:26 VideoA brief tutorial on Dijkstra's Shortest Path First Algorithm. This algorithm is used by most link state routing protocols, including OSPF and IS-IS.
RIPv2
September 22, 2006 05:25 VideoRIP version 2 includes subnet information in the route advertisement. It also improves efficiency by multicasting to RIPv2 routers instead of broadcasting to all hosts.
Migrating from RIPv1 to IGRP via route redistribution
July 25, 2006 05:21 VideoIf you run two different routing protocols in two different parts of your network, you need to redistribute routes between the two routing protocols. This session is an introduction to route redistribution by example. In production you must be cautious about route redistribution because the route metric is not converted in a meaningful manner. This can result in routing loops.
Migrating from RIPv1 to IGRP via "ships in the night" routing
July 10, 2006 05:17 Video"Ships in the night" routing refers to two routing protocols which do not interact with each other. We can migrate from one routing protocol to a more believable one by simply turning on the new protocol then turning off the old protocol. Bug be careful to turn the new protocol on in the entire routing domain before turning off the old protocol.
IGRP: Interior Gateway Routing Protocol
June 29, 2006 05:14 VideoIGRP is a Cisco-proprietary routing protocol. It is a classful distance vector protocol with a metric based on bandwidth and delay. This is superior to RIP, whose metric is based on hop-count. IGRP's classfulness makes it a bad choice for new deployments, but its advanced metric is worth study.
RIPv1 distribute lists and offset-lists
June 21, 2006 05:12 VideoRIP distribute lists deny specific route advertisements. RIP offset-lists increase the metric (hopcount) for specific route advertisements.
Problems with RIP Version 1
June 19, 2006 05:08 VideoRIP version 1 route advertisements do not include a field for the netmask. This means receiving routers have to gess the netmask based on whatever information they have available. That includes the "natural" netmask of that classful network. That also includes the receiving routers own configuration. This means that variable length subnets and discontiguous classful network have problems with RIP version 1. The lack of the netmask field in the route advertisement is a real problem.
RIP Version 1
June 17, 2006 05:05 VideoRIP version 1 is a classful routing protocol. We cover the RIP packet format and configuration. We see examples of split horizon and triggered updates using the RIP debug commands.
Static routing and introduction to CEF
June 13, 2006 05:04 VideoRouting protocols (and static routing) update the route table. The route table is used to forward packets. Cisco Express Forwarding (CEF) is a special route table optimized to forward packets more efficiently.
Serial and ethernet point-to-point links
June 11, 2006 04:59 VideoWe cable and configure ethernet and synchronous serial point-to-point links. In the next session these will be the "legs" of our triangle.
Classful IP addressing
June 08, 2006 04:54 VideoRouters route packets based on the destination IP address: a 32-bit number included in the header of every IP packet. Historically, "large" sites were allocated IP address blocks starting with 0 (binary). Medium sites were allocated address blocks starting with the bits 10. "Small" sites were allocated address blocks starting with the bits 110.
Cisco 2500 password recovery
June 03, 2006 04:42 VideoEvery network engineer needs to be able to deal with a router with an unknown password. Whether you are taking over a site where the previous engineer was "hit by a bus", or scrounging routers from the storage closet, good network engineers can deal with routers with unknown passwords.
Scrounging Cisco Gear and Using the Console
June 02, 2006 03:59 VideoYou can best take advantage of the Cisco training podcast series by getting routers and following along. First you need to scrounge or buy routers and cables. This episode helps you decide what to get. This episode also explains how to access the console.