Cisco Hands On Training Podcast
Darrell Root
A video podcast showing Cisco hands-on training exercises.
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Top 10 Cisco Hands On Training Podcast Episodes
Goodpods has curated a list of the 10 best Cisco Hands On Training Podcast episodes, ranked by the number of listens and likes each episode have garnered from our listeners. If you are listening to Cisco Hands On Training Podcast for the first time, there's no better place to start than with one of these standout episodes. If you are a fan of the show, vote for your favorite Cisco Hands On Training Podcast episode by adding your comments to the episode page.
IPv6 theory
Cisco Hands On Training Podcast
03/14/10 • -1 min
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 headers. As a result most IPv6 packets will have simpler headers than their IPv4 counterparts. IPv6 eliminates broadcast, and instead uses multicast for most neighbor discovery functions. This is more efficient CPU-wise because hosts only need to subscribe to the multicast groups they require. IPv6 hosts use stateless autoconfiguration to acquire link-local and internet routable IPv6 addresses. In many cases this can eliminate the need for a separate DHCP server. And of course IPv6 includes 128-bit addresses, allowing 256 billion billion billion billion hosts.
The migration from IPv4 to IPv6 will be the highlight and most significant change of our networking careers. Most of us were not in this business during the IPv3 to IPv4 migration on January 1st 1983 (a 'flag day' migration). Odds are IPv6 will remain the dominant internet protocol until after we retire.
A PDF version of my presentation will be attached to the comments section.
IOS Access Control Lists
Cisco Hands On Training Podcast
03/14/10 • -1 min
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 incorrect.
PIXes, FWSMs, and ASA's use a netmask format for ACLs. It is vitally important not to make the mistake of accidentally pushing a netmask format ACL line to an IOS device. That sort of error could result in an unplanned hole in your firewall and a serious security incident.
802.1q and ISL trunks
Cisco Hands On Training Podcast
03/14/10 • -1 min
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 whether to enable a trunk.
Intermediate spanning tree
Cisco Hands On Training Podcast
03/14/10 • -1 min
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 dangers of using bpdufilter to ignore and delete BPDUs. How uplinkfast can enable access switches to failover between uplinks without delay. And using backbone fast to improve responsiveness to indirect link failures by eliminating the need for the 20 second maxage timeout.
VLANs and spanning tree
Cisco Hands On Training Podcast
03/14/10 • -1 min
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 due to looping ethernet frames. Spanning tree blocks ports in your switch mesh to change a topology of loops into a non-looping tree. Then if you suffer a link outage, spanning tree will reconverge in a new fully operational tree. This reconvergence make take significant time (30-50 seconds) with the old spanning tree protocol.
More modern improvements to the spanning tree protocol, including RSTP (rapid spanning tree) and MST (multiple spanning tree) will be covered in a later episode.
BGP route selection with MEDs
Cisco Hands On Training Podcast
03/14/10 • -1 min
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, by default MEDs are only compared when multiple paths exist between the same two autonomous systems.
BGP MEDs are fairly late in the BGP route selection process, coming after local-preference and AS-PATH length.
In this episode we show how to inject MEDs into BGP advertisements, and how they are used to influence routing decisions.
BGP route filtering
Cisco Hands On Training Podcast
03/14/10 • -1 min
We filter BGP routes in 4 different ways.
eBGP and iBGP
Cisco Hands On Training Podcast
03/14/10 • -1 min
We put together what we learned about eBGP, iBGP, and OSPF.
eBGP
Cisco Hands On Training Podcast
03/14/10 • -1 min
An eBGP example with 3 autonomous systems with 1 router each.
IPv6 Static Routing
Cisco Hands On Training Podcast
03/14/10 • -1 min
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 implement our routing. Even then we do not achieve full redundancy, because static routes do not reroute around network failures. Even a small production network with approximately 20 routers would have too many static route commands necessary to make a static-route implementation feasible. In the real world, using dynamic routing protocols to minimize manual configurations (minimizing both effort and errors) is necessary to achieve a robust environment.
That said, static routes are sometimes useful at the edge of your network. You redistribute static routes into your routing protocol at the edge of your network where you don't want to dynamically route with routers outside your administrative control. The goal there is just to use the static route to inject a route into your routing protocol. Not to use the static route as your primary routing mechanism.
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FAQ
How many episodes does Cisco Hands On Training Podcast have?
Cisco Hands On Training Podcast currently has 41 episodes available.
What topics does Cisco Hands On Training Podcast cover?
The podcast is about How To, Podcasts, Technology, Education and Cisco.
What is the most popular episode on Cisco Hands On Training Podcast?
The episode title 'IPv6 Static Routing' is the most popular.
When was the first episode of Cisco Hands On Training Podcast?
The first episode of Cisco Hands On Training Podcast was released on Mar 14, 2010.
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