4 - VLANs - In-Depth Trunking

Below shows how things were done in the years of hubs :oP - this is how the Native VLAN would play its part....

But now we dont have hubs, BUT we are using IP Phones as hubs.  This is where the native vlan command comes in handy, which basically says that on the trunk if any packets come into the trunk untagged, tag it with the native vlan (i.e 20)

5 - VLANs - VLAN Trunking Protocol

VTP RUNS ON TRUNKS

vtp = not really trunking protocol, more like a replicating protocol

with revision numbers (the double edged sword)

sends VTP update with new revision

the switch updates its database and updated with new one

this is a great feature in a large scale network/campus, smaller networks ... well, lets go 

over the bad ....

so you plug in your new ebay switch to config etc 

when u connected the switch if it managed to negotiate a trunk, it will send its VTP out to the network, and as works switches database is on revision 3 and our new switch is on 1302....

it updates the others!

So now all the ports that were assigned to VLANs .... are gone! everything goes down :0(

(if a switchport is assigned to a vlan that does not exist the port light goes amber  - test this)

So the admin/you will have to configure the VLANs again, then jump on all switches to assign ports to VLANs

although in real world, the VTP domain would have to match, also password if configured etc

SO USE WISELY

moda/password/pruning = under VTP config ...

VTP mode 1 = transparent mode = no pass through for boradcast, it is stopped
VTP mode 2 = transparent mode = allows VTP updates to pass through

show vtp status
Configuration Revision - IMPORTANT
VTP Domain Name - BE VERY CAREFUL WITH THIS, when this is null/empty it is in its most vunerable state
SO you dont even need password or domain password! to get the updates, it will auto config itself
to it ....... (sent in clear text also)

moral - hardcode switchports to accessports to stop this!!!

NULL = susceptible to VTP updates

although it says running version 2, notice it says version 1 is disabled, so ergo we are running version 1

6 - STP - Foundation Per-VLAN Spanning Tree Concepts 1

3 - VLANs - Configuration and Verification

4 - VLANs - In-Depth Trunking

Video 6 - STP - Foundation Per-VLAN Spanning Tree Concepts 1

The Studies for CCNP Switch(642-813) have begun...

CBT Nuggets - Switch 642-813 

Video 1 - Intro to Switch

Video 2 - The Switches Domain - Core Concepts and Design

Hub

Every frame/packet is flooded out of all ports (if get to 20 or so daisy chained) you get alot of collisions and things sloooooow down

Layer 2 switch

Every port is a collision domain, your traffic only goes to the destination port, unless it is a broadcast, that was a limiting factor .... so its a scalability limitation, whereby if the devices get to many broadcasts on a segment(but that would have to be lots) it would affect performance

Then we saw that we could scale things up with VLANS, they changed everything, we didnt have to have routers everywhere to segment the network, this is where we used "router on a stick" for inter-vlanning, but this was a limitation tooo as the trunk link from the router to the switch was the bottleneck.

Layer 3 Switch

Then L3 Switches came out and changed it, it splices a router into a switch.

Here we can have SVI (Switch Virtual Interfaces) as the VLANs and the bottle neck now is the backplane speed of the switch (typical lots though, Gigs)

Now this is where design comes in ... Where do the L3 switches go etc

This is where the Enterprise Composite Model (ECM) comes in, however before that:

Typically the first basic network design consists of a L3 switch and x2 L2 switches, but already this is way to much for a small/home business,

Performance

The ECM addresses performance by dividing functional areas into modules, and connecting them together over a high speed backbone. This allows for efficient summarization of networks, and more efficient use of high speed uplink ports.

Scalability
With its modular approach, the ECM is scalable. Simply add on more function modules as required.

Availability
Again, modules can be connected in a redundant fashion to the core/distribution layers.

Role of switches in ECM
Access – layer 2 switches connecting workstations and other devices to the distribution. Here, basic protocol filtering and QoS marking would happen

Distribution – either L2 or L3 switches depending on the size and needs. These switches will bring in multiple access switches, perform more advanced QoS and filtering. Distribution connects back into the core/campus backbone

Backbone – again, either L2 or L3 switches depending on needs. Primary goal is to switch packets, so switches will be acting on tagged QoS packets rather than marking, and perform basic routing.

A block doesn't represent just 1 vlan, it could be/typically lots of vlans

vlans provide scaliability and don't slow you down (as in the old days any time you wanted to segment you had to have a router - which are slow, compared to switches.)

With the L3 switches we now have CEF (Cisco Express Forwarding) for caching info and route between vlans as if we didnt have them (so the number of VLANs is not an issue, it is not a limitation.)

Cisco are trying to move people in the direction of layer 3 vlans /localised vlans
vlans stay within there switch blocks - very efficient


The Managment vlan (as covered in the CCNA-S)
is where that port on the device is for the ssh, tftp upgrades, syslog all traffic to and from device for management (Out Of Band) - isolated, reason doesnt always work like this, fairly recent kit to implement/wealthy companies etc