LAN vs WAN speeds

Okay as you all know, an internetwork consists of 3 Layers of Routing/Switching. The Core, Distribution and Access Layers. I've read in my CCNA book that the Core has to be the FASTEST so that it can keep up with all the other connected LANs etc.. Now im reading that WAN Speeds are Slower than LAN Speeds. Sounds like a contradiction..

As I understand, as you go UP the chain of an Internetwork toward the Core, the pipe only gets bigger to withstand all the traffic flowing to deliver the appropriate bandwidth.

Is it saying WAN Speeds between the LAN and the Core are slower? Or is it saying the Core is slower? I understand the CORE aka "ISP" is aka the WAN Service. Someone clear this up? Appreciate it !

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Comments

kalebksp

The Core, Distribution and Access layers in one site is all part of the LAN, connections to remote sites and to the internet are WAN connections. The core is not the ISP, in a campus network the core would be where traffic goes to get to other buildings or sections.

DerekAustin26

So the Access Layer is to End Users. The Distribution is between Access Layer and Core and it is usually a rack of blades connected to a large number of Access Layer switches, backed up with Redundancy "the Core" which is the Top of the LAN Pyramid before any traffic flows out to the WAN? Sound correct?

LBC90805

DerekAustin26 wrote: »

So the Access Layer is to End Users. The Distribution is between Access Layer and Core and it is usually a rack of blades connected to a large number of Access Layer switches, backed up with Redundancy "the Core" which is the Top of the LAN Pyramid before any traffic flows out to the WAN? Sound correct?

Correct.

And mind you that less traffic will have to jump from the LAN to the WAN to go to remote networks or the Internet. That is why WAN links are generally slower than the Local Area Networks!

DerekAustin26

hows that?

Netwurk

DerekAustin26 wrote: »

hows that?

He's just reminding you that your WAN speed tends to be slower than your LAN speed.

An example of a WAN connection might be a 1 Mbps link to your ISP

The LAN connections in your lab probably vary from 10 Mbps to 100 Mbps

Even then they are much faster than your WAN link

Of course once FIOS speeds become common (don't hold your breath), those 10 Mbps links will start to look mighty slow.

malcybood

This is an extract from the Cisco quick ref notes gives an explanation. It's only a few pages long as it's a demo but it should clear up how the Campus (Core, distribution and access) layers fit in with the Enterprise Edge (WAN, ecommerce, internet and remote access) and service provider edge (the actual internet, frame relay, ATM, MPLS network) modules

If you tie together figures 1-3 & 1-4 you should be able to piece it together

http://www.ciscopress.com/content/images/9781587053122/excerpts/1587053128.pdf

Just for info we're also beginning to see Ethernet WAN circuits become more common place by the use of ethernet over fiber giving speeds usually up to 10Mbps or 100Mbbs and shaped to something lower.

For example a 10Mbps pipe could be commissioned to site but shaped to only operate at 2Mbps. This makes upgrades easy and speedy, but it's probably still taking off in the bigger picture. Most people still use Frame Relay and ATM and are migrating to MPLS which gives the ethernet over fiber WAN capability.

LBC90805

DerekAustin26 wrote: »

hows that?

Well maybe if you can afford an OC 192 or Gigamon Ethernet connection then you will hustle right a long.