[c-nsp] Cisco Layer 3 Switch Recommendation

[Ivan Groenewald]

Okay. I'll bite.

Inc(silly_count,1);  // one more left!


> 1) Something that can shuttle packets between multiple interfaces on layer
2 is a switch.

Your definition could perhaps include a hub then, no? </pedantic>
I say a switch is a device that separates collision domains. Switches are
essentially evolved bridges (more ports, better hardware, more features). A
conventional Ethernet switch makes a "switching" decision based on the
destination MAC-address of an Ethernet *frame*.

> 2) Something that can shuttle packets between multiple interfaces on layer
3 is a router.

A router is a device that can separates broadcast and collision domains. By
definition a router determines the next network point for a layer 3 *packet*
and forwards it to there. This is done by keeping a forwarding table with
static and/or dynamic entries.

> 3) Something that can shuttle packets between multiple interfaces on
either layer 2 or layer 3 is thus both a switch and a router, and can be
referred to by either term.

I call them all layer 3 devices. 


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-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Andy Dills
Sent: 12 November 2004 17:18
To: Scott Weeks
Cc: Hudson Delbert J Contr 61 CS/SCBN; cisco-nsp at puck.nether.net
Subject: RE: [c-nsp] Cisco Layer 3 Switch Recommendation

On Fri, 12 Nov 2004, Scott Weeks wrote:

>
>
> On Fri, 12 Nov 2004, Hudson Delbert J Contr 61 CS/SCBN wrote:
>
> : i dont remember who stated that 'switchs do l3 and routers do L2.
> :
> : wrong!!!
>
>
> The person that said that was doing tongue-in-cheek w/o putting a smiley
> face a the end of the email.  I am pretty sure randy knows a little bit
> about the differences in LAN switching and routing.  Just a little... :-)
>
> c'mon, it was fun for a while, but this is getting silly.  For the new-b
> folks, just think of the functionality of the various *parts* of the box.
> A router segments an address space and forwards packets between them.  A
> LAN switch broadcasts frames to every node within one of those segmented
> address spaces.  If performance becomes an issue, talk to the SE of the
> vendor about what you're trying to do, not the marketing person.  Leave it
> to the mgmt folks to talk to the marketing droids.  They speak the same
> language.

It's even easier in my mind; this thread is two more posts away from being
ridiculous:

1) Something that can shuttle packets between multiple interfaces on layer
2 is a switch.
2) Something that can shuttle packets between multiple interfaces on layer
3 is a router.
3) Something that can shuttle packets between multiple interfaces on
either layer 2 or layer 3 is thus both a switch and a router, and can be
referred to by either term.

Don't let marketing get in the way of simple logic.

Andy

---
Andy Dills
Xecunet, Inc.
www.xecu.net
301-682-9972
---
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