Layer 3 Switch

typesh

Hey everyone,

I have (2) Layer 3 Switch Questions:


Question 1:
Looking into getting a L3 switch for my home lab. Came across some information I found confusing: http://www.techexams.net/forums/ccna-ccent/47911-layer-3-switch.html#post355568

I found a 3512 for $80, so I decided to do some research on it. I came across the above link. Why is the 3512 being replaced with a 2950 model? The 2950 is only an L2 switch.


Question 2:
I'm still on CCNA material and I know this must be covered elsewhere, but I cannot seem to understand something. If we have a few different remote sites and a head office that we need to connect, then we can have a router at each site to allow communication. But since layer 3 switches can process IP address, can they be used for WAN connections? I don't see Serial interfaces on them... Yet aren't they used at the Core Layer?

What I am imagining is this:
If we have a bunch of PCs connected into a L3 switch with VLANs 100, 200, 300 set up, then we can turn on ip routing to have switch route between different VLANs. To do this we need to create SVIs and set them as the default gateway of nodes in that subnet (this is as much as I know about it so far). Now suppose nodes on VLAN 100, 200, and 300, need to actually send information across a WAN link to another office located miles away. The routing decision PCs would make is to send the packets to its default gateway (which is the SVI of the L3 switch). Since there are no Serial ports on the L3 switch, how can we allow this type of WAN communication? If we hooked up a router, then the PC would have a default gateway assigned to the SVI, not the router interface. Can anyone simplify how this works for me please...

Thank you

mikej412

The 3512 is an OLD 3500XL series LAYER 2 switch. You're confusing it with the 3550, 3560, 3750, etc switches -- which some sellers on eBay try to take advantage of....

There are also the old 2900XL switches -- but since the 2950 are pretty cheap now it doesn't make sense to worry about the 2924-XL-EN for a home lab, except as a 3rd switch (but only if it's CHEAP) for the ISL trunking. Same with the old 3500XL series -- if it's CHEAP it's a good 3rd switch.

If you have WAN connections -- you'd need a router that supports the required interface. And from a security (and basic network design) point of view, even if you had Metro Ethernet you wouldn't plug it directly into your core switches.

mikej412

typesh wrote: »

If we hooked up a router, then the PC would have a default gateway assigned to the SVI, not the router interface.

The Layer 3 switch could exchange routing information with that router -- or get a default route -- and route the packets one step closer to their ultimate destination. And that router would have to know about the networks attached to the Layer 3 switch, so it knows where to send the "return traffic" -- either via routing protocol or static routes.

typesh

mikej412 wrote: »

The 3512 is an OLD 3500XL series LAYER 2 switch. You're confusing it with the 3550, 3560, 3750, etc switches -- which some sellers on eBay try to take advantage of....

Hey thanks so much for your responses Mike!

Just saved $80

Bl8ckr0uter

For a 3550 you can expect to spend around 200-300 dollars and sometimes a lot higher on ebay or on some other sites, so save you money up for that one.

here is one from cables and kits
here are some on ebay

typesh

knwminus wrote: »

For a 3550 you can expect to spend around 200-300 dollars and sometimes a lot higher on ebay or on some other sites, so save you money up for that one.

here is one from cables and kits
here are some on ebay

Thank you as well

ncsugrad2002

3550 is the cheapest true (modern) layer 3 switch that you'll find. on a good day you can get one for $200'ish on eBay. I found a buy it now with a decent volume of them for $225 not long ago..

You won't do much better than that