Cisco Catalyst 3550

Hi,

Can anybody describe what exactly is Layes 3 switches ? Also if possible provide with links to it.

Also where is the Cisco 3550 used. Are they used in ISPs.
If somebody can give a network topology of 3550 being used it would be a great benefit. Or also links to different network topology?

Thank you in advance.

Layer 3 refers to the third layer of the OSI model. Switches normally work at Layer 2 which is the MAC address level. However you can get switches with more intelligence built in that allows them to examine the source and destination IP addresses in a packet, i.e. look at the Layer 3 information as well. With a layer 3 switch you can do things like set up VLANs and sometimes route between them as well

I'm not too familar with the Cisco product range as my skillset is 3Com. So I'll let one of the other guys answer your second point

Hi there huliyar,

Your in luck! My baby network at my company consist of around 12 3550 Catalyst switches configured for VLANs, VoIP and interVLAN routing. I must admit its simply great working with them... after all.. they are my babies

Now, to save me from posting half of the VLAN topic I am currently covering, can you be more specific on your question? Is there something in particular that you are after ?

The new VLAN topic I am working on is going to be exactly what your are looking for, as its based on the Catalyst 3550 series. Apart from the endless theory, it will also include step-by-step instructions on how to install and configure VLANs using the above switches, configure them for routing, access lists, Quality Of Service, using the VTP protocol for automatic VLAN configuration and much more ... so, you can either be patient and wait for the goodies to be published, or let us know what exactly you need.

You can also check the following post, which also contains a diagram from the new section and shows the difference between a standard switched environment and a nice vlan powered network

www.firewall.cx/modules.php?name=Forums&...7&highlight=vlan

Cheers,

[code:1] I've added the magic word 'Catalyst' to your thread, to help make it clearer for anyone browsing the threads[/code:1]

12 3550 Catalyst switches? and all to yourself? *drool*

Nice set of equipment I can only imagine how good your wiring closet looks like after looking at your neat home network configuration ( Here if anyone hasn’t seen it yet )

You got a photo of all the stuff I love looking at other peoples networks I recently went down to a company and went into their wiring closets that had I dunno around a few hundred switches! I almost died when I saw them, and the technician in there looked like he had a headache

Some pictures of the Shafted Big Day In LAN event that consisted of 1000 players… Too bad I wasn’t an admin in the event

Brains of the network

Hi,

To be more specific about my question.

Whether Cisco 3550 is used as a regular router with 24 ethernet ports by entering the following commands

config)#interface fastethernet 0/[1|2..24]
config-if)#no switchport
config-if)#ip address <ip> <subnet> (different subnet for each of the ports)


OR

for example: If I have 24 systems and 3 vlans

config)#interface fastethernet 0/[1|2.. 8]
config-if)#switchport access vlan 1
config-if)#switchport mode access


config)#interface fastethernet 0/[9|10.. 16]
config-if)#switchport access vlan 2
config-if)#switchport mode access


config)#interface fastethernet 0/[17|18.. 24]
config-if)#switchport access vlan 3
config-if)#switchport mode access

config)#interface vlan [1|2|3]
config)#ip address <ip> <subnet> (different for each vlan)
config)ip routing

This way I enable all the sytems default gateway to their particular vlan ip address.


And more over Cisco 3550 doesn't have a WAN interface, I feel it cannot be connected remote sites. And hence it is used within and campus network only.

huliyar,

The second part of your post is correct. Your moving along the right path!

To take advantage of the layer 3 switching capabilities, you enable ip routing, create your VLANs and assign one IP address per VLAN on the switch, this way the switch is able to route packets from one VLAN to another! Each host in any of the VLANs will have the switch's VLAN IP Address as a gateway so no routing problems surface.

Lastly, the switch will obviously not have a WAN interface because its a switch, not a router. The fact it can do layer 3 routing, doesn't make it a router replacement. Its just an enhancement, allowing the switch to send packets from one VLAN too another.

Cheers,