Difference Between L3 & L2 Switches

a layer 2 device is a switch(communicates at frame level), a layer 3 is a router(communicates at packet level).

a layer 2 device is a switch(communicates at frame level), a layer 3 is a router(communicates at packet level).

Hi, I think you are at the verge of buying new switches and you want to decide if you want to pay the price and buy a layer 3 switch . First two layers in OSI Model ( Layer 1 & 2 ) are the Physical layer and the Data Link layer . As their name implies they work with NICs, cables , connectors and mac addresses and DO NOT KNOW ( ARE NOT AWARE OF ) IP addresses . So layer two switches are just busy with transferring the stuff given to the from upper layers ( layer 3 - Network Layer ) to the mac addresses . Layer 3 switches are at the Network Layer and are aware of the IP addresses . So applications that work with or can manipulate IP addresses can be "added" to the capabilities of the switch to be implemented on the switch . These applications are protocol based capablities in line with specific standart that YOU SEE as a list of features of a layer 3 switch . Whether to buy an intelligent switch depends on your enterprise size and cost/performance considerations of your bosses.

Layer 2 - MAC and LLC ONLY! So this means that you are getting a "real" switch.

Layer 3 - A "smart" switch. You can see the network layer so you can see IPs and some datagram packets.

Which do you need? I don't know, but I tend to suggest springing for the Layer 3 switch if you are unsure...

What also appears to be overlooked is that a layer 3 switch performs the function of a router-on-a-stick in a VLAN environment. As such, the switch can route information between different VLANS. The bennefits is the reduction on hops required, speed and less equipment to purchase.

Layer 2 Switches basically works at datalink layers and here are some of its features

a)Layer 2 Switches forwards the frames using MAC address.
b)MAC address table is maintained and updated preodically for associated switch ports.
c)Broadcast & multicast frames are flooded out to all the ports except the port from which it originated.
and is primarily used for workgroup connctivity and network segmentations.

Layer 3 Switches basically works with Network layer with layer 2 capabilities,
some of its features are
a) Packets are forwarded at layer 3 just as routers,
b) packets r switched using specialized hardware ASICs
c)packets can be forwarded with security control & QOS (quality of service) using Layer 3 address information.
Layer 3 Swicthes are designed to examine & forward the packets in high speed LAN environment.

Layer 2 Switches basically works at datalink layers and here are some of its features

a)Layer 2 Switches forwards the frames using MAC address.
b)MAC address table is maintained and updated preodically for associated switch ports.
c)Broadcast & multicast frames are flooded out to all the ports except the port from which it originated.
and is primarily used for workgroup connctivity and network segmentations.

Layer 3 Switches basically works with Network layer with layer 2 capabilities,
some of its features are
a) Packets are forwarded at layer 3 just as routers,
b) packets r switched using specialized hardware ASICs
c)packets can be forwarded with security control & QOS (quality of service) using Layer 3 address information.
Layer 3 Swicthes are designed to examine & forward the packets in high speed LAN environment.

Layer 2 Switches basically works at datalink layers and here are some of its features

a)Layer 2 Switches forwards the frames using MAC address.
b)MAC address table is maintained and updated preodically for associated switch ports.
c)Broadcast & multicast frames are flooded out to all the ports except the port from which it originated.
and is primarily used for workgroup connctivity and network segmentations.

Layer 3 Switches basically works with Network layer with layer 2 capabilities,
some of its features are
a) Packets are forwarded at layer 3 just as routers,
b) packets r switched using specialized hardware ASICs
c)packets can be forwarded with security control & QOS (quality of service) using Layer 3 address information.
Layer 3 Swicthes are designed to examine & forward the packets in high speed LAN environment.

Difference between L2&L3 Switches

layer 2 is for peer to peer communication,
layer 3 is for process to process communication.layer 2 do the routing function with the mac address(ie peer to peer delivery) but laywr 3 do the routing function with the ip address(process to process delivery)

There is only one big diffrence between layer 2 and layer 3 swithces is that we are able to do routing in interanetwork with Layer 3 swithces which is not possible to do with layer 2.

Layer 2 switch has multi collision and single broadcast domain whereas Layer 3 switch has multi collision and multi broadcast domain.

L2 - No Routing, no vlans property.
L3 - Routing and vlans
It means that in Layer 2 switch only one VLAN is active at a time where as in L3 switch we can use as much of VLAN we want.As routing is not possible in L2 switch, we need router for the communication between two or more VLANs but in L3 switch router is not required for the inter VLAN communication.It is the main reason for the use of L3 switch others are secondary reasons.

Please provide me the perticular
Thanks
Nihsit

Generally, Layer 3 switches are faster than routers, but they usually lack some of the advanced functionalities of routers.

Specifically, a router is a device that routes the packets to their destination. What this means is that a router analyzes the Layer 3 destination address of every packet, and devises the best next hop for it. This process takes time, and hence every packet encounters some delay because of this.

In a Layer 3 switch, on the other hand, whenever a routing table searches for any specific destination, a cache entry is made in a fast memory. This cache entry contains the source-destination pair and next hop address. Once this cache entry is in place, the next packet with the same source and destination pair does not have to go through the entire process of searching the routing table. Next hop information is directly picked up from the cache. That's why it is called route once switch many. This way, a Layer 3 switch can route packets much faster than the router.

Having explained the mechanism of both a router and a Layer 3 switch, let me also tell you that router has some advanced routing functionality, which Layer 3 switches lack. Layer 3 switches are primarily used in the LAN environment, where you need routing. Routers are used in the WAN environment. These days lots of people have started using layer 3 switches in WAN environment, like MPLS.

There is only one big difference between the Layer-2 and Layer-3 switches is that we are able to do routing in interne work with layer-3 switches which is not possible to do with layer-3. Cisco 2950 catalyst switch is the example.
Layer 2 switch is for peer to peer communication and Layer-3 is for Process to Process communication.

hi,
layer 2 switch is a peer to peer communication. layer 3 switch is a process to process communication.
Layer 2 switch: 2950, 1900
layer 3 switch: 4503, 5500

on layer 2 in the header portion(H2) contains source and destination physical addresses...(means all the computers which are in the same network can communicate.......)

while on layer 3 in the header portion(H3) contains logical ip of the source and in the destination portion it contains logical ip of gateway of that(of source) network. and then in the second pass in H3 it contains in the source portion address of the gateway and in the destination portion address of the real destination.( packet can be trasferred though source and the destination are of the different networks)

source 192.168.0.12 subnet255.255.255.0 (here n/w id =192.168.0.0.0)

destination 100.100.100.13 subnet 255.255.255.0 (here n/w id =100.100.0.0)

so with layer 3 switch

pass1----source(192.168.0.12) to gateway(192.168.0.1)

pass2----gateway(100.100.100.1) to destination(100.100.100.13)

where gateway contains both ip addresses of both the networks.