# Difference between a bridge and a switch?



## imagineer_aman (Nov 8, 2005)

Dear Team
I am new to networking(ethernet). 
I am unable to understand the difference between a bridge and a switch!
Pls explain it in detail with CLEAR FUNDAS.
Thanks.
Aman


----------



## Keith Sebastian (Nov 9, 2005)

A bridge with more than two interfaces (ports) is also known as a switch.

Detailed info here - *www.erg.abdn.ac.uk/users/gorry/course/lan-pages/bridge.html

If you're new to networking, you should start by understanding the OSI model architecture. 
*www.erg.abdn.ac.uk/users/gorry/course/intro-pages/osi.html

Keith


----------



## theraven (Nov 9, 2005)

simply put
 a bridge is used to divide a network into 2
whereas a switch connects multiple terminals together centrally

if u have a really large network u can divide it with the help of a bridge

it would work something like 

10 computers connected to switch (1st network)
10 computer connected to another switch ( 2nd network)
and both networks connected thru a bridge !

and ofcourse detailed explaination is in the links above


----------



## rachitar (Nov 9, 2005)

A bridge connects two different LAN networks
A switch is something like you can connect many computers to a switch and then one computer can connect to another through the switch.
Switch is a unicast one to one connection


----------



## imagineer_aman (Nov 9, 2005)

thanks Keith,theraven,rachitar.

As of now i understand that...
A bridge can connect ONLY 2 networks(2 ports).
A switch can connect MORE THAN 2 networks(Many ports).


----------



## rachitar (Nov 10, 2005)

imagineer_aman said:
			
		

> thanks Keith,theraven,rachitar.
> 
> As of now i understand that...
> A bridge can connect ONLY 2 networks(2 ports).
> A switch can connect MORE THAN 2 networks(Many ports).



Switch cant connect MORE THAN 2 networks
It can connect more than 2 COMPUTERS


----------



## imagineer_aman (Nov 11, 2005)

Dear rachitar..
I dont understand..
I mean when a switch CAN connect 2 or more NETWORKS..then y not 2 or more COMPUTERS???


----------



## digen (Nov 11, 2005)

rachitar said:
			
		

> Switch cant connect MORE THAN 2 networks
> It can connect more than 2 COMPUTERS



From when did switches have to bother about networks? Ofcourse its can be correct when the switch is a Layer 3 switch,but under most cases a switch is referred with the Layer 2 tag.
The concept is simple,I dont understand why there is so much fuss about?

Switch is nothing but a multi-port bridge.They both break collision domains & enhance the performance of a network but at the same time they create a single broadcast domain.

Routers deal with connecting networks & not bridge/switch.


----------



## LordDJ (Nov 13, 2005)

When networks (LANs) expand, it's generally a good idea to separate them. Both bridges and switches help you here.  The former divides it into a couple of segments, whreas it's possible to divide them into many segemnts using a switch.



> When the switch receives a packet, it reads the destination address from the header information in the packet, establishes a temporary connection between the source and destination ports, sends the packet on its way, and then terminates the connection[\quote]
> 
> Both bridges and switches operate primarily in the Data Link Layer (Layer 2).


----------



## imagineer_aman (Nov 13, 2005)

thanks guys for the answers...
Let me see if I have got it...
1)a bridge connects 2 networks(it can connect computers,but that wud be ridiculous).
2)a switch connects MORE THAN 2 networks.
3)in other words..switch is a multi port bridge(as digen suggested).
Hope I am right..or is there more to it??


----------



## theraven (Nov 14, 2005)

yes but dont refer to it as networks 
that completely changes the meaning !
its all in a single network
u cant have multiple networks with bridge/switch since they are layer 2 devices
if u want u need to use layer 3 devices like ROUTERS


----------



## indro (Nov 18, 2005)

If switch or bridge can seperate networks? then what do routers do ? 

A switch is a multiport bridge in short.

Yes a switch is only capable of seperating two networks when its a multilayer switch or works on layer 2 and layer 3 i.e. router layer.


----------



## jay4u (Nov 18, 2005)

seems pretty much the same to me... well ofcourse if you take the names apart


----------



## adil (Jul 23, 2009)

Bridges are really just like switches, but there are a few differences. These are the following:

    *

      Bridges are software based, while switches are hardware based because they use an ASICs chip to help them make filtering decisions.

    *

      Bridges can only have one spanning-tree instance per bridge, while switches can have many.

    *

      Bridges can only have upto 16 ports, while a switch can have hundreds !

That's pretty much as far as we will go with the bridges since they are pretty much old technology and you probably won't see many around.


----------



## sv_23s (Jul 29, 2010)

Very nice it is the major difference between bridge and switch.....

dridge is software based and switch are hardwre based...

u can also know much more about this technology...

Hub The hub allows branching of the cable which then might form a loop-free tree of cables with the same appearance to the computers. The hub may shape and amplify the signal. The hub sends the incoming signal out on each of the lines that it did not come in on. I don’t know how smart it is upon packet collisions. It has no storage beyond about one bit. Ethernet theory calls this a Repeater and includes bridges in the hub category.  Bridge The bridge examines the 48 bit destination address for the packet and directs the packet only to the cable where the recipient resides. One packet causes less congestion thereby. A bridge may buffer enough bits to interpret the destination address. It could buffer a whole packet and queue it for the correct outgoing link. I don’t know if they do. Bridges learn who’s where by watching return addresses. Bridges may join into the Stp.  Switch A switch will typically talk some protocol besides Ethernet, such as PPP over longer lines provided by the Telco. The switch knows about IP (internet protocol) packets within the Ethernet packets and routes according to 32 bit IP addresses. The switch will typically buffer and queue packets. It will to talk to the LAN with Ethernet as well.  Router “A router is a node that forwards IP packets not explicitly addressed to it.” The router talks PPP over very fast links such as fiber. It probably talks only to switches and other routers. Routers must be know to confine packets with IP addresses that are of local scope. Network Address Translation (NAT) happens in routers.


----------

