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Question: What is the difference between L3 Switch and Router, If they Perform the same function why we need both of them?

Answer: Layer 3 switches do routing with ASIC chips. Routers do it with a microprocesor and its associated software. Therefore the Layer 3 switches are much faster than traditional routers, but cost more. We need them both because in many situations a slow router is sufficient and cheaper than a gigabit layer 3 switch router.



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Question: What is the difference between L3 Switch and Router, If they Perform the same function why we need both of them?
Answer:

Layer 3 switches do routing with ASIC chips. Routers do it with a microprocesor and its associated software. Therefore the Layer 3 switches are much faster than traditional routers, but cost more. We need them both because in many situations a slow router is sufficient and cheaper than a gigabit layer 3 switch router. Source: CoolInterview.com

Answered by: Dural Lexan | Date: 9/25/2007 | Contact Dural Lexan Contact Dural Lexan

When we use multiple subnets in an organization, then a switch can do the routing between the subnets internally much faster than an external router, because the switch doesnt have to send the packets to another device. another important reason why should we must use a router is the position where we use the router. The router is supposed to sit in between your private network and the public network then it is not wise using a switch here because it will expose your private network in to the public network Source: CoolInterview.com

Answered by: padmaraj | Date: 4/8/2008 | Contact padmaraj Contact padmaraj

Switches are really just multiple port bridges with more intelligence. They breakup collision domains but create on large broadcast domain by default. Switches use hardware addresses to filter the network. Routers break up broadcast domains(and collision domains) and use logical addressing to filter the network. Source: CoolInterview.com

Answered by: Tharis | Date: 1/25/2009 | Contact Tharis Contact Tharis

well when we talk about switches they still work at layer 2 but can perform the functioning same as layer 3 but doesnt make them equivalent to a router as they pass frames between the segments created on high end switches and they can forward frames in between what we popularly know as VLAN(virtual LANS).
In case of routers however we find that they route packets between two heterogenous networks and can do protocol conversions as well .
both switches and routers have their respective applications but as i mentioned before the layer 3 functionality achieved on switches cost a lost and therefore cost VS performance analysis needs to be done before settling for a choice. Source: CoolInterview.com

Answered by: aspiring_perspiring | Date: 3/8/2009 | Contact aspiring_perspiring Contact aspiring_perspiring

Layer 3 switch are almost same as a router with following differences
Layer 3 switch is optimized to data as fast as layer2 switch but it makes the decision on how to transmit traffic at layer 3 (just like a router)

Perfect in Lan environment as it is built on switching hardware. Another thing is it is faster than a router in LAN environment. Layer 3 use route once switch many policy. It means when it search for specific destination using a routing table, it creates a cache entry in a switch RAM. So next time it does not have to search again for a routing table for same source and destination address. It also picks up hop information from cache.
So you can say that Layer 3 switch has the ability to reprogram the hardware dynamically with the current Layer 3 routing information. That is why it is faster than a router.

Source: CoolInterview.com

Answered by: shahed | Date: 3/12/2009 | Contact shahed Contact shahed

there are many causes
first
ecnomic becauce it is the soul of orginization.
ok
answer is scinse L3 switches are more costly then routers then it is better to use router in place of L3 switches.
now security-The router is supposed to sit in between your private network and the public network then it is not wise using a switch here because it will expose your private network in to the public network
3rd-
perfromance-
scinse switches are more faster then router but one demarit is there they have multiple collison doman and single broad cast domain.due to that in the large n/w convegence time get higher then router.
Source: CoolInterview.com

Answered by: jitendera kumar | Date: 3/19/2009 | Contact jitendera kumar Contact jitendera kumar

In Layer3 switch first packet will be routed & after that all packet will be switch but in case of router all packet will be switch and moreover switch use ASIC cheap i.e., hardware,any hardware device is much faster than software that's router use. Source: CoolInterview.com

Answered by: Sudhir Singh | Date: 5/27/2009 | Contact Sudhir Singh Contact Sudhir Singh

When we use multiple subnets in an organization, then a switch can do the routing between the subnets internally much faster than an external router, because the switch doesnt have to send the packets to another device. another important reason why should we must use a router is the position where we use the router. The router is supposed to sit in between your private network and the public network then it is not wise using a switch here because it will expose your private network in to the public network


Source: CoolInterview.com

Answered by: chetan rumane | Date: 6/16/2009 | Contact chetan rumane Contact chetan rumane

Layer 3 switch is also called multilayer switch.It uses ASIC means application specific IC,uses layer 2 MAC address and layer 3 IP address for switching packets.Read also layer 4 protocol.It is faster.Router are based on software running in microprocessor. Source: CoolInterview.com

Answered by: Yogendra karemore | Date: 10/20/2009 | Contact Yogendra karemore Contact Yogendra karemore

Layer 3 Switch can work only on Ethernet technology while Router can work on multiple technology like Ethernet, ISDN, Serial Source: CoolInterview.com

Answered by: Solomon Alex | Date: 1/26/2010 | Contact Solomon Alex Contact Solomon Alex


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