Diff b/t L3 Switch and Router

[sureshkum]

Hi,

Can any one describe the points--Diff b/t L3 Switch and Router

Thanks in advance

[Giuseppe Larosa]

Hello,

a L3 switch is also a L2 switch so you can choice for every port the role you need using the switchport command.

A L3 switch with the execption of high end platforms (like C6500 with special linecards) is LAN oriented : it can have several fast / giga ethernet ports.

A router is more WAN oriented and has less interfaces, it operates at layer 3 (you can configure some bridging capabilites that are used for example for DLSW).

Modern routers and multilayer switches share the CEF switching technology that is topology based and not flow based.

L3 switches have forwarding implemented in HW so they can perform very well for intended traffic.

A router, if it is not a highend router (example 12000), works on software using its main cpu and line card cpus (if any in modular platforms)

best regards

Giuseppe

[sureshkum]

Thanks for all..

[mohammedmahmoud]

Hi,

Layer 3 switches are superfast routers that do Layer 3 forwarding in hardware (ASIC chips) at very high speeds - at wire speeds (In general-purpose routers, packet switching takes place using a microprocessor (CPU) and a software, whereas a Layer 3 switch performs this using application-specific integrated circuit (ASIC) hardware) , there is no functional difference between layer 3 switching and routing. For Layer 3 switches to completely eliminate the need for the traditional router they need to provide WAN connectivity, all IP Services supplied by traditional routers, and be able to run all the required routing protocols (IGPs and BGP), its all a commercial game now, since all the current high end routers has inherited the layer 3 switches hardware architecture - the clearest example is Cisco Catalyst 6500 and Cisco 7600 routers which are clones.

Please check the below document:

http://www.cisco.com/web/about/ac123/ac147/archived_issues/ipj_1-2/switch_evolution.html

BR,

Mohammed Mahmoud.

[raju.talele]

Hi,

The L3 switch uses hardware for switching and routing known as ASIC Application Specific Integrated Circuit which is faster as compare to Router which uses Microprocessor software based routing which is slow.