Why we are using Router if a Smart switch(L3) can do the same?

Why we are using Router if a Smart switch can do the same?

The purpose of L3 switches , is to do routing within an organization specially when they have multiple VLAN’s or Local network whereas it provide s more interfaces than a router. It’s correct that there are lots of similarities between L3 switch and a Router, but still some of work only router can do like NAT, QOS,MPLS,VPN and some advance routing features which you can’t achieve with L3 switch.

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@Arun-Verma L3 switches can perform NAT (Network Address Translation), QoS (Quality of Service), MPLS (Multiprotocol Label Switching), and VPN (Virtual Private Network) functionalities. L3 switches, also known as multilayer switches or routing switches, combine the features of traditional Layer 2 switches and Layer 3 routers.

L3 switches perform NAT ? Have you Tried ?

Namaste sir,

Here I am pinging from interface e0/3 to host with the help of NAT.

R2 Configuration(Switch OS)-----------------------------

int e0/3

no switchport

ip address

no sh

ip nat inside

int e1/0

no switchport

ip address

no sh

ip nat outside

access-list 1 permit host log

access-list 1 deny any log

ip nat inside source list 1 interface e 1/0 overload

ip route

R1 Configuration(Switch OS)-----------------------------------------

interface e 0/1

no switchport

ip add

no sh

int e 0/3

no switchport

ip address

no sh

ip access-group 1 in

access-list 1 deny host

access-list 1 permit any

L3 switch only has Ethernet port modules limited to Ethernet technology and nothing more.
Ethernet net ports are ASIC-based, and decisions are made at lightning speed when their control plan is full of data like a cam table.

On the other hand, Routers are Designed to talk with Wan Technologies. If you connect the Serial module, you can talk through the serial cable after the configuration. You want to connect to phone cables and swap the modules, and the router is ready to communicate through RJ 11. Configure PRI and BRI lines too. The control plane stays the same, But Data play is made for WAN communication.

In short, Routers are superior in that manner of modular software enabling one to talk to anything related to wan.

Hope I explained the sense in my rambling above. Here is the Link to Cisco websites on Modules a router can have. You can go off and have that mental pleasure reading this post.
Overview of Cisco Network Modules and Service Modules for Cisco Access Routers - Cisco.