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Community Member

Layer 3 switch or Router

Hi All,

what please is the difference between a layer 3 switch and a router?

Is it more safe to use a router than a layer 3 switch? In general, when overloaded, a router drops packets, a switch forwards all packets to all ports... or a router without config does not forward any packet, a switch without config forwards all packets... so is it more safe to use a router???

Is this all true anymore? Please correct me if I'm wrong!

On the other hand i. e. the 6500 and the 7600 use the same supervisor engine, use the same (ethernet) modules... so is there any difference anymore?

I know that i. g. a router does support a lot of WAN-Interfaces, but beyond this, is there any significant difference between a layer 3 switch and a router anymore, especially regarding security issues???

You help is highly appreciated

Werner

2 ACCEPTED SOLUTIONS

Accepted Solutions

Re: Layer 3 switch or Router

Hi Werner,

L3 Switching (MLS) has become a highly desired method of accelerating routing performance through the use of dedicated Application Specific Integrated Circuits (ASICs). Traditional routing is done through a central CPU and software. L3 switching offloads a significant portion of routing (packet rewrite) to hardware, and thus has also been termed switching.

1.It is not about safety, but it is about business requirement , which decides to go for L3 switch or Router

2.When any interface overutilized , it will start dropping packets whether it is router or switch, that's why congestion management & congestion avoidance features of QoS are available in router as well as L3 switch

3.Yes a lot more difference are there..

-L3 switch gives a lot more port density

-CEF gives the edge to L3 switches over Router

-L3 switch like Catalyst 6500 also supports lot of interfaces & media like T1/E1, DS3 , STM.You need to have compatible port adapter to install these modules.

-L3 switches like Catalyst 6500 supports Firewall Service Module ( FWSM ) which acts like PIX/ASA , gives the edge to 6500 over router's IOS Firewall Feature Set.

HTH...rate if helpful..

Super Bronze

Re: Layer 3 switch or Router

Generally, the primary difference between a L3 switch and a router is performance vs. features. Performance being the plus of L3 switches, features being the plus of routers.

On the issue of flooding packets, believe you might be confusing the operation of L2 switches with L3 switches (or the latter operating at L2).

I don't believe there is major difference between L3 switches vs. routers when it comes which is "more safe" to use.

The 6500 and 7600 share many modules, but not all. IMO both are very powerful L3 switches with the latter providing more router type features. (Also IMO, the differences between the 6500 and 7600 seems to have more to do with Cisco marketing strategy vs. underlying technology.)

4 REPLIES

Re: Layer 3 switch or Router

Hi Werner,

L3 Switching (MLS) has become a highly desired method of accelerating routing performance through the use of dedicated Application Specific Integrated Circuits (ASICs). Traditional routing is done through a central CPU and software. L3 switching offloads a significant portion of routing (packet rewrite) to hardware, and thus has also been termed switching.

1.It is not about safety, but it is about business requirement , which decides to go for L3 switch or Router

2.When any interface overutilized , it will start dropping packets whether it is router or switch, that's why congestion management & congestion avoidance features of QoS are available in router as well as L3 switch

3.Yes a lot more difference are there..

-L3 switch gives a lot more port density

-CEF gives the edge to L3 switches over Router

-L3 switch like Catalyst 6500 also supports lot of interfaces & media like T1/E1, DS3 , STM.You need to have compatible port adapter to install these modules.

-L3 switches like Catalyst 6500 supports Firewall Service Module ( FWSM ) which acts like PIX/ASA , gives the edge to 6500 over router's IOS Firewall Feature Set.

HTH...rate if helpful..

Super Bronze

Re: Layer 3 switch or Router

Generally, the primary difference between a L3 switch and a router is performance vs. features. Performance being the plus of L3 switches, features being the plus of routers.

On the issue of flooding packets, believe you might be confusing the operation of L2 switches with L3 switches (or the latter operating at L2).

I don't believe there is major difference between L3 switches vs. routers when it comes which is "more safe" to use.

The 6500 and 7600 share many modules, but not all. IMO both are very powerful L3 switches with the latter providing more router type features. (Also IMO, the differences between the 6500 and 7600 seems to have more to do with Cisco marketing strategy vs. underlying technology.)

Hall of Fame Super Gold

Re: Layer 3 switch or Router

Werner

There used to be very clear differences between a switch and a router (layer 2 vs layer 3, forward in hardware vs forward in software, etc) but with the introduction of layer 3 switches the differences get smaller and smaller. And in terms of IP packet forwarding and routing protocols there is really very little difference any more.

As Joseph says the difference now is in features that are supported on routers that are not supported on switches. For example if you want to do Network Address Translation you need a router (or a 6500 switch).

HTH

Rick

Community Member

Re: Layer 3 switch or Router

Dear All,

thanks a lot for your help and sharing your knowledge & experience with all of us!

best regards from good old Germany :-)

Werner

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