regarding SVI's

Unanswered Question
Nov 14th, 2007

What is the difference between an SVI and a routed port?

I have this problem too.
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Kevin Dorrell Wed, 11/14/2007 - 08:36

An SVI is an interface that represents the gateway for a VLAN, in other words it is the router interface for a set of switchports on a VLAN.

A routed port is a physical interface that you have declared as no switchport. You are treating like the Ethernet interface of a router. It is essentially a point-to-point link to another router or to a routed port in another switch.

Kevin Dorrell

Luxembourg

Edison Ortiz Wed, 11/14/2007 - 08:38

A routed port is configuring an IP address under a switchport. This connection is considered point-to-point.

SwitchA

interface f0/0

no switchport

ip address 192.168.1.1 255.255.255.252

SwitchB

interface f0/0

no switchport

ip address 192.168.1.2 255.255.255.252

______________________

A SVI is a logical interface that represents a Vlan. This connection is accessible to all members on that Vlan holding a common IP subnet.

interface vlan 192

ip address 192.168.1.1 255.255.255.0

then you can have workstations with ip subnet 192.168.1.0/24 on the following ports

interface f0/0

switchport mode access

switchport access vlan 192

interface f0/1

switchport mode access

switchport access vlan 192

interface f0/2

switchport mode access

switchport access vlan 192

etc...

hi.622823 Wed, 11/14/2007 - 09:57

Wow, fast responses...

I do have one follow up question though, which relates to why I posted this question.

What is the difference between routing in the context of an L3 switch and a router (or routed port)? Let's assume the switch and router are running CEF.

hi.622823 Wed, 11/14/2007 - 10:10

Ok, does it make sense to say an L3 switch does routing ie route table lookups?

hi.622823 Wed, 11/14/2007 - 10:18

Alrighty. What I was trying to get at is how is that functionality different from a traditional router (or is there something I'm missing)?

Edison Ortiz Wed, 11/14/2007 - 10:39

The functionality is the same from a traditional router. Many organizations have replaced traditional routers with Layer3 switches since they provide higher port density in addition to full routing services.

hi.622823 Wed, 11/14/2007 - 10:50

Great.

Thanks again everyone for your timely responses (especially Edison).

This is exactly the sort of thing that encourages quality participatiion in the Cisco forums.

prabhdeepnijjar Wed, 11/14/2007 - 23:33

to clear your confusion for the difference between L3 swith and router.Th L3 switch works using the hardware i.e the routing in them is hardware based and it is more fast .While the routers are software based .i.e they make decisions using the software which is much slower than the hardware based switching.

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