Cisco Systems Layer 3 routing with 3550

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Subject Author Date
Layer 3 routing with 3550 Aman 03-07-06
Posted by Aman on March 7, 2006, 7:13 pm
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Hi All ,

will appriciate some feedback and help regarding this.

Can this be done ,if yes how

DLINK SWITCH(1) -- UPLINK -- CISCO 3550 ---UPLINK TO DSL ROUTER--
Internet (VLAN1 )
DLINK SWITCH(2) ---UPLINK -- CISCO 3550 -- UPLINK TO DSL ROUTER--
Internet
( VLAN 2)
PC'S -- CISCO 3550 -- UPLINK TO CISCO
ROUTER-Internet ( VLAN 3 )

Intervlan routing between all three vlans using 3550 and also vlan 3
should be able to access vlan 2 and vlan 1 but vlan 2 and vlan 1 should
not able to access vlan 3,can all this be configured on a 3550 switch.

Thanks
Aman


Posted by Scooby on March 7, 2006, 8:26 pm
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> Hi All ,
>
> will appriciate some feedback and help regarding this.
>
> Can this be done ,if yes how
>
> DLINK SWITCH(1) -- UPLINK -- CISCO 3550 ---UPLINK TO DSL ROUTER--
> Internet (VLAN1 )
> DLINK SWITCH(2) ---UPLINK -- CISCO 3550 -- UPLINK TO DSL ROUTER--
> Internet
> ( VLAN 2)
> PC'S -- CISCO 3550 -- UPLINK TO CISCO
> ROUTER-Internet ( VLAN 3 )
>
> Intervlan routing between all three vlans using 3550 and also vlan 3
> should be able to access vlan 2 and vlan 1 but vlan 2 and vlan 1 should
> not able to access vlan 3,can all this be configured on a 3550 switch.
>
> Thanks
> Aman
>

Separating the 3 vlans and routing between them is pretty simple. Just make
sure the command 'ip routing' is on the switch. That enables the L3
Switching. An access list on each vlan will allow/disallow traffic as you
like. Each vlan interface will need its own IP address in order to pass
between the Vlans.

Now, here's a very important point. If you are going to do this, you either
can not use the 3550 for routing to the internet, or you need to apply
policy based routing rules. So, what I would suggest is that devices on
each vlan use their internet router as a default gateway, not the 3550.
Each internet router will use a static route back to the other 2 vlans.
Then, the 3550 only comes into play when you want to route between the
vlans.

Somehow that is much clearer in my mind than it came out on the page. Let
me know if that wasn't quite clear..

Hope that helps,

Jim



Posted by Aman on March 8, 2006, 7:59 am
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Hi Jim,

Thanks for helping out ,Right now I have each device in vlan 1 is
configured to use there internet gateway as default gateway ,As I have
understood ,if I would create a svi for each vlan and assign it an
ipaddress and then how I would be able to route packtes between vlans
and to internet for each vlan.

for eg vlan 1 has ip address of 10.28.250.0 /24
each device in it has default Gw set 10.28.250.1 which is there
internet Gw,now if I create a svi for vlan 1 on the switch , what ip
address shuld i assign to it and how do i route pacekts to internet
from this gw and other vlans like vlan 2 is 10.28.249.0 /24

TIA
Aman


Posted by Aman on March 8, 2006, 8:21 am
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Hey Jim,

I read through ur reply again and I will try what you have mentioned
this weekend,I will try putting a static route on each of the dsl
routers back to svi of a vlan and see if that works. Will keep you
posted on how it goes ,Thanks again for helping out.

Aman.


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