setting up vlan1 & default gateway

solnsusie

Hi
I have a network from 6 pc’s, 3 switches, and 1 router, each Switch has 2 pc’s connected, each in a different vlan and of course in different subnets, and the 3 switches connected to the router, between this 6 pc’s there is 3 vlans, and I set the router’s interface fa0/1 with 3 different sub interfaces, each with the correct ip address it should match each vlan’s subnet,
So my question is, what is the subnet for the vlan 1, is it a 4th subnet range, and I have to get another sub interface on the router? Or I can use the regular interface on the router for this vlan and not a sub interface?
And what is the default gateway for each switch? is it the sub interface ip address? Then I need a 2 default gateways for each vlan and not for each switch? And this doesn’t make sense, Or is the default gateway the ip address from the regular interface? But this is as I mentioned a minute ago that maybe this interface ip address is set for the vlan 1?
please help me out with this.
Thanks a lot

mattau

i think you have most of it right. sounds like your trying to do "router on a stick" for intervlan routing.

in which case the routers physical interface has to be open but no ip address is assigned to it. you would need 4 sub interfaces on it and a seperate subnet for each vlan with all the pc's and switches default gateway assigned to the ip on the router on a stick. (relative to the vlan you are routing for)

you would also have to set up dot1q encapsulation for the vlan you are routing for and a trunk link to the router

hope i got most of that right. disclaimer i dont have any certificates

solnsusie

mattau wrote: »

you would need 4 sub interfaces on it and a seperate subnet for each vlan with all the pc's and switches default gateway assigned to the ip on the router on a stick. (relative to the vlan you are routing for)

each switch has 2 pc's in different vlans, so what is the default gateway? the router has 2 ip address, 1 for each vlan, so on the switch which is connected to 2 pc's in 2 different vlans what default gate am I setting on the switch??

mattau wrote: »

you would also have to set up dot1q encapsulation for the vlan you are routing for and a trunk link to the router

i did that....

mattau wrote: »

hope i got most of that right. disclaimer i dont have any certificates

it's not a problem, as long the problem is getting solved,
thanks

mattau

example. switches are in vlan 1.

switch 1. 192.168.1.2 - dg 192.168.1.1
switch 2 192.168.1.3 - dg 192.168.1.1
pc 1 - switch 1- vlan 20 172.16.1.2 - dg 172.16.1.1
pc 2 - switch 2. vlan 30 10.10.10.2 - dg 10.10.10.1

Router on a stock

int fa0/0.1 192.168.1.1
int fa0/0.20 172.16.1.1
int fa0/0.30 10.10.10.1

solnsusie

mattau wrote: »

example. switches are in vlan 1.

switch 1. 192.168.1.2 - dg 192.168.1.1
switch 2 192.168.1.3 - dg 192.168.1.1
pc 1 - switch 1- vlan 20 172.16.1.2 - dg 172.16.1.1
pc 2 - switch 2. vlan 30 10.10.10.2 - dg 10.10.10.1

Router on a stock

int fa0/0.1 192.168.1.1
int fa0/0.20 172.16.1.1
int fa0/0.30 10.10.10.1

thank you
beautiful!!!! , in other words, vlan 1 is just like any other vlan's regarding ip address and default gateway....

but what about the interface FA0/1, not the sub interface? isn’t it getting any ip address? and what will happen if I do use this interface for any vlan?

thanks again..

mattau

the management vlan for the switches is just like any old vlan. seems you have a few other vlans and want them to communicate with each other so you just point them all to the router on a stick in their respective default gateways and let that deal with finding the different vlans on the different subnets.

its just like frame relay point to point links going to several different offices, the physical interface must not have an ip other wise it just wont work because the logical interfaces get treated like they are separate physical interfaces, and its not possible to have 3 subnets on 1 physical interface and still get it to work.

solnsusie

mattau wrote: »

the management vlan for the switches is just like any old vlan. seems you have a few other vlans and want them to communicate with each other so you just point them all to the router on a stick in their respective default gateways and let that deal with finding the different vlans on the different subnets.

its just like frame relay point to point links going to several different offices, the physical interface must not have an ip other wise it just wont work because the logical interfaces get treated like they are separate physical interfaces, and its not possible to have 3 subnets on 1 physical interface and still get it to work.

thanks a million!!!! now I understand everything, I was a little confused about the logical and physical ip address on the router, now I have it!!!

one more quick question, what is the difference between a “router on stick” and not on stick? im looking for a brief explanation

mattau

a router on a stick is used when you only have 1 physical interface and need to route between many subnets.

say in the example you were using without a router on a stick you would have to have like 3 or 4 physical interfaces each connecting to the switches and pc's to enable the connectivity between vlans's. there would be cables n stuff everywhere.

you would have to have heaps of ethernet interfaces in the router which most dont have and if you had quite a few vlans this is not a scalable solution.

it would be the same thing ie. you have the switches and pcs on their own subnet and the default gateway would be on the router but you just have to think about it as in 1 cable per 1 subnet, vs just using 1 trunk link to the ROAS and as many subinterfaces as you like.

solnsusie

mattau wrote: »

a router on a stick is used when you only have 1 physical interface and need to route between many subnets.

say in the example you were using without a router on a stick you would have to have like 3 or 4 physical interfaces each connecting to the switches and pc's to enable the connectivity between vlans's. there would be cables n stuff everywhere.

you would have to have heaps of ethernet interfaces in the router which most dont have and if you had quite a few vlans this is not a scalable solution.

it would be the same thing ie. you have the switches and pcs on their own subnet and the default gateway would be on the router but you just have to think about it as in 1 cable per 1 subnet, vs just using 1 trunk link to the ROAS and as many subinterfaces as you like.

thanks, you are a gret help!!!!! i got it...