Question about Subinterface in trunking a router on astick

chinaman

guys need your help, I am confuse about seting up a subinterface in a router.

Example:

I have 3 vlan and we know that vlan separate broadcast domain.
Now I know it is not required to separate each vlan in diff. subnet but as cisco said we need to design the optimal network.

Now when I configure my vlan trunking to a router I separate each VLAN in diff subnet let say 33,65,97 this are my assign ip subinterface address on my router.

Here's the question in my head, DO I NEED TO advertise them, let say I want to use Static routing.

I hope you got my point. All i want to know if do I need to advertise this ip to other networks let say I have 3 more router and this address are in my router A that is connected to my ethernet port and that 3 vlan is connected to a 2900 sw that support both isl and dot1q.


THANKS GUYSS....

By the way I didn't stop since I failed my 1 and 2nd intro exam and I decided to move and target the 801 certification and It feels good that I learned many things.

CHINAMAN

EdTheLad

You have multiple Vlan's, why? because you want to limit the broadcast domain.This means users in vlan 1 cannot send frames to users in vlan 2.If you want a device in vlan 1 to communicate with a device in vlan 2 you need a router.The router will look at layer 3 so therefore each vlan needs its own subnet address.So your router interface is divided into subinterfaces with different subnets corresponding to different vlans.If a remote router needs to
route to one of these subnets it will look in its routing table for the next hop router.So you can either use static routing or dynamic routing to adverise these routes.

chinaman

Man you didn't answer my question, Do I need to advertise this subnet so other remote router knows about my subnet either static or dynamic
let say
vlan 2 to 4 are in subnet 32 64 and 96
and on my router it is configure on sub interface we called it ON A STICK.

the cidr I used is /27 that gives me block size of 32

I am using 2600 series
int e0
no ip address
no shut

int fa0/0.2
encapsulation dot1q 2
ip address 192.168.10.33 255.255.255.224

int fa0/0.3
encapsulation dot1q 3
ip address 192.168.10.65 255.255.255.224

int fa0/0.4
encapsulation dot1q 4
ip address 192.168.10.33 255.255.255.224


Serial 0 which is connected to another router
let say I am using RIP2 to advertise my subnet networks.
172.16.10.1 is my ip I used vlsm

Now again my question is Do i need to advetise my subinterface.

EdTheLad

chinaman wrote:

Now again my question is Do i need to advetise my subinterface.

You dont advertise the subinterface,you advertise the networks attached to the subinterface.
I think you should reread my post.At the end i wrote "So you can either use static routing or dynamic routing to adverise these routes"
It looks like your missing out the foundations of routing if you ask such a question.How do you expect remote routers to know where the vlan subnets are if you dont advertise them or create static routes.

lwwarner

The fact that you are using vlans is irrelevant. Like any network, if you want it to be reachable from anywhere but the local router you have to advertise it via a routing protocol or create static routes on your other routers.

You are just confusing the issue by thinking that this has anything to do with vlans.

chinaman

your right I am confused, that no ip address command confused me.
grr.... so I need to advertise that subnet networks assigned to my subinterface.

so if I have 3 subneted ip assigned in my fa0/0.2 to fa0/0.3 I need to advertised them.

eample
router rip
//this are my subinterface ip address assigned in vlan 2,3,4
network 192.168.10.33
network 192.168.10.65
network 192.168.10.97
// this is my serial0 ip address
172.16.10.1/30

Im sorry if I ask this stupid question,

Humper

RIP doesnt allow classless routing. You would use

router rip
network 192.168.10.0

That would advertise all networks in the 10 subnet. Remember you cannot have an IP on a physical interface when you are using subinterfaces (fa0/0.1 fa0/0.2...etc)

EDIT:

I believe it wouldn't advertise the .33,.65 ..etc because RIP doesnt support VLSM & CIDR...It's a classful routing protocol. I need to boot up a router and check that out.

chinaman

Sorry I forgot to inform you that it should be rip2

grr...... I am messed up.

chinaman

I see, so it is not allowed to assigned an ip address when using subinterface but how can I advertised this ip subinterface.

Sorry I forgot to inform you that it should be rip ver 2

grr...... I am messed up. and by the way thanks for the help

EdTheLad

Ripv1 or Ripv2 doesnt matter,same as modemhumper has specified.RIPv2 can support vlsm but it is still configured with the classful network number.
By configuring network 192.168.10.0 all subnets belonging to this classful address will be advertised.

Humper

The fact that you are using vlans is irrelevant. Like any network, if you want it to be reachable from anywhere but the local router you have to advertise it via a routing protocol or create static routes on your other routers.

You are just confusing the issue by thinking that this has anything to do with vlans.

Read what lawwarner wrote..ANY network you want to advertise WHETHER it's a subinterface or a physical interface (doesn't matter) can be done with a static route or a dynamic routing protocol.

example with rip 1:

Three subinterfaces, networks 192.168.10.0,20.0 and 30.0

router rip
network 192.168.10.0
network 192.168.20.0
network 192.168.30.0


You are advertising these routes to all other routers in the internetwork. It's like saying "Hi I'm Jesse and I can be reached at 123 Apple Street".

EdTheLad

Hi Jesse,im Ed gimme your phone number!

Humper

ed_the_lad wrote:

Hi Jesse,im Ed gimme your phone number!

Ok now Im scared

chinaman

It's getting complicated and I am totally confused.

It's only simple question, Do I need to advertised my subninterface or not?

How should be my configuration like this
subinterface 0/0.2 = 33, 0/0.3 = 65, 0/0.4 = 97
and i used network 192.168.10.0


Router rip
version 2
network 192.168.10.0
network 172.16.10.0


So does my configuration will advertised the network 192.168.10.0
and 172.16.10.0?

gabrielbtoledo

Yes, that should do it. Unless you have more networks to advertise.

mikej412

ModemHumper wrote:

ed_the_lad wrote:

Hi Jesse,im Ed gimme your phone number!

Ok now Im scared

Why, are you Jesse? Or are you afraid that Ed will want to call you next?

Humper

mikej412 wrote:

ModemHumper wrote:

ed_the_lad wrote:

Hi Jesse,im Ed gimme your phone number!

Ok now Im scared

Why, are you Jesse? Or are you afraid that Ed will want to call you next?

lol, that he will call me!!!!

pizzafart

That bit about calling folks was pretty funny.


anyway,
Chinaman, your last post helped frame your question better because it included all the variables: the networks (e.g. 192.168.10.32), the subinterface numbers (e.g. 0/3.2), and the commands for the routing protocol (network 192.168.10.0).


You do NOT have to advertise the subinterface numbers in any way. Subinterface numbers are a syntax that's completely unrelated to IP addressing. Often someone will name a subinterface number to match a network (e.g. fa0/2.12, but this is only to help keep track of things and has no technical relevance to routing or addressing.

You DO have to advertise the networks that you've assigned to each vlan (e.g. in your post you have the network 192.168.10.32 /27.) The routing commands that you've placed in your recent post look like they will do the job.

Hope this helps and good luck.

chinaman

Thanks a lot. its clear to me now

chinaman

I bought some ccna ref command and try to test it in the netsim 6, and I am so amaze that it works, however I am wondering what is the use of loopback in the confiuration.

chinaman

Do I need to set up the default gateway on the switch or it will work without DG because on th host the DG is already set and it is diff on the DG of the SW.

I hope you got my idea.
Thanks a lot and wish me on 25 may for my exam

Humper

chinaman wrote:

Do I need to set up the default gateway on the switch or it will work without DG because on th host the DG is already set and it is diff on the DG of the SW.

I hope you got my idea.
Thanks a lot and wish me on 25 may for my exam

You will need to configure the default-gateway on the switch. You are asking alot of questions...I hope you can manage to study everything on the cisco blueprint and have time to do practice questions....There is nothing wrong with failing of course, but it's nice to get it on the first try