Intervlan routing in a 2500 router

loboernesto

Hi guys,

A while ago I was practicing configurations of VLANs and intervlan routing but the lab I was following said that it wasn't possible to configure intervlan routing with the 2500 series routers since they only have 10bt interfaces, I wasn't really bothered at the moment since I only had power cords for the routers OR the switches. I've just received a couple of new power cords and was thinking some configuration with the routers and switches to practice. Is there anyway that intervlan can be configured in a 10bt interface? is it an IOS version or hardware restricion??
thanks.

bmauro

It is IOS restrictions and I know that has changed as well. You can do inter-vlan on a 10Mbit interface, you just need the right IOS. I'd look it up for ya - but Dynamips is boggin my system down quite a bit right now.

keenon

your going to have to use 12.2(29) enterprise plus if memory serves me

mp3spy

You can only use the ISL protocol....

bmauro

mp3spy - kinda confused on your statement.

Are you implying that with a 10Mb Ethernet port that you can only do ISL encapsulation?

Now I'm not 100% - but I am pretty sure that once you find the correct IOS version you should have no problem encapsulating the subinterface with either ISL or dot1q.

loboernesto

My newest IOS is 12.3(5b)... I guess is not the one I need for intervlan since it doesn't support

You can only use the ISL protocol....

I would have also thought that If I had the right IOS I could use either ISL or dot1q..

Thanks for your help.

mp3spy

bmauro wrote:

mp3spy - kinda confused on your statement.

Are you implying that with a 10Mb Ethernet port that you can only do ISL encapsulation?

Now I'm not 100% - but I am pretty sure that once you find the correct IOS version you should have no problem encapsulating the subinterface with either ISL or dot1q.

I believe dot1q only supports 100 meg trunk links. ISL is cisco proprietery and supports 10/100 meg trunks...

Netwurk

You can always use two 2500's to route between your VLANs. One way is to connect the two routers with a serial cable and plug an ethernet connection into each vlan port. You don't trunk on the connection of course.

dissolved

You need a 2600 router to do this. I've never heard of 2500 supporting inter-vlan routing.

Actually, the low end 2600s (2610, 2612) didnt support inter-vlan routing for a while. That is of course, until an IOS release came out that permitted inter-vlan routing on 10mbps interfaces.

So in a nutshell: 2600 router with the right IOS. It will be dot1q encapsulation btw

macwhizard

Yes, 26xx series with IOS 12.3 will do. make sure you have enough RAM and Flash.

loboernesto

I only got a few 25xx guys...
i think i will have to think of other router<-->switch configs for my lab.

thanks to everybody.

Netwurk

Just remember that you can route between VLANs with multiple 2500's. You just can't do router-on-a-stick.

loboernesto

Yes, I've that a coplue of times when I didn't have enough power cords to power on the routers and the switches at the same time.

Thanks anyway.

Spudage

I think some of you are getting confused between inter-vlan routing and inter-vlan routing utilising trunks.

A 2500 can perform inter-vlan routing, but you wont be able to use the router-on-a-stick method.

For example, consider the following logical diagram.

Have a go at configuring it yourself.

I have used a 2514 router with 2 ethernet ports and a 2950 switch.

loboernesto

My 25xx only got 1 ethernet interface...

cheers anyway

Spudage

Oh sorry. In that case, you can do a similar setup by using two 2500s, connected via the serial ports as someone mentioned above.

ebykm

Spudage wrote:

A 2500 can perform inter-vlan routing

what commands did u use, the 2510's running 12.2(26) can't even create a subinterface / doesn't know encapsulation command.

Danman32

I believe what he is saying is that you can route between vlans by having a discrete connection between each vlan and the router. In other words, treat each VLAN as if it were a totally different subnet/switch.

He did say the router could not do trunking.

Spudage

ebykm wrote:

Spudage wrote:

A 2500 can perform inter-vlan routing

what commands did u use, the 2510's running 12.2(26) can't even create a subinterface / doesn't know encapsulation command.

Please re-read the first two lines of my first post in this thread. The term "inter-vlan routing" does not imply the use of sub-interfaces or trunking.

Danman32 wrote:

I believe what he is saying is that you can route between vlans by having a discrete connection between each vlan and the router

Yep, that's what I was getting at.

Paul Boz

You CAN do that, but it's not the RIGHT way to do it for the CCNA tests. I would definitely study VLAN trunking with a simulator so that you can at least use a 2600 series router and do routing on a stick, because it's the most common and "right" way to do inter VLAN trunking.

lwwarner

Paul Boz wrote:

... do routing on a stick, because it's the most common and "right" way to do inter VLAN trunking.

I wouldn't go that far. The router-on-a-stick idea with subinterfaces was invented primarily because of high per port costs and the low port density of conventional routers.

As per port costs come down, and port densities increase, (think about high density layer 3 switches) router-on-a-stick style interVLAN routing becomes both less important and less attractive. R-O-A-S does have some disadvantages.

Of course, we're talking about the CCNA exam here... So, yes, be sure you know how to do R-O-A-S.

As for the original question, you cannot do R-O-A-S on a 25xx router.

Spudage

Paul Boz wrote:

You CAN do that, but it's not the RIGHT way to do it for the CCNA tests. I would definitely study VLAN trunking with a simulator so that you can at least use a 2600 series router and do routing on a stick, because it's the most common and "right" way to do inter VLAN trunking.

Have you done the CCNA exams? I don't recall seeing any configuration questions that were specific to router-on-a-stick.

There is no wrong and right, but if there was, using a layer 3 switch would be much more "right" than your suggestion.

I never said that you shouldn't study VLAN trunking. I offered a practical exercise that the original poster (and others) can use to play with inter-VLAN routing. That is alot more helpful for their learning than just being told to go buy something more expensive.

EdTheLad

How to do routing on a stick with only a 2500, a layer 2 switch and 2 pc's guide for dummies!!

1)Power on PC1
2)Install dynamips
3)Connect your switch to the eth int of PC1.
4)Configure a router instance for routing on a stick using the pcs eth interface, i.e. 2 different subnets.
5)Connect the 2500 and PC2 to an available switchport setup for two different
vlans,configure trunking on the interface connected to PC1.
6)Ping the 2 different subnets addresses on the router from PC2 and the 2500.

Now stop the fighting,routing-on-a-stick is possible with a 2500!