CCNP - Inter V-LAN Router ?

Author

Inter V-LAN Router ?

wirelessboy

2003-07-28, 8:40 am

dear members

what is the lowest router series i can use for inter vlan routing, i thought it was any 2600 series with fast-ethernet, but now i guess both are not required, i heard some 1700 series supports it, and also remembered someone in this forum saying only 10 mbps is enough, please confirm the IOS image and Model number.

thanks in advance

Townsend

2003-07-28, 11:35 am

wirelessboy,
The 1700 series is the lowest number series that can perform router on a stick, with more than one vlan traveling through one interface. In this situation you need a 100baseT fast ethernet conection. You can do routing across vlans with 10baseT if you use a separate interface for each vlan.
Hope this helps.
Best of luck!

darthfeces

2003-07-28, 12:52 pm

you can only do 802.1q on a 10mb int
isl requires 100/mb int

SureshHomepage

2003-08-01, 11:44 pm

Inter-Vlan Routing is the capability to route traffic between VLANs. This functionality could be on the Switch itself (for Layer 3 Switches), on another module or card on the switch (for modular switches) or even an external router.

Lets consider the last option of a Switch and an external Router combination:

Physical Connection:

http://www.cisco.com/warp/public/473/50a.jpg

Fast Ethernet interface on the Router is split into 2 sub interfaces as shown above. They are actually logical interfaces. Any Router with an Ethernet interface(not necessarily Fast Ethernet) can do this job.

For others...Common guys! lets brush up some VLAN routing?

Each (logical) sub-interface represent one VLAN...For example VLAN 1 and VLAN 2.

VLAN 10 contains one IP subnet 10.10.10.3/24 and VLAN 2 contains another IP subnet 10.10.11.3/24 (considered here the Per-VLAN Subnet model).

You assign an IP address that belongs to the respective VLAN's IP subnet on each of these sub-interfaces.
Example...sub-interface FE0.1 is assigned and IP address of 10.10.10.1/24 and sub-interface FE0.2 is assigned 10.10.11.1/24
These IP addresses would be the 'default gateways' for the PCs that fall under the respective VLANs.

Now get into your switch. Configure the VTP parameters. Assign the individual ports to respective VLANs.

Trunking
The switch port that connects the Router R1 and the Switch needs to be configured as 'trunk' now. For this you would use any of the the trunk encapsulations either ISL or dot1Q.

Trying to connect the Cisco Router to a non-Cisco switches?...use dot1Q. Otherwise you can use any of them.

In case of using dot1q, you need to make sure that the native VLAN matches across the trunk link.

Townsend

2003-08-02, 7:56 am

SureshHomepage,
Thanks for your input, it's always great.
What then is the answer to the original question of what is the lowest series of router that can be used here?
I was unable to set up router on a stick with a 2501.
Thanks.

wirelessboy

2003-08-03, 12:01 am

hi guys

thanks to suresh sir

well i tried with 1751 12.2 IOS, FE Port, encapsulation ISL is not supporting.

i also tried it with 2501, 2503.

i heard an IOS Upgrade to something like enterprise edition IOS would help, please can someone help me on this.

i need to prove a point to a customer.

thanks

sukuvi

2003-08-03, 1:24 am

quote:
well i tried with 1751 12.2 IOS, FE Port, encapsulation ISL is not supporting.

I did some digging on the Cisco site and the following is what I found. The IOS supports only 802.1Q (ISL is not supported).
http://www.cisco.com/warp/public/cc...lit/1750_ds.htm

I also checked the different IOS Feature Packs available but I didn't see any listed with 802.1Q, so I'm assuming even the basic IP might have it.

So Wirelessboy, it appears you were looking for ISL but you didn't find it because the IOS doesn't come with it. So look for 802.1Q now and try to configure the router using it and let's see what you come up with. If your configuration doesn't work, just post the running-config for us all to take a look at and hopefully one of us will find the problem.

SureshHomepage

2003-08-08, 8:50 pm

Sukuvi is correct. 1700 seems to be not supporting the ISL encap for VLAN routing. You can resort to the dot1q encap.

About the 2500 series routers not supporting the ISL encap is merely an IOS feature related issue. You need to select an IOS that supports ISL. Key value names such as "Plus" feature sets supports one or more features such as NAT, RMON, ISL, Lane, modem management, or V.120.

eg. IP Plus, Enterprise Plus

Just a qucik question for you Wireless boy what stops you from using the dot1q? Inreal time network we do not worry much about these encap types provided we don't face any performance related issues on the network.

thanks

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