Want to protect your cyber security and still get fast solutions? Ask a secure question today.Go Premium


is there a way? 2500router 1900 switch and VLAN

Posted on 2003-03-15
Medium Priority
Last Modified: 2010-04-17
Hi !!

First...I'm a student taking my ccna /ccnp and I have bit off more than I can chew!!! I have elected myself to proove to my prof that a Cisco 2500 Router and a 1900 switch can create 2 VLAN's on the same switch, routed through the single ethernet port ( using trunking and subinterfaces) on the 2500. I create the vlans on the switch we'll say and /24 for the vlans respectivly. On the router I know that i'm not supposed to assign e0 an ip address and assign e0.1 with one ip and e0.2 with the other. This is where im stuck....I'd like to use either 802.10 or ISL, which cisco says is supported on the 2500, but i cannot for the life of me find what command is used to encapsulate isl on the two interfaces on the router. I have found a bridge command and have found a way of adding the MAC addresses of the switch to BRIDGE 1, which I would assume I would then "bridge-group 1" on the interface e0.1 and e0.2. I know that the trunked link needs 100MB and the 2500 has only a 10MB connection, but there must be some way of acheiveing my routed VLAN on a single switch. Any help would be great ( even if it tells me I'm screwed ) and I appologise for the run-on paragraph.

Question by:puddincup
  • 2
  • 2
LVL 79

Expert Comment

ID: 8142727
802.1Q, nor ISL is supported on 2500 series. It requires a 100Mb interface and 2500 only supports 10Mb.
I'm not even sure that the Catalyst 1900 supports ISL or vlans. I do know for sure that it does not support .1Q

You can still have two subnets creating the same effect as two vlans, but without the sparation of the broadcast domains of a true vlan.

subnet 1 = /24
subnet 2 = /24

Create a workstation on each subnet connected to the 1900, any two ports

On your 2500, use a secondary interface on the ethernet port:
interface eth 0
 ip add
 ip add secondary

As long as the workstations point to their respective .1 as the gatway, you can communicate between the two subnets. This is an IP only solution for separating the groups, netbeui, ipx and other broadcast protocols will not be separated.

Author Comment

ID: 8143092
what about IEEE 802.10 and the bridging command on the router. The 1900 allows me to create the 2 vlans on the switch. I will be unsuccessfull if I cannot break up the broadcast domain. Can I use the secondary in that instance?
LVL 79

Accepted Solution

lrmoore earned 200 total points
ID: 8143203
You can bridge across different interfaces only using the bridge-group commands. When you bridge, you combine broadcast domains which is counter to what you are trying to accomplish anyway. Only the encapsulation isl (if it were supported on the eth 0 interface, which it is not) would give you the capability to create subinterfaces for each VLAN.
Secondary addressing will not break up the broadcast domain, just the layer3 subnets.

"Only routers with 100MB or faster Ethernet ports with the appropriate software (as specified below) can do this VLAN-trunking."

Although your 1900 does support 2 vlans (if you have the EN version software), VTP or ISL is only supported on the two fast ethernet ports. One more reason you can't use the 10m ethernet port of the 2500 router.


Author Comment

ID: 8143971
Thanks...your help is greatly appreciated... I figured that to be solution this afternoon. Bridges by default have 2 collision domains and 1 broadcast domain, and therefore will never be able to be part of a true vlan....guess thats why he's the professor and I'm the student....tail between my legs on Monday...


Featured Post

Hire Technology Freelancers with Gigs

Work with freelancers specializing in everything from database administration to programming, who have proven themselves as experts in their field. Hire the best, collaborate easily, pay securely, and get projects done right.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

We've been using the Cisco/Linksys RV042 for years as: - an internet Gateway - a site-to-site VPN device - a leased line site-to-site subnet-to-subnet interface (And, here I'm assuming that any RV0xx behaves the same way as an RV042.  So that's …
The Cisco RV042 router is a popular small network interfacing device that is often used as an internet gateway. Network administrators need to get at the management interface to make settings, change passwords, etc. This access is generally done usi…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…

564 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question