How do I Configuring multiple VLANS on a Catalyst 5000 to use seperate uplinks to a 2600 router

Posted on 2005-05-09
Medium Priority
Last Modified: 2008-03-17
I have a Catalyst 5000 with 1 supervisor module, and 4 12 port ethernet modules.

I have created 4 separate vlans using ports 1/1-12, 2/1-12, 3/1-12, and 4/1-12

How would I go about setting port 1/1, 2/1,3/1, and 4/1 as seperate uplinks for all hosts within those vlans. My goal is to have the Catalyst 5000 act as 4 seperate switches which all link to my 2600 router for access-lists and routing between the 4 VLANS.

Also, would it be possible to have all the VLANS use a single port for the uplink to the router and how would that be configured.

For my router, I have 4 ethernet interfaces that connect to ports 1/1, 2/1, 3/1, and 4/1 with the following ip's:

Each host within the corresponding VLAN has an ip in the same network. I.e if the host was in VLAN 1 it would have an ip in the range.

Question by:jcc05
  • 2
LVL 27

Expert Comment

ID: 13962131
Yes, you could use a single uplink - turning your router into a "one armed router" so that all four vlans would pass through 1 link.  I think it would depend on your code - but you would use 802.3q VLAN trunking and make both ports tagged so that that traffic from VLAN1 would be tagged and so on.  On the router, you'd have that port tagged as well and the interface would have 4 subinterfaces on it with different IP's.
LVL 28

Accepted Solution

mikebernhardt earned 1000 total points
ID: 13964086
Unless your switch and router code is very current, you'll need to use ISL trunking. On the switch you simply turn trunking on on the desired port. Only 100Mb ports do ISL trunking though so hopefully your router qualifies.
set trunk 1/1 on isl

The switch will automatically trunk all configured vlans unless you prune them. On the router you would do the following, assuming that the vlans are 2,3,4 & 5 (bad idea to use 1 for traffic):

interface fasthernet 0/0
 no shut
interface fastethernet 0/0.2
 encapsulation isl 2
 ip address
interface fastethernet 0/0.3
 encapsulation isl 3
 ip address
interface fastethernet 0/0.4
 encapsulation isl 4
 ip address
interface fastethernet 0/0.5
 encapsulation isl 5
 ip address

The subinterface number is arbitrary, but the encapulation number is the VLAN number.
LVL 11

Expert Comment

ID: 13981220
Some newer Cisco 5000 10/100 blades support 802.1q trunking as an alternative to ISL.  Some recent Cisco routers support only 802.1q and not ISL.  (We learned this the hard way; you could get lucky.)

Note that you could probably buy four 2912XLs for less than the 5000 cost.  Using VLANs *just* to make a big switch act as several small switches is not a cost-effective approach.  It's when you add trunking that you start to see some payoff from VLANs.

LVL 28

Expert Comment

ID: 13981519
As I said, the ROUTER may not support 802.1q. But if it's a 2600, it definitely supports ISL on a 100mb interface. And the switch you have definitely will too. It was Cisco's pre-802.1q trunking protocol, and all the 5000s will do it.

Featured Post

Keep up with what's happening at Experts Exchange!

Sign up to receive Decoded, a new monthly digest with product updates, feature release info, continuing education opportunities, and more.

Question has a verified solution.

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

While it is possible to put two routes in place with the secondary having a higher metric, this may not always work. In the event of a failure that does not bring down the physical interface on the router the primary route is not removed. There is a…
New Server  was moved from behind Router R2 f0/1 to behind router R1 int f/01 and has now address But we want users still to be able to connected to it by old IP. How to do it ? We can used destination NAT (DNAT).  In DNAT…
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…

840 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