Hey guys & gals,

Sumosid is worried and needs to confirm a few thoughts and facts before implementing changes to an enterprise environment. So experts only, please… 

Simple change really but no way to test the change before I go and do it so I need some serious been there done that advise…

Environent:
BIG data center! Running a layer 2/3 Cisco 4006 with fiber trunk links to outlying buildings each building has multiple floors and vlans for each floor. The 4006 acts as the vtp domain server, all other switches are clients.

I am a newbie to the job and really don’t want to mess up on this simple assignment.

Assignment:
In building 6, vlan 90 (10.9.105.0/24) we currently have 3 cisco 3548xl’s trunked (cascaded GBIC yellow cables 1M in length) this vlan is connected together with fiber links to the floors above (different vlans), the last floor and vlan 90 (first floor) are fiber linked back to the cisco 4006 creating in essence a triangle loop to the datacenter. Remodel needs more ports opened on vlan 90. Fine…got another switch laying in the back, Cisco 2548xl.
I have put on order two more gbic cables to enter the 2548xl into the cascade. Being new to the job and having never worked within a VTP server environment. I am worried.
So far, I have found that the 2548xl that I want to use doesn’t support ISL (hmmm….cisco seems to brag about this encapsulation but….anyway) The gigaethernet links from the 4006 to the building are encapusulated in ISL.
Solution so far:
I have found that the company doesn’t have passwords for the switches in building 1. I have passwords for the 4006. I have reset the password on the 2548 and I have assigned vlan 90 to all the fastethernet ports and entered no shutdown. I have assigned a static ip to vlan 1 and default gateway. I have checked the native vlan on the 4006 and it is vlan1. So I shouldn’t have to vlan 90 the gigaethernet port on the 2548, should I??? Particularly with the VTP server running… I have done some homework, and I have made sure that the new switch is a client and has low revision number, the 4006 has a revision number of 2, I am not sure if a client revision number matters or not but I set that to 1. so basically this is how it looks without visio

Fiber link to datacenter
Switch1
Gbic linked
Switch 2
Gbic linked
Proposed entry of the new 2548.
Gbic linked
Switch 3
Fiber linked
Etc…
Fiber link to datacenter..

What do I need to do further to ensure that I do not drop the ball on this when I plug it in…. with the current setup it should be simple unplug this switch and that one, get the new guy into the cascade (mind your gbic ports so that they are alternating) , part of vlan 90 will drop, but the rest or the floors shouldn’t drop right?

In cascade, I should be able to plug the gbics of switched together without any config and they will pass along the multiple vlans to other switches…

Do I need to change the ISL link from the 4006 to 802.1q? as well as all the switches in building 1??? Or should I just tell the managers and construction guys to hold up until I get a 48 port switch that supports isl…? I need to get the switch passwords as well, so that it going to mean downtime, unless I hack a switch OS but they are level 5 and 7 it could take forever…

Let me know what you think…. This is boring simple stuff to cisco guys of 20 years experience but I only have 6 years experience and my number one concern is my enduser. I want to make sure that I have thought of everything.

Thanks,

Sumosid.

Sorry that was a 2950XL not a 2548. My brain tumor

Well you need to look and see if the gig connections between SW1 , Sw2 , and 3 are just single vlan connection or are they trunked . If they are trunked it becomes a little more involved because the 2950 is a dot1q switch only , does not run ISL . So what you would have to do is check the 3548's to see if they support dot1q or not , some of the early ones did not . If they do then what you would have to do is where you break the stack those connecting links from the 3548 to the 2950 would have to be reconfigured for dot1q instead of ISL . Allow whatever vlans you want across those trunks . so basically you would have sw1--->ISL-->Switch2---->dot1q --->2950--->dot1q--> Sw3---->isl---> datacenter. You can trunk encapsulations on a per port basis . If you are just passing vlan 90 down the stack from the top stack switch then the connecting ports would just be plain switchports assigned to vlan 90. You will have to determine that if they are plain switchports or trunks.

When I went live with this it was very straight forward. The SW will encapsulate the from dot1q to ISL if the switch switches it---IE if I have fiber on one gbic port and ethernet on the other I can run different encapsulations on each trunk and if informations needs to travel on it can.

Thanks for your advise. This is one of the those lessions that I will not forget. The answer was impossible to fine Cisco's website.