Solved

Cisco Catalyst VLAN Trunkinq Question

Posted on 2007-03-29
4
358 Views
Last Modified: 2010-04-12
Here is a slice of config from a 2950XL

!
interface FastEthernet0/1
switchport trunk encapsulation dot1q
 switchport mode trunk
!

OK I know what thats doing - but! If I try to do the same on a 2950T or 2950G then "switchport trunk encapsulation dot1q" is unrecognised

Fair enough - but if I want to replace a 2950XL with one of these other switches is it going to work?
The reason Im asking is,

There is a PIX firewall in Fe0/1 of the switch configured thus.....................

interface Ethernet2
 no nameif
 no security-level
 no ip address
!
interface Ethernet2.2
 vlan 2
 nameif dmz1
 security-level 50
 ip address 172.31.5.1 255.255.255.0
!
interface Ethernet2.3
 vlan 3
 nameif dmz2
 security-level 55
 ip address 172.31.4.1 255.255.255.0


So will one othe the other switches work?
what commands need to be input for FE0/1 to trunk traffic from other VLANS on THIS switch to the ethernet card of the PIX?
0
Comment
Question by:Pete Long
  • 2
  • 2
4 Comments
 
LVL 79

Expert Comment

by:lrmoore
ID: 18818143
The 2900XL supports both ISL and dot1q trunking.
The 2950 series supports only dot1q and therefore there is no option to specify which encapsulation
Yes, it will work if you simply specify mode trunk on the interface

 interface fast 0/1
  switchport mode trunk

Done.
0
 
LVL 57

Author Comment

by:Pete Long
ID: 18822047
Great - I thought as much but I couldnt find any proof.

Is that because Cisco is turning its back on ISL ? (I seem to remember ISL is a Cisco standard)

on the 2950XL did you "HAVE TO" specify? or did it default to ISL? - was there any benefit to manually setting dot1q, or it that just a quirk of the old switch?

0
 
LVL 79

Accepted Solution

by:
lrmoore earned 500 total points
ID: 18822666
Yes, Cisco has abandoned proprietary ISL in favor of the industry standard dot1q.
I can't say that I know what the default was on the old XL switches..but I found this tidbit in 2900XL documentation, which says ISL is the default:

"100BASE-T and Gigabit Ethernet trunks use Cisco Inter-Switch Link (ISL), the default protocol, or industry-standard IEEE 802.1Q to carry traffic for multiple VLANs over a single link."
0
 
LVL 57

Author Comment

by:Pete Long
ID: 18823894
Sorted

Cheers Again - Im still playing with the ASA so Expect some more questions soon - Have a good Weekend m8
0

Featured Post

Microsoft Certification Exam 74-409

Veeam® is happy to provide the Microsoft community with a study guide prepared by MVP and MCT, Orin Thomas. This guide will take you through each of the exam objectives, helping you to prepare for and pass the examination.

Question has a verified solution.

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

David Varnum recently wrote up his impressions of PRTG, based on a presentation by my colleague Christian at Tech Field Day at VMworld in Barcelona. Thanks David, for your detailed and honest evaluation!
Arrow Electronics was searching for a KVM  (Keyboard/Video/Mouse) switch that could display on one single monitor the current status of all units being tested on the rack.
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…
In this tutorial you'll learn about bandwidth monitoring with flows and packet sniffing with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're interested in additional methods for monitoring bandwidt…

740 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