Cisco Catalyst VLAN Trunkinq Question

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?
LVL 58
Pete LongTechnical ConsultantAsked:
Who is Participating?
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

lrmooreCommented:
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
Pete LongTechnical ConsultantAuthor Commented:
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
lrmooreCommented:
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

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
Pete LongTechnical ConsultantAuthor Commented:
Sorted

Cheers Again - Im still playing with the ASA so Expect some more questions soon - Have a good Weekend m8
0
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Cisco

From novice to tech pro — start learning today.

Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.