Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

onther differance between 802.1Q and ISL????

i know diff. of frame i wnat to know other disadvantage of 802.1Q ..?

3 REPLIES

Re: onther differance between 802.1Q and ISL????

HI Devang,

There is no disadvantage of dot1q. Infact there are some cisco devices which only supports dot1q like 2950 and old cat4k switches with sup 1 and sup 2.

Regards,

Ankur

Re: onther differance between 802.1Q and ISL????

thank you ankur

Re: onther differance between 802.1Q and ISL????

Hi Devang,

One more advantage of dot1q over isl is that dot1q is 4 bytes which means 32 bits not out of 32 bits 12 bits are used for vlan id which means dot1q supports 4096 vlan ids over the trunk.

Now is ISL there are 15 bits which are for vlan id but CISCO only use lower 10 bits for vlans which results into support of only 1024 vlan ids on the trunks.

So in any case dot1q is better then ISL.

HTH

Ankur

118
Views
0
Helpful
3
Replies