Per the 802.1Q spec the max possible vlan's is a 12 bit field in the Tag Control
Information field (2 Bytes length) which allows for a maximum of 4096 possible
VLAN's.
Bits 1-3 are the User Priority Bit's which are capable of representing 8
priority levels (think of TOS).
Bit 4 is the CFI bit (Canonical Form Indicator) which in english means weather
you read the byte in Big or Little Endian format (IE: Ethernet or Token Ring or
FDDI).
Bit's 5-8 of 1st byte then bits 1-8 of 2nd byte make up the Virtual LAN ID Tag
for a total of 12 bits. This is your VLAN ID for a possible 4096 VLAN's
supported (varies from vendor to vendor and usually depends on Hardware/software
issues and customer needs/wants).
ISL allows for 1023 max (you cannot use 0 if I remember correctly) with 5+
reserved for various frame types if I remember (I may be wrong so verify this
for yourself). Since Cisco is pushing DOT1Q they could support the maximum of
4096 in the future although I still think their current hard limit is 1024 on
DOT1Q and my experience was to never have more than 50 on a router interface and
100 on a switch.
I would check Cisco's reference's on CCO. I bet it's tied to software version's
more than hardware in anything that is a standardized CLI for their
switch/router IOS's (which would make more sense). Check Cisco for the
definitive answer for their product models.
The 802.1Q spec says 4096. If you get a test question though, you will need to
know how it applies to Cisco and that model, not the spec.
Cheers,
Julian
--
Julian Eccli
Technical Support Engineer
Juniper Networks
""Hitesh Pathak (CSD-BBYRO-RTSG)"" <[EMAIL PROTECTED]> wrote in message
EA1BEFF8C198D31183DD00104B233921D82049@MERCURY">news:EA1BEFF8C198D31183DD00104B233921D82049@MERCURY...
: Friends,
:
: I hv a question.....
:
: Can anyone tell me What is the MAX. no. of vlan's can be created using a
: switch/switches . Is there any limitation to it or it is model specific.
: What is the max no. of switches we can have per VLAN.
:
: thanx
: HP
:
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