>It really comes down to how many hosts you have and the amount of inter-VLAN
>traffic you expect. There are also many options to use in increasing
>performance, such as:
>
>etherchannel with ISL trunking
>multi-layer switching (if the switch and router support it)
>sending various VLANs to different routers
And avoiding inter-VLAN routing by:
VLAN-aware cards in servers
Multiple NICs in servers
application gateways between VLANs
>
>It all depends on what you want to do, how your network is set up, what kind
>of equipment you have, and how much money you're willing to spend.
>
>Tony Olzak, CCNP, MCSE
>
>"Curly G. Craddlerock" <[EMAIL PROTECTED]> wrote in message
>8l4ile$4eu$[EMAIL PROTECTED]">news:8l4ile$4eu$[EMAIL PROTECTED]...
> > How many VLAN/sub-int can I effectivly put on an interface. I would like
>to
> > buy a dedicated router and run my VLAN's off of it. Any suggestions on the
> > router or my thinking? Does the DCN class cover these design issues? I'm a
> > CCNA, but I have a lot of design ?'s. Thanks for your help.
There's some coverage in CID, but I always found that it was one of
those areas where good instructors went considerably outside the
course notes. I analyzed the subnet size issue in my book _Designing
Addressing Architectures for Routing & Switching_, still with the
caveat "it depends". I looked at the management and processing
aspects in my second book, _Designing Routing and Switching
Architectures for Enterprise Networks_, and still observed "it
depends."
Leaving inter-VLAN traffic aside for the moment, the protocol limits
on numbers of VLANs (IIRC 1000 in ISL and somewhat more in 802.1Q
[it's a 16 bit field but I don't remember how much is taken up for
other things--at least 4 bits]) are highly unlikely to be the
limiting factors. The IOS limit on number of subinterfaces
(traditionally 300, but increased in recent releases) is another high
limit.
A much more likely limit is the bandwidth of trunks. If you have 3
Fast Ethernet VLANs that average 50% utilization, you may (not a
given) have trouble trunking all of them over a single 100 Mbps
trunk.
More often than not, a limitation is less the number of VLANs, but
the number of hosts per VLANs. This limit is highly dependent on the
protocols used (especially how much they broadcast and multicast),
the power and efficiency of the host OS and NIC in handling
broadcasts and multicasts, and total traffic.
"What Problem are you trying to solve?"
***send Cisco questions to the list, so all can benefit -- not
directly to me***
Howard C. Berkowitz [EMAIL PROTECTED]
Technical Director, CertificationZone.com
Senior Product Manager, Carrier Packet Solutions, NortelNetworks (for ID only)
but Cisco stockholder!
"retired" Certified Cisco Systems Instructor (CID) #93005
___________________________________
UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html
FAQ, list archives, and subscription info: http://www.groupstudy.com
Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
