VLAN's are not routable. The layer 3 address space (ie. IPv4/6) used within a VLAN can be routed but it does not have to be.
When I see the term "unrouted VLAN" I understand that the L3 address space used in a VLAN is not to be advertised. Why would I not want to advertise that L3 space? Not all devices with an L3 address space have to be reachable outside that range. When would I use a "unrouted VLAN"? When clustering servers, network based backups using production network, link between firewalls/load balancers configured in HA mode to exchange health status info and sync configs/sessions/etc, iSCSI networks, etc. These are just a few examples of "unrouted VLAN's". In most cases I'd probably use dedicated hardware in an IP based SAN to avoid network congestion/STP, better security, etc. I'd recommend to do the same with network for back ups. Unfortunately I can't control layers 8 and above (ie. money, politics). HTH Sent from my iPhone On Feb 10, 2011, at 6:46 PM, Matt Hill <[email protected]> wrote: > NAC Quarantine vlan is a common use for an unrouted vlan. > > On 11 February 2011 09:48, Matlock, Kenneth L <[email protected]> wrote: >> If I had to guess, I'd say the context is something like a load balancer >> or such (like the older Cisco Local Director), where the L2 packets must >> flow 'through' the chassis. >> >> What I'd do is have the 'real' VLAN with an SVI, and then a 'dummy' >> L2-only (no SVI) VLAN behind the Local Director. The servers 'live' on >> the dummy VLAN, and the Local Director acts as a bridge between the two. >> >> >> Ken Matlock >> Network Analyst >> Exempla Healthcare >> (303) 467-4671 >> [email protected] >> >> >> >> -----Original Message----- >> From: [email protected] >> [mailto:[email protected]] On Behalf Of Marko >> Milivojevic >> Sent: Thursday, February 10, 2011 2:40 PM >> To: [email protected] >> Cc: . >> Subject: Re: [OSL | CCIE_RS] Unrouted VLAN >> >> On Thu, Feb 10, 2011 at 21:04, <[email protected]> wrote: >> >>> What is a Unrouted VLAN and why would you use? >>> >> >> Could you please give some context for the question? >> >> -- >> Marko Milivojevic - CCIE #18427 >> Senior Technical Instructor - IPexpert >> >> FREE CCIE training: http://bit.ly/vLecture >> >> Mailto: [email protected] >> Telephone: +1.810.326.1444 >> Web: http://www.ipexpert.com/ >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, >> please visit www.ipexpert.com >> _______________________________________________ >> For more information regarding industry leading CCIE Lab training, please >> visit www.ipexpert.com >> > _______________________________________________ > For more information regarding industry leading CCIE Lab training, please > visit www.ipexpert.com _______________________________________________ For more information regarding industry leading CCIE Lab training, please visit www.ipexpert.com
