Re: Stupid Question maybe?
On Wed, 2018-12-19 at 14:54 +, Naslund, Steve wrote: > I am wondering how a netmask could be not contiguous when the network > portion of the address must be contiguous. I suppose a bit mask > could certainly be anything you want but a netmask specifically > identifies the network portion of an address. Before CIDR, subnets allowed further subdividing Classful addresses and the mask bits after the network part could be non-contiguous. For a class A network the first 8 bits covered the classful network, but the remaining subnet bits did not have to be contiguous. Most network admins made the subnet part contiguous, but allowing non-contiguous subnet masks simplified the actual implementation. There was no need to check if the bits were contiguous in the code. Also subnet masks had to be the exactly the same on all devices. You could not have variable length masks. A common practice if you could get a Class B network (16 bit network part) was to use a 24 bit mask to divide the network into 254 subnetworks which was adequate for most purposes at the time. -- Smoot Carl-Mitchell System/Network Architect voice: +1 480 922-7313 cell: +1 602 421-9005 sm...@tic.com
Re: Cisco ISE
On Fri, 2017-10-06 at 20:41 +, Christopher J. Wolff wrote: > Is anyone successfully deploying ISE 2.X? I’m six months into it on > about 10,000 endpoints and it seems like it’s a highly challenged > product. I’d love to hear your experiences on or off-list. Thanks > in advance. ISE is challenging. I helped deploy and manage a 2.1.0.474 installation with about 5,000 end points. The hardest part was designing the access policies There is also some quirkiness depending on what switches you have in your environment. Different switches and different IOS levels require in some cases slightly different switchport configurations. Keeping everything in sync can also be painful. I ended up writing a web based tool to audit the switch configurations. The device profiler is less than perfect. We ended up having to statically configure some of the devices (notably printers and thin clients) to get them authorized correctly. Sometimes the RADIUS sessions from a switch to the ISE servers would hang in odd ways which required shutting and reenabling the port. Looking at the logs on the switches was vital to sorting out various issues. We also have DHCP snooping enabled in our environment which further complicated debugging. Also be aware upgrading the software can be painful and takes a long time. Our last upgrade required 18 hours of time. Mostly this was waiting around for the software to do the upgrade. Having an environment where you have redundancy is really a requirement for deploying ISE. Conversion to ISE also needs to be done switch by switch with lots of hand holding the users. Users do get irritated when their computers no longer work. A good communications plan is vital to be successful. -- Smoot Carl-Mitchell System/Network Architect voice: +1 480 922-7313 cell: +1 602 421-9005 sm...@tic.com