Best guide for first time Cisco switch programming

mac_cnc

mac_cnc

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Oct 14, 2000
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Hello all. I am getting a 2960g switch or two from work and want to practice "building" one from scratch. I want the basic network functions and some VLANs to play with. Does anyone have a good resource for a step by step style for this. I have books and stuff but was wondering people's personal resources they have enjoyed and can recommend. Thanks.
 
If you have not worked with Cisco switches and routers before, remember to unlearn every other networking concept as far as subnetting (IPv4) goes since they use reverse notation. Google Cisco Subnet Mask. Still makes my brain hurt every time I think about it.

Literally, you want 4 hosts, your mask is 0.0.0.3 (0, 1, 2, 3 = 4) hosts, not 255.255.255.252.

You can search for Cisco 2960 configuration guide and there should be a link to documents on the Cisco site as far as how to configure the device (commands & how to use them).
 
evilwon said:
If you have not worked with Cisco switches and routers before, remember to unlearn every other networking concept as far as subnetting (IPv4) goes since they use reverse notation. Google Cisco Subnet Mask. Still makes my brain hurt every time I think about it.

Literally, you want 4 hosts, your mask is 0.0.0.3 (0, 1, 2, 3 = 4) hosts, not 255.255.255.252.

You can search for Cisco 2960 configuration guide and there should be a link to documents on the Cisco site as far as how to configure the device (commands & how to use them).
Click to expand...

You are confusing a subnet mask with what Cisco calls a wildcard mask (which is probably why your brain hurts). A wildcard mask isn't necessarily an inverse of a subnet mask btw. You could make a wildcard mask of 1.1.1.1 or 128.128.128.128 which means its examining those certain bits.

Cisco very much uses a typical subnet mask notation just like anyone else, like addressing a L3 interface.

Wildcard masks are used for things like OSFP and ACLs.
 
Sometimes you don't know what you don't know, so learning from a book will only tell you so much.

I had a mentor when I started out, so I could ask questions. In your case, you might want to search up some example configs that are littered all over the Interwebs and reverse "learn" what & why the commands do in there. Take your approach too, but then this way you can see some real life examples as well.

I'll start by saying 'switchport mode access' and 'spanning-tree portfast' are your friends. :)
 
Thanks for the tips so far. We use Cisco in our environment and I primarily work with the Network assistant app to do most of my VLAN changes on ports and port labeling etc. I have done command line stuff before but never done a ground up build on one.
 
AeonF1 said:
You are confusing a subnet mask with what Cisco calls a wildcard mask (which is probably why your brain hurts). A wildcard mask isn't necessarily an inverse of a subnet mask btw. You could make a wildcard mask of 1.1.1.1 or 128.128.128.128 which means its examining those certain bits.

Cisco very much uses a typical subnet mask notation just like anyone else, like addressing a L3 interface.

Wildcard masks are used for things like OSFP and ACLs.
Click to expand...

X2. I use Cisco gear day in and out and they very much use the standard notation for subnet masks. Also with ACLs, the wildcard is used on both standard and extended lists. Standard notation is also used if you are assigning DHCP pools, reserved DHCP clients, and as Aeon pointed out L3 interfaces.

Fun fact/tip-- If you want to find out what your Wildcard mask is quick and simple. From the broadcast address of 255.255.255.255 subtract your subnet mask that you are using. I.E. 255.255.255.255 - 255.255.255.240 = 0.0.0.15
 
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