From: Fred Ingham (fningham@xxxxxxxxxxxxxxxx)
Date: Tue Feb 13 2001 - 16:13:17 GMT-3
Frank: The basic idea is sound but before you assign a given range to a
router I suggest you read the instructions for any fixed addresses. If
there is a required loopback of 172.16.225.0/30 on r2, for instance,
your scheme falls apart.
I suggest ranges of 32 rather than 16 (will work for 8 routers) and also
space out the networks to the lowest mask requested. For instance if
there is a required network of /22 somewhere in the network I would
space my subnets acccordingly for all routers. This guarantees no
overlaps.
There are no points in the lab for saving address space. You should
complete your addressing before configuring the routers and also draw a
network diagram. Going into the lab with a fixed addressing scheme can
cost you time. Rather, you should be able to construct addressing
quickly after reading the requirements. On rebooting - in the lab I
recommend you do this often - there are no points for not rebooting and
it can
clear up nagging problems.
My opinion, Fred.
frank wells wrote:
>
> I am giving a little thought to how I am going to handle the IP addressing
> in the lab. Regardless of the IP address/mask I am given I want to come up
> with a scheme which allows me easy summarization of all routers and their
> connected OSPF network segments.
>
> I am almost certain Cisco will throw the VLSM-FLSm issues at me and I want
> to be prepared.
>
> Lets say we get the following address/mask given to use: 172.16.0.0 and we
> are able to cut it up any way we want.
>
> Give me your thoughts on the following idea:
>
> 172.16.0.0 use mask 255.255.240.0 to get 14 useable subnets (not including
> subnet zero) I chose the 24 bit subnet mask to anticipate being given
> possible RIP/IGRP FLSM addresses to
> deal with. I assign a contiguous range of subnets to each router like so:
>
> R1=172.16.16.0 - 172.16.31.0
> R2=172.16.32.0 - 172.16.47.0
> R3=172.16.48.0 - 172.16.64.0
> R4=172.16.64.0 - 172.16.71.0
> R5=172.16.72.0 - 172.16.87.0
> R6=172.16.88.0 - 172.16.95.0
> R7=172.16.96.0 - 172.16.111.0
> R8=172.16.112.0 - 172.16.127.0
>
> Now when asked to do something like intra-area summarization to the max, I
> can easily summarize each routers connected networks with a simple command
> like area 1 range 172.16.16.0 255.255.240.0 right?
>
> Also, by planning this way I would like to be able to address my network
> before I begin typing it into the routers. This would give me an advantage
> as I would be able to assign the highest IP addresses in the respective
> subnets to a/the loopback addresses etc. Ultimately I want to not have to
> reboot the routers because I created an OSPF adjacency prior to adding the
> loopbacks etc.
>
> I am also thinking about drawing a line on top of my picture and deviding it
> into as many segemnts as I have routers like so:
>
> R1 R2 R3 R4 R5 R6 R7 R8
> |-------|-------|-------|-------|-------|-------|-------|-------|
> 16 32 48 64 72 88 96 112 127
>
> By doing this I can easily mark off along my line which subnets I have
> already used too which may prove to be useful. Plus, it takes up little to
> no room on your paper.
>
> Hope the ASCII pic isn't mangled too bad...
>
> Good idea/bad idea?, thoughts please.
>
This archive was generated by hypermail 2.1.4 : Thu Jun 13 2002 - 10:28:47 GMT-3