[cisco-voip] Network Change Recommendations

[Tim Fletcher]

My $.02 below.

TechGuy wrote:
> We have some engineers in helping with a new callmanager and IPCC 
> implementation at a secondary company of ours.
>  
> They have made some recommendations on some network changes and I 
> wanted to ask others about the changes and what you think would be the 
> pro's and con's of doing so and why do you think they are suggesting 
> these changes.
>  
> 1.  Move the inter-VLAN routing to the switches.  (This office has a 
> maxed out 3845 acting as the core router and voice gateway, it 
> currently does all routing)
This is fairly simple to do, and there is no real down side. I would 
absolutely do this.
>  
> 2.  Seperate VLANs for servers, pc's, callmanagers, phones  (Currently 
> we have one vlan for servers and pc's, and one VLAN for callmanagers 
> and phones)
If I'm understanding this correctly, you currently have 2 VLANs, one for 
voice and one for data, and they are recommending 4 VLANs. On most small 
to mid sized networks, I would recommend keeping the phones and CMs in 
the same VLAN. So the question becomes, should you put the servers and 
desktops in separate VLANs? And the answer is, it depends on the size of 
the network and what administrative or security controls you want. In 
most small to mid sized networks I don't really see much advantage to 
splitting them up. Also keep in mind, splitting the servers and desktops 
to separate VLANs will require re-addressing (more on that below).
>  
> 3.  Remove class B addressing and utilize Class C addressing (The 
> internal network was originally configured with Class B addressing 
> throughout)
Are they talking about splitting up the network, or just re-addressing. 
If they are just talking about re-addressing, I would recommend against 
it. Re-addressing can be difficult and risky, and should probably not be 
done without a good reason. If they are talking about splitting up the 
network, that may or may not be a good idea. There are two reasons to 
split up a network. The 1st is for administrative or security controls, 
which doesn't sound like an issue here. The 2nd is to reduce the amount 
of broadcast traffic (ARP, etc.). Do you know how much broadcast traffic 
you have on your network now? Unless there is a problem here, I would 
have to agree with your management on this one.
>  
> Thats the bigger changes that I really just want to understand the 
> various pro's for why they would recommend them.  They make sense and 
> I don't question that these are not best practices but I want to 
> really understand why the changes to sell it to management.  Their 
> philosophy is "if its not broke dont fix it" and feel that the network 
> has been working fine so why all the changes.
>  
> Thanks for your time!
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