Basic Network design upgrade

Unanswered Question

Hi,

We recently added some workstation, ip phones and servers to our existing network.

It seem that we need to upgrade our simple network design.

I would really welcome suggestions.

Here is what we actually have:

1x router 2801 w/ CCME & CUE for 16 users

1x Switch CE500 24 port 10/100 w/POE & 2 10/100/1000 BaseT uplink.

14x IPHONE 7931G

1x 7921G wireless IPHONE

2x Wireless Access Point (Linksys and Dlink)

2x Server: 1x IBM xSeries and 1x HP DL160G5, both with 2 gigabytes NIC

Some of our 18 workstation have a Gigabyte NIC also.

We need to increase reliability and if possible performance and plan a little headroom for expansion for future needs.

There is no more available port on our CE switch and our 2 server is already using the 2 available uplink Gb ports.

any idea where we should begin.

budget is the biggest issue.

Thanks,

I have this problem too.
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Joseph W. Doherty Wed, 10/08/2008 - 14:58

Obtain a 2nd switch that offers multiple gig copper ports; something like the Cisco Catalyst Express 520G-24TC.

Interconnect this switch with your existing CE500; ideally on a two port gig Etherchannel (if supported between the two switches).

Place gig hosts on new switch, non-gig hosts on existing switch. (Optionally place non-gig hosts that might be "busy" hosts on new gig switch.)

If budget is the biggest issue, perhaps the only way to increase reliability might be to have an additional switch or switches available either as a cold spare or deploy multiple smaller switches such that loss of one does take out your entire network and excess ports are available for repatching around failed switch.

An example of single spare might be purchase of second 520G-24TC and second CE500. If they support STP, they could be left hot.

An example of multiple smaller switches would be usage of something like usage of multiple 2960PD-8TT-L for non-gig POE ports 2960G-8TC-L for gig ports. Buy minimal number of swithes you need for port counts and one extra of each type for on-hand replacement.

paul.matthews Fri, 10/10/2008 - 03:00

If all you have is gig to the server, I would be wary of giving users more than 100M - just because a PC has a gig NIC does not mean you have to use it. Keeping the users to 100 gives a little protection to the servers against a user or two hogginh it.

When you say budget is the issue, how big an issue is it? I will admit to not being totally familiar with the CE500s, but if that was all you could afford I would add another similar switch, join them using gig and have one server on each. This won't however let you run all four server NICs at full speed.

Joseph W. Doherty Fri, 10/10/2008 - 05:31

Paul makes an interesting point about the possiblity of some users "hogging" a server if both the clients and servers have the same bandwidth connection. Normally, server clients draw much more data than they push to a server, and with normal server multi-tasking, there shouldn't be an issue from server to client.

If, however, you do have the uncommon situation where multiple clients send lots of data to the server (e.g. client backups to a server), it's easy to encounter saturation on the the switch port from the switch to the server. This will likely increase latency due to switch queueing and cause many packet drops. However, if TCP is the data transport, and with typical LAN latencies, TCP will sort itself out quickly and usually the perceived service reduction is very, very minor. (I.e. good chance you wouldn't even notice.)

In other words, assuming typical client server data transfers, having both clients and servers at gig provides better overall performance then restricting client bandwidth to avoid issues for uncommon situations.

However, Paul's suggestion does have merit if you do encounter very heavy traffic generation sending host clients. If so, Paul's suggestion doesn't have to be implemented all or nothing, if only one or two host clients are causing problems, just they could be moved to 100 Mbps.

Other alternatives would be implmentation of QoS on the switch to sort between traffic when there's congestion. (Don't know whether CE series supports any QoS.) Or, some servers support using multiple NICs to increase bandwidth to/from server; they sometimes call this NIC teaming.

Thanks for the reply...

Budget is the issue, meaning that we already spent this year IT budget and a little bit beyond with unexpected business expansion needs.

Adding a switch or another component to our network would be a very interesting fight to watch ;-)

Initially, i was thinking to add a gig switch, like the CE500G-12TC (8 gig port with 4 gig uplink).

So i could connect my 4 gig NIC from my 2 servers, the 2801 and the CE500 using the 2 uplink (etherchannel).

I was seeing this as creating a head switch with gig capability for layer 2 and 3 and a user switch for user and apps.

When you mention using 2 gig NIC on my server, are you suggesting to team (bridge) the NIC or use a different IP config ?

Joseph W. Doherty Fri, 10/10/2008 - 16:11

Don't see why you can't use a CE500G-12TC other than the limited number of gig ports. But if you keep most hosts on 100, that shouldn't be a problem.

Believe the 2801 only has 100 Mbps ports.

For server NIC teaming, I did not have in mind multiple IP configs, since you don't have fast L3 forwarding. (L3 could be done on the 2801, but a 2801's performance isn't suitable for 100 Mbps and faster LAN routing.)

Basicly, just to make sure that i am really following,..

I should go with one gig switch with more port or 2 or 3 smaller gig switch to increase redundancy in case of hardware failure, do NIC teaming for my 2 server (if they support it) and keep the host on the 100 as much as possible ?

Yes, the 2801 only have 2x 100 port.

Does the router could be a performance issue? since L3 Forwarding performance isn't suitable for 100 and faster LAN

Right now, i am using 1x 100 port to connect to my switch and the other port to connect to my ASA5505 which connect to the internet.

Joseph W. Doherty Mon, 10/13/2008 - 03:49

"I should go with one gig switch with more port or 2 or 3 smaller gig switch to increase redundancy in case of hardware failure, do NIC teaming for my 2 server (if they support it) and keep the host on the 100 as much as possible ? "

Correct, although you should only keep normal hosts at 100 if you belive you might overwhelm server hosts sending data to them. If you can get the server hosts to NIC team at gig, this would also mitigate the need to keep client hosts at 100. You could also keep client hosts at 100 just to reduce the demand for more expensive gig ports, which you might especially use if you go with the multiple smaller switches.

"Does the router could be a performance issue? since L3 Forwarding performance isn't suitable for 100 and faster LAN

Right now, i am using 1x 100 port to connect to my switch and the other port to connect to my ASA5505 which connect to the internet."

The 2801 should be give for 10 (to 15?) Mbps full duplex on a LAN. Unless your Internet connection supports more than that, the 2801 should be fine.

We only have a 5Mbps ADSL connexion.

I guess the 2801 is fine.

I have 6 non-used 100 ports on my ASA5505, which is in between the router (connected to the second Fe port) and the ADSL modem.

Right now i am using the ASA only as a bridge for internet communication security.

Would you recommend a different setup, where i can re-use theses ports on my LAN ?

....

Thanks,

Joseph W. Doherty Wed, 10/15/2008 - 14:53

Don't have any experience with ASA series, so unable to comment on using its extra ports.

Yes, 2801 should be fine with a 5 Mbps ADSL link.

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