Cisco student needs help please???

[danabersoch]

Hi guys,

Iam in year one ccna and for my first assignment I have to design a network with:

3 departments each in there own subnet salesX50 hosts, WarehouseX30 hosts and AdminX20 hosts.

There is a lot of other stuff i have to do for the assignment but I'm really struggling to design it.

Its sort of up to me, what demands each department have on the network so Ive put that there are two shared databases and file transfers from the sales department to the warehouse (trying to keep it simple, but not too simple)

At the moment (with packet tracer) I have a generic cisco router with 4 fast ethernet ports where three of which are connected to cisco switches for the stated departments/subnets. (every connection is 100mbps)

I need help with:

Should I stick with cat 5 100mbps utp or because of the 50 hosts in the sales department should I go for cat 6 gigabit or fibre ( just for the connection from the switches to the router to prevent bottlenecks)???

And what are my options with cisco routers, I'm not familiar with them so if you can give me any models I can go research

Please help me any sort of input is really needed, cheers.

[DELL ACORD]

What kind of traffic are you going to support?

Are there any servers involved?

Are you going to implement any kind of QoS?

Most Cisco routers are robust enough to support enough routing on a stick with a single interface.

[danabersoch]

I will have one server hosting two databases (customer and stock databases) with all departments having access to them. there wont be anything complex or high demand like voip or video nor will I be implementing QoS.

Also the warehouse dep will be downloading files from the sales for the following day's orders, without to much affect on the rest of the network, my worry would be bottlenecks at the sales gateway??

[danabersoch]

If you could tell me if a 100mbps connection will be good enough or if I would need somthing faster between the routers and the switches ????

and if you happen to know of any models that would fit the bill that would be brilliant???

[danabersoch]

models of router

[lcleverley]

Your "design" decision is not what switches or routers to use but how you would break down your addressing structure. This is what they're trying to elicit from you...

50 Hosts Sales

30 Hosts Warehouse

20 Hosts Admin

[danabersoch]

Ive already done all the addressing which was pretty straight forward, Ive handed in a draft submission using a generic router and not much of actuall models (because I don't know what to use and nothing stands out) and my tutor told me to do more work on real devices.

[Joseph W. Doherty]

For 100 hosts, you could run your whole network as L2. Nothing wrong with using subnets, but if you do, for LAN performance, would recommend a L3 switch for LAN routing vs. a typical router. Selection of L2 or L3 switches would depend on feature needs and placement of devices. If you can place all you network devices together, you might consider stackable switches, either 3750 series (L3) or the new 2975 (L2).

For a non-stackable L3 switch, you'll want to look at the 3560 series. Cisco offers various non-stackable L2 switches. (If you have seperate L2 and L3 switches, you might want to select both that support Etherchannels to allow for interdevice bandwidth growth.

As for connection speeds, you would likely want gig between network devices (hopefully copper to keep costs down) and gig to server hosts. User hosts are normally okay at 100 Mbps, but if you can afford it, would recommend gig copper ports on your network devices and gig cabling plant. Recommend, if possible, Cat6, or at least Cat5E, so you have the option for gig.

[danabersoch]

Thank you for your reply

My big problem is that, even though using a layer 3 switch is the best option (this is the advice i got from other forums) we havn't covered them yet (this is my first assignment and I started this course in sept) nor have we done routing on a stick or Vlans (sorry for the lack of knowledge).

So, please correct me if Im wrong, the only way I can keep the departments in seperate subnets and in there own broadcast domains is to have my central device as a router, and this is where Im struggling!! thanks again - good advice!

[Joseph W. Doherty]

Correct, to have your departments in separate subnets (and broadcast domains) does require routing (this also assumes you do want to be able to communicate between them). The device, itself, doesn't have to be a "router". L3 or multilayer switches can route, some dedicated security devices can route, many host systems can route. The placement of the device doesn't have to be "central" plus you could have more than one (routing device). (Central L3 deployment likely would be best for your network, if you're going to support L3. Again, for a network of your size, L2 would likely be fine from a performance viewpoint. Most larger network subnets contain as many or more hosts as yours. However, the other main advantage of using routing in a network of your size might be to implement security between the subnets since you seem to be planning on having logical subnet groups.)

The reason a L3 switch usually would be considered the best option is because they're "inexpensive" for the performance and features they offer. Most of the small Cisco "routers" have much less performance but are much richer in features, which often makes them a better choice for low bandwidth (several Mbps vs. 100s to 1,000s of Mbps) WAN connections.

Usage of VLANs or routing on a stick would depend much both on your selection of devices and physical topology. You might not need to implement VLANs and/or routing on a stick, or you might need one or both. If departments wouldn't need to share the same physical device, you may not need VLANs. If the L3 device has sufficient physical ports to interconnect any downstream L2 switches, you don't need to route on a stick. (What's also often confusing when seen for the first time in mixing L2 and L3 on the same device, as often done with a multilayer switch.)

[danabersoch]

Cheers again,

Ive been looking at the basics of Vlans and how it works, by assigning the Vlan number to the appropriate ports.

I'm not going to have more than one department to switches.

Im now thinking:

Have switches in each area, Gigabit uplinks to the central device,

the central device being a layer 2 switch OR a L3 switch,,,,,

My new problems for these solutions:

Mainly Packet tracer -

I have got the three area switches with the uplink to the central L2 switch and then to a router (reason - because I think I just read somwhere that connecting the switch to a router is how we get connection between the different Vlans)

Ive put put the Vlans in the Vlan database then assigned the port the appropriate Vlan number and I can't ping one vlan host from a different vlan - need help with - trunk or access and how to configure the connection to the router.

I can imagine the whole point of a multilayer switch is to do all this in one device (Hope so) so I configure the Vlan database in the central multilayer switch (e.g? Vlan name - Sales, Vlan number - 10 etc) and what else do I have to do (remebering that I have to keep them in seperate broadcast domains but still have connectivity). Thanks a lot for your replies and thanks in advance!!

[Joseph W. Doherty]

If your area switches only host one subnet, you don't need to define VLANs on them. (Managed switches will likely have a native default VLAN for all ports.)

A central router, with ports for each area switch, you just define the subnet on the router's link to the switch.

A central L2 switch will need to define VLANs for the downlink ports. To get traffic between VLANs, you need to connect a router. If the router has mutiple ports, it can connect an interface to each VLANs. (If you can do this, not much point in having a central L2 switch unless you extend VLANs across multiple switches.) Otherwise, you define a VLAN trunk port and connect that to the router (which then sees the VLANs as separate logical interfaces).

A central L3 switch, supporting different area switches, will either need to place downlink ports into different VLANs, or you might define the ports like you would on a router. The L3 switch then either routes between the "routed ports" or between VLANs (a separate router wouldn't be needed).

[danabersoch]

Cheers I will have another play tomorrow and let you know how I get on, thanks a lot for the help

[danabersoch]

Ive got a layer 2 central switch with downlinks to area switches.

On the L2 central I have 3 Vlan names and numbers and then assigned the Vlan number to the correct interfaces.

I then have configured an interace on the central switch as a trunk to a router.

I still can't ping from one Vlan/subnet to another? Is this down to the gateway address and what address do I give the interface on the router?

The network addresses are:

Sales 192.168.11.0 /26

Warehouse 192.168.11.64 /26

Admin 192.168.11.128 /26

[danabersoch]

Ive just done a bit more research on Vlans and routing on a stick.

I believe to have found what I think is the answer to the previous Q, do I have to configure addresses and subnets to sub interfaces on the router as logical gateway addresses for each subnet?