Configuring Multiple VLANs on Campus Network upto 800 Users

Answered Question
Nov 10th, 2011

Hi All,

I am designing a network for our customer which has a campus Network of upto:

currently: 250 Users, Near Future Expansion(3Months): Upto 650 Users; Future Expansion(6 Months):upto 1000 Users

There are different departments such as Students, Teachers, Admin, Accounts & WiFi. Right now they have HP/3Com Switches all connected in a single broadcast domain.

Now to put the differnet deptts. into different VLANs, I am planning to physically segregate them initially & use a single Multi-layer Cisco Switch at the Core for configuring VLANs for each deptt. This way the Switches in use will be simply used as Access Swiches (no config needed).

The New Core switch will be connected to a WAN/Internet Router already in place i.e. 1841.

Q) Please suggest a suitable Switch in this regard t handle the users (250 to 1000)? such as 3500 or 3700 etc.

Q2) Since most user groups will be connected on separate Uplink port on new Switch, what level of redundancy should we have? i.e. only redundant Power Supply is enough or shall we have 24 Port switches Qty:2 for complete redundancy?

Q3)Can we have different VLAN connections on a single Uplink Port of Switch, & further the Switch can differentiate on the basis of subnet ID?

Q4) Im not sure how I will connect the WiFi APs which are installed as standalone Brides at the moment? Should they also be connected to Trunk Port on the new VLAN Switch?

We will further have a Domain Controller, DHCP Server & Proxy Server on the network which will be connetected to the Siwtch (Trunk) port to serve all VLANs.

Regards,

Tek

I have this problem too.
0 votes
Correct Answer by naiduccnp about 2 years 3 weeks ago

What I understand by your post is whether or not you can configure a specific DHCP pool for each VLAN and the answer is yes.

Now what you need to do is, create a DHCP scope on a 3560 just like any other IOS DHCP configs ...here is a sample config:


interface vlan 1
ip add 1.1.1.1 255.255.255.0

interface vlan 2
ip address  2.2.2.1 255.255.255.0


ip dhcp excluded-address 1.1.1.1 1.1.1.10
ip dhcp excluded-address 2.2.2.1 2.2.2.10
!
ip dhcp pool vlan1
   network 1.1.1.0 255.255.255.0
   domain-name cisco.com
   dns-server 4.4.4.2 4.4.4.1
   default-router 1.1.1.1
   lease 3
!
ip dhcp pool vlan2
    network 2.2.2.0 255.255.255.0
    domain-name cisco.com
    dns-server 4.4.4.2 4.4.4.1
    default-router 2.2.2.1
    lease 3

!
Here is the link for configuring IOS DHCP services:
http://www.cisco.com/en/US/docs/ios/ipaddr/configuration/guide/iad_dhcp_svr_cfg_ps6441_TSD_Pro

Please rate the helpfull posts.
Regards,
Naidu.

Correct Answer by naiduccnp about 2 years 3 weeks ago

Q) in the line "ip dhcp pool DATA", the term DATA rerfers to VLAN ID? e.g if we have VLAN 20 than we will configure:
The word "DATA" I mentioned in as dhcp pool is just for comfort level and it is not and no need as a VLAN ID, it can be any word as per your comfort.
Say for example I have named the dhcp pool as "DATA" because the pool is particularly defined for DATA network means users. There can be another pool seperately for VOICE (IP phones) then that would be named as VOICE as per my comfort levels.

So the naming word can be anything just for your understand and comfort.


Please rate the helpfull posts.
Regards,
Naidu.

Correct Answer by naiduccnp about 2 years 4 weeks ago

Hi Tek,


Q) For DHCP, could you please elaborate the "IP Helper Addresss" i.e. how we can use it. Can we configure DHCP Server on Cisco 3560? please give some example.
IP helper address command used when you have the DHCP server either Windows machine or Router in different VLAN (different network).
Say for example you have multiple vlans configured in your 3560 and you have that DHCP server in one vlan (say vlan 10 IP: 192.168.10.0/24), you have another multiple vlans and those need to get IP from this DHCP server then you have to redirect the dhcp request from the particular vlan to DHCP server which is posible with the "ip helper-address" command


Q) With inter-vlan routing on 3560, we are further connected to the 1841 Router, can we use it for DHCP Server using IP Helper Address? please give some example.
I would suggest you to user your 3560 switch as a DHCP server not that 1841 because it is a edge router and you can use it for WAN routing.

Please find the below related config for DHCP in 3560:

ip dhcp pool DATA
   network 10.110.224.128 255.255.255.240
   default-router 10.110.224.129
   dns-server 10.98.112.32 10.55.0.32
   netbios-name-server 10.52.64.37 10.24.128.151
   lease 0 1
!

you can adapt this to your needs.
you need to exclude ip addresses that are statically assigned including C3560 SVI interface IP address

with commands like the following:

ip dhcp excluded-address 10.110.224.129 10.110.224.132
ip dhcp excluded-address 10.110.224.145


Please rate the helpfull posts.
Regards,
Naidu.

Correct Answer by naiduccnp about 2 years 5 months ago

Hi Tek,

Please see the below comments for your plan and hope that will help you.


Q) Please suggest a suitable Switch in this regard t handle the users (250 to 1000)? such as 3500 or 3700 etc.
I would suggest you go with 3750 24 port switch (if your budget is ok then go with 4506 considering future expansions)


Q2) Since most user groups will be connected on separate Uplink port on new Switch, what level of redundancy should we have? i.e. only redundant Power Supply is enough or shall we have 24 Port switches Qty:2 for complete redundancy?

If you need connection redundancy between access and distribution switch then please go with STP where you will have one path (physical connection) active and another path (another physical connection) is standby.

Q3)Can we have different VLAN connections on a single Uplink Port of Switch, & further the Switch can differentiate on the basis of subnet ID?
Yes, if you configured that port as a trunk port which carry all the vlans over the trunk and you can assign the desigered vlan to the specific physical port.

We will further have a Domain Controller, DHCP Server & Proxy Server on the network which will be connetected to the Siwtch (Trunk) port to serve all VLANs.
You can have DHCP assign IP's to computers in the specific vlan by adding ip helper command under the specific vlan.

Please rate the helpfull posts.
Regards,
Naidu.

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Correct Answer
naiduccnp Thu, 11/10/2011 - 04:51

Hi Tek,

Please see the below comments for your plan and hope that will help you.


Q) Please suggest a suitable Switch in this regard t handle the users (250 to 1000)? such as 3500 or 3700 etc.
I would suggest you go with 3750 24 port switch (if your budget is ok then go with 4506 considering future expansions)


Q2) Since most user groups will be connected on separate Uplink port on new Switch, what level of redundancy should we have? i.e. only redundant Power Supply is enough or shall we have 24 Port switches Qty:2 for complete redundancy?

If you need connection redundancy between access and distribution switch then please go with STP where you will have one path (physical connection) active and another path (another physical connection) is standby.

Q3)Can we have different VLAN connections on a single Uplink Port of Switch, & further the Switch can differentiate on the basis of subnet ID?
Yes, if you configured that port as a trunk port which carry all the vlans over the trunk and you can assign the desigered vlan to the specific physical port.

We will further have a Domain Controller, DHCP Server & Proxy Server on the network which will be connetected to the Siwtch (Trunk) port to serve all VLANs.
You can have DHCP assign IP's to computers in the specific vlan by adding ip helper command under the specific vlan.

Please rate the helpfull posts.
Regards,
Naidu.

Tekkie123 Tue, 03/20/2012 - 22:42

Hi Naidu,

Thanks for ur earlier positive feedback. Now we have purchased the cisco 3560 for Cire/Distribution Switch & Cisco 1841 as Internet Router. I have planend to configure all VLANs in 3560 as well as Inter-VLAn Routing in it.

Further, my question is:

Q) For DHCP, could you please elaborate the "IP Helper Addresss" i.e. how we can use it. Can we configure DHCP Server on Cisco 3560? please give some example.

Q) With inter-vlan routing on 3560, we are further connected to the 1841 Router, can we use it for DHCP Server using IP Helper Address? please give some example.

Thx/Tek

Correct Answer
naiduccnp Wed, 03/21/2012 - 02:51

Hi Tek,


Q) For DHCP, could you please elaborate the "IP Helper Addresss" i.e. how we can use it. Can we configure DHCP Server on Cisco 3560? please give some example.
IP helper address command used when you have the DHCP server either Windows machine or Router in different VLAN (different network).
Say for example you have multiple vlans configured in your 3560 and you have that DHCP server in one vlan (say vlan 10 IP: 192.168.10.0/24), you have another multiple vlans and those need to get IP from this DHCP server then you have to redirect the dhcp request from the particular vlan to DHCP server which is posible with the "ip helper-address" command


Q) With inter-vlan routing on 3560, we are further connected to the 1841 Router, can we use it for DHCP Server using IP Helper Address? please give some example.
I would suggest you to user your 3560 switch as a DHCP server not that 1841 because it is a edge router and you can use it for WAN routing.

Please find the below related config for DHCP in 3560:

ip dhcp pool DATA
   network 10.110.224.128 255.255.255.240
   default-router 10.110.224.129
   dns-server 10.98.112.32 10.55.0.32
   netbios-name-server 10.52.64.37 10.24.128.151
   lease 0 1
!

you can adapt this to your needs.
you need to exclude ip addresses that are statically assigned including C3560 SVI interface IP address

with commands like the following:

ip dhcp excluded-address 10.110.224.129 10.110.224.132
ip dhcp excluded-address 10.110.224.145


Please rate the helpfull posts.
Regards,
Naidu.

Tekkie123 Thu, 03/22/2012 - 01:03

Thanks again. If Cisco 3560 can be a DHCP server, as u mentioned in Q2 than i will certainly use it to keep things simple.

For my clarity, please confirm:

Q) in the line "ip dhcp pool DATA", the term DATA rerfers to VLAN ID? e.g if we have VLAN 20 than we will configure:

"ip dhcp pool 20" ? pls confirm

For rest of things i am quite clear & will apply it.

Thx/Tek


Correct Answer
naiduccnp Thu, 03/22/2012 - 01:56

Q) in the line "ip dhcp pool DATA", the term DATA rerfers to VLAN ID? e.g if we have VLAN 20 than we will configure:
The word "DATA" I mentioned in as dhcp pool is just for comfort level and it is not and no need as a VLAN ID, it can be any word as per your comfort.
Say for example I have named the dhcp pool as "DATA" because the pool is particularly defined for DATA network means users. There can be another pool seperately for VOICE (IP phones) then that would be named as VOICE as per my comfort levels.

So the naming word can be anything just for your understand and comfort.


Please rate the helpfull posts.
Regards,
Naidu.

Tekkie123 Thu, 03/22/2012 - 03:17

Thx again Naidu for your response. But could you please help me with following:

Example: we have 3 VLANs i.e. VLAN 10, 20 & 30. So, we will have three such pool like following:

!

ip dhcp pool abc (pool name as mentioned could be any)

   network 192.168.1.0 255.255.255.0

ip dhcp pool efg

   network 192.168.2.0 255.255.255.0

ip dhcp pool xyz

   network 192.168.3.0 255.255.255.0

(remaining configuration will be done as you mentioend earlier)

Q1) How will the above commands associate the defined pool to particular vlan?

Q2)Will the users in each VLANs get DHCP addresses assigned automatically through the Networks (192.168.x.0) defined under each Pool?

Q3)or do we have to further configure something under particluar VLAN as well?

Reg/Tek

Correct Answer
naiduccnp Thu, 03/22/2012 - 03:52

What I understand by your post is whether or not you can configure a specific DHCP pool for each VLAN and the answer is yes.

Now what you need to do is, create a DHCP scope on a 3560 just like any other IOS DHCP configs ...here is a sample config:


interface vlan 1
ip add 1.1.1.1 255.255.255.0

interface vlan 2
ip address  2.2.2.1 255.255.255.0


ip dhcp excluded-address 1.1.1.1 1.1.1.10
ip dhcp excluded-address 2.2.2.1 2.2.2.10
!
ip dhcp pool vlan1
   network 1.1.1.0 255.255.255.0
   domain-name cisco.com
   dns-server 4.4.4.2 4.4.4.1
   default-router 1.1.1.1
   lease 3
!
ip dhcp pool vlan2
    network 2.2.2.0 255.255.255.0
    domain-name cisco.com
    dns-server 4.4.4.2 4.4.4.1
    default-router 2.2.2.1
    lease 3

!
Here is the link for configuring IOS DHCP services:
http://www.cisco.com/en/US/docs/ios/ipaddr/configuration/guide/iad_dhcp_svr_cfg_ps6441_TSD_Pro

Please rate the helpfull posts.
Regards,
Naidu.

Tekkie123 Thu, 03/22/2012 - 05:48

Dear Naidu,

Thanks a lot. Lastly, I want to just confirm one more thing.

We have Cisco 3560 with IP Base software (not the IP Services feature set). I hope IP Base IOS will support DHCP Server configurations?

Thx/tek

naiduccnp Mon, 03/26/2012 - 01:01

Hi Tek,

You are absolutely ok with that, the 3560 IP base image will support DHCP relay with the ip helper-address command

For your knowledge, please see the below thred which explained the differences between IP base & IP services images.
https://supportforums.cisco.com/docs/DOC-3362

Please rate the helpfull posts.
Regards,
Naidu.

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Posted November 10, 2011 at 4:30 AM
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