Using three routers as dhcp relay help

Hi i am having trouble configuring a network consisting of about 80 clients, 3 routers(4400N) and 3 range extenders(802.11g) i want to know how to configure all the routers to relay one dhcp server and also give client pcs the ability to connect to the best working signal at any given time without having to put in a wpa2 key or manually choose the network. What would be the best way to accomplish this?

Without knowing the LAN communication requirements it is difficult to say how to do this.
You write something about a DHCP server. Do you run your own DHCP server somewhere? Is that required for all clients?
What communication between different computers in the LAN is required, e.g. for file sharing?
What do you mean with "without having to put in a wpa2 key"? How do you want to configure the wireless clients initially?
So far, the easiest setup for you would be to run a single ethernet LAN, i.e. using one router as internet gateway and setting up the other ones as simple access points (without DHCP server, modified LAN IP address inside main LAN and connected through LAN port instead of internet port). All clients get their IP address from the one DHCP server in the LAN.
When all wireless routers bridge into the same Ethernet LAN a seamless roaming handover is possible. All wireless routers must have identical settings (SSID, wireless security) but should use different channels. This creates a roaming wireless network. However, I don't know how the N routers handle that and how it works together with the G extenders. Maybe it will be necessary to run the N routers in G only mode.

Similar Messages

DHCP Relay Help

I would like to use the ip address-helper feature of my 3560 switch to point 10.1.0.0/24 to my Windows DHCP Server on 10.0.0.0/24 and I am unsure how to go about doing this.
Below is a diagram of the network.

Michael Conway wrote:I would like to use the ip address-helper feature of my 3560 switch to point 10.1.0.0/24 to my Windows DHCP Server on 10.0.0.0/24 and I am unsure how to go about doing this. Below is a diagram of the network.
Use the IP helper command on the SVI for VLAN 20
#configure terminal
(configure)#interface vlan20
(configure-if)#ip helper-address 10.0.0.245
(configure-if)#exit
(configure)#exit
copy run start
Of course, you then need to configure an additional scope in the Windows DHCP server to allocate for the 10.1.0.0/24 subnet, with appropriate options.
Cheers

VLAN - DHCP Relaying - Help

4503 Sup IV
We have 3 VLans,
VLAN 10 10.150.0.0/24
IPHELPER 10.150.0.117
VLAN 11 10.150.1.0/24
IPHELPER 10.150.0.117
VLAN 12 10.150.2.0/24
IPHELPER 10.150.0.117
On 10.150.0.117 we have two scopes set up. One for 10.150.1.x and another for 10.150.2.x.
DHCP clients on VLAN 12 are getting DHCP addresses but not on VLAN 11? HELP PLEASE

Did you activate both scopes on the DHCP server ?
Do you see anything on the DHCP Server log regarding clients requesting IP from that subnet ?
At the 4503 switch issue the following commands:
debug ip dhcp server events
debug ip dhcp server packets
do an ipconfig /renew from a workstation on that subnet
then post the log here.
Please rate helpful posts.
Thanks

PXE with IP Helpers/DHCP Relay

I'm a Sysadmin and I have a question about what is best practice in regards to PXE servers. We are currently using DHCP Options for PXE clients (options 66,67). This works for most clients but is not the recommended method from either of the vendors we have used (Microsoft or Symantec). They recommend using IP Helpers / DHCP relay to forward the DHCP discover request to the PXE servers so that the PXE server is getting the actual request. This is more of an issue now with UEFI-based machines where the boot file would be different based on if the client is UEFI.
My Network team is against using IP Helpers and thinks it can cause issues. This doesn't seem to make much sense to me, as from what I understand, all that happens is both the DHCP server and the PXE servers get the DHCP discover and respond with their relevant info. Can someone clarify what, if any, issues there are using multiple IP helpers/DHCP relay with PXE Servers like SCCM & Altiris? Is this not standard practice?

It's very common to use DHCP relays (IP helpers) in order to centralize DHCP infrastructure. Larger organizations will frequently use this approach in order to avoid having to manually edit DHCP configurations at the router or switch level. Having a few servers with a central DHCP configuration for all segments is a good management proposition.
In most environments, there isn't a problem with doing this, but it is a major architectural consideration and not something you just turn on without consideration. This is largely because DHCP works on a broadcast principle. The clients are going to broadcast for the first DHCP server that answers with an acceptable offer, which they will take. If you have a mixture of local DHCP servers and relays, the local servers will respond faster and may not provide the configuration you want to deploy... at best. At worst, you will have a mix of acceptable responses and a lot of potential for conflicting addresses. On any network segment where you're using DHCP relays, the local server needs to be disabled.
It might be worthwhile going back to your network team and asking what sorts of "issues" that they feel the implementation of DHCP relays would cause. There may be something unique to your environment that makes them reluctant to pursue this approach.

Switches that do dhcp relay (ip helper address)

Hi all,
I'm looking at this switch the 1810 24g and I was wondering whether it dose dhcp relay (ip helper address) ie forward dhcp addresses from the dhcp server to the switch?
Many thanks
Rob

Hi,
on all the vlan interfaces where the DHCP server doesn't reside you must configure
interface Vlan
description Client VLAN
ip helper-address
When a client now sends DHCP request, the router
forwards this request to the ip helper-address.
Because the router also puts in its own interface ip address as source ip, the packet finds the way back.
DHCP uses UDP port 67 and 68. With the command ip helper-address, there are also some other ports which are opened for udp. To close this ports you configure (global command)
no ip forward-protocol udp tftp
no ip forward-protocol udp nameserver
no ip forward-protocol udp domain
no ip forward-protocol udp time
no ip forward-protocol udp netbios-ns
no ip forward-protocol udp netbios-dgm
no ip forward-protocol udp tacacs
On your DHCP Server you have to configure a scope for each ip subnet.
If your dhcp server is located at ther server vlan, do NOT configure a helper-address there.
For the migration I would suggest to use two different ip subnets. Image all your clients are now in VLAN2 10.2.0.0/16. If you have this IP subnet on your Router you can't add a new VLAN with 10.2.1.0/24, because this overlaps.
So make the new VLANs with 10.3.1.0/24, 10.3.2.0/24, ... and move the clients to the new
vlans by change the vlan of the port where the PC is conneted to. When you then reboot the PC it shoud get a new ip from the dhcp and everything sould be fine.
Bye
Jo

DHCP Relay using Brocade Switches

Hi
I have a large project with 3 UCM cluster with unity cluster and UCCX
The network is a Brocade switch environement,
The Core is using OSPF and distribution is Layer 2.
I have configured the Cluster with a dedicated DHCP and TFTP service.
DHCP relay is not working, but when i configure one of the phones with a static IP address it registers and I have full functionality
When I connect my server dirrectly to the core which is not the design then the dhcp relay works and I get an IP address, but when i traverse the layer2 then i do not get an address.
In the same topology I connected a Windows DHCP server on the same vlan as my UCM cluster and change the relay address to point to the windows dhcp the i do get an address.
In an additional test i configured the same setup on cisco switches then the relay works great.
If anyone has seen or knows of any bug regarding DHCP relay i would be greatful for info
Thanks
Lance

Hi Experts,
i forgot to mention that i was reading an interesting document on Cisco website "network virtualization design guide", and they clearly mentioned the below:
"""VRF-awareness for DHCP-relay functionality is currently not supported on any Catalyst platform, but it is required only for supporting overlapping IP addresses"""
So i would like to ask you if you have any workaround to be done in such deployments
Thank you in advance
Samer Labaky
CCIE # 24675

Hello, my ipad mini doent work i charged it till the next day and it didn't work i charged it again till the next day and it didn't work what should i do i didn't use my ipad for three days please i need help????

hello, my ipad mini doent work i charged it till the next day and it didn't work i charged it again till the next day and it didn't work what should i do i didn't use my ipad for three days please i need help????

Didn't work in what way. Are you unable to start it up? Does it start but then freezes? Does the screen stay black when you turn it on?
Try this - press the home and power buttons and keep pressing them until the apple logo appears.

Need help to join two tables using three joins, one of which is a (between) date range.

I am trying to develop a query in MS Access 2010 to join two tables using three joins, one of which is a (between) date range. The tables are contained in Access. The reason
the tables are contained in access because they are imported from different ODBC warehouses and the data is formatted for uniformity. I believe this cannot be developed using MS Visual Query Designer. I think writing a query in SQL would be suiting this project.
ABCPART links to XYZPART. ABCSERIAL links to XYZSERIAL. ABCDATE links to (between) XYZDATE1 and ZYZDATE2.
[ABCTABLE]
ABCORDER
ABCPART
ABCSERIAL
ABCDATE
[ZYXTABLE]
XYZORDER
XYZPART
XYZSERIAL
XYZDATE1
XYZDATE2

Thank you for the looking at the post. The actual table names are rather ambiguous. I renamed them so it would make more sense. I will explain more and give the actual names. What I do not have is the actual data in the table. That is something I don't have
on this computer. There are no "Null" fields in either of the tables.
This table has many orders (MSORDER) that need to match one order (GLORDER) in GLORDR. This is based on MSPART joined to GLPART, MSSERIAL joined to GLSERIAL, and MSOPNDATE joined if it falls between GLSTARTDATE and GLENDDATE.
[MSORDR]
MSORDER
MSPART
MSSERIAL
MSOPNDATE
11111111
4444444
55555
2/4/2015
22222222
6666666
11111
1/6/2015
33333333
6666666
11111
3/5/2015
This table has one order for every part number and every serial number.
[GLORDR]
GLORDER
GLPART
GLSERIAL
GLSTARTDATE
GLENDDATE
ABC11111
444444
55555
1/2/2015
4/4/2015
ABC22222
666666
11111
1/5/2015
4/10/2015
AAA11111
555555
22222
3/2/2015
4/10/2015
Post Query table
GLORDER
MSORDER
GLSTARTDATE
GLENDDATE
MSOPNDATE
ABC11111
11111111
1/2/2015
4/4/2015
2/4/2015
ABC22222
22222222
1/5/2015
4/10/2015
1/6/2015
ABC22222
33333333
1/5/2015
4/10/2015
3/5/2015
This is the SQL minus the between date join.
SELECT GLORDR.GLORDER, MSORDR.MSORDER, GLORDR.GLSTARTDATE, GLORDR.GLENDDATE, MSORDR.MSOPNDATE
FROM GLORDR INNER JOIN MSORDR ON (GLORDR.GLSERIAL = MSORDR.MSSERIAL) AND (GLORDR.GLPART = MSORDR.MSPART);

I have use three free apple Id and now when I am creating a fourth time it's saying that it is the maximum. What must I do to create a new apple id. Plz help

I have use three free apple Id and now when I am creating a fourth time it's saying that it is the maximum. What must I do to create a new apple id. Plz help

Sorry, no way around this limitation on an iOS device. To use a new iCloud account, you need to create such on a computer first, then setup the account on your iOS device.

Setting up a DHCP relay agent

Hello,
I'm trying to setup a relay agent for an XP client to obtain configuration through 2 routers on a VM LAB
I have 3 Segments/subnets 1,2 and 3
the topology is the following:
1- server 2008 R2 AD DS DC on subnet 1 (192.168.1.0) and a DHCP server with 2 scopes
Internal 192.168.1.0 (subnet1)
external 192.168.3.0 (subnet 3)
2- server 2008 R2 with RRAS installed
Interface 1 pointing to the internal subnet1 192.168.1.0
Interface 2 pointing to subnet2 192.168.2.0
3- server 2003 with RRAS installed
Interface 1 pointing to subnet2 192.168.2.0
Interface 2 pointing to subnet3 192.168.3.0
relay agent installed on Interface 2
(servers/Routers 2 and 3 running RIP v2)
4- XP client on subnet3 (192.168.3.0) and the client trying to obtain config.
The XP client is unable to contact the DHCP to obtain config.
server 2003 relay agent receiving requests with no replies.
How do i get this to work?

Hi,
First, let’s see how DHCP relay agent works:
1. The DHCP client broadcasts a DHCPDISCOVER packet.
2. The DHCP relay agent on the client’s subnet forwards the DHCPDISCOVER message to the DHCP server by using unicast.
3. The DHCP server uses unicast to send a DHCPOFFER message to the DHCP relay agent.
4. The DHCP relay agent broadcasts the DHCPOFFER packet to the DHCP client’s subnet.
5. The DHCP client broadcasts a DHCPREQUEST packet.
6. The DHCP relay agent on the client’s subnet forwards the DHCPREQUEST message to the DHCP server by using unicast.
7. The DHCP server uses unicast to send a DHCPACK message to the DHCP relay agent.
8. The DHCP relay agent broadcasts the DHCPACK to the DHCP client’s subnet.
We can see in the second step, DHCP relay agent send unicast to DHCP server after receiving DHCP request. So confirm unicast communication between DHCP server
and DHCP relay agent works fine. At least ping should be working. You can use the following commend to add the route entry.
Add a static IP route
http://technet.microsoft.com/en-us/library/cc757323(v=ws.10).aspx
The result should be based on your test. If it doesn’t work it just indicates that we cannot configure another DHCP relay agent behind a relay agent.
Hope this helps.

DHCP Relay Cisco SG500X

Hi,
I've create 2 vlan in a cisco SG500X-24 and a DHCP server on vlan 2. I just want to dhcp server assign ip to devices on vlan 3. I've configured the vlan and dhcp server relay commands.
ip dhcp relay address 192.168.1.11
ip dhcp relay enable
ip dhcp information option
interface vlan 2
ip address 192.168.1.250 255.255.255.0
interface vlan 3
ip address 192.168.51.254 255.255.255.0
ip dhcp relay enable
The dhcp server gets the request from pc, and sends a new address, but the offer packet not comes to device. With Wireshark a see like offer dhcp packet can't jump to vlan 3.
It's the first time a work with SMB series, and this never happens with catalyst. I'm turning crazy.
Anyone can help me? Thank you in advances.
Victor.

Hi,
Yes, also I configured ip dhcp relay on intefaces.
Yesterday I found the trouble. I was using the tftpd32 dhcp server, and I tested with a Windows DHCP server and everything works like a champ. I didn't know what have do, and i turned crazy, so I began to change every element on solution, finally the DHCP server that it was the key.
Thank you so much for your answer.
KR!

How to configure Dhcp relay agent

How I can to configure the wrt54g like a dhcp relay agent? please i need help, tell me

A DHCP relay agent is any host that forwards DHCP packets between clients and servers. Relay agents are used to forward requests and replies between clients and servers when they are not on the same physical subnet. Relay agent forwarding is distinct from the normal forwarding of an IP router, where IP datagrams are switched between networks somewhat transparently. By contrast, relay agents receive DHCP messages and then generate a new DHCP message to send out on another interface. The relay agent sets the gateway address (giaddr field of the DHCP packet) and, if configured, adds the relay agent information option in the packet and forwards it to the DHCP server. The reply from the server is forwarded back to the client after removing option .

Windows DHCP Server and Linux DHCP Relay Agent

We are trying to organize a VLAN (say VLAN 1) for guests who must be assigned IP addresses from a DHCP server in a different VLAN (VLAN 2). This DHCP server is configured with two scopes - 172.16.0.0/24 (for VLAN 2) and 172.16.4.0/24 (for the Guests
VLAN 1). The DHCP server successfully distributes addresses to clients in its VLAN (it has the IP address 172.16.0.2). For the clients in the other VLAN a DHCP Relay Agent has been setup on the router. It is DHCRELAY running on Linux (CentOS) which has
been configured to accept the DHCPDISCOVER broadcasts coming on the VLAN1 interface of the router and forward these to the DHCP server. The IP address of the VLAN1 interface of the router is 172.16.4.254 and on the VLAN2 interface - 172.16.0.254
The problem is that the DHCP server won't respond with a DHCPOFFER message to the relay agent. I have traced the frames on the router and on the DHCP server. They arrive on the DHCP server with the correct GIADDR of the relay agent. According to all documentation,
if a scope has been configured on the DHCP server and it receives a unicast message with the GIADDR set by a relay agent that matches one of the configured scopes, the DHCP server must send a unicast DHCPOFFER to the relay agent. But it doesn't.
Here is what Wireshark reports (ignore the Destination port unreachable messages, the DHCP service was stopped at the time Wireshark was running)
When the service is running, there are just DHCPDISCOVERs - no OFFER. You can see that the server has the two scopes configured:
The relay agent seems to work normally - it forwards the DHCPDISCOVERs to the server continuously (tried many times with ipconfig /renew on the client).
I read many posts about this problem. Some users had other services running on the DHCP server that used the DHCP port, but I don't have such an issue (you see that when the service is stopped, an ICMP port unreachable is sent which is correct). Others however
did not find a solution. Am I missing something? Is there something specific when using the DHCRELAY agent from DHCPD? Can I turn on some verbose logging to track this down? Thanks in advance.

WIth DHCP, there is really nothing to configure. If the Relay Agent/IP Helper is pointing to it, and the VLAN subnet exactly matches the scope subnet, then it should just work.
What I've seen in the VLAN config is either a static route back to the subnet the DHCP server itself is sitting on is not configured or incorrectly configured, or there are ports blocked (need UDP, too, since that's what DHCP uses to pass the OFFER), and
other necessary ports are opened, then it should just work.
Sometimes NIC teaming on the DHCP server will cause it. Not sure. Microsoft doesn't support teaming prior to Windwos 2012, but it doesn't mean that it doesn't work. Don't get me wrong, teaming works nicely, but they just don't support it because they never
certified the drivers, that's all.
The issues I've seen with DHCP relays and VLANs in the forums are usually based on misconfigs in the VLAN or ports blocked. Sometimes we'll refer to call Microsoft Support for specific, hands-on assistance. And searching the threads, from what
I've found that if they did call support, they've never posted back what the problem was based on or the resolution. I can post a couple of them for you to read through, but there were never any response with the actual resolution.
If you like, you also have the option to contact Microsoft Support. Here's a list of phone numbers if you choose this option:
http://support.microsoft.com/contactus/
Ace Fekay
MVP, MCT, MCITP/EA, MCTS Windows 2008/R2 & Exchange 2007, Exchange 2010 EA, MCSE & MCSA 2003/2000, MCSA Messaging 2003
Microsoft Certified Trainer
Microsoft MVP - Directory Services
Technical Blogs & Videos: http://www.delawarecountycomputerconsulting.com/
This post is provided AS-IS with no warranties or guarantees and confers no rights.

How to create extended range network using three apple airport extremes?

Hello! The idea is, I want to use Apple routers to create a large range network for a hotel that has 300 FT Hallway. I have tried everything in the airport utility but nothing works. The idea is, in the whole 300 FT hallway, i want to put three apple airport extreams. one in the middle of the hallway which will be connected to the modem, one on the each end of the hallway that will be connected to the middle airport extreme via eithernet or extend network range option from airport utility.
Image shows, what I am trying to achieve.
http://imageshack.us/scaled/landing/35/10e6.jpg
These what I have tried so far. Airport extreme is refered here as "airport"
1. Connect Airport 1 to modem, then on Airport 2 use extend network feature to extend the range of airport 1 network. This did not work. Airport 2 keeps on blinking yellow.
2. Did same thing as step 1 but also tried it using ethernet cable going from Airport 1 in to Airport 2's ethernet inbound port.
3. Connected modem to switch, from swith one ethernet cable goes in to Airport 1 and one cable from SWITCH goes in to the airport 2's ethernet port.
Only thing that works is, if I connect ONLY ONE airport to the modem or the switch. I am not able to use two airport extremes together.
Please advise what I can do using these or other apple products to have extended wifi coverage in the entire hallway.
I, however do need to use three extremes as one is not enough to cover the area.
Thank you.
Hopefully some one can help me and correct me where I am doing something wrong.
Thanks.

Exactly what model extreme are you using??
What device is being used as setup with airport utility?
1. Connect Airport 1 to modem, then on Airport 2 use extend network feature to extend the range of airport 1 network. This did not work. Airport 2 keeps on blinking yellow.
Amber blinking just means something needs adjusting.. it should still show up in the utility and you can find out what the extreme is complaining about. If not start over.. it is absolutely crucial you factory reset and start over.. the extreme must present as a new wireless device in wifi and then you can setup to extend the existing wireless.
2. Did same thing as step 1 but also tried it using ethernet cable going from Airport 1 in to Airport 2's ethernet inbound port.
This is a much better arrangement.. The Extreme plugged into the Modem.. what mode is it in? It must create a wireless network.. make sure the network name is short.. no spaces and pure alphanumeric.
The extreme plugged into to give better range.. must be in bridge mode.
It must create a wireless network of the exact same name.. exact same security settings and same password.
Follow the instructions here if you do not follow.
http://support.apple.com/kb/HT4260
3. Connected modem to switch, from swith one ethernet cable goes in to Airport 1 and one cable from SWITCH goes in to the airport 2's ethernet port.
This is the same configuration as 2. There is no difference where you put the switch.
Only thing that works is, if I connect ONLY ONE airport to the modem or the switch. I am not able to use two airport extremes together.
Setup according to the apple instructions for roaming network.. it will work.
If it fails give us more info.. what model AE. etc.
Also give us the IP address and screenshot of each units setup for wireless.

DHCP Server & DHCP Relay on the same box

Hi,
I was wondering if there was any tricky way to have both the DHCP server and DHCP Relay present at the same time and have router use Relay option before local DHCP pool?
I must say that both DHCP Pool and "ip helper address" command serve the same interface. By default, router will look for locally available pools and send DHCPOFFER by itself without relaying the DHCPDISCOVER to a remote DHCP server, so incoming interface takes precedence over DHCP-relay option and I was wondering if you could tweak that...
Thanks,
David

Well.. as far as I know what you are asking is not possible... :(
Did it help?

Using three routers as dhcp relay help

Similar Messages

Maybe you are looking for