Design for DHCP redundancy.

Hi,
Can somebody advice , how can i have dhcp server redundancy in my network. I need to design a network that will have around 30 vlans spanned across 50 buildings.

Hi Renzil,
I'm actually working on a similar solution at work at the moment. There are a couple of options (some have mentioned already)
1. Have two dhcp servers in different locations, with the same scopes and settings configured. Add the IP helper address for both servers to any device that needs to relay dhcp broadcasts. Then choose either;
a) Active/Standby - Configure the dhcp servers to act as a Primary/Secondary, by disabling all scopes on the secondary server until a situation arises where you need to failover. When you failover, enable the scopes on the secondary dhcp server. Be careful to prevent the Primary from giving lease when it comes back online.
b) Active/Active - Split the scopes across both dhcp servers in a 20/80 or 30/70 configuration as mentioned above. You will need to ensure the same reservations are configured on each dhcp server.
c) Active/Active - Disable some scopes on one of the servers, and have the same scopes active on the other server. When failover occurs, enable the scopes that are disabled on the server that is still reachable. Again be careful of the failed server issuing leases when it comes back online.
2. If you have the option, Windows Server 2008 Enterprise now offers High Availability Clustering for DHCP servers. This is a good solution because the DHCP database is shared between the two DHCP servers, so you don't need to worry about duplicate addresses being issued. This also works across geopgraphically dispersed sites, which is great if you have multiple data centres in different locations. You need to have a storage solution in place thatcan replicate the DHCP database to the failover location.
HTH
Paul

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hello all,
I have the following design for a site:
Provider delivers channel with HSRP redundant routers, but access level in not redundant and represented by one switch.
Am I correct that there is no way no provide redundancy on access level only with access switches or there are any design proposals?!

Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
As Reza describes, many hosts only have a single connection to network, so that single connection is always a possible point of failure. But there's a couple of things you can do to minimize the impact of a network infrastructure device failure.
When working with small appliance type switches, you might have multiple smaller switches rather than one large switch. For example, instead of having one 48 port switch, you might have two 24 ports switches, or six 8 port switches, etc.. If a switch fails, not all hosts lose connectivity.
You can also have additional ports, ideally enough to handle lost of any one unit of hardware, So, for example, if you have seven 8 port switches, when you only need 48 ports, if a switch fails, you only lose 1/7 of your hosts until they can be repatched into available ports on the other switches.
If some of your hosts have multiple NICs, then there are various method to use the two NICs to avoid a single network unit failure from dropping the host. Usually only shared servers merit that level of redundancy.

What is the best design to connect redundant Firewalls to redundant switches?

Hi All,
I would like to know the best possible design to connect redundant Firewalls(Netscreen,FortiGate etc) to redundant switches.I have dealt with Cisco FWSM's in which both the Firewall and switch is in the same chassis. So for the Vlan's behind the Firewall, we just create the L3 interface on the fwsm and do a static route in the switch. The Gateway IP will be tied to the primary fwsm and the failover happens through the network. But now i need to know the best possible design when i am connecting to a different vendor firewall.
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subhash007 wrote:It's not 802.3ad link aggreagated interface. In the switch side, the ports will be configured as normal access ports and the bonding config will be done on the server side.
To be honest, I don't understand how the Linux bonding mode can work without anything configured the other end.
My understanding of 'bonding' comes from Multilink PPP (MLP) where the data stream is chopped up and split across two (or more) circuits. At the other end, a similar MLP-enabled device reforms the data stream from the multiple circuits, maintaining packet order. But this requires MLP-enabled 'bonding' devices at each end.
Perhaps you could help me better understand the Linux bonding...
subhash007 wrote:If any single homed server is connected to Switch 2, what will be traffic path for its data packets?Switch 2 ------------------> Switch 1 ----------------------> Active firewall ORSwitch 2 ------------------> Passive Firewall -----------> Active Firewall
If the firewalls operate in the same fashion as Cisco ASAs, then the inter-firewall link doesn't carry traffic. It's for failover detection and HTTP replication only. But like I said, I'm not familiar with this vendor's products.
subhash007 wrote:Also will there be any change in traffic path if the trunk between Switch 1 & Switch 2 is converted to L3 routed interface? Since there is no VRRP, i can convert the trunk to L3 right?
Same as above.

Firewall Port for DHCP 2012 R2 Failover (Load Sharing mode)

Hi Everyone,
I was wondering if anyone can help me with finding a document for required Firewall Ports for DHCP 2012 R2 Failover (Load Sharing mode)
or just confirm if this is correct or not ?
TCP 647 for
DHCP failover messages between DHCP servers
TCP/UDP 67 and 68 initiate communication between the client and server
I am not sure if there is anything else
thanks in advance
Reza Negarestani

it was for a technical design document and I put this table for Firewall requirements what do you think ?
Direction
Port(s)
Bidirectional
TCP 647
Bidirectional
TCP 2535
UDP 2535
Bidirectional
TCP 67
TCP 68
UDP 67
UDP 68
Reza Negarestani

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Disclaimer
The Author of this posting offers the information contained within this posting without consideration and with the reader's understanding that there's no implied or expressed suitability or fitness for any purpose. Information provided is for informational purposes only and should not be construed as rendering professional advice of any kind. Usage of this posting's information is solely at reader's own risk.
Liability Disclaimer
In no event shall Author be liable for any damages whatsoever (including, without limitation, damages for loss of use, data or profit) arising out of the use or inability to use the posting's information even if Author has been advised of the possibility of such damage.
Posting
As Reza describes, many hosts only have a single connection to network, so that single connection is always a possible point of failure. But there's a couple of things you can do to minimize the impact of a network infrastructure device failure.
When working with small appliance type switches, you might have multiple smaller switches rather than one large switch. For example, instead of having one 48 port switch, you might have two 24 ports switches, or six 8 port switches, etc.. If a switch fails, not all hosts lose connectivity.
You can also have additional ports, ideally enough to handle lost of any one unit of hardware, So, for example, if you have seven 8 port switches, when you only need 48 ports, if a switch fails, you only lose 1/7 of your hosts until they can be repatched into available ports on the other switches.
If some of your hosts have multiple NICs, then there are various method to use the two NICs to avoid a single network unit failure from dropping the host. Usually only shared servers merit that level of redundancy.

How will an external Hard drive designed for the macbook Pro work with my White Macbook? My white macbook has a Firewire 400 and the G-Tech HD has a 800 to 400 compatible cable for the firewire.

I am asking this because I want the G-Tech Hard drive says that it is designed for the macbook pro. Yet, I want to back up faster with by using my firewire 400 which is not an option on the one designed for the white macbook that does not have a firewire (only a USB port.) The G-Tech Hard drive comes with the 800 to 400 compatible cable and has 5400 RPM with 750 GB. Also, I've heard that laptops with low battery (mine all the time) won't have the power for a bus powered Hard drive (as in no ac plug in adaptor.) Can I just plug in my laptop? Any one know the answers from experience with this hard drive?

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Hi,
Thanks for your posting.
This development mode can exclude some errors, such as the file upload complete at the same time... from my experience, this is a good choice to achieve the goal.
Best Regards,
Jambor
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Getting error while publishing workflow using SP designer for SharePoint 2013

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According to your post, my understanding is that you got error while publishing workflow using SharePoint designer for SharePoint 2013.
Please check whether the Central Admin > Manage Service Application-> “App Management Service” is started.
Please check whether the “Configure service application associations”, ”App Management Service” is already associated.
Then please check whether the “Manage Services on server” and the “App Management Service” is started.
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Troubleshooting the Service Bus for Windows Server then retry your action related to publishing workflows
More information:
http://wp.ahcheng.com/2013/03/23/error-were-found-when-compiling-the-workflow-the-workflow-files-were-saved-but-cannot-be-run/
http://sp2013.pro/2013/04/solution-errors-were-found-when-compiling-the-workflow-the-workflow-files-were-saved-but-cannot-be-run-cannot-set-unknown-member/
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How many ssl modules are needed for a redundant configuration?

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there is no need for 2 modules.
You would use 2 modules if you need more power [handle more connections].
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Gilles.

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By doing this way, we need to create TP for each and every type of message which reads the files from its own specified directory location on the network based on the the polling interval.Why cann't you have only one TP with multiple documents, channels and agreements?
My question is, instead of creating TPs for each and every type of file, is there a way by which I can write a common web service that reads the source files from the network and based on the type of the file route to the proper destination folders. If it is possible, I would like to know the architecture for accomplishing this task.Depends on your use case and products you want to use. You can very well use FTP adapter with BPEL and poll for files. Use DVM in composite to figure out the destination and send it there. You may use OSB if it is a typical routing case with heavy load and performance is a concern. You may use B2B as well here. So ultimately you need to figure out what you want and what tools you want to use.
Regards,
Anuj

Design for DHCP redundancy.

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