DHCP services

[teotr]

Can the DHCP services of HP-UX handle 2 million users in a country? And by the way, what is the IP address assigning rate? (i.e. the maximum Number of IP's per second that HP-UX assign)

If not, what DHCP server software and/or appliance do you recommend instead of HP-UX?

[A. Clay Stephenson]

This is nuts. What network with 2 million hosts is going to allow broadcasts?

[teotr]

2 million is the number of clients, planned to be IP TV users, and this DHCP software is planned to be the IP number distributor of this environment. By the way, I am not a networking guy; I just asked. don't know whether it is logical or not... and need the correct answer

[Bill Hassell]

Well, let's figure it out. If you use PPP or SLIP over a modem, you might get from 1 to 3 packets per second. If all 2 million users are connected to a fiber optic cable, and your server is high end rp-series such as an rp8440 with several 4-channel Gibgabit LAN cards, then you can supply thousands of requests per second. And you did not define the DHCP services to be provided. Is it just the IP address or will it provide a gateway address too? What about a DNS address? And will your DHCP server be providing dynamic DNS services to link IP's to a unique hostname?

But as Clay mentions, it is very unlikely that all 2 million users are connected to a single, unrouted subnet. DHCP requests are not forwarded through routers unless unusual configurations are created.

[teotr]

Thank you for your answer. Now I see that HP-UX DHCP service software itself doesn't have a limit for the number of IP assignments per second. It only depends on the hardware. Am I right? So what Integrity server will you recommend? rx66XX? rx76XX? rx86XX? with what hardware spec.s (i.e. CPU, memory, HDD, ethernet ports)?

I will be asking the gateway and DNS IP requirement.

2 million users won't be in a single subnet. The DHCP server is required to manage many subnets and domains as well.

By the way, we need 2 servers with the same configuration for high availability. What should be used for clustering, so that the second continues servicing if the first one fails? Is there a network load balancing solution among a couple servers like in MS Windows? Or do I need MC ServiceGuard, etc.?

Actually the main thing I need to know is can I comfortably propose HP-UX's DHCP services for a that kind of requirement; or should I forget about HP-UX for a this level of requirement and look for a 3rd party appliance solution like metainfo's (www.metainfo.com)?

[Bill Hassell]

DHCP is a trivial task for the Integrity servers so hardware is fairly simple. Yes, you will need two systems and they must be setup with Service Guard. With a few 4-channel Gigabit LAN cards, you will won't be able to overload the server. But the CPU is the SMALLEST part of this setup! Management of all these addresses and subnets will be very labor intensive without some smart DHCP software. Metainfo supplies a number of packages but they appear to only run on Windows, Linux and Solaris. Otherwise, you'll need a database, a lot of scripts and programs to manage the information.

As far as load balancing, not even Windows can accomplish this sort of task. DHCP is a very short handshake (Discovery, Offer, Request, Acknowledge or DORK by network admins) of a few packets and then it's done. The only practical load balancing would be done with routers and subnets. Putting 16 to 32 LAN ports into an Integrity server is easy. Planning the front end network is the big job. CPU count and RAM is unknown because no workload has been defined yet.

But this task is far too complex to start choosing a CPU. Obviously, there must be an existing system, so what are the maximum request rates right now (hundreds, thousands per second)? Is the current system limited by the network design? Have you asked other DHCP software/hardware vendors about your requirements?

[teotr]

Thaks for the clusterin answer.

No DNS and/or gateway IP assigning, only client IP assigning will be required. There's no minimum IP assignments per second. requirement. Only the information on maximum value is required.

Sorry I didn't get the exact point. Do I need 16-32 LAN ports in order to support 2 million users? and still can't figure out CPU and memory requirement for 2 million users?

By the way, Does HP-UX's DHCP service have an SNMP interface? If yes, how many SNMP interfaces can be used simultaneously?

yes we have asked metainfo about the situation. But they provided a complex answer

[Matti_Kurkela]

First, what kind of DHCP lease length are you planning to use?
In other words, when a client gets an IP address, how long should that client be able to use it without further confirmation? Minutes? Hours? Days? Weeks?

Answer to this question determines how large an address assigning rate you'll need: as a standard DHCP client will try to renew the lease of the IP address when half of the lease time is gone, your long-term average address assigning rate will be >= (total number of users / (DHCP lease length / 2) )

I specify it as "greater or equal to" because some new clients will be joining to the network, and some of the existing clients may be reset (power outage, hardware failure&replacement, people redecorating or moving to another house or whatever).

Bill's comment about 16-32 LAN ports probably means "getting enough network bandwidth won't be a problem". Whether those ports should be used as individual ports (for separate network segments) or grouped into trunks using APA is decided mainly by your network architecture.

Using a single server will create a single point of failure that can effectively disable your entire network. Splitting the load to two servers guarantees that a total failure of one server will affect at most only about half of your clients, assuming you don't have any other single points of failure; splitting to four limits the maximum extent of failure to about a quarter of your clients, and so on.

With DHCP servers, this kind of splitting is easiest to do by network segments; i.e. server 1 handles network segments A, B and C while server 2 handles segments D, E and F and so on.

HP-UX does have an SNMP interface, but it is not specific to the DHCP server: it works at the level of the entire OS. There seems to be no DHCP subagent that would return any DHCP service specific information. There is certainly no practical way to configure HP-UX standard DHCP service over SNMP.

I don't understand how the number of simultaneous SNMP interfaces might be a factor in your situation: are you trying to run multiple network monitoring systems in parallel, or something?

MK