Static ip address DSL customers

Answered Question
May 31st, 2007
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Hello !!

I have a question about MAC-IP address binding. The problem is, today we use the PPPoE for DSL customers, but we will begin to give them "static ip address" for those who need it, I know we can sett the dynamic ip as static in the RADIUS server, but I will rater skill it the PPPoE is dynamic ip address assigment while the static must not be trough PPPoE but we just give them static ip address, so the customers can configure that ip address in their routers.


So back to my problem and question, the question is how can I bind the ip address for these users ?? We use IP-DSLAM (ATM Switch) in the PSTN. Our router is already configured for static ip in the separate VLAN, so I am not sure how can I bind the ip address because let`s say we give one user the ip address 80.80.80.5 and we will this user be able to use ONLY this ip address, so EVEN if he tries to sett 80.80.80.6 than he must not be able to use this ip address, but the only one we gave him.


I was thinking about static ARP table where we bind ip address to an MAC address of the IPDSLAM switch port, but this is not a solution because he can than just pick up another ip and put it manually in the router, so this is not good chooice.


Any great suggestions ?? how these things are handled in case static ip address assigment anyway ??

Correct Answer by bjornarsb about 9 years 12 months ago

Hi,


I've got an answer:

DHCP is the only option. (policy)

They say:

"If someone assign an ip statically they will create problems for themselves, because

the ip will not get renewed and "soon" assigned to another customer"


So I think you might use DHCP exclude address on your server , and use the same policy as stated: if someone use another IP address they will create problems for themselves :)




BR,

Bjornarsb

Correct Answer by bjornarsb about 9 years 12 months ago

Hi,


I belive that not every customer wants fixed ip, but of cource you can use the range command, but that depends on you vp vc assignment :)

Like this:


Router(config)# interface atm 6/0.200 point-to-point

Router(config-subif)# ip unnumbered loopback 1

Router(config-subif)# atm route-bridged ip

Router(config-subif)# range range1 pvc 1/200 1/299

Router(config-if-atm-range)# end


BR,

Bjornarsb

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bjornarsb Fri, 06/01/2007 - 00:27
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Hi,


As far as I can see you have to options:

either use PPPoE dynamic assigment and configure radius to assign same ip.

But if you do not want that, I believe that you must create a subinterface with a /30 mask. (vp/vc or vlan)


HTH,

Regards

Bjornarsb

050878james Fri, 06/01/2007 - 01:02
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Hello !!


Thank You for reply !!

hmm I am not sure why /30 ? and if I understand You than if I have 20 000 - 25 000 dsl customers it means I need to create the sub interface for each user ?? I know that IOS Supports up to 4,2 billion sub interfaces so that is not a problem.


But is it correct ?? sure that there is no other ways to do this ? Can You provid me an example ??


Cheers

James

Correct Answer
bjornarsb Fri, 06/01/2007 - 03:06
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Hi,


I belive that not every customer wants fixed ip, but of cource you can use the range command, but that depends on you vp vc assignment :)

Like this:


Router(config)# interface atm 6/0.200 point-to-point

Router(config-subif)# ip unnumbered loopback 1

Router(config-subif)# atm route-bridged ip

Router(config-subif)# range range1 pvc 1/200 1/299

Router(config-if-atm-range)# end


BR,

Bjornarsb

050878james Fri, 06/01/2007 - 03:14
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well, can I use the vlan instead ? for example


int fa0/0.200

encapsulation dot1Q 200

description static_ip_address_user

ip address 80.80.80.5 ............ ??


is it possible ? instead of ATM interface, I am not so familiar with ATM interfaces and I am not sure what is that used for ? we use the Zyxel IP DSLAM but Cisco Router 7200.


Cheers

050878james Fri, 06/01/2007 - 03:20
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for example let`s say we have this subnet for the users who want static ip address.


80.80.80.5/25 here is 126 hosts


now I will give the ip address 80.80.80.6 to one customer and next can than get the ip 80.80.80.7 and I will pervent the first customer to use 80.80.80.7 but he can only use the 80.80.80.6 understand my point now ?


Cheers

bjornarsb Fri, 06/01/2007 - 03:30
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Hi!,


Then the challenge is that each sub-int cannot belong to more than one vlan.

So then you have to go for /30

as far as I know :)


BR,

Bjornarsb

050878james Fri, 06/01/2007 - 03:35
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Well, seems that I have not a lot of chooses, any googd links or explanations for ATM interfaces ?


Thank You very much for helping !!!!


Cheers

050878james Fri, 06/01/2007 - 03:43
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I see, this is very useful link, thank you for helping me again !! have a nice day dude, so I`ll figure this out :) !!


Cheers

bjornarsb Fri, 06/01/2007 - 04:16
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Hi again,


Challenge however is that have to add ATM links from your dslam's....

Next is static mac....ip binding

So if this is a limitted number of customers you might go for vlan sub int....



BR,

Bjornarsb

050878james Fri, 06/01/2007 - 05:00
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as as undersot you now, I need to create the ATM interface for all dslams and than bind ip address to the mac address (mac address of ipdslam ports where the users are connected ???)


Cheers

bjornarsb Fri, 06/01/2007 - 06:41
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Hi,


I'm not working with xDSL , so to be 100% sure I need to ask my old collegue this evening and come back to you.

I remeber that we sat up /30 sub int, but as you have stated it will not work if you have a lot of customers that wants static assigned IP's. You could use a script or so ?

But the case for us was that not many asked for static ip's so it was ok to set-up a few sub interfaces.

I beleive that today, the isp "says" that if you cannot receive IP from dhcp you must by buy a "box" that supports ip add dhcp.

Each customer gets same ip but by DHCP.


I will come back to you.


BR,

Bjornarsb


Correct Answer
bjornarsb Fri, 06/01/2007 - 07:02
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Hi,


I've got an answer:

DHCP is the only option. (policy)

They say:

"If someone assign an ip statically they will create problems for themselves, because

the ip will not get renewed and "soon" assigned to another customer"


So I think you might use DHCP exclude address on your server , and use the same policy as stated: if someone use another IP address they will create problems for themselves :)




BR,

Bjornarsb

050878james Fri, 06/01/2007 - 08:53
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Hi again, sorry for little late response, I was driving from the office and I am home now.


Well dude :) if that works you made me very very happy :), any example maybe ?? have you tried it ? I can try it if I can find some examples, but I will just deny users from typing static address and using it on the network I will they can use only the one we give them ! so your example makes good sense.


I`ll try find some examples.

Thank You again for suggestions and help !!


Cheers

050878james Fri, 06/01/2007 - 09:01
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say thank you to your collegue from me ;) this was great idea anyway.


Well just today we have around 25 000 dsl customers, and over 2 000 have asked us for static ip address, often young peoples :) p2p sharing and BitTorrent downloads, problems with opening ports if the ip is not fixed.... So you understand the rest.


And we have a great policy, if our customers will have static ip address they are welcome to get it !! Many isp`s denies this solution maybe it is not so easy to find a secure way to assign them these ip addresses, same problem as I have, therfore I am looking for someone who did this before. PPPoE is not an option in my case because I see the static ip AS FIXED IP and no PPPoE I think you understand me. And there where some problems at the begining with activations of the modems very wired things, but fixed ip just write it in the config and you`re on the net :) the best solution.


cheers

050878james Sun, 06/03/2007 - 12:46
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I know one ISP near me is assigning only static ip addresses to their customers, they never used PPPoE. And I called one of their customers and I asked him to make some test, and it was:


I asked him the ip address, and let`s say that ip address was 80.80.80.5 so I told him log on to the router and change it to 80.80.80.6 and let me know if you can access the internet, and he tryed and tol me NO no way, ok I said try now 80.80.80.4 the same again, ok I said try use DHCP option se if they will assign that ip to you, hi tried but the router have not received any ip address, which means no dhcp is used at all and he can only use the assigned address 80.80.80.5. and after I saw there was not tolk about /30 network addresses.


So it is possible but I am not sure how :(

No help to ask them, because I know they wont tell it anyway..


Is there peoples who you could ask about it ?? So we don`t need to use the DHCP server at all.


Cheers

bjornarsb Sun, 06/03/2007 - 23:10
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Hi again!


I've talked with the isp and he says that depending on your DSLAM this can be done at the dslam port. i.e the dslam does not perform routing but it "understands" and can analyse layer 3, and then you map the dsl port with one ip, and thats the only ip thats works. I'm not sure about your Zyxel dslam, but ask your distributor. I know that some IPS's actually have implemeting routing on their dslam's but then you have to "replan" your subnet and summary policies.


HTH,

Regards

Bjornarsb



aftabsiddiqui Sun, 06/03/2007 - 22:50
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For static IP assignment in DSL, we are using the following technique. This will assign the IP from the BRAS without going to RADIUS.


interface ATM1/0.x multipoint

ip address 80.80.80.1 255.255.255.0


pvc user_pvc 1/2

protocol ip 80.80.80.2

ubr/cbr xxx


Client will take 80.80.80.2 as its WAN IP and 80.80.80.1 as gateway for /24 subnet. Other than WAN IP it will not be able to use any other IP from the subnet because only one IP is mapped against its VPI/VCI.

050878james Sun, 06/03/2007 - 23:16
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THANK YOU very much for helping !!!


just little explanation, we use Zyxel IPDSLAM, and VPI/VCI are configured on IPDSLAM, so we have VLANS configured on the 7200 Router. Example below :


On 7200 router:


int fa0/0.20

Description ip_addresses_for_dsl

encapsulation dot1Q 20

ip address 80.80.80.0 255.255.255.0


On the IPDSLAM VPI VCI are configured 0/33, so the switch ports on the DSLAM are assigned to VLAN 20.


Than the question is how it will be now with example you provided me ?? I can`t see any VLAN definitions, how can I know that this ip 80.80.80.2 the client will use is binded to the IPDSLAM port ??


Thank you again !!

Cheers


050878james Mon, 06/04/2007 - 02:07
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in my last post I forgot to describe this better :


Than the question is how it will be now with example you provided me ?? I can`t see any VLAN definitions, how can I know that this ip 80.80.80.2 the client will use is binded to the IPDSLAM port ??


I mean:


Than the question is how it will be now with example you provided me ?? I can`t see any VLAN definitions, how can I know that this ip 80.80.80.2 the client will use belongs the DSLAM switch port where this user is connected to ??

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