[c-nsp] BRAS Redundancy

[Anthony McGarry]

Arie,

I am going to set up the lab and do some testing with radius providing 
the IP and redistributing connected routes.
I might also have a look at providing a L2 link between the BRASs or 
mobile IP.

Thanks
Anthony

Arie Vayner (avayner) wrote:
> Anthony,
>
> I have never really seen static IP assignments in this environments
> using DHCP... Usually you would use a PPP (PPPoE?) session which would
> be terminated on a specific BRAS, and then provisioned with the fixed IP
> information coming from RADIUS.
>
> If your environment is small (will not grow beyond this scale) then
> maybe you could use a DHCP pool on each router, setting the gateway
> locally, while providing the actual address from the DHCP server.
>
> Arie
>
> -----Original Message-----
> From: cisco-nsp-bounces at puck.nether.net
> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Anthony McGarry
> Sent: Tuesday, February 23, 2010 13:07
> To: cisco-nsp at puck.nether.net
> Subject: Re: [c-nsp] BRAS Redundancy
>
> Arie,
>
> Seems straight forward. Would there be an issue with the default gateway
>
> assignment from the DHCP server.
>
> BRAS-A
> Loopback 0
> x.x.96.1/21
>
> BRAS-A DHCP scope
> x.x.96.20 - x.x.103.254
> options router x.x.96.1
>
> BRAS-B
> Loopback 0
> x.x.104.1/21
>
> BRAS-B DHCP scope
> x.x.104.20 - x.x.111.254
> options router x.x.104.1
>
> So if a client logs into BRAS-A and is assigned a static IP from the 
> DHCP scope x.x.96.54 with a default gateway of x.x.96.1 there is no
> problems
> If the same client logs into BRAS-B and is assigned the same static IP 
> x.x.96.54 with a default gateway of x.x.96.1 how would the client route 
> out of his subnet.
>
> client --------------------------- BRAS-B 
> ---------------------------------- BRAS-A ------------
> x.x.96.54 ----------- x.x.104.1 ----- x.x.1.1 -- iBGP -- x.x.1.2 
> ----------- x.x.96.1 -------
>
> I am not even sure that what I want to do is possible because the DHCP 
> server will see the giaddr in the dhcp request from BRAS-B as x.x.104.1 
> and will try assign an address from the the BRAS-B scope and my static 
> assignment is from the BRAS-A scope.
> I use username to assign static address on the DHCP server
> host custid_xxxxxxxxxx { option dhcp-client-identifier 
> "\xxxxxxxxxxxx at xxxxxxx.xxx"; fixed-address x.x.96.54; }
>
> Maybe I need to revisit how I assign IP to customers. Would you have any
>
> recommendations.
>
> Thanks
> Anthony
>
> Arie Vayner (avayner) wrote:
>   
>> Anthony,
>>
>> Usually for static IP assignments you would have to redistribute the
>> connected/static (static for routes) prefixes into the routing
>>     
> protocol
>   
>> (I would recommend BGP) so that you advertise them as /32. No magic...
>>
>> Arie
>>
>> -----Original Message-----
>> From: cisco-nsp-bounces at puck.nether.net
>> [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Anthony
>>     
> McGarry
>   
>> Sent: Monday, February 22, 2010 13:50
>> To: cisco-nsp at puck.nether.net
>> Subject: [c-nsp] BRAS Redundancy
>>
>> Hi,
>>
>> I was hoping someone can help me with the following issue.
>>
>> I currently have a 7301 acting as my BRAS running on 12.2(33)SRD3. I
>>     
> use
>   
>> the ISG feature to terminate PPPoE sessions on QinQ subinterfaces.
>>
>> The virtual templates associated with the bba groups use ip unnumbered
>>     
>
>   
>> loopback 0.
>> The IP on loopback 0 is x.x.96.1/21
>>
>> DHCP is configured for client IP address assignment using DHCP pools
>>     
> as 
>   
>> relay agents to a central DHCP server.
>>
>> ip dhcp pool DHCP
>>    relay source x.x.96.0 255.255.248.0
>>    class DHCP
>>       relay target x.x.111.5
>>
>> I would now like to install a second 7301 for load
>>     
> balancing/redundancy.
>   
>> I currently trunk the QinQ vlans to the existing 7301 so I just do the
>>     
>
>   
>> same for the second 7301.
>>
>> On the second 7301 I assign a new /21 network for DHCP assignment.
>> This works fine for dynamic IP assignment.
>>
>> My problem is that we have multiple customers with static IP address 
>> assignment from the DHCP server.
>>
>> How can I assign the same IP address to a certain client session if
>>     
> they
>   
>> login to either BRAS when each BRAS has a unique network associated
>>     
> with
>   
>> the loopback 0 interface.
>>
>> I was thinking mobile IP but I have not tested in the lab and not sure
>>     
>
>   
>> if it is a supported solution.
>>
>> Anthony
>>
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>>   
>>     
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