Junos
Junos

MX BRAS DHCP Server and change subscriber CPE/MAC

‎08-01-2017 12:24 AM

Hi!

 

I have a MX104 as BRAS (Subcriber Management). MX have role dhcp-local-server and subscribers have a static IP that assignet by radius from base. Authentication user name - option-82.

 

Problem: If subscriber have active session and subsciber change CPE (or change MAC address) new sessions cannot start because previous session exist (user name - option-82). Have to wait until the lease time ends...

There are ideas how this can be solved?

1 REPLY 1
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Junos

Re: MX BRAS DHCP Server and change subscriber CPE/MAC

‎04-02-2018 12:36 PM

Hi,

 

Unlike PPPoE, in which the session is maintaned via PPP LCP Keeplive mechanism however in DHCP, there is no such mechanism.  DHCP clients often do not send DHCP release messages before exiting the network.

To address similar funtion in DHCP, there is DHCP Liveness Detection.

There are two methods:
DHCP Liveness Detection using ARP & ND or DHCP Liveness Detection with BFD; details below:

https://www.juniper.net/documentation/en_US/junos/topics/concept/subscriber-management-dhcp-liveness...
https://www.juniper.net/documentation/en_US/junos/topics/topic-map/dhcp-liveness-detection-arp-nd-pa...
https://www.juniper.net/documentation/en_US/junos/topics/example/subscriber-management-dhcp-local-se...


Another option for your case: Use the "delete-binding-on-renegotiation" statement  (If in case your dont change MAC everytime) to override the default action, DHCP tear down the existing matching client entry and to process the message as a new client entry.

https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/delete-bi...

 

/Karan Dhanak
# Please mark my solution as accepted if it helped, Kudos are appreciated as well.