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Juniper SRX Config on PlusNet FTTC BT Infinity

The following JunOS configuration has been tested on PlusNet Fibre broadband running with external BT Openreach Modem. This setup should work with other VDSL/FTTC providers since they use the same underlaying BT infrastructure.

  • The configuration has been tested on SRX210H running JunOS 11.4R9.4 & 12.1X44-D35.5
  • BT Openreach modem connect to interfaces fe-0/0/7 on the SRX

Set the underlaying interface encapsulation to be PPP-Over-Ethernet.

set interfaces fe-0/0/7 unit 0 encapsulation ppp-over-ether

Set PPP Options with Authentication method CHAP.

If your ISP happen to use PAP Authentication method, then you need to reflect that.

set interfaces pp0 unit 0 ppp-options chap default-chap-secret YOUR-PASSWORD
set interfaces pp0 unit 0 ppp-options chap local-name YOUR-USERNAME
set interfaces pp0 unit 0 ppp-options chap no-rfc2486
set interfaces pp0 unit 0 ppp-options chap passive

Set the PPPoE Options to the underlaying interface along with connection options.

set interfaces pp0 unit 0 pppoe-options underlying-interface fe-0/0/7.0
set interfaces pp0 unit 0 pppoe-options idle-timeout 0
set interfaces pp0 unit 0 pppoe-options auto-reconnect 1
set interfaces pp0 unit 0 pppoe-options client

Set the pp0 interface MTU.

Your ISP might use a different MTU, so do check it before applying the command.

set interfaces pp0 unit 0 family inet mtu 1492

Set the IP Address on the pp0 interface.

set interfaces pp0 unit 0 family inet address 80.xxx.xxx.xx/32

If you happen to get dynamic IP address, you need to use the below negotiate-address option instead of the above static IP(s).

set interfaces pp0 unit 0 family inet negotiate-address

Set the security zone pp0.0 interface WAN (untrust)

set security zones security-zone WAN interfaces pp0.0

If you are experiencing any fragmentation issue, you may want to adjust the tcp-mss setting as below.

set security flow tcp-mss all-tcp mss 1300
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