Router - Juniper SRX

The Juniper SRX range of routers are high-performance routers, intended for small business and branch networks. The can often be bought cheaply on eBay.

Known working setups

Router	JunOS Version	Modem	Who	IPv6	Status
SRX100B	12.1X44-D40.2	ZyXEL P660R in bridge mode	Nhumfrey	✗	✗ PADI sent but no PADO response
SRX100B	12.1X44-D40.2	BT Provided Huawei HG612 FTTC Modem	Nhumfrey	✗	✓ Working 2015-01-13
SRX100B	12.1X46-D30.2	BT Provided Huawei HG612 FTTC Modem	Nhumfrey	✓	✓ Working 2015-03-22

Steps for Configuring IPv6 over PPPoE on an SRX router

There is very limited information on the internet on how to configure a Juniper SRX router use IPv6 over PPPoE, so I have written out these steps, which I have found to work. But there may be other/better ways to configure it. Where you see XXXX in the configuration, insert your own IPv6 subnet block, as allocated to you.

1. Add an IPv6 address for your router to the local loopback interface (lo0)

set interfaces lo0 unit 0 family inet6 address 2001:8b0:XXXX::1/128

2. Enable IPv6 on the pp0 interface. I did this by specifying a MTU value:

set interfaces pp0 unit 0 family inet6 mtu 1492

3. Add an IPv6 address to the LAN/trust interface. I match my IPv6 subnet number to my VLAN number, and give the router host address 1:

set interfaces vlan unit 3 family inet6 address 2001:8b0:XXXX:3::1/64

4. Set pp0 to be the default next hop in the IPv6 routing table:

set routing-options rib inet6.0 static route 0::0/0 next-hop pp0.0

5. Enable forwarding/routing of IPv6 packets on the router. Flow based means it will use stateful firewall rules.

set security forwarding-options family inet6 mode flow-based

6. If you want machines on your internal subnet to automatically discover the IPv6 router, then enable Router Advertisements (RA). You could alternatively configure a DHCPv6 server or use static routing.

set protocols router-advertisement interface vlan.3 prefix 2001:8b0:XXXX:3::/64

7. Finally, if you want to be able to ping hosts on your internal network, then see the ping6-to-trust policy in the example config below.

Note that the first time you enable IPv6 based routing (the security forwarding-options), you will have to reboot the router.

Dual-stack Example Config

• Statically configured IPv4 and IPv6 for a single AAISP line
• Trust VLAN on Ethernet Port 0-6
• PPPoE configured on Ethernet Port 7
• Pinging (ICMPv6) from untrusted to trusted hosts is enabled

## Last changed: 2015-03-29 17:42:36 BST
version 12.1X46-D30.2;
system {
    host-name dsl-router;
    domain-name aa.net.uk;
    time-zone Europe/London;
    root-authentication {
        encrypted-password "XXXX";
    }
    name-server {
        217.169.20.20;
        217.169.20.21;
    }
    services {
        ssh;
        xnm-clear-text;
        web-management {
            http {
                interface vlan.3;
            }
            https {
                system-generated-certificate;
                interface vlan.3;
            }
        }
        dhcp {
            name-server {
                217.169.20.20;
                217.169.20.21;
            }
            pool 192.168.1.0/24 {
                address-range low 192.168.1.100 high 192.168.1.250;
                router {
                    192.168.1.1;
                }
            }
        }
    }
    syslog {
        archive size 100k files 3;
        user * {
            any emergency;
        }
        file messages {
            any critical;
            authorization info;
        }
        file interactive-commands {
            interactive-commands error;
        }
    }
    max-configurations-on-flash 5;
    max-configuration-rollbacks 5;
    license {
        autoupdate {
            url https://ae1.juniper.net/junos/key_retrieval;
        }
    }
    ntp {
        server 90.155.53.94;
        server 90.155.53.93;
    }
}
interfaces {
    interface-range interfaces-trust {
        member fe-0/0/0;
        member fe-0/0/1;
        member fe-0/0/2;
        member fe-0/0/3;
        member fe-0/0/4;
        member fe-0/0/5;
        member fe-0/0/6;
        unit 0 {
            family ethernet-switching {
                vlan {
                    members vlan-trust;
                }
            }
        }
    }
    fe-0/0/7 {
        description "PPPoE Port";
        unit 0 {
            encapsulation ppp-over-ether;
        }
    }
    lo0 {
        unit 0 {
            family inet6 {
                address 2001:8b0:XXXX::1/128;
            }
        }
    }
    pp0 {
        unit 0 {
            description AAISP;
            point-to-point;
            ppp-options {
                chap {
                    default-chap-secret "XXXX";
                    local-name "XXXX@a";
                    no-rfc2486;
                    passive;
                }
            }
            pppoe-options {
                underlying-interface fe-0/0/7.0;
                idle-timeout 0;
                auto-reconnect 5;
                client;
            }
            family inet {
                mtu 1492;
                negotiate-address;
            }
            family inet6 {
                mtu 1492;
            }
        }
    }
    vlan {
        unit 3 {
            family inet {
                address 192.168.1.1/24;
            }
            family inet6 {
                address 2001:8b0:XXXX:3::1/64;
            }
        }
    }
}
routing-options {
    rib inet6.0 {
        static {
            route 0::0/0 next-hop pp0.0;
        }
    }
    static {
        route 0.0.0.0/0 next-hop pp0.0;
    }
}
protocols {
    router-advertisement {
        interface vlan.3 {
            prefix 2001:8b0:XXXX:3::/64;
        }
    }
}
security {
    forwarding-options {
        family {
            inet6 {
                mode flow-based;
            }
        }
    }
    screen {
        ids-option untrust-screen {
            icmp {
                ping-death;
            }
            ip {
                source-route-option;
                tear-drop;
            }
            tcp {
                syn-flood {
                    alarm-threshold 1024;
                    attack-threshold 200;
                    source-threshold 1024;
                    destination-threshold 2048;
                    timeout 20;
                }
                land;
            }
        }
    }
    nat {
        source {
            rule-set trust-to-untrust {
                from zone trust;
                to zone untrust;
                rule source-nat-rule {
                    match {
                        source-address 0.0.0.0/0;
                    }
                    then {
                        source-nat {
                            interface;
                        }
                    }
                }
            }
        }
    }
    policies {
        from-zone trust to-zone untrust {
            policy trust-to-untrust {
                match {
                    source-address any;
                    destination-address any;
                    application any;
                }
                then {
                    permit;
                }
            }
        }
        from-zone untrust to-zone trust {
            policy ping6-to-trust {
                match {
                    source-address any-ipv6;
                    destination-address any-ipv6;
                    application junos-pingv6;
                }
                then {
                    permit;
                }
            }
            policy reject-untrust-to-trust {
                match {
                    source-address any;
                    destination-address any;
                    application any;
                }
                then {
                    reject;
                }
            }
        }
        default-policy {
            deny-all;
        }
    }
    zones {
        security-zone trust {
            host-inbound-traffic {
                system-services {
                    all;
                }
                protocols {
                    all;
                }
            }
            interfaces {
                vlan.3;
                lo0.0;
            }
        }
        security-zone untrust {
            screen untrust-screen;
            host-inbound-traffic {
                system-services {
                    ping;
                }
            }
            interfaces {
                pp0.0;
            }
        }
    }
}
vlans {
    vlan-trust {
        vlan-id 3;
        l3-interface vlan.3;
    }
}

Higher MTU values

It does look like the SRX ethernet interface supports Baby Jumbo Frames, however I asked about using an MTU of 1500 on the PPP link and received the following response from Danilo Quesada – Juniper SRX Support:

Increasing the MTU on the PPPoE interface to a value greater that 1492 would go against RFC2516 A Method for Transmitting PPP Over Ethernet (PPPoE).

RFC4638 is currently not supported on any SRX Junos code. Junos enforces RFCs, so there is no way round this but to wait until is implemented. Currently there is no roadmap information available. Please submit a product enhancement request through your Juniper Account Team or sales Representative.