Bridging on the MX platform

I recently had the pleasure of setting up some bridging interfaces (or IRB) on an MX960 router. It wasnt very complex and after a few hours in the lab doing some testing I was ready to deploy. While I was waiting on the outage window, I decided to note some things down about this task in order to help my support guys better understand the solution.

The first step in configuring the router is configuring Layer 3 information on logical units within the IRB interface:

interfaces {
    ge-3/1/0 {
        encapsulation flexible-ethernet-services;
        flexible-vlan-tagging;
        unit 0 {
            encapsulation vlan-bridge;
            vlan-id 100;
        }
        unit 1 {
            encapsulation vlan-bridge;
            vlan-id 200;
        }
    }
    ge-3/1/1 {
        encapsulation flexible-ethernet-services;
        flexible-vlan-tagging;
        unit 0 {
            encapsulation vlan-bridge;
            vlan-id 100;
        }
        unit 1 {
            encapsulation vlan-bridge;
            vlan-id 200;
        }
    }
    ge-3/3/0 {
        encapsulation flexible-ethernet-services;
        flexible-vlan-tagging;
        unit 0 {
            encapsulation vlan-bridge;
            vlan-id 100;
        }
        unit 1 {
            encapsulation vlan-bridge;
            vlan-id 200;
        }
    }
    irb {
        unit 0 {
            family inet {
                address 172.17.1.2/24;
            }
        }
        unit 1 {
            family inet {
                address 12.12.1.2/28;
            }
        }
    }
}

In such a router configuration, you must configure a bridge domain with the interfaces through which the host traffic can travel. In this configuration, the bridge domains are configured on a virtual switch and the interfaces are divided into logical units within each bridge domain. The following example shows the bridge domain customer0_bd0 that is within the virtual switch routing instance customer. Note that there are MAC limits in place for the the logical interfaces configured on this bridge domain:

routing-instances {
    customer {
        instance-type virtual-switch;
        bridge-domains {
            customer0_bd0 {
                domain-type bridge;
                vlan-id 100;
                interface ge-3/1/0.0;
                interface ge-3/1/1.0;
                interface ge-3/3/0.0;
                routing-interface irb.0;
                bridge-options {
                    mac-table-size {
                        1048575;
                    }
                    interface ge-3/1/0.0 {
                        interface-mac-limit {
                            131071;
                        }
                    }
                    interface ge-3/1/1.0 {
                        interface-mac-limit {
                            131071;
                        }
                    }
                    interface ge-3/3/0.0 {
                        interface-mac-limit {
                            131071;
                        }
                    }
                }
            }
        }
    }
}

The bridge domain customer1_bd1, which is also configured under the customer virtual switch routing instance, is configured for a VLAN ID of 200 and
routing-interface irb.1. There are no MAC limits set for this bridge domain:

routing-instances {
    customer {
        instance-type virtual-switch;
            bridge-domains {
            customer1_bd1 {
                domain-type bridge;
                vlan-id 200;
                interface ge-3/1/0.1;
                interface ge-3/1/1.1;
                interface ge-3/3/0.1;
                routing-interface irb.1;
            }
        }
    }
}

Thank you

Andy Wilson

This entry was posted in Routing, Switching. Bookmark the permalink.

Leave a Reply