Routing

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  • 1.  Outgoing routing over IRB/LT interface problem

    Posted 06-14-2024 05:26

    Hello, please could someone help me understand why following scenarios has a problem with routing thru lt-0/0/0?

    In case of A, packets(icmp) from HOST1 to HOST2 arrive to MX (verified by mirroring on sw1) and it's all, routing doesn't working.

    In case of B, packets(icmp) from HOST1 to HOST2 arrive to MX and is forwarded to HOST2. Response packets to HOST1 arrive to MX and it's all, routing doesn't working.

    In case of B, pure l2 from other hosts connected to SW1/2 in same vlans(1234/1235) thru MX working fine.

    In case of both interfaces/units are in the same LS, all working like expected.

    Many thanks for your time, Lukas

    Topology-A:

    HOST1(1.2.3.1/24)---v1234---\
                                                                          SW1----(et-0/0/0, trunk)MX204
    HOST2(1.2.4.1/24)---v1235---/


    Configuration-A:

    #show interfaces
    lt-0/0/0 {
        unit 1 {
            peer-unit 0;
            family bridge {
                interface-mode trunk;
                vlan-id-list 1234-1235;
            }
        }
    }
    et-0/0/0 {
        unit 0 {
            family bridge {
                interface-mode trunk;
                vlan-id-list 1234-1235;
            }                               
        }
    }

    #show bridge-domains
    test1 {
        vlan-id 1234;
    }
    test2 {
        vlan-id 1235;
    }


    #show logical-systems test   
    interfaces {
        lt-0/0/0 {
            unit 0 {
                peer-unit 1;
                family bridge {
                    interface-mode trunk;
                    vlan-id-list 1234-1235;
                }
            }
        }
        irb {
            unit 1234 {
                family inet {
                    address 1.2.3.5/24;
                }
            }
            unit 1235 {
                family inet {
                    address 1.2.4.5/24;
                }
            }
        }
    }
    bridge-domains {
        test1 {
            vlan-id 1234;
            routing-interface irb.1234;
        }
        test2 {
            vlan-id 1235;
            routing-interface irb.1235;
        }
    }

    Topology-B:

    HOST1(1.2.3.1/24)---v1234---SW1----(et-0/0/0, trunk)MX204(xe-0/1/4, trunk)----SW2---v1235---(1.2.4.1/24)HOST2

    Configuration-B:

    #show interfaces
    lt-0/0/0 {
        unit 1 {
            peer-unit 0;
            family bridge {
                interface-mode trunk;
                vlan-id-list 1234-1235;
            }
        }
    }
    et-0/0/0 {
        unit 0 {
            family bridge {
                interface-mode trunk;
                vlan-id-list 1234-1235;
            }                               
        }
    }

    #show bridge-domains
    test1 {
        vlan-id 1234;
    }
    test2 {
        vlan-id 1235;
    }


    #show logical-systems test   
    interfaces {
        lt-0/0/0 {
            unit 0 {
                peer-unit 1;
                family bridge {
                    interface-mode trunk;
                    vlan-id-list 1234-1235;
                }
            }
        }
        xe-0/1/4 {
            unit 0 {
                family bridge {
                    interface-mode trunk;
                    vlan-id-list 1234-1235;
                }
            }
        }
        irb {
            unit 1234 {
                family inet {
                    address 1.2.3.5/24;
                }
            }
            unit 1235 {
                family inet {
                    address 1.2.4.5/24;
                }
            }
        }
    }
    bridge-domains {
        test1 {
            vlan-id 1234;
            routing-interface irb.1234;
        }
        test2 {
            vlan-id 1235;
            routing-interface irb.1235;
        }
    }



    ------------------------------
    Lukas
    ------------------------------



  • 2.  RE: Outgoing routing over IRB/LT interface problem

    Posted 06-16-2024 02:51

    Hi,

    Well, first of all, why would you even need lt for this?

    Why wouldn't you assign to each host port relevant VLAN and then do inter-vlan routing on MX, to which these VLANs are passed inside trunk port? The implementation does not seem to be reasonable.



    ------------------------------
    FARID AKHUNDOV
    ------------------------------



  • 3.  RE: Outgoing routing over IRB/LT interface problem

    Posted 30 days ago

    Hi Farid and thank you for reply...

    It's maybe a bit weird setup, but in the reality MX sits between two infrastructure (et-0/0/0, xe-0/1/4), not just between few hosts and i have to have transparent L2 in the same vlan in which there is a bgp peers. So I'm trying to solve in this way.



    ------------------------------
    Lukas
    ------------------------------



  • 4.  RE: Outgoing routing over IRB/LT interface problem

    Posted 13 days ago

    Hi,

    not sure if this just a copy past issue, but
    - for A, I do not see what is the physical port in logical-instance -- so what would be the "exit port"? 

    BR



    ------------------------------
    Andrei Cebotareanu
    ------------------------------



  • 5.  RE: Outgoing routing over IRB/LT interface problem

    Posted 9 days ago

    Since you have two physical interfaces that you want to connect layer 2, you could use bridge domains. 

    This simply puts the interface and unit of each port into the same bridge domain and they are layer 2 adjacent on the MX.

    https://www.juniper.net/documentation/us/en/software/junos/bridging-learning/topics/example/layer-2-single-vlan.html



    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP - Retired)
    http://puluka.com/home
    ------------------------------