Description

This article provides a sample interface-mode configuration to make an MX device to behave like a switch, when ports are configured as access ports of the same VLAN. This setup can switch traffic only between access ports and between access ports and trunks ports.

Symptoms

Topology :

                                                                                              
R1-----------------------------------------R2---------------------------------------------------R3
192.168.100.1            (xe-0/0/0-access port) (xe-0/0/1-access port)           
192.168.100.3/24
  • R2 has two ports connecting to R1 and R3.

  • Both these ports are access-ports under the same VLAN.

  • R2, which is an MX device, needs to behave like a switch between R1 and R3.

  • The requirement is to route traffic of the same VLAN from R1 to R3, with the minimal configuration on R2.

Solution


Configuration :


R2 - Access ports Interface configuration :

interfaces {
    xe-0/0/0 {
        unit 0 {
            family bridge {
                interface-mode access;
                vlan-id 100;
            }
        }
    }
xe-0/0/1 {
    unit 0 {
        family bridge {
            interface-mode access;
            vlan-id 100;
        }
    }
}

R1 :

[edit interfaces xe-1/2/0]
lab# show
unit 0 {
    family inet {
        address 192.168.100.1/24;
    }
}


R3 :

[edit interfaces xe-1/2/0]
lab@R3# show
unit 0 {
    family inet {
        address 192.168.100.3/24;
}


Ping test between R1 and R3 and vice-versa; without any Bridge-Domain configuration:

Test 1 - Ping from R3 to R1 :

lab@MX-240# run ping 192.168.100.1
PING 192.168.100.1 (192.168.100.1): 56 data bytes
^C
--- 192.168.100.1 ping statistics ---
10 packets transmitted, 0 packets received, 100% packet loss



Test 2 - Ping from R1 to R3 :

lab@MX-240# run ping 192.168.100.3
PING 192.168.100.3 (192.168.100.3): 56 data bytes
^C
--- 192.168.100.3 ping statistics ---
14 packets transmitted, 0 packets received, 100% packet loss

R2 Bridge Domain Configuration:

bridge-domains {
    test {
        vlan-id 100;
    }
}

Ping test after configuring the Bridge-domain:

R3 to R1 :

lab@MX-240# run ping 192.168.100.1
PING 192.168.100.1 (192.168.100.1): 56 data bytes
64 bytes from 192.168.100.1: icmp_seq=0 ttl=64 time=0.558 ms
64 bytes from 192.168.100.1: icmp_seq=1 ttl=64 time=0.534 ms
64 bytes from 192.168.100.1: icmp_seq=2 ttl=64 time=0.545 ms
64 bytes from 192.168.100.1: icmp_seq=3 ttl=64 time=0.501 ms
64 bytes from 192.168.100.1: icmp_seq=4 ttl=64 time=0.504 ms
64 bytes from 192.168.100.1: icmp_seq=5 ttl=64 time=0.503 ms
64 bytes from 192.168.100.1: icmp_seq=6 ttl=64 time=0.545 ms
64 bytes from 192.168.100.1: icmp_seq=7 ttl=64 time=0.521 ms
64 bytes from 192.168.100.1: icmp_seq=8 ttl=64 time=0.547 ms
64 bytes from 192.168.100.1: icmp_seq=9 ttl=64 time=0.548 ms
64 bytes from 192.168.100.1: icmp_seq=10 ttl=64 time=0.548 ms
64 bytes from 192.168.100.1: icmp_seq=11 ttl=64 time=0.548 ms
64 bytes from 192.168.100.1: icmp_seq=12 ttl=64 time=0.492 ms

R1 to R3 :

lab@we-labmx4801# run ping 192.168.100.3
PING 192.168.100.3 (192.168.100.3): 56 data bytes
64 bytes from 192.168.100.3 icmp_seq=0 ttl=64 time=1.331 ms
64 bytes from 192.168.100.3: icmp_seq=1 ttl=64 time=0.655 ms
64 bytes from 192.168.100.3: icmp_seq=2 ttl=64 time=0.602 ms
64 bytes from 192.168.100.3: icmp_seq=3 ttl=64 time=0.584 ms
^C
--- 192.168.100.3 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss

Troubleshooting and Verification :

  1. Run the show bridge mac-table command:
    MAC flags (S -static MAC, D -dynamic MAC, L -locally learned
    SE -Statistics enabled, NM -Non configured MAC, R -Remote PE MAC)

    Routing instance : default-switch
    Bridging domain : test, VLAN : 100
    MAC MAC Logical
    address flags interface
    00:24:dc:b9:90:f7 D xe-0/0/1.0
    80:71:1f:10:9c:1f D xe-0/0/0.0

 

  • Run the show bridge domain command:
    Routing instance Bridge domain VLAN ID Interfaces
    default-switch test 100
    xe-0/0/0.0
    xe-0/0/1.0

  • Run the show bridge domain command:

    Local interface: xe-0/0/1.0, Index: 322
    Broadcast packets: 35
    Broadcast bytes : 2100
    Multicast packets: 0
    Multicast bytes : 0
    Flooded packets : 0
    Flooded bytes : 0
    Unicast packets : 2
    Unicast bytes : 196
    Current MAC count: 1 (Limit 8192)
    Local interface: xe-0/0/0.0, Index: 329
    Broadcast packets: 7
    Broadcast bytes : 420
    Multicast packets: 0
    Multicast bytes : 0
    Flooded packets : 0
    Flooded bytes : 0
    Unicast packets : 7
    Unicast bytes : 610
    Current MAC count: 1 (Limit 8192)

 

Modification History

Dec 17 - Specified that the Bridge domain configuration is on R2 for clarity.