Description

This article describes how to configure VLAN translation by using Enhanced Layer 2 Software Support (ELS) on Junos OS.

 

Solution

Example Topology

  

        +---------+ Trunk-all       +---------+ Trunk-all       +----------+
        |         |ge-0/0/1         |         | ge-0/0/0        |          |
        | SW-A    +-----------------+ EX4300  +-----------------+ SW-B     |
        |         |        ge-0/0/1 |         |         ge-0/0/0|          |
        +---------+                 +---------+                 +----------+

Vlan.10 --> 10.0.0.1/24                                          ge-0/0/0.10  --> 10.0.0.2/24
Vlan.20 --> 20.0.0.1/24                                          ge-0/0/0.220 --> 20.0.0.2/24
  • If SW-A pings SW-B on vlan10, the ping works without any translation.
  • If SW-A pings SW-B on vlan20, then vlan20's traffic will be translated to vlan220 by EX4300.
  • The return traffic from SW-B on vlan220 will be translated back to vlan20 while egressing to SW-A by EX4300.

 

Example Configuration

Switch-A 

{master:0}[edit]
root@SW-A# run show configuration vlans
V10 {
    vlan-id 10;
    l3-interface vlan.10;
}
V20 {
    vlan-id 20;
    l3-interface vlan.20;
}

root@SW-A# run show configuration interfaces
ge-0/0/1 {
    unit 0 {
        family ethernet-switching {
            port-mode trunk;
            vlan {
                members all;
            }
        }
    }
}
vlan {
    unit 10 {
        family inet {
            address 10.0.0.1/24;
        }
    }
    unit 20 {
        family inet {
            address 20.0.0.1/24;
        }
    }
}​

 

​ EX4300 

root# run show configuration vlans
V10 {
    vlan-id 10;
}
V220 {
    vlan-id 220;
}

root# run show configuration interfaces
ge-0/0/0 {
    unit 0 {
        family ethernet-switching {
            interface-mode trunk;
            vlan {
                members all;
            }
        }
    }
}
ge-0/0/1 {
    flexible-vlan-tagging;
    unit 0 {
        family ethernet-switching {
            interface-mode trunk;
            vlan {
                members [ 10 220 ];
            }
            vlan-rewrite {
                translate 20 220;
            }
        }
    }
}
irb {
    unit 10 {
        family inet {
            address 10.0.0.5/24;
        }
    }
    unit 220 {
        family inet {
            address 20.0.0.5/24;
        }
    }
}

 

​ Switch-B 

root@SW-B# run show configuration interfaces
ge-0/0/0 {
    vlan-tagging;
    unit 10 {
        vlan-id 10;
        family inet {
            address 10.0.0.2/24;
        }
    }
    unit 220 {
        vlan-id 220;
        family inet {
            address 20.0.0.2/24;
        }
    }
}

 

Results

From Switch-A 

root@SW-A# run ping 10.0.0.2
PING 10.0.0.2 (10.0.0.2): 56 data bytes
64 bytes from 10.0.0.2: icmp_seq=0 ttl=64 time=3.886 ms
64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=3.239 ms
64 bytes from 10.0.0.2: icmp_seq=2 ttl=64 time=3.266 ms
64 bytes from 10.0.0.2: icmp_seq=3 ttl=64 time=3.104 ms
^C
--- 10.0.0.2 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max/stddev = 3.104/3.374/3.886/0.302 ms

root@SW-A# run ping 20.0.0.2
PING 20.0.0.2 (20.0.0.2): 56 data bytes
64 bytes from 20.0.0.2: icmp_seq=0 ttl=64 time=4.044 ms
64 bytes from 20.0.0.2: icmp_seq=1 ttl=64 time=3.614 ms
64 bytes from 20.0.0.2: icmp_seq=2 ttl=64 time=3.256 ms
64 bytes from 20.0.0.2: icmp_seq=3 ttl=64 time=3.918 ms
^C
--- 20.0.0.2 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max/stddev = 3.256/3.708/4.044/0.304 ms

 

From Switch-B 

root@SW-B# run ping 10.0.0.1
PING 10.0.0.1 (10.0.0.1): 56 data bytes
64 bytes from 10.0.0.1: icmp_seq=0 ttl=64 time=3.895 ms
64 bytes from 10.0.0.1: icmp_seq=1 ttl=64 time=3.147 ms
64 bytes from 10.0.0.1: icmp_seq=2 ttl=64 time=4.050 ms
64 bytes from 10.0.0.1: icmp_seq=3 ttl=64 time=4.092 ms
^C
--- 10.0.0.1 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max/stddev = 3.147/3.796/4.092/0.382 ms


root@SW-B# run ping 20.0.0.1
PING 20.0.0.1 (20.0.0.1): 56 data bytes
64 bytes from 20.0.0.1: icmp_seq=0 ttl=64 time=3.878 ms
64 bytes from 20.0.0.1: icmp_seq=1 ttl=64 time=29.827 ms
64 bytes from 20.0.0.1: icmp_seq=2 ttl=64 time=2.829 ms
64 bytes from 20.0.0.1: icmp_seq=3 ttl=64 time=4.449 ms
^C
--- 20.0.0.1 ping statistics ---
4 packets transmitted, 4 packets received, 0% packet loss
round-trip min/avg/max/stddev = 2.829/10.246/29.827/11.320 ms

{master:0}[edit]

 

Modification History

2020-08-25: Article reviewed for accuracy; no changes required; article valid and relevant

 

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