Junos OS

Expand all | Collapse all

Bridge-domain,multiple vlans and flooding domains

Jump to Best Answer
  • 1.  Bridge-domain,multiple vlans and flooding domains

    Posted 08-09-2017 20:17

     Hello everyone.

     

    Please consider the following example:

     

    MX4 R1:

     

    EXAMPLE {
    domain-type bridge;
    interface x0-0/0/0.0  (  Trunk port carring vlans 4)
    Interface x0-2/2/2.0  ( trunk port carrying vlan 5)
    interface x0-1/1/1.0  ( access port in vlan 4)
    vlan-id 4,5
     

     

     

    Let say R1 receives a frame on xo-1/1/1.0 which is an access port in vlan 4,  with destination ffff.ffff.ffff

     

    Will R1 flood that frame out of trunk port x0-2/2/2.0 too because vlan 5 is a part of same  bridge domain" EXAMPLE" ?

     

    Thanks and have a nice day!!

     

     

     

     

     



  • 2.  RE: Bridge-domain,multiple vlans and flooding domains

    Posted 08-09-2017 21:11
    Packets received on a trunk interface are forwarded within a bridge domain that has the same VLAN identifier

    https://www.juniper.net/documentation/en_US/junos/topics/concept/layer-2-services-bridging-overview.html



  • 3.  RE: Bridge-domain,multiple vlans and flooding domains
    Best Answer

     
    Posted 08-10-2017 04:18

    Hi,

     

    I was wondering whether the config is a valid working one as I am not sure more than one vlan-id [vlan-id 4,5] can be configured under bridge-domains.

     

    For multiple vlan-ids in bridge-domain, vlan-id-list needs to be configured. Example:

    # show bridge-domains
    test {
        vlan-id-list 4-5;
    }
    
    # show interfaces
    ge-0/0/1 {
        unit 0 {
            family bridge {
                interface-mode access;
                vlan-id 4;
            }
        }
    }
    ge-0/0/2 {
        unit 0 {
            family bridge {
                interface-mode trunk;
                vlan-id-list [ 4 5 ];
            }
        }
    }
    ge-0/0/4 {
        unit 0 {
            family bridge {
                interface-mode trunk;
                vlan-id-list 5;
            }
        }
    }
    
    # run show bridge domain brief
    
    Routing instance        Bridge domain            VLAN ID     Interfaces
    default-switch          test-vlan-0004           4
                                                         ge-0/0/1.0
                                                         ge-0/0/2.0
    default-switch          test-vlan-0005           5
                                                         ge-0/0/2.0
                                                         ge-0/0/4.0
    
    
    

    BUM traffic from an access port gets flooded to member interfaces of that vlan only.

     

    In the example, BUM from ge-0/0/1 [access vlan4] will be flooded to ge-0/0/2 [trunk vlan4,5] but not flooded to ge-0/0/5 [trunk vlan5].

     

    Cheers,

    Ashvin



  • 4.  RE: Bridge-domain,multiple vlans and flooding domains

    Posted 08-10-2017 19:03

    Hi Ashvin,

     

    Thanks for your response, yes it was a typo, vlan-id list shuld be there.

     

    I have some questions ( unfortuantely I do not have access to real gear so can not check myself):

     

    This is I noticed in your config:

     

    You defined single  bridge-domain " test" with vlan 4,5

     

     

    But your command below shown separte bridge domains were created for each vlan even though you defined single bridge domain  " test":

     

    So is it correct if I define single bridge domain X with two vlans 1,2 , we will end up with two bridge domains X-vlan 1, X vlan-2?

     

    Apprecaited!!

     

     run show bridge domain brief
    
    Routing instance        Bridge domain            VLAN ID     Interfaces
    default-switch          test-vlan-0004           4
                                                         ge-0/0/1.0
                                                         ge-0/0/2.0
    default-switch          test-vlan-0005           5
                                                         ge-0/0/2.0
                                                         ge-0/0/4.0

     

     



  • 5.  RE: Bridge-domain,multiple vlans and flooding domains

     
    Posted 08-10-2017 21:45

    Hi, 

     

    This is correct. I guess it is single vlan per bridge-domain, however still a under single virtual-switch instance [default-switch].

    If I add another vlan to the list, another bridge-domain gets created:

    root@Bridge# set bridge-domains test vlan-id-list 10 
    
    [edit]
    root@Bridge# show bridge-domains 
    test {
        vlan-id-list [ 4-5 10 ];
    }
    
    [edit]
    root@Bridge# commit and-quit 
    commit complete
    Exiting configuration mode
    
    root@Bridge> show bridge domain brief 
    
    Routing instance        Bridge domain            VLAN ID     Interfaces
    default-switch          test-vlan-0004           4        
                                                         ge-0/0/1.0
                                                         ge-0/0/2.0
    default-switch          test-vlan-0005           5        
                                                         ge-0/0/2.0
                                                         ge-0/0/4.0
    default-switch          test-vlan-0010           10 

    Cheers,

    Ashvin



  • 6.  RE: Bridge-domain,multiple vlans and flooding domains

    Posted 08-11-2017 07:31

    Awesome!!

     

    Thanks and have a great weekend!!!