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mcae-mac-synchronize in QFX

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  • 1.  mcae-mac-synchronize in QFX

    Posted 01-27-2020 04:54

    could you please explaine why i used mcae-mac-synchronize in qfx when i use same ip ( irb) on both mc-lag peers and  the drawbacks if i don't use this command 



  • 2.  RE: mcae-mac-synchronize in QFX

     
    Posted 01-27-2020 07:28
     
    If you are using IRB on MC-LAG peer, you need to come up with a mechanism to provide a gateway adress to the dowstream clients/host.

    The most common implementation is using VRRP along with IRB. It doesn't require " mcae-mac-synchronize" knob as VRRP takes care of gateway address.

    However, if you want to use same IP address on the IRBs "mcae-mac-synchronize" is mandatory. If you don't use this knob MC-LAG wouldn't function properly.

    Mcae-mac-synchronize’ knob is for synching irb mac between PE’s in MCLAG A/A. You can have same IRB IP address on both PE’s and on enabling this knob, lowest IRB MAC address among PE’s, will be synced to other PE and will be published to CE’s for gateway MAC. Hence CE devices will be sending traffic with the lowest IRB mac. If lowest IRB MAC device goes down, currect active PE will send it’s own IRB mac as gateway mac to CE devices.

    Refer: https://www.juniper.net/documentation/en_US/junos-space-apps/connectivity-services-director2.0/topics/concept/multichassis-link-aggregation-groups-overview.html

    PS: Please accept my response as solution if it answers your query, kudos are appreciated too!
    Thanks
    Vishal


  • 3.  RE: mcae-mac-synchronize in QFX

     
    Posted 01-27-2020 07:34

    Hello,

     

    Don't know why my previous post didn't go through. Here we go again.

     

    If you want to use IRB on MC-LAG peer we need to come up with a mechanism to provide gateway address to downstream hosts/clients. There are two way we can do that.

     

    1) Configure different IP addresses on IRB or RVI interfaces, and run Virtual Router Redundancy Protocol (VRRP) over the IRB or RVI interfaces. The virtual IP address is the gateway IP address for the MC-LAG clients.

     

    2) Configure the MAC address synchronization feature using the mcae-mac-synchronize statement, and configure the same IP address on each of the IRB or RVI interfaces on the MC-LAG peers. This IP address is the gateway IP address for the MC-LAG clients. In case you want to use same IP address on both IRB "mcae-mac-synchronize" knob is mandatory.

     

    Mcae-mac-synchronize’ knob is for synching irb mac between PE’s in MCLAG A/A. You can have same IRB IP address on both PE’s and on enabling this knob, lowest IRB MAC address among PE’s, will be synced to other PE and will be published to CE’s for gateway MAC. Hence CE devices will be sending traffic with the lowest IRB mac. If lowest IRB MAC device goes down, current active PE will send it’s own IRB mac as gateway mac to CE devices.

     

    Refer: https://www.juniper.net/documentation/en_US/junos-space-apps/connectivity-services-director2.0/topics/concept/multichassis-link-aggregation-groups-overview.html

     

    PS: Please accept my response as solution if it answers your query, kudos are appreicated too!

     

    Thanks

    Vishal



  • 4.  RE: mcae-mac-synchronize in QFX

    Posted 01-29-2020 01:40

    thanks for your reply , i undranstad the purpose of mcae-mac-synchronize but my concern what if i don't use this command could you please till me the impact 



  • 5.  RE: mcae-mac-synchronize in QFX
    Best Answer

     
    Posted 01-29-2020 09:43

    Hi Abdelrahman,

    If the mcae-mac-synchronize is not used the MAC synchronization facility won't work and MC-LAG peer won't exactly behave as L3 gateway conseidering both peer will have their own MACs and won't be aware of other devices MAC address.  It won't allow the active active forwarding and packet hitting one peer may need to be forwarded to another peer via the ICL link.

     

    Refer the link below:

     

    https://www.juniper.net/documentation/en_US/junos/topics/concept/mc-lag-feature-concepts.html

     

    Virtual Router Redundancy Protocol (VRRP) over IRB and MAC Address Synchronization:

     

    MAC address synchronization enables MC-LAG peers to forward Layer 3 packets arriving on multichassis aggregated Ethernet interfaces with either their own IRB or RVI MAC address or their peer’s IRB or RVI MAC address. Each MC-LAG peer installs its own IRB or RVI MAC address as well as the peer’s IRB or RVI MAC address in the hardware. Each MC-LAG peer treats the packet as if it were its own packet. If MAC address synchronization is not enabled, the IRB or RVI MAC address is installed on the MC-LAG peer as if it were learned on the ICL.

    PS: Please accpet my response as solution if it asnwers your query, kudos are appreciated too!

    Thanks
    Vishal



  • 6.  RE: mcae-mac-synchronize in QFX

     
    Posted 01-27-2020 15:57

    Hey abdelrahman_25

     

    In short, If MAC address synchronization is not enabled, the IRB or RVI MAC address is installed on the MC-LAG peer as if it were learned on the ICL

     

    Please keep in mind If you are using the VRRP over IRB or RVI method to enable Layer 3 functionality (which is the method I prefer ), you must configure static ARP entries for the IRB or RVI interface of the remote MC-LAG peer to allow routing protocols to run over the IRB or RVI interfaces.

    https://kb.juniper.net/InfoCenter/index?page=content&id=KB27865&actp=RSS

     

     

    And last but not least, you can't have both options enabled. 

     


    Regards,
    Lil Dexx JNCIE-ENT#863

     

    If this solves your problem, please mark this post as "Accepted Solution" so we can help others too



  • 7.  RE: mcae-mac-synchronize in QFX

    Posted 01-29-2020 01:42

    MAC address is installed on the MC-LAG peer as if it were learned on the ICL

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    could you please make more clarification for this point