Switching

Hi all,

Can someone explain to me in which use case/situation below knob "bold" need to use in MC-LAG setup? I try to google but not found any good explanation.

irb {
unit 300 {
description "ICCP Connection to DC2-MX-5";
family inet {
address 10.42.14.3/24;
}
mac 00:11:10:42:34:03;
}
unit 104 {
description "Connection Layer 3 to DC2-QFX-5";
family inet {
address 10.40.114.2/24 {
arp 10.40.114.3 l2-interface ae0.0 mac 00:00:42:13:40:03 publish;
arp 10.40.114.4 l2-interface ae1.0 mac 00:00:42:13:40:04 publish;
}
}
mac 00:00:42:13:10:02;
}
}

Thanks and appreciate any feedback

Hi kronicklez

Greetings,  The static arp is to overcome the well-known limitation of dropping arp replies over the ICL you can find more information here: https://kb.juniper.net/InfoCenter/index?page=content&id=KB27865

The publish knob:

You can optionally configure the router to respond to ARP requests for the specified IP address by using the publish option with the arp statement.

Source: https://www.juniper.net/documentation/en_US/junos/topics/topic-map/switches-interface-arp.html

Also please be aware that starting with Junos OS 15.1R3, dynamic ARP learning over ICL for IRB interfaces will happen when VRRP is configured without static ARP configuration.

Please check: KB32549

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

Regards,

Lil Dexx
JNCIE-ENT#863, 3X JNCIP-[SP-ENT-DC], 4X JNCIA [cloud-DevOps-Junos-Design], Champions Ingenius, SSYB

Hi LilDexx,

So it means if i'm using MX with version 18.x then that knob dont need right? Also i check with KB info that u mention. It's look like if i configure VRRP then that knob dont need anymore right? Please correct me if i wrong.

https://kb.juniper.net/InfoCenter/index?page=content&id=KB32549

Thanks and appreciate your feedback

Hey kronicklez,

Greetings gentleman, your understanding is correct, from 15.1R3/16.1R1, mc-lag does not need static entry (ARP/NDP) for remote IRB, this will overcome the ICL arp reply limitation. 

NOTE: 

If you already configured the static entry(ARP/NDP) and then try to remove it on any version higher than 15.1, remote IRB arp resolution will not happen automatically due to the static programming that was in place before, in order to solve this problem you will have to reconfigure the IRB & restart l2-learning process on both the MC-LAG peers.

Example:

root#delete interface irb.123
root#commit
root#rollback 1
commit
root# run restart l2-learning
Layer 2 address flooding and learning process started, pid 12435

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

Regards,

Lil Dexx
JNCIE-ENT#863, 3X JNCIP-[SP-ENT-DC], 4X JNCIA [cloud-DevOps-Junos-Design], Champions Ingenius, SSYB

Hi LilDexx,

Thanks for the confirmation n explanation.