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[EX/QFX] Example - Dynamic ARP learning for IRB interface over an ICL link without static ARP configuration

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Article ID: KB32549 KB Last Updated: 02 Apr 2018Version: 2.0
Summary:

This article provides an example of dynamic ARP learning for an IRB interface over an ICL link.

Symptoms:

When MC-LAG Active-Active is used, dynamic ARP learning does not happen over an ICL link.

Solution:
Starting with Junos OS 15.1R3, dynamic ARP learning over ICL for IRB interfaces will happen when VRRP is configured without static ARP configuration.
 
In the ARP table, ARP entries are shown as “permanent remote”. This eliminates configuring static ARP for all IRB interfaces in an MC-LAG Active-Active scenario.
 
Lab output:
 
EX9200:
                               ICCP
+-----------------+ ge-0/1/3            ge-0/1/3 +----------------+
|                 +------------------------------+                |
|  EX9200         |                              |   EX9200       |
|  SW-1           |                              |   SW-2         |
|                 +------------------------------+                |
+-----------------+ ge-0/1/4    ICL     ge-0/1/4 +----------------+
 
root@EX9200-SW1# show interfaces irb.10
family inet {
    address 10.10.10.1/24 {
        vrrp-group 10 {
            virtual-address 10.10.10.50;
            priority 150;
        }
    }
}
 
root@EX9200-SW2# show interfaces irb.10
family inet {
    address 10.10.10.2/24 {
        vrrp-group 10 {
            virtual-address 10.10.10.50;
        }
    }
}
 
root@EX9200-SW1# run show arp no-resolve
MAC Address       Address         Interface         Flags
d8:b1:22:93:9d:70 10.10.10.2      irb.10 [ge-0/1/4.0]      permanent remote
00:00:5e:00:01:0a 10.10.10.50     irb.10                   permanent published
d8:b1:22:93:9d:70 10.10.100.2     irb.100 [ge-0/1/3.0]     none
00:00:5e:00:01:14 10.219.41.65    fxp0.0                   none
d8:b1:22:93:9d:70 20.20.20.2      irb.20 [ge-0/1/4.0]      permanent remote
00:00:5e:00:01:14 20.20.20.50     irb.20                   permanent published
 
root@EX9200-SW2# run show arp no-resolve
MAC Address       Address         Interface         Flags
d8:b1:22:93:95:70 10.10.10.1      irb.10 [ge-0/1/4.0]      permanent remote
00:00:5e:00:01:0a 10.10.10.50     irb.10                   permanent published
d8:b1:22:93:95:70 10.10.100.1     irb.100 [ge-0/1/3.0]     none
00:00:5e:00:01:14 10.219.41.65    fxp0.0                   none
d8:b1:22:93:95:70 20.20.20.1      irb.20 [ge-0/1/4.0]      permanent remote
00:00:5e:00:01:14 20.20.20.50     irb.20                   permanent published
02:00:00:00:00:10 128.0.0.16      em0.0                    none
02:00:00:00:00:11 128.0.0.17      em0.0                    none
02:00:00:00:00:12 128.0.0.18      em0.0                    none
 

QFX5100:

+-------------+                              +------------+
|  QFX5100    |           [ICCP/ICL]         |QFX5100     |
|  SW-1       +------------------------------+SW-2        |
|             | xe-0/0/1            xe-1/0/1 |            |
+-------------+                              +------------+
 
root@SW-1> show version
fpc0:
--------------------------------------------------------------------------
Hostname: SW-1
Model: qfx5100-48t-6q
Junos: 15.1R3.6
JUNOS Base OS boot [15.1R3.6]
JUNOS Base OS Software Suite [15.1R3.6]
JUNOS Crypto Software Suite [15.1R3.6]
JUNOS Online Documentation [15.1R3.6]
JUNOS Kernel Software Suite [15.1R3.6]
JUNOS Packet Forwarding Engine Support (qfx-ex-x86-32) [15.1R3.6]
JUNOS Routing Software Suite [15.1R3.6]
JUNOS Enterprise Software Suite [15.1R3.6]
JUNOS py-base-i386 [15.1R3.6]
JUNOS Host Software [14.1X53-D35.3]
 
root@SW-1# show interfaces irb.10
family inet {
    address 10.10.10.1/24 {
        vrrp-group 10 {
            virtual-address 10.10.10.50;
            priority 150;
            accept-data;
        }
    }
}
 
{master:0}[edit]
root@SW-1# show interfaces irb.20
family inet {
    address 20.20.20.1/24 {
        vrrp-group 20 {
            virtual-address 20.20.20.50;
            accept-data;
        }
    }
}
 
root@SW-2# show interfaces irb.10
family inet {
    address 10.10.10.2/24 {
        vrrp-group 10 {
            virtual-address 10.10.10.50;
            accept-data;
        }
    }
}
 
{master:1}[edit]
root@SW-2# show interfaces irb.20
family inet {
    address 20.20.20.2/24 {
        vrrp-group 20 {
            virtual-address 20.20.20.50;
            priority 110;
        }
    }
}
 
root@SW-1# run show interfaces mc-ae
 Member Link                  : ae2
 Current State Machine's State: mcae active state
 Local Status                 : active
 Local State                  : up
 Peer Status                  : active
 Peer State                   : up
     Logical Interface        : ae2.0
     Topology Type            : bridge
     Local State              : up
     Peer State               : up
     Peer Ip/MCP/State        : 1.1.1.2 xe-0/0/1.0 up
 
{master:0}[edit]
root@SW-1# run show arp no-resolve
MAC Address       Address         Interface         Flags
44:aa:50:25:3d:80 10.10.10.2      irb.10 [xe-0/0/1.0]      permanent
44:aa:50:25:3d:80 10.10.100.2     irb.100 [xe-0/0/1.0]     permanent published
00:00:5e:00:01:15 10.219.42.193   em0.0                    none
0c:86:10:99:d5:2c 10.219.42.194   em0.0                    none
44:aa:50:25:3d:80 20.20.20.2      irb.20 [xe-0/0/1.0]      permanent
20:4e:71:a6:7e:e5 30.0.0.1        xe-0/0/3.0               none
44:aa:50:25:29:83 192.168.1.1     em2.32768                none
Total entries: 7
 
In Junos OS 15.1, ARP entries for 10.10.10.2 and 20.20.20.2 are flagged as permanent without static ARP configuration in an MC-LAG Active-Active scenario.

Starting with Junos OS 16.1, the ARP entries will be flagged as “permanent remote”.
 
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