Description

This article explains the JDHCP relay server-group address limit on SRX platforms, which is five (5) server-group addresses prior to 18.4R1 Release.

Symptoms

When attempting to configure six addresses under "service-group" for JDHCP relay, it returns the following error :

root@SRX# show forwarding-options
dhcp-relay {
    server-group {
        HELPER {
            1.1.1.2;
            1.1.1.3;
            1.1.1.4;
            1.1.1.5;
            1.1.1.1;
            1.1.1.6;
        }
    }
}

[edit]
root@SRX# commit
error: Check-out failed for Junos Dynamic Host Configuration Protocol process (/usr/sbin/jdhcpd) without details
error: configuration check-out failed

Solution

The JDHCP relay server-group address limit on SRX platforms is hard-coded to five (5) before 18.4R1 .

Starting in Junos OS Release 18.4R1, up to 32 server IP addresses are supported per DHCPv4 server group. In earlier releases, a maximum of 5 server IP addresses are supported for DHCPv4 servers. Configuring more than the maximum number of server addresses results in a commit check failure.

For more details, refer to Configuring Active Server Groups to Apply a Common DHCP Relay Agent Configuration to Named Server Groups  

Modification History

2020-10-08: Updated the limit as it increased after 18.4R1. Added tech pubs reference link.