Routing

Hello Forum,

Now before I start, I would like to say I googled this tp the best of my abilites but did nit find the answer I was looking for, so I bring my question to the community!

Ok so, the situation is this. We are proof of concept testing the MX series 240 before getting the 960's

The concept we are testing at the moment it IPv4 and IPv6 helper addresses on a dual stack deployment utilizing irb interfaces, which must allow option 82 to pass freely to the v4 and v6 server which is on LINUX.

This is the config I have for v4:

set forwarding-options helpers bootp relay agent-option

set forwarding-options helpers bootp server 2.2.2.2 routing-instance VRF-MANAGEMENT

!

set forwarding-options helpers bootp interface irb.900 broadcast <--Dual stack interface

Which I will test in the lab real soon.

Now what I cant find for the life of me is the equilivent IPv6 commands. I have seen many ways with the dhcp-relay option, but no real good examples, using it in a VRF.

Any help would be apprecated!

Hello,

There are no such thing as IPv6 "helper" as IPv6 has no "broadcast".

http://packetpushers.net/ipv4-dhcp-vs-ipv6-dhcpv6/

If You are looking at JUNOS equivalent of HP' "ipv6 helper-address unicast" command https://www.terena.org/activities/campus-bp/pdf/gn3-na3-t4-cbpd115.pdf then DHCPv6 relay is the way to go as HP implements DHCPv6 relay via "ipv6 helper-address" CLI.

https://www.juniper.net/documentation/en_US/junos15.1/topics/concept/dhcp-extended-dhcpv6-relay-overview.html

https://www.juniper.net/techpubs/en_US/junos14.2/topics/example/subscriber-management-dhcpv6-relay-groups-vendor-option-strings-example.html

If You need to use it inside VRF, then place Your DHCPv6 replay-agent config under [edit routing-instances BLAH1 forwarding-options dhcp-relay]

HTH

Thanks

Alex

Thanks aarseniev,

At the moment I am testing IPv4 helpers (VRF aware) It works very well in the old bootp method:

routing-instances VRF-MANAGEMENT{
forwarding-options {
    helpers {
        traceoptions {
            file dhcp-relay.log;
            level all;
            flag bootp;
        }
        bootp {
            interface {
                irb.70 {
                    broadcast;
                    server 10.0.254.250 routing-instance VRF-MANAGEMENT;
                }
                irb.200 {               
                    broadcast;          
                    server 172.16.0.250 routing-instance VRF-MANAGEMENT;
                }                       
            }                           
        }                               
    }                                   
}
}

But the new way with DHCP-RELAY, doesn't work so well. One of the options we need to passthough transparently is option-82.

Depending on what you read about dhcp-relay the caveats usually say option-82 is not supported. Im not sure if this means injecting option 82 or trusing this option and relaying the option to the remote DHCP server.

Config Snippet:

 }
 routing-instances VRF-MANAGEMENT{
        forwarding-options {
            dhcp-relay {
                overrides {
                    allow-snooped-clients;
                }
                relay-option-82;
                server-group {
                    GROUP-1 {
                        172.16.0.250;
                    }
                    GROUP-2 {
                        10.0.254.250;
                    }
                }            
                group GROUP-200 {
                    active-server-group GROUP-1;
                    relay-option-82;
                    interface irb.200;
                }
                group GROUP-70 {
                    active-server-group GROUP-2;
                    relay-option-82;
                    interface irb.70;
                }
            }
        }
    }

This is all VRF aware, with two server groups as we have 2 seperate DHCP servers dishing out seperate leases for 2 subinterfaces on the CPE.

Perhaps my syntax is wrong, or perhaps dhcp-relay is dropping the requests?

labrat@CAB-GATEWAY> show dhcp relay statistics routing-instance VRF-MANAGEMENT    
Packets dropped:
    Total                      1
    No binding found           1

Messages received:
    BOOTREQUEST                134
    DHCPDECLINE                0
    DHCPDISCOVER               128
    DHCPINFORM                 0
    DHCPRELEASE                0
    DHCPREQUEST                6

Messages sent:
    BOOTREPLY                  5
    DHCPOFFER                  5
    DHCPACK                    0
    DHCPNAK                    0
    DHCPFORCERENEW             0

labrat@CAB-GATEWAY> show dhcp relay binding routing-instance VRF-MANAGEMENT       

IP address        Session Id  Hardware address   Expires     State      Interface
0.0.0.0           1           00:0c:29:06:6b:eb  0           SELECTING  irb.70