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SRX340 DHCPv6 clients options limitations ?

  • 1.  SRX340 DHCPv6 clients options limitations ?

    Posted 04-22-2022 14:52
    Hello,

    I'm trying to set some custom DHCP options using the DHCP Client for IPv6 and it seems that they are some limitation on the length of the hex-string value ? Release 22.1R1.10 (so the latest).
    This is my interface :
     ge-0/0/5 {
    	vlan-tagging;
    	unit 0 {
    		vlan-id 832;
    		family inet {
    			dhcp {
    				no-dns-install;
    				vendor-id sagem;
    				options {
    					number 77 hex-string 2946535644534c5f6c697665626f782e496e7465726e65742e736167656d2e4c697665626f7850726f33;
    					number 90 hex-string 0000000000000000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff;
    				}
    			}
    		}
    		family inet6 {
    			dhcpv6-client {
    				client-type stateful;
    				client-ia-type ia-pd;
    				client-identifier duid-type duid-llt;
    				options {
    					number 11 hex-string 0000000000000000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff;
    					number 15 hex-string 002946535644534c5f6c697665626f782e496e7465726e65742e736167656d2e4c697665626f7850726f33;
    					number 16 hex-string 0000040e0005736167656d;
    				}
    				no-dns-install;
    				update-router-advertisement {
    					interface ge-0/0/5.0;
    				}
    			}
    		}
    	}
    }​

    Capturing the DHCP request using wireshark, I can see the option 90 on DHCPv4 that is correct with the hex-string provided.
    The DHCPv6 request does NOT include the option 11 though. It seems that there is some limitation to the length of the hex-string, because if I config :
     ge-0/0/5 {
    	vlan-tagging;
    	unit 0 {
    		vlan-id 832;
    		family inet {
    			dhcp {
    				no-dns-install;
    				vendor-id sagem;
    				options {
    					number 77 hex-string 2946535644534c5f6c697665626f782e496e7465726e65742e736167656d2e4c697665626f7850726f33;
    					number 90 hex-string 0000000000000000000000ffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff;
    				}
    			}
    		}
    		family inet6 {
    			dhcpv6-client {
    				client-type stateful;
    				client-ia-type ia-pd;
    				client-identifier duid-type duid-llt;
    				options {
    					number 11 hex-string 0000000000000000000000fffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff;
    					number 15 hex-string 002946535644534c5f6c697665626f782e496e7465726e65742e736167656d2e4c697665626f7850726f33;
    					number 16 hex-string 0000040e0005736167656d;
    				}
    				no-dns-install;
    				update-router-advertisement {
    					interface ge-0/0/5.0;
    				}
    			}
    		}
    	}
    }​

    this time the option 11 is included on the DHCPv6 request. Adding anything more to the hexstring and the option disappear.

    Does anybody have any explanation ? I do need to send the correct option11 so my ISP respond to my DHCP request (otherwise it is ignored).

    Regards,

    ------------------------------
    Francois Miermont
    ------------------------------