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Default ipv6 loopback address, lo0.0 question!!!!

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  • 1.  Default ipv6 loopback address, lo0.0 question!!!!

    Posted 11-13-2018 21:13

    I have setup my loopback, it works fine. I let the SRX allocate the address for starters

    just to see what it produced. This is fine because it is best to let loopback do its own

    work as far as the SRX is concerned. This question is only about the address it alots

    by itself. It isnt about what i have added.




    I want to make the address that it allocates automatically, into a static address, for obvious reasons.


    My question is this.


    Is the prefix a /64 , /128 or what? Im not worried about a real detailed explanation but

    i'd like to know how it decides this. Is it route driven(/64)? My config is all /64 except

    where /128 is needed such as ndp-proxy and others. Is it loopback(64 or higher) driven?

    It isnt a /128 most likely because the default loopback ipv6 is obviously ::1/128 .


    Here is my output....

    It is the second to last line in the command output.

    It is a local address on the SRX.


    xxxxxx@MySRX240> show interfaces lo0.0 extensive
      Logical interface lo0.0 (Index 67) (SNMP ifIndex 16) (Generation 132)
        Flags: SNMP-Traps Encapsulation: Unspecified
        Traffic statistics:
         Input  bytes  :                    0
         Output bytes  :                    0
         Input  packets:                    0
         Output packets:                    0
        Local statistics:
         Input  bytes  :                    0
         Output bytes  :                    0
         Input  packets:                    0
         Output packets:                    0
        Security: Zone: trust
        Allowed host-inbound traffic : bootp bfd bgp dns dvmrp igmp ldp msdp nhrp ospf ospf3 pgm pim rip ripng
        router-discovery rsvp sap vrrp dhcp finger ftp tftp ident-reset http https ike netconf ping reverse-telnet
        reverse-ssh rlogin rpm rsh snmp snmp-trap ssh telnet traceroute xnm-clear-text xnm-ssl lsping ntp sip dhcpv6 r2cp
        Flow Statistics :
        Flow Input statistics :
          Self packets :                     0
          ICMP packets :                     0
          VPN packets :                      0
          Multicast packets :                0
          Bytes permitted by policy :        0
          Connections established :          0
        Flow Output statistics:
          Multicast packets :                0
          Bytes permitted by policy :        0
        Flow error statistics (Packets dropped due to):
          Address spoofing:                  0
          Authentication failed:             0
          Incoming NAT errors:               0
          Invalid zone received packet:      0
          Multiple user authentications:     0
          Multiple incoming NAT:             0
          No parent for a gate:              0
          No one interested in self packets: 0
          No minor session:                  0
          No more sessions:                  0
          No NAT gate:                       0
          No route present:                  0
          No SA for incoming SPI:            0
          No tunnel found:                   0
          No session for a gate:             0
          No zone or NULL zone binding       0
          Policy denied:                     0
          Security association not active:   0
          TCP sequence number out of window: 0
          Syn-attack protection:             0
          User authentication errors:        0
        Protocol inet, MTU: Unlimited, Generation: 144, Route table: 0
          Flags: Sendbcast-pkt-to-re
          Addresses, Flags: None
            Destination: Unspecified, Local:, Broadcast: Unspecified, Generation: 142
        Protocol inet6, MTU: Unlimited, Generation: 145, Route table: 0
          Flags: None
          Addresses, Flags: Primary Preferred
            Destination: Unspecified, Local: ::1
        Generation: 144
          Addresses, Flags: Preferred Is-Default Is-Preferred Is-Primary
            Destination: 800:4156:1545:800d::/80, Local: 800:4156:1545:800d::1
        Generation: 146
          Addresses, Flags: Preferred Is-Preferred
            Destination: 1000:82ab::/112, Local: 1000:82ab::1
        Generation: 148
          Addresses, Flags: Preferred Is-Preferred
            Destination: 1800::/96, Local: 1800::1
        Generation: 150
            Destination: Unspecified, Local: fe80::2a8a:1c0f:fc40:1500
        Generation: 152



    Your answers are greatly appreciated.....

  • 2.  RE: Default ipv6 loopback address, lo0.0 question!!!!
    Best Answer

    Posted 11-14-2018 00:05


    It is IPv6 link local address which is created by default whenever you enable IPv6 on a interface. The address block fe80::/10 has been reserved for link-local unicast addressing. The complete address is derived from the MAC address of the Management interface (Hig End SRX) or the first interface (Branch SRX) (eg: ge-0/0/0) and inserting 0f:fc in between the 3 octets of the MAC address.