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  • 1.  Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 02-26-2021 13:49
    I have two vMX routers with GRE connection.

    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 tunnel source 172.30.15.3
    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 tunnel destination 172.30.15.1
    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 family inet address 172.30.0.130/30
    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 family inet6 address fd17:f0f4:f691:3::6/126

    set interfaces gr-0/0/10 unit 0 tunnel source 172.30.15.1
    set interfaces gr-0/0/10 unit 0 tunnel destination 172.30.15.3
    set interfaces gr-0/0/10 unit 0 family inet address 172.30.0.129/30
    set interfaces gr-0/0/10 unit 0 family inet6 address fd17:f0f4:f691:3::5/126

    GRE works fine.
    On both routers, I have ospf3 configurations as follows:

    root@SRX1-ISP1# show | display set | match ospf3 | match gr-0/0
    set protocols ospf3 realm ipv4-unicast area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p
    set protocols ospf3 area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p

    root@SRX3-SRX4# show logical-systems | display set | match ospf3 | match gr-0/0
    set logical-systems SRX3 protocols ospf3 realm ipv4-unicast area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p
    set logical-systems SRX3 protocols ospf3 area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p

    I got the following from traceoptions:

    Feb 26 08:26:09.608565 OSPF rcvd Hello fe80::200:0:2800:0 -> ff02::5 (gr-0/0/10.0 IFL 340 area 0.0.0.3)

    Feb 26 08:26:09.608571   Version 3, length 36, ID 172.30.15.3, area 0.0.0.3

    Feb 26 08:26:09.608575   checksum 0x0, instance-id 0

    Feb 26 08:26:09.608587   intf_id 0.0.0.5, prio 128, opts 0x13, hello_ivl 10

    Feb 26 08:26:09.608591   dead_ivl 40, DR 0.0.0.0, BDR 0.0.0.0

    Feb 26 08:26:09.608609 OSPF packet ignored: our interface address is source address fe80::200:0:2800:0 on intf gr-0/0/10.0 area 0.0.0.3

    Feb 26 08:26:11.623628 task_process_events: recv ready for OSPF3 I/O./var/run/ppmd_control

    Feb 26 08:26:11.623680 task_process_events: recv ready for OSPF3 I/O./var/run/ppmd_control

    Feb 26 08:26:11.623696 task_timer_uset: timer OSPF3 I/O./var/run/ppmd_control_PPM Hold <Touched> set to offset 2:00 at 8:28:11.623680

    Feb 26 08:26:11.623719 Received OSPF packet of type and wire_length 1, 40

     

    root@SRX3-SRX4# run show interfaces gr-0/0/10 terse

    Interface               Admin Link Proto    Local                 Remote

    gr-0/0/10               up    up

    gr-0/0/10.0             up    up   inet     172.30.0.130/30

                                       inet6    fd17:f0f4:f691:3::6/126

                                                fe80::200:0:2800:0/64

     

    root@SRX1-ISP1# run show interfaces gr-0/0/10 terse

    Interface               Admin Link Proto    Local                 Remote

    gr-0/0/10               up    up

    gr-0/0/10.0             up    up   inet     172.30.0.129/30

                                       inet6    fd17:f0f4:f691:3::5/126

                                                fe80::200:0:2800:0/64

    I noticed both link-local addresses are the same. Do you think I need to manually configure link-local address on gre itnerfaces ?

    thanks in advance !!!



  • 2.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 02-28-2021 07:27
    The link local addresses are only used by the local link devices that are connected.  So they are locally agreed upon and it makes no difference if they are reused in other parts of the network.

    ------------------------------
    Steve Puluka BSEET - Juniper Ambassador
    IP Architect - DQE Communications Pittsburgh, PA (Metro Ethernet & ISP)
    http://puluka.com/home
    ------------------------------



  • 3.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 02-28-2021 08:56
    From the traceoption,  GRE tunnel should be OK, right?

    172.10.0.129 and 172.10.0.130 are locally linked via GRE,  they should have different link-local addresses normally, right ?

    In my understanding,  the OSPF complains the source IP is the same as the local IP, right ?

    thank so much for your help !!!


  • 4.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 03-05-2021 10:49
    Yes, OSPF3 use the link local address to exchange packets.  If you check the OSPF3 adjacency it is down, right? 
    It's like trying to create an OSPFv2 adjacency between two routers with the same IP address. 

    Regards,


  • 5.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 03-05-2021 19:10
    thanks so so much !!


  • 6.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 03-05-2021 22:43
    I tested it again and could not figure it out.  I am not quite understanding what you mean "It's like trying to create an OSPFv2 adjacency between two routers with the same IP address. "

    thanks for coaching !!



  • 7.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 03-05-2021 23:05
    I manually configured link-local address on one site, the OSPFv3 neighbor is up.
    Not sure whether this is a right way.

    thanks !!!


  • 8.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 03-05-2021 22:38
    I have a GRE tunnel between two vMX routers.  I need to configure OSPFv3 over GRE tunnel.

    On R1
    set interfaces gr-0/0/10 unit 0 tunnel source 172.30.15.1
    set interfaces gr-0/0/10 unit 0 tunnel destination 172.30.15.3
    set interfaces gr-0/0/10 unit 0 family inet address 172.30.0.130/30
    set interfaces gr-0/0/10 unit 0 family inet6
    set protocols ospf3 realm ipv4-unicast area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p
    set protocols ospf3 area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p

    On R3
    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 tunnel source 172.30.15.3
    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 tunnel destination 172.30.15.1
    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 family inet address 172.30.0.129/30
    set logical-systems SRX3 interfaces gr-0/0/10 unit 0 family inet6
    set logical-systems SRX3 protocols ospf3 realm ipv4-unicast area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p
    set logical-systems SRX3 protocols ospf3 area 0.0.0.3 interface gr-0/0/10.0 interface-type p2p

    The neighbor is not established. After checking traceroute, it complains the remote IP is the same as the local IP.

    root@SRX1# run show interfaces gr-0/0/10 terse
    Interface Admin Link Proto Local Remote
    gr-0/0/10 up up
    gr-0/0/10.0 up up inet 172.30.0.130/30
    inet6 fe80::200:0:2800:0/64


    root@SRX3-SRX4# run show interfaces gr-0/0/10 terse
    Interface Admin Link Proto Local Remote
    gr-0/0/10 up up
    gr-0/0/10.0 up up inet 172.30.0.129/30
    inet6 fe80::200:0:2800:0/64

    Do you think this is limitation for vMX image ?   GRE for ospfv2 does not have any issue.  OSPFv3 needs IPv6 address. it uses link-local address to establish the neighbor. So I am stuck here.

    I did multiple times and got the same result.  I like to take Juniper Lab Exam. I do not know how to handle this if I come across it.

    Really appreciate any insights in advance !!







  • 9.  RE: Need assistance for GRE tunnel interface IPv6 link-local address
    Best Answer

    Posted 03-06-2021 21:09
    Edited by gongyayu 03-06-2021 22:51
    This is what I was saying: 

    You are configuring the IPv4 addresses explicitly and they are unique.  If you configured OSPFv2 the adjacency would come up.  If you misconfigured the IPs and use the same on both ends, the adjacency would fail. 
     
    Same requirements exists for OSPFv3, but the addresses used for communication, regardless of whether the routes are V4 or V6 is the link-local address (IPv6) addresses. 

    Since you are NOT configuring the link local addresses manually, the routers are autoconfiguring them using the MAC address of the gre interfaces. (I used 0123:4567:89AB in my example below). 
      


    Since you are using vMX, my guess is that you created one instance, saved it as a template, and then used it to create the next one (or something like that). This can cause the two instances to have the same MAC addresses (I've had my own headaches with this!). That is why you need to manually configure the link local address, at least on one end, to make sure they are unique. Optionally, you can manually configure the MAC addresses. 

    Regards, 


  • 10.  RE: Need assistance for GRE tunnel interface IPv6 link-local address

    Posted 03-06-2021 22:53
    WOW, thanks a million !!