Home > Ticket 15 – IPv6 GRE Tunnel

Ticket 15 – IPv6 GRE Tunnel

April 22nd, 2018 in TSHOOT v2 Go to comments

Problem: Loopback address on R1 (2026::111:1) is not able to ping the loopback address on DSW2 (2026::102:1).

Configuration of R3:
!
interface Tunnel34
 no ip address
 ipv6 address 2026::34:1/122
 ipv6 enable
 ipv6 ospf 6 area 34
 tunnel source Serial0/0/0.34
 tunnel destination 10.1.1.10
 tunnel mode ipv6
!

Configuration of R4:
interface Tunnel34
 no ip address
 ipv6 address 2026::34:2/122
 ipv6 enable
 ipv6 ospf 6 area 34
 tunnel source Serial0/0/0
 tunnel destination 10.1.1.9
!

Answer:
Ans1) R3
Ans2) Ipv4 and Ipv6 Interoperability
Ans3) Under the interface Tunnel34, remove ‘tunnel mode ipv6’ command

Comments (28) Comments
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  1. 戦艦
    November 15th, 2017

    R3:show ipv6 ospf neighbor

  2. Greg
    December 6th, 2017

    Still valid but not able to ping 2026::1:2 from R1

  3. Fattah RazzaqghanimughnI
    January 5th, 2018

    on packet tracer lab:
    Ans1) R4
    Ans2) IPv4 and IPv6 interoperability
    Ans3) under “interface tunnel 34”, execute command “no tunnel mode”

  4. Frankie96
    January 9th, 2018

    There is no s0/0/0.34 sub interface on R4.. is the topology diag incorrect? Can networktut advise?

  5. CCNP
    January 10th, 2018

    Per JJ link:
    https://supportforums.cisco.com/t5/wan-routing-and-switching/is-tunnel-mode-a-mandatory-command-when-configuring-ipv6-tunnels/td-p/3007202

    Since : ‘tunnel mode ipv6’ is mandatory
    The tunnel will function without the tunnel mode command, but not as an IPv6 tunnel.
    Ticket is IPv6 ticket in this case.
    can network tut or any one explain if it ‘tunnel mode ipv6’ is mandatory why “remove tunnel mode” or “no tunnel mode”

  6. CCNP
    January 10th, 2018

    Will it also fix issue if add “tunnel mode ipv6” to R4? Both sites have the same configurations

  7. emk
    January 11th, 2018

    @ccnp
    no, there is no ipv6 config on r3/4 s0/0/0/34 interfaces. so you want to use v4 to transport v6

  8. CCNP
    January 13th, 2018

    Thank you emk for the explaination!!!!

  9. Test
    February 2nd, 2018

    Ticket 15 – IPv6 GRE Tunnel

    Can somebody please let me know how to identify the above TICKET ?

  10. Test
    February 3rd, 2018

    Question 1
    Gre Tunnel Header Mandatory and Optional ??
    Mandatory: Reserved0, Version, Protocol Type
    Optional: Checksum, Reserved1, Key, and Sequence Number

    Question 2
    Gre tunnel Header,which one is standard,witch one Extended? (4 Standard,2 Extended)

    Standard Header :Reserved0 , Version , Protocol Type , Checksum , Reserved1
    Extended Header : Key , Sequence Number

    For the above two DnD is there like a sequence in which we have to drop them ?

  11. Hunter
    February 9th, 2018

    @Test

    No particular sequence needed to drop. Just Drop em into the correct boxes.

  12. Hunter
    February 9th, 2018

    IPv6 tickets are on R2, R3, R4. Narrow down pinging loss and figure which two routers are not having routes..
    IPv6 Ping Plan
    R1#ping ipv6 2026::1:2 (Can you reach the R3 Area 0 interface)
    No –> IPv6 OSPF
    Yes R1# ping ipv6 2026::34:2 (Can you reach the R4 GRE tunnel interface)
    No –> IPv6 GRE Tunnel
    Yes –> IPv6 RIPng OSPFv3
    You can also determine the answer using sh ipv6 ospf nei on DSW1.
    No routes for ospf area 12 (2026::12) –> R2: IPv6 OSPF Routing
    No routes for ospf areas 12, 0, or 34 –> R3: IPv6 GRE Tunnel
    All ospf routes for areas 12, 0, & 34 –> R4: IPv6 RIPng OSPFv3 redistribution

    Or
    ipv6 ospf 6 area 0 – R2
    R1 and R2 are not ospf6 neighbors with each other, after runing sh ipv6 ospf nei. R2 has no
    interfaces in area 0. As a result, R1 will have no OI routes for area 0 (2026::1) nor 2026::34 (area 34) that connects to area 0. But DSW will have routes for area 0 (2026::1) and 2026::34 (area 34), but not area 12 (2026::12)
    IPV6 Tunnel problem – R3
    R4 has no ospf6 neighbors because the tunnel mode on R3 is not compatible. As a result
    R3 will have no redistributed routes (OE2) from the DSW Ripzone (2026::3), (2026::102), and DSW will not have any routes to the OSPF6 network area 0 (2026::1), 2026::34 (area 34), or area 12 (2026::12)
    Redistribute Ripzone into OSPF -R4
    No missing ospf neighbors but R3 has no redistributed routes (OE2) from the DSW Ripzone (2026::3), (2026::102). DSW1 will however have routes to ALL OSPF6 area 0 (2026::1), 2026::34 (area 34) and area 12 (2026::12)

  13. KUROSAWA
    February 23rd, 2018

    When show ipv6 route is done on R4, tunnel 34 is built although it is built but if it is confirmed by int tunnel 34, there is an error in the tunnel protocol and it can not be constructed. Is sh ipv6 route output error?

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    March 2nd, 2018

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  15. Rollodus
    March 15th, 2018

    Of course, again the simulator it is useless, allow me to demonstrate:
    R3:
    interface Tunnel34
    no ip address
    mtu 1476
    ipv6 address 2026::34:1/122
    ipv6 ospf 6 area 34
    tunnel source Loopback3
    tunnel destination 4.4.4.4
    tunnel mode ipv6ip

    R4:
    interface Tunnel34
    no ip address
    mtu 1476
    ipv6 address 2026::34:2/122
    ipv6 ospf 6 area 34
    tunnel source Loopback4
    tunnel destination 3.3.3.3
    tunnel mode ipv6ip

    I has nothing to do -again- with the answer– the client can ping the web server, without any fixes, it defeats the purpose from the very beginning…so what other options are there, learn by hear as a parrot???

    Sorry to say this: the guy that put together it is an IDIOT!!!!You either to a thing insanely good, or better don’t do anything that other can’t use!!!!

  16. Teddyme
    April 4th, 2018

    Thanks Networktut. I did it T_shoot ,940 scored.
    you guys almost all questions are similar to Networktu
    t but there is one new ticket in R1 . Networktut should find this and
    clear for members.

  17. Anonymous
    April 5th, 2018

    @teddyme do you remember what was the issue on R1 with the new ticket? Maybe it was old BGP issue ?

  18. Bala
    April 8th, 2018

    @Teddyme I am doing my exam tomorrow. do u remember what was the new ticket?

  19. Confuse guy
    April 17th, 2018

    @Rollodus

    calm down man. you are posting working configuration

    if you want to simulate the error exactly as the ticket pls remove this line in one of the router

    “tunnel mode ipv6ip”

    they guy that put together is NOT an idiot. he is definitely good and selfess guy LOL.

  20. CCNP2BE
    April 25th, 2018

    @Hunter, can you state whether Tipu Pasha’s strategy is effective in solving the tickets. i.e. for ticket 1, ospf issue, ping 10.1.1.1 if NO then ping 10.1.1.2 if YES then ticket one.

  21. CHILEAN
    May 14th, 2018

    INTERFACE TUNNEL 34
    IPV6 ENABLE

    IN R3 – R4

  22. 46598dasd
    May 14th, 2018

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  23. dhcp ticket
    June 6th, 2018

    guys this ticket is dhcp ticket not gre tunnel ticket.

  24. X
    June 8th, 2018

    Team, the correct answer is remove ‘tunnel mode ipv6’ under the R3’s tunnel34 configuration (R3 is the issue).

    CCNP-1000, ccnp-mx, Peter They got 1000 and they removed that command (Thank you guys). You may look for their comment in this ticket.

    Also we may identify IPv6 tickets using the following method mentioned by ‘Hopeful June 7th, 2017’

    “IPv6 Ping Plan
    R1#ping ipv6 2026::1:2 (Can you reach the R3 Area 0 interface)
    No –> IPv6 OSPF
    Yes R1# ping ipv6 2026::34:2 (Can you reach the R4 GRE tunnel interface)
    No –> IPv6 GRE Tunnel
    Yes –> IPv6 RIPng OSPFv3

    You can also determine the answer using sh ipv6 ospf nei on DSW1.
    No routes for ospf area 12 (2026::12) –> R2: IPv6 OSPF Routing
    No routes for ospf areas 12, 0, or 34 –> R3: IPv6 GRE Tunnel
    All ospf routes for areas 12, 0, & 34 –> R4: IPv6 RIPng OSPFv3 redistribution”

    *Probably he wanted to say ‘show ipv6 route’ on DSW1.

    Thank you.

  25. Neemo143
    June 30th, 2018

    @Networktut
    I am not able to use ping command for ipv6. Is this experienced by every one?

  26. Martin P
    July 3rd, 2018

    Regarding discussion about correct tunnel mode I have tried the tunnel configuration at Cisco ASR920 and the tunnel works with default „tunnel mode gre ip“. This mode is described as GRE and it can tunnel more protocols and one of them is IPV6. The „tunnel mode ipv6“ uses IPV6 as a transport protocol so it cannot work if the src/dst are IPV4 addresses as in this case.
    https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/command/ir-cr-book/ir-t2.html#wp4269279348

    ASR920#sh run all | b 111
    interface Tunnel111
    no ip address
    ipv6 address 2A00:ABCD:1:2::1/64
    ipv6 enable
    tunnel source Loopback0
    tunnel mode gre ip ! default command
    tunnel destination 192.168.8.16

    ASR920#sh interface tunnel111
    Tunnel111 is up, line protocol is up
    Hardware is Tunnel
    Tunnel source 192.168.8.197 (Loopback0), destination 192.168.8.164
    Tunnel protocol/transport GRE/IP

    ASR920#ping 2A00:ABCD:1:2::2
    Type escape sequence to abort.
    Sending 5, 100-byte ICMP Echos to 2A00:ABCD:1:2::2, timeout is 2 seconds:
    !!!!!
    Success rate is 100 percent (5/5), round-trip min/avg/max = 1/2/4 ms
    ASR920#

  27. RF
    July 18th, 2018

    How do you know if it’s ipv6 and not an ipv4 ticket? Does the test state to look at the ipv6 topology when it’s ipv6?

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