This topic is to discuss the following lesson:
Hello,
please help me with IPv6 default route.
for example:
Futura(config)#ipv6 route ::/0 fastEthernet 0/0 FE80::CE0A:22FF:FED5:0
so ::/0 means, any address, where must match 0 bytes.
Is my example of default route correct?
Thank you
Hi,
Using ::/0 for the default route is correct. The :: part means all 0s and the /0 represents the network mask, not the bytes.
Rene
1 Like
Hello Rene,
Thanks alot for your amazing way to explain this.
I have a question, how did you get the address FE80::CE0A:22FF:FED5:0
is it any address start with FE80 (link local) or what? I did not get it.
Thanks in advance
Wisam
Hi Wisam,
Everything that starts with FE80::/10 is a link-local address. The remaining part of the address was generated with EUI-64. This article will help:
Rene
Hello Rene,
Thanks alot for your reply.
I still did not get how you get it to write it in your command line below,
“Futura(config)#ipv6 route 2001::2/128 fastEthernet 0/0 FE80::CE0A:22FF:FED5:0”
where we can find it? do we have to use show command before we add this line.
Thanks Rene
Wisam
Hi Wisam,
You can lookup the link-local address of the router with the “show ipv6 int brief” command.
Rene
awesome lesson rene! question, you said that when making a static route we can use any ip address, but if we use link local address, we need to specify the outgoing interface, so meaning, if i use the global unicast address on static route, i will not need the outgoing interface? basically it will contain only ?
Thanks John. When you use a link local address as the next hop then you have to include the interface.
When you use a global unicast address as the next hop then that’s all you need…you don’t have to add the interface.
Dear Rene,
My scenario I created a loopback interface in R1 as well as R2 and created a static route in R1 with the following command.
IOU1(config)#ipv route 2001:2::/64 e0/0 FE80::A8BB:CCFF:FE00:300
Router 1 routing table.
IOU1#show ipv route
C 2001:1::/64 [0/0]
via Loopback0, directly connected
L 2001:1::1/128 [0/0] (<em>the additional loopback created</em>)
via Loopback0, receive
S 2001:2::/64 [1/0]
via FE80::A8BB:CCFF:FE00:300, Ethernet0/0
L FF00::/8 [0/0]
via Null0, receive
R2 Routing Table.
IOU2#sho ipv route
<em><strong>ND ::/0 [2/0]</strong></em>
<em><strong> via FE80::A8BB:CCFF:FE00:200, Ethernet0/0</strong></em>
C 2001:2::/64 [0/0]
via Loopback0, directly connected
L 2001:2::1/128 [0/0]
via Loopback0, receive (<em>R2 loopback</em>)
L FF00::/8 [0/0]
via Null0, receive
Â
How the default route is added to the routing table of Router 2, but the same is missing or not shown in R1
ND ::/0 [2/0]
via FE80::A8BB:CCFF:FE00:200, Ethernet0/0
The ND entry is a default route that was learned through neighbor discovery (router advertisement).
1 Like
Hi Rene
In the static route statement you used “ipv6 route 2001::2/128 fastEthernet 0/0 FE80::CE0A:22FF:FED5:0”, which router’s Link Local IPV6 address is this?
Thanks
Palani
Hello Palaniappan.
The “ipv6 route 2001::2/128 fastEthernet 0/0 FE80::CE0A:22FF:FED5:0” command uses the link local IP address of the FastEthernet 0/0 interface of the Destiny router. You can determine this IP address by issuing the the “show ipv6 int brief” command on the Destiny router.
I hope this has been helpful!
Laz
I am having trouble routing between ipv6 routers. I created a lab with 3 routers as follows. Router A with f0/0 ipv6 autoconfig and router B with f0/0 autoconfig. Router C has 2 interfaces f0/0 and f0/1. Router A has ipv6 address autoconfig off f0/0 of Router C and Router B has ipv6 address auto config off f0/1 of Router C. Static routing is configured on both router A and B. However I can’t ping from router A to Router B and vice versa. What could be wrong.?
Below is my config
Router B routing table 'S 2001:DB8:124:71::/64 [1/0]
via ::, FastEthernet0/0
C 2001:DB8:124:72::/64 [0/0]
via ::, FastEthernet0/0
L 2001:DB8:124:72:C608:6FF:FEDD:0/128 [0/0]
via ::, FastEthernet0/0
L FE80::/10 [0/0]
via ::, Null0
L FF00::/8 [0/0]
via ::, Null0 '
-
Router A routing table info ' S ::/0 [1/0]
via ::, FastEthernet0/0
C 2001:DB8:124:71::/64 [0/0]
via ::, FastEthernet0/0
L 2001:DB8:124:71:C606:6FF:FE45:0/128 [0/0]
via ::, FastEthernet0/0
L FE80::/10 [0/0]
via ::, Null0
L FF00::/8 [0/0]
via ::, Null0'
-
Router C config. `router_c#show ipv6 int brief | exclude down
FastEthernet0/0 [up/up]
FE80::C607:6FF:FEC4:0
2001:DB8:124:71::1
FastEthernet0/1 [up/up]
FE80::C607:6FF:FEC4:1
2001:DB8:124:72::1`Could you give the output for A and B the same way you did for C (show ipv6 int brief). Could you also give a show run int fa0/0 and fa0/1 for each?
My first thought is whether you have “ipv6 enable” set on A and B. I notice that link-local routes seem to be missing from these.
Please don’t mind the config looks a little different. I am using GNS3 at home and at the office I have packet tracer installed. But my configuration is almost indentical and I have the exact same problem. At first I thought it was a packet tracer limitation but I used GNS3 at home and encountered the same problem. Usually when I am doing labs I like to get all my lab exercises working before I move on to another issue. I work a problem until I solve it unless it can’t be solved. So I am willing to learn maybe I am missing something and you guys can point me in the right direction.
So Andrew according to what you ask see below my outputs plus additional details.
A#show ipv6 int brief
GigabitEthernet0/0 [up/up]
FE80::240:BFF:FEEA:9201
2001:DB8:3C4D:1:240:BFF:FEEA:9201
show run...
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address autoconfig
ipv6 enable
-
A#show ipv6 route
IPv6 Routing Table - 4 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route, M - MIPv6
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
D - EIGRP, EX - EIGRP external
S ::/0 [1/0]
via GigabitEthernet0/0, receive
C 2001:DB8:3C4D:1::/64 [0/0]
via GigabitEthernet0/0, directly connected
L 2001:DB8:3C4D:1:240:BFF:FEEA:9201/128 [0/0]
via GigabitEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
-
B#show ipv6 int brief
GigabitEthernet0/0 [up/up]
FE80::230:A3FF:FEA1:4201
2001:DB8:3C4D:1:230:A3FF:FEA1:4201
show run...
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address autoconfig
-
B#show ipv6 route
IPv6 Routing Table - 4 entries
Codes: C - Connected, L - Local, S - Static, R - RIP, B - BGP
U - Per-user Static route, M - MIPv6
I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary
O - OSPF intra, OI - OSPF inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2
ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2
D - EIGRP, EX - EIGRP external
C 2001:DB8:3C4D:1::/64 [0/0]
via GigabitEthernet0/0, directly connected
L 2001:DB8:3C4D:1:230:A3FF:FEA1:4201/128 [0/0]
via GigabitEthernet0/0, receive
S 2001:DB8:3C4D:2::/64 [1/0]
via GigabitEthernet0/0, receive
L FF00::/8 [0/0]
via Null0, receive
-
C#show ipv6 int brief
GigabitEthernet0/0 [up/up]
FE80::201:96FF:FE01:6D01
2001:DB8:3C4D:1::1
GigabitEthernet0/1 [up/up]
FE80::201:96FF:FE01:6D02
2001:DB8:3C4D:2::1
show run...
!
interface GigabitEthernet0/0
no ip address
duplex auto
speed auto
ipv6 address 2001:DB8:3C4D:1::1/64
ipv6 enable
!
interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
ipv6 address 2001:DB8:3C4D:2::1/64
ipv6 enable
Here my result trying to ping to D.
B#ping 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Here’s trying to ping from B to g0/1 on router C
B#ping 2001:DB8:3C4D:2::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:3C4D:2::1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
Here’s D config.
D#show ipv6 int brief
GigabitEthernet0/0 [up/up]
FE80::2E0:F7FF:FE42:A001
2001:DB8:3C4D:2:2E0:F7FF:FE42:A001
Here’s the debug info from router C
C#*Mar 9 20:04:34.192: ICMPv6-ND: Received NS for 2001:DB8:3C4D:2::1 on GigabitEthernet0/0 from 2001:DB8:3C4D:1:230:A3FF:FEA1:4201
*Mar 9 20:04:36.194: ICMPv6-ND: Received NS for 2001:DB8:3C4D:2::1 on GigabitEthernet0/0 from 2001:DB8:3C4D:1:230:A3FF:FEA1:4201
*Mar 9 20:04:38.195: ICMPv6-ND: Received NS for 2001:DB8:3C4D:2::1 on GigabitEthernet0/0 from 2001:DB8:3C4D:1:230:A3FF:FEA1:4201
*Mar 9 20:04:40.544: ICMPv6-ND: Received NS for 2001:DB8:3C4D:2::1 on GigabitEthernet0/0 from 2001:DB8:3C4D:1:230:A3FF:FEA1:4201
*Mar 9 20:04:42.550: ICMPv6-ND: Received NS for 2001:DB8:3C4D:2::1 on GigabitEthernet0/0 from 2001:DB8:3C4D:1:230:A3FF:FEA1:4201
*Mar 9 20:04:44.560: ICMPv6-ND: Received NS for 2001:DB8:3C4D:2::1 on GigabitEthernet0/0 from 2001:DB8:3C4D:1:230:A3FF:FEA1:4201
Similarly Router D trying to ping to Router C’s G0/0 interface
D#ping 2001:DB8:3C4D:1::1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:DB8:3C4D:1::1, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
*Mar 9 20:09:27.955: ICMPv6-ND: Received NS for 2001:DB8:3C4D:1::1 on GigabitEthernet0/1 from 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001
*Mar 9 20:09:29.954: ICMPv6-ND: Received NS for 2001:DB8:3C4D:1::1 on GigabitEthernet0/1 from 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001
*Mar 9 20:09:31.956: ICMPv6-ND: Received NS for 2001:DB8:3C4D:1::1 on GigabitEthernet0/1 from 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001
*Mar 9 20:09:34.317: ICMPv6-ND: Received NS for 2001:DB8:3C4D:1::1 on GigabitEthernet0/1 from 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001
*Mar 9 20:09:36.320: ICMPv6-ND: Received NS for 2001:DB8:3C4D:1::1 on GigabitEthernet0/1 from 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001
*Mar 9 20:09:38.332: ICMPv6-ND: Received NS for 2001:DB8:3C4D:1::1 on GigabitEthernet0/1 from 2001:DB8:3C4D:2:2E0:F7FF:FE42:A001First, let me say that I built this (I ignored router D, and just did an A-B-C triangle), and it worked fine. Obviously, this topology is different from the first one you asked about, so let’s keep our references the same from here out.
I am suspicious of your IPv6 global addresses. Here’s a break down from your output above:
A:
2001:DB8:3C4D:1:240:BFF:FEEA:9201
B:
2001:DB8:3C4D:1:230:A3FF:FEA1:4201
C
0/0
2001:DB8:3C4D:1::1/64
0/1
2001:DB8:3C4D:2::1/64
It appears to me that A and B both have 2001 addresses on the same /64 subnet, while C is using addresses on different subnets on Gig0/0 and Gig0/1. You see how Gig0/1 is using :2::/64, while everything else is using :1::/64? What’s going on there?
When A wants to contact B, it will believe it is on the same subnet, so it will try to do neighbor discovery on its own network segment instead of going through its gateway (router C).
Well as far as I understand and you can correct me as I am teachable, Router A, B and C’s G0/0 are on the same subnet. My understanding is that the subnet address is 2001:db8:3c4d:1::/64 for everything left of router C. and for the right side is 2001:db8:3c4d:2::/64 which is a different subnet. BTW I didn’t make this up I took this from a lab exercise question on IPV6 chapter, so maybe the whole problem question is incorrect. Router A and B are using EUI-64 addresses. Does it mean that because Router C’s interfaces are not using EUI-64 addresses that the subnet is different and that is where the problem is? BTW I even added ipv4 addresses into the mix and was able to route without any issues. So maybe something is up with the ipv6 addresses. I will await your clarification re what I have shared as far as my understanding goes. Thanks for your feedback.
It would be helpful if you could take a picture of the lab’s diagram and attach it so I could see the layout–obviously my first assumption about the topology was incorrect!
Here’s the image layout.
