IPV6 issue to ping from Router A to C

mikecolson

Hello Geeks,
I am preparing for CCNA reading Lammle's book
I follow instruction on the book but cannot ping from Router A to Router C. See my Diagram .
If am doing process with ipv4 is ok .

IPv6 is giving me problem.
Here is configuration.
Router B has two subnets
int f0/0 is configured ipv6 address 2001:db8:3c4d:1::1/64
int f0/1 is configured ipv6 address 2001:db8:3c4d:2::1/64

Router A:i configured :
Ipv6 address autoconfig


Router C used
ipv6 address autoconfig

This IPV6 I tried to ping from router A
A#ping 2001:dB8:3C4D:2:201:42FF:FE27:5C02 Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:dB8:3C4D:2:201:42FF:FE27:5C02, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)

This ipv6 tried to ping from Router C
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2001:dB8:3C4D:1:2D0:BAFF:FEC7:2E01, timeout is 2 seconds:
.....
Success rate is 0 percent (0/5)
now ping int f0/1 of Router B is fine
c#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 100 percent (5/5), round-trip min/avg/max = 0/0/1 ms

Zhire

what is the routing table on Router B? You set a routing path for A and C. However, in this particular layout for ping, your icmp would send from Router A, Int FA0/0 to its gateway, which would need to be B, on its Fa0/0 Address. The routing Table in Router B would need to have routing entries for both A and C. This would be my next ping using a logical progression. Example Ping RA to Local loopback, next step to external f0/0 interface, next stage to Router B F0/0 (already done), at this point the next step would be to check if F0/1 on RB. From this point you have at least figure out that you have path progression to a point of failure. The final check would be obviously to ping the desired port interface on fa0/1 on RC.

Without a sim or router in front of me to determine, but I think this is the over all problem,
1. Router B needs the routing table path from A to be submitted with a Fa0/1 interface on RB
2. Router B needs the Routing table from C to be submitted with a Fa0/0 interface on Rb.

This would then tell Router B (the default gateway for both other Routers) to forward packets destined from different subnets to go out the designated interface.

Though I will obviously admit I am not a Cisco certified anything at this point.

mikecolson

What is interesting if I place static route in Router A
ipv6 destination and next hop ip{ipv6 route 2001:db8:3c4d:2::/64 2001:db8:3c4D:1::1 }
and Router C
ipv6 destination and next hop ip{ipv6 route 2001:db8:3c4D:1::/64 2001:db8:3c4d:2::1 }
They work, they can ping each other .

if I use like this
ipv6 destination and exit interface{ipv6 route 2001:db8:3c4d:2::/64 f0/0 }
and Router C
ipv6 destination and exit interface{ipv6 route 2001:db8:3c4D:1::/64 f0/1 }
Not working.
When I read the book it said :
use exit interface or next hop ip address
Related to router B they are both connected so I shouldn't enter static.

EdTheLad

So the question is "Why does a route to exit interface" not work in ipv6? Or another question "how does a route to interface work in ipv4?".

R1

---

R2

---

R3(100.100.100.100)
eth0/0 eth0/0
192.168.1.x

A packet arrives on R1, router looks in rib, rib points to exit interface, router must now encapsulate the packet to send out over ethernet to R2.
Router needs to know destination mac, so it sends an arp request to R2 for 100.100.100.100, this ip is not local to R2 eth0/0 so it will not reply with a mac....unless proxy arp is enabled on R2 eth0/0.

So you would need IPv6 proxy arp equivalent "Proxy NDP" enabled on R2 eth0/0. Not sure if its supported on cisco.