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IPv6 ND Issues?

jim_r
Level 1
Level 1

‎02-19-2024 08:54 AM

Greetings.

I have a simple set up consisting of a Cisco 4321 router, 2960 switch, and a Windows 11 host.

The router is running IOS XE 16.6.4 and the switch is IOS 15.5(2).

The router and switch are configured for IPv6, and the host (eventually) gets an IPv6 GUA, but can never ever ping the router's GUA or the switches GUA.

The router is configured for ipv6 unicast-routing. Here is the router configuration for the relevant interfaces:

 

 

 

!
interface GigabitEthernet0/0/0.224
 description HOST_SUPPORT
 encapsulation dot1Q 224
 ip address 180.11.3.129 255.255.255.128
 ipv6 address FE80::1 link-local
 ipv6 address 2001:1824:11:224::1/64
!
interface GigabitEthernet0/0/0.226
 description MGMT_NETWORK
 encapsulation dot1Q 226
 ip address 180.11.4.1 255.255.255.192
 ipv6 address FE80::1 link-local
 ipv6 address 2001:1824:11:226::1/64
end

 

 

 

and here is the config on the switch (SDM is set to dual default):

 

 

 

interface Vlan226
 ip address 180.11.4.2 255.255.255.192
 ipv6 address FE80::2 link-local
 ipv6 address 2001:1824:11:226::2/64
end

 

 

 

Obviously the intent is to use SLAAC. The host receives the RA and builds both a permanent and a temporary GUA. The host is never able to ping the GUA or LLA of the router or the GUA of switch. Attempts to ping the router at 2001:1824:11:224::1 receive Destination Host Unreachable. Pings to fe80::1 receive Request Timed Out. Pings to the GUA of the switch (2001:1824:11:226::2) receive Request Timed Out.

The switch can ping the router (226::1 and 224::1), but cannot ping the host (permanent or temporary IPv6 GUA).

What's odd is the router is not keeping the host in it's ND cache. The RS/RA process works, since the host is creating an address from the correct prefix, but then the host's entry in the neighbor table just.. goes away. Here is the output of debug ipv6 nd and show ipv6 neighbors after I issue the ipconfig /renew6 command on the host:

 

 

 

r11#
r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         3 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     3 3473.2d25.6e41  STALE Gi0/0/0.226

r11#debug ipv6 nd
  ICMP Neighbor Discovery events debugging is on
  ICMP ND HA events debugging is ON
r11#
*Feb 17 22:44:05.329: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Received RS
*Feb 17 22:44:05.329: ICMPv6-ND: Validating ND packet options: valid
*Feb 17 22:44:05.329: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Glean
*Feb 17 22:44:05.329: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) LLA cc96.e51b.ac2a
*Feb 17 22:44:05.329: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) INCMP -> STALE
*Feb 17 22:44:05.330: ICMPv6-ND: (GigabitEthernet0/0/0.224) Sending solicited RA
*Feb 17 22:44:05.330: ICMPv6-ND: (GigabitEthernet0/0/0.224) The interface media type supports ND resolution.
r11#
*Feb 17 22:44:05.330: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) send RA to FF02::1
*Feb 17 22:44:05.330: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) Sending RA (1800) to FF02::1
*Feb 17 22:44:05.330: ICMPv6-ND:   MTU = 1500
*Feb 17 22:44:05.330: ICMPv6-ND:   prefix 2001:1824:11:224::/64 [LA] 2592000/604800
*Feb 17 22:44:05.856: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) Received NS from FE80::5BD5:A9B8:693D:348C
*Feb 17 22:44:05.856: ICMPv6-ND: Validating ND packet options: valid
*Feb 17 22:44:05.856: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) Sending NA to FE80::5BD5:A9B8:693D:348C
r11#
*Feb 17 22:44:05.857: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) STALE -> DELAY
r11#show ipv6 nei
*Feb 17 22:44:10.917: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) DELAY -> PROBE
*Feb 17 22:44:10.917: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#show ipv6 nei
*Feb 17 22:44:11.943: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#show ipv6 nei
*Feb 17 22:44:12.969: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#debug ipv6 nd
*Feb 17 22:44:13.994: ICMPv6-ND: PROBE deleted: FE80::5BD5:A9B8:693D:348C
*Feb 17 22:44:13.994: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) PROBE -> DELETE
*Feb 17 22:44:13.996: ICMPv6-ND:  Remove ND cache entry
r11#             
r11#
r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         3 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     3 3473.2d25.6e41  STALE Gi0/0/0.226

r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         3 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     3 3473.2d25.6e41  STALE Gi0/0/0.226

r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         3 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     3 3473.2d25.6e41  STALE Gi0/0/0.226

r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         3 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     3 3473.2d25.6e41  STALE Gi0/0/0.226

r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         3 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     4 3473.2d25.6e41  STALE Gi0/0/0.226

r11#
*Feb 17 22:45:05.840: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) Received NS from FE80::5BD5:A9B8:693D:348C
*Feb 17 22:45:05.840: ICMPv6-ND: Validating ND packet options: valid
*Feb 17 22:45:05.840: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Glean
*Feb 17 22:45:05.840: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) LLA cc96.e51b.ac2a
*Feb 17 22:45:05.840: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) INCMP -> STALE
*Feb 17 22:45:05.841: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) Sending NA to FE80::5BD5:A9B8:693D:348C
r11#
*Feb 17 22:45:05.841: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) STALE -> DELAY
r11#
*Feb 17 22:45:10.902: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) DELAY -> PROBE
*Feb 17 22:45:10.903: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#
*Feb 17 22:45:11.992: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#
*Feb 17 22:45:13.082: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#
r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         4 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     4 3473.2d25.6e41  STALE Gi0/0/0.226

r11#
*Feb 17 22:45:14.171: ICMPv6-ND: PROBE deleted: FE80::5BD5:A9B8:693D:348C
*Feb 17 22:45:14.171: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) PROBE -> DELETE
*Feb 17 22:45:14.172: ICMPv6-ND:  Remove ND cache entry
r11#
r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         4 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     4 3473.2d25.6e41  STALE Gi0/0/0.226

r11#
r11#
*Feb 17 22:45:48.711: ICMPv6-ND: (GigabitEthernet0/0/0.101,FE80::1) send RA to FF02::1
*Feb 17 22:45:48.711: ICMPv6-ND: (GigabitEthernet0/0/0.101,FE80::1) Sending RA (1800) to FF02::1
*Feb 17 22:45:48.711: ICMPv6-ND:   MTU = 1500
*Feb 17 22:45:48.711: ICMPv6-ND:   prefix 2001:1824:11:101::/64 [LA] 2592000/604800
r11#
r11#
r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         5 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     5 3473.2d25.6e41  STALE Gi0/0/0.226

r11#
*Feb 17 22:46:05.057: ICMPv6-ND: (GigabitEthernet0/0/0.30,FE80::1) send RA to FF02::1
*Feb 17 22:46:05.058: ICMPv6-ND: (GigabitEthernet0/0/0.30,FE80::1) Sending RA (1800) to FF02::1
*Feb 17 22:46:05.058: ICMPv6-ND:   MTU = 1500
*Feb 17 22:46:05.058: ICMPv6-ND:   prefix 2001:1824:11:30::/64 [LA] 2592000/604800
*Feb 17 22:46:05.874: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) Received NS from FE80::5BD5:A9B8:693D:348C
*Feb 17 22:46:05.874: ICMPv6-ND: Validating ND packet options: valid
*Feb 17 22:46:05.874: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Glean
r11#
*Feb 17 22:46:05.874: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) LLA cc96.e51b.ac2a
*Feb 17 22:46:05.874: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) INCMP -> STALE
*Feb 17 22:46:05.875: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::1) Sending NA to FE80::5BD5:A9B8:693D:348C
*Feb 17 22:46:05.877: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) STALE -> DELAY
r11#
*Feb 17 22:46:10.937: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) DELAY -> PROBE
*Feb 17 22:46:10.937: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#
*Feb 17 22:46:12.030: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#
*Feb 17 22:46:13.119: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) Sending NS
r11#
r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         5 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     5 3473.2d25.6e41  STALE Gi0/0/0.226

r11#
*Feb 17 22:46:14.211: ICMPv6-ND: PROBE deleted: FE80::5BD5:A9B8:693D:348C
*Feb 17 22:46:14.211: ICMPv6-ND: (GigabitEthernet0/0/0.224,FE80::5BD5:A9B8:693D:348C) PROBE -> DELETE
*Feb 17 22:46:14.211: ICMPv6-ND:  Remove ND cache entry
r11#
*Feb 17 22:46:15.236: ICMPv6-ND: (GigabitEthernet0/0/0.201,FE80::1) send RA to FF02::1
*Feb 17 22:46:15.237: ICMPv6-ND: (GigabitEthernet0/0/0.201,FE80::1) Sending RA (1800) to FF02::1
*Feb 17 22:46:15.237: ICMPv6-ND:   MTU = 1500
*Feb 17 22:46:15.237: ICMPv6-ND:   prefix 2001:1824:11:201::/64 [LA] 2592000/604800
r11#
r11#show ipv6 nei
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         5 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     5 3473.2d25.6e41  STALE Gi0/0/0.226

r11#show clock
*22:46:22.979 UTC Sat Feb 17 2024
r11#! the host just now shows a GUA 
r11#
r11#show ipv6 nei                  
IPv6 Address                              Age Link-layer Addr State Interface
2001:1824:11:226::2                         5 3473.2d25.6e41  STALE Gi0/0/0.226
FE80::2                                     6 3473.2d25.6e41  STALE Gi0/0/0.226

r11#

 

 

 

Any suggestions would be greatly appreciated!

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