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Delayed Ping of a link-local address

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Juergen Bachsteffel
Occasional Advisor

Delayed Ping of a link-local address

I have a strange effect here, which I do not understand.

Hopefully someone can help me.

PS C:\Users\user1> ping fe80::219:bbff:fe0e:c600%16  -t

Ping wird ausgeführt für fe80::219:bbff:fe0e:c600%16 mit 32 Bytes Daten:
Zielhost nicht erreichbar.
Zielhost nicht erreichbar.
Zielhost nicht erreichbar.
Zielhost nicht erreichbar.
Zielhost nicht erreichbar. (Destination is unreachable)
Zielhost nicht erreichbar.
.
.
.
Antwort von fe80::219:bbff:fe0e:c600%16: Zeit=1ms
Antwort von fe80::219:bbff:fe0e:c600%16: Zeit<1ms
Antwort von fe80::219:bbff:fe0e:c600%16: Zeit<1ms
.
.

As you can see the host is not reachable for a while (1 or 2 minutes)and then it changes.
I have this effect only with Windows 7 (Server 2008 R2, Server 2012 R2).

When I do a ping with a Linux-System (e.g. SLES12) or even with Windows XP the gateway is
reachable immediately! So i think my conig can't be so wrong.

Neighbor Discovery gives me:

netsh interface ipv6>show neighbors interface=16

Schnittstelle 16: LAN-Verbindung 2


Internetadresse                              Physische Adresse   Typ
--------------------------------------------  -----------------  ---------
fda0:65da:e55a:1::1                           00-0c-29-56-69-f6  Abgelaufe 
fda0:65da:e55a:1::2                           00-0c-29-41-b8-97  Abgelaufe
fda0:65da:e55a:1::3                           00-0c-29-02-da-0b  Abgelaufe
fda0:65da:e55a:1:89f6:fad7:862a:c2e4          00-0c-29-41-b8-97  Abgelaufe
fda0:65da:e55a:1:e49b:4bb8:df52:d34a          00-0c-29-56-69-f6  Abgelaufe
fda0:65da:e55a:1:ecb9:2efb:ffa5:770b          00-0c-29-1a-a5-e4  Abgelaufe 
fe80::219:bbff:fe0e:c600                      00-19-bb-0e-c6-00  Abgelaufe (Stale) (this changes to Reachable when ping is successful)
fe80::3aea:a7ff:fe6a:6b43                     38-ea-a7-6a-6b-43  Abgelaufe
fe80::6651:6ff:fe27:6a8d                      64-51-06-27-6a-8d  Abgelaufe
fe80::6651:6ff:fe27:7ab0                      64-51-06-27-7a-b0  Abgelaufe
fe80::a248:1cff:fe6c:7a02                     a0-48-1c-6c-7a-02  Abgelaufe
fe80::a2d3:c1ff:feea:4359                     a0-d3-c1-ea-43-59  Abgelaufe
fe80::fe15:b4ff:fe2c:d338                     fc-15-b4-2c-d3-38  Abgelaufe
fe80::fe15:b4ff:fe2c:e3f0                     fc-15-b4-2c-e3-f0  Abgelaufe
fe80::fe15:b4ff:fe2c:e3f5                     fc-15-b4-2c-e3-f5  Abgelaufe
fe80::fe15:b4ff:fe2c:e3f6                     fc-15-b4-2c-e3-f6  Abgelaufe
fe80::fe15:b4ff:fe2f:ff46                     fc-15-b4-2f-ff-46  Abgelaufe
fe80::fe15:b4ff:fe31:e7c6                     fc-15-b4-31-e7-c6  Abgelaufe
ff02::1                                       33-33-00-00-00-01  Permanent
....

The host is my default gateway. It is a HP5406. (release #K.15.06.0017).
I have configured two VLAN's for IPv6.

The effect is in the default VLAN, which I am in.

All IPv6-traffic within this VLAN is working correctly! Windows Hosts use it by default.
I can see it via wireshark.

 

SW5406-1# show ipv6

 Internet (IPv6) Service

  IPv6 Routing    : Enabled
  ND DAD          : Enabled
  DAD Attempts    : 3

                                                                       VLAN Interfaces

  Interface Name  : DEFAULT_VLAN
  IPv6 Status     : Enabled
  Layer 3 Status  : Enabled

  Address    |                                             Address
  Origin     | IPv6 Address/Prefix Length                  Status
  ---------- + ------------------------------------------- -----------
  manual     | fda0:65da:e55a:1::feed:1/64                 preferred
  autoconfig | fe80::219:bbff:fe0e:c600/64                 preferred

  Interface Name  : Firewall
  IPv6 Status     : Disabled
  Layer 3 Status  : Enabled

  Interface Name  : RFID
  IPv6 Status     : Disabled
  Layer 3 Status  : Enabled

  Interface Name  : Voice
  IPv6 Status     : Disabled
  Layer 3 Status  : Enabled

  Interface Name  : DPC
  IPv6 Status     : Enabled
  Layer 3 Status  : Enabled

  Address    |                                             Address
  Origin     | IPv6 Address/Prefix Length                  Status
  ---------- + ------------------------------------------- -----------
  autoconfig | fe80::219:bbff:fe0e:c600/64                 preferred

Any hint could be useful for me.
Let me know if you need further information.

 

Thank you!

Greetings,
                  Juergen

    

3 REPLIES
16again
Respected Contributor
Solution

Re: Delayed Ping of a link-local address

I once had cisco877 ios with similar behavior.  It didn't respond to neighbor discovery. 
I lowered the router advertising interval to low value like 5 or 10 seconds

Juergen Bachsteffel
Occasional Advisor

Re: Delayed Ping of a link-local address

Thank you.

I have added the following to my switch config:

vlan 1
   ipv6 nd ra max-interval 20
   ipv6 nd ra min-interval 5
   exit

Now, my ping looks like this:

Ping wird ausgeführt für fe80::219:bbff:fe0e:c600%16 mit 32 Bytes Daten:
Zielhost nicht erreichbar.  (Not Reachable)
Antwort von fe80::219:bbff:fe0e:c600%16: Zeit=2623ms
Antwort von fe80::219:bbff:fe0e:c600%16: Zeit<1ms
Antwort von fe80::219:bbff:fe0e:c600%16: Zeit<1ms

Ping-Statistik für fe80::219:bbff:fe0e:c600%16:
    Pakete: Gesendet = 4, Empfangen = 3, Verloren = 1
    (25% Verlust),
Ca. Zeitangaben in Millisek.:
    Minimum = 0ms, Maximum = 2623ms, Mittelwert = 874ms

It is much better now!
I think I have to experiment a little bit, for the optimal values.

 

I can not understand why Windows is doing the "Neighbor Solicitation" again and again. After a minute or so it makes
the same NS-Discoveries. I think Windows should cache the address for a longer time.

539	63.591851	fe80::90c5:2b00:b1ad:98a0	ff02::1:ff0e:c600	86	ICMPv6	Neighbor Solicitation for fe80::219:bbff:fe0e:c600 from 00:0e:0c:a2:32:2e
541	64.026379	fe80::90c5:2b00:b1ad:98a0	ff02::1:ff0e:c600	86	ICMPv6	Neighbor Solicitation for fe80::219:bbff:fe0e:c600 from 00:0e:0c:a2:32:2e
.
.
(5 times)

Greetings,
              Juergen

 

 

Juergen Bachsteffel
Occasional Advisor

Re: Delayed Ping of a link-local address

I have experimented a little bit.

You should also set 'ipv6 nd ra-ns-interval' and 'ipv6 nd ra reachable time'.

vlan 1
   ipv6 nd ra ns-interval 1000
   ipv6 nd ra reachable-time 1800000
   ipv6 nd ra min-interval 5
   ipv6 nd ra max-interval 20
   exit

The values are taken from Windows 7 via netsh-command. These are the Windows default values.

There is also a small bug in the firmware. If save your config you get:

ipv6 nd ra min-interval 20
ipv6 nd ra max-interval 5

You must change/switch it to:

 ipv6 nd ra min-interval 5
 ipv6 nd ra max-interval 20

Otherwise you get an error.

Greetings,
           Juergen