(IPv6) DHCP-Server is not reachable (via connection)

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Jun 10th, 2010

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We are trying to setup an IPv6 DHCP-Server on a Cisco 878 (c870-advipservicesk9-mz.124-15.T13.bin). There is another problem with the availability of the router. When you boot the router, he is broadcasting the IP-addresses but after about 30 minutes he going “stealth”. He doesn´t broadcast any more and he is not reachable via ping. Only a reboot can “solve” the misery/situation.

Do you have any guess/clue?

Here is a part of the code:



ip name-server 2001:XXX:XXXX:6::53


ipv6 unicast-routing

no ipv6 source-route

ipv6 cef

ipv6 dhcp pool dhcppool

prefix-delegation 2001:XXX:668::/48 0007

dns-server 2001:XXX:XXXX:6::53

dns-server 2001:XXX:XXXX:6:0:153:235:53

domain-name blablabla.com



interface Loopback0

no ip address

ipv6 address 2001:XXX:668:111::1/128

ipv6 enable


interface Vlan20

ip address 10.X.X.1

ipv6 address 2001:XXX:668:1::1/64

ipv6 enable

ipv6 dhcp server dhcppool


ipv6 local pool dhcppool 2001:XXX:668::/48 50


I have this problem too.
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Giuseppe Larosa Thu, 06/10/2010 - 09:38

Hello Hannes,

this looks like a SW bug so I would suggest to download and install a newer image for your router and to test with it

I couldn't find a match using IPv6 DHCP in bug toolkit

Hope to help


ilgorro2010 Mon, 06/14/2010 - 23:35

Fine Thnx. I will try a newer one, if i find one that maches my needs.

ilgorro2010 Tue, 06/15/2010 - 04:05

I´m now booting the latest (stable) version (c870-advipservicesk9-mz.124-22.T5.bin) but the problem is still the same.

For testing reasons i disabled the whole ipv6 code to see how it is running only with ipv4, and under ipv4 everything works fine.

Hmmm. Any other guesses?

ilgorro2010 Wed, 06/16/2010 - 05:17

Status update: When I´m pinging the DNS-server and the router from my pc, the router won´t ever crash. But when i start a download from an ipv6 ftp-server, the router is not reacheable after a few minutes.  It looks like that he can only handle icmpv6 messages but no ftp transfer. ;(


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