Showing results for 
Search instead for 
Did you mean: 

Initial feedback/findings for Cisco 837 + Linux/Win7 clients

Posts: 1,318
Thanks: 161
Fixes: 5
Registered: ‎26-08-2010

Initial feedback/findings for Cisco 837 + Linux/Win7 clients

Warning: Lengthy post ahead but hopefully some of it might be of interest/use! Undecided
Hi everyone,
I'm seeing some good results in the other threads and if one thing's clear I'd say we're probably all scratching our heads at some stage in the process so I thought I'd share my findings in case they're of any use, and indeed will continue to read what others have to say to fill in my own gaps.
Cisco 837 Router Config
I'm using a Cisco 837 (IOS c837-k9o3sy6-mz.124-25d.bin [24/08/2010]) which was previously configured with a Hurricane Electric IPv6-in-IPv4 tunnel. I stripped the old IPv6-related config (truth be told I initially kept it all in but it made it practically impossible to test the new config properly!) and replaced/added the following:
(Note: Non IPv6/connectivity config removed for clarity - I can post the whole lot if it's of interest)

ipv6 unicast-routing                              ! Enable IPv6 routing between interfaces
ipv6 dhcp pool IPV6DHCP                          ! Define an IPv6 DHCP pool called 'IPV6DHCP'
dns-server 2001:470:20::2                        ! Define an IPv6 DNS resolver for clients to use
!                                                ! Note: Client addresses not being handed out by DHCP!
interface Ethernet0                              ! LAN switchports
ipv6 address MYPLUSNETPREFIX ::/64 eui-64        ! Autoconfigure an IPv6 address using MYPLUSNETPREFIX+MAC
ipv6 enable                                      ! Enable IPv6 on this interface (LAN)
ipv6 nd other-config-flag                        ! Announce that non-address info can be obtained by DHCP
ipv6 dhcp server IPV6DHCP                        ! Provide a DHCP service using my 'IPV6DHCP' pool/config
interface Dialer1                                ! Dialer interface (connects over int atm 0) (=WAN)
encapsulation ppp                                ! Use PPP encapsulation
dialer pool 1                                    ! Define dialer pool '1'
ipv6 address autoconfig                          ! Autoconfigure a (link-local) IPv6 address
ipv6 enable                                      ! Enable IPv6 on this interface (WAN)
ipv6 dhcp client pd MYPLUSNETPREFIX rapid-commit ! Obtain IPv6 prefix via DHCP from Plusnet (and call
                                                  ! it 'MYPLUSNETPREFIX' for use elsewhere)
ppp chap hostname <removed>          ! Trial account username from Dave
ppp chap password 7 <removed>                    ! Trial account password from Dave
ipv6 route ::/0 Dialer1                          ! Set default route to Dialer 1 (WAN)

As you can see I have configured an IPv6 DHCP service for LAN clients however I am only using this to dish out the address of an IPv6-enabled DNS server (at Hurricane Electric) and, notably, will not be using DHCP to provide clients with their IPv6 addresses. Instead, they will be expected to use autoconfiguration (i.e. concatenation of network prefix + MAC/other-identifier) to define their addresses or define their own static address (e.g. on my servers). I did it this way primarily to broaden the scope of the testing.
Router address and DHCP config can be verified with show ipv6 interface brief and show ipv6 dhcp interface respectively:

Cisco837#sh ipv6 int brief
FastEthernet1              [up/up]
FastEthernet2              [down/down]
FastEthernet3              [down/down]
FastEthernet4              [down/down]
Ethernet0                  [up/up]
ATM0                      [up/up]
Ethernet2                  [administratively down/down]
Tunnel0                    [administratively down/down]
Dialer1                    [up/up]
NVI0                      [up/up]
Virtual-Access1            [up/up]
Virtual-Access2            [up/up
Cisco837#sh ipv6 dhcp int
Ethernet0 is in server mode
  Using pool: IPV6DHCP
  Preference value: 0
  Hint from client: ignored
  Rapid-Commit: disabled
Dialer1 is in client mode
  State is OPEN
  Renew will be sent in 7w0d
  List of known servers:
    Reachable via address: FE80::90:1A00:3A3:BA15
    DUID: 000200000A4C453332302F373435414333334558322F03
    Preference: 0
    Configuration parameters:
      IA PD: IA ID 0x000D0001, T1 INFINITY, T2 INFINITY
        Prefix: 2A02:16C8:2000:6000::/56
                preferred lifetime INFINITY, valid lifetime INFINITY
      DNS server: 2001:470:20::2
  Rapid-Commit: enabled

Linux Client Config
My main Linux box is running Kubuntu 6.06 (yes, it's old!) however its config will be similar across most distros, particular others that are Debian-based. Configuration was done at the command line and so GUI tools might represent things slightly differently.
First off I configured a static IPv6 address (as it acts as a server):
(Note: Again any non-IPv6 config is removed for clarity)

auto eth0
iface eth0 inet6 static
        pre-up modprobe ipv6                    ! Ensure the IPv6 kernel module is loaded
        address 2a02:16c8:2000:6000::50        ! Configure a static IPv6 address
        netmask 64                              ! Configure the subnet size (a /64 from the /56 allocation)

Whilst this gave the server IPv6 connectivity it will still perform DNS lookups over IPv4. In particular, it can fetch IPv6 records (AAAA) but won't be using IPv6 transport. As prepared for on the router, DHCPv6 is one solution and for this I installed a DHCPv6 client apt-get install wide-dhcpv6-client and enabled it on eth0 by specifying INTERFACES="eth0" in /etc/default/wide-dhcpv6-client (method/config might differ on other distros).
A packet trace showed the DHCP solicit/response/request/reply DHCPv6 dialogue with the DNS server address included, however, I was still seeing DNS lookups going over IPv4 to Plusnet's IPv4 DNS servers. This could well be a problem with my old installation so I will need to look into this further. [Edit: It was - having tried a newer version on Debian Squeeze it now comes with a script to automatically put the DHCPv6-obtained DNS servers into /etc/resolv.conf] In the meantime I manually defined an IPv6 DNS server in /etc/resolv.conf:

# Hurricane Electric DNS server (IPv6)
nameserver 2001:470:20::2
# Plusnet DNS servers - see

Now, packet traces showed the Hurricane Electric DNS server taking primacy and queries going over IPv6.
Windows 7 Config
My laptop runs Windows 7 however I only really use it for sat-in-the-lounge web browsing and I am not too familiar with low-level configuration of it, particularly for IPv6. However, I worked out enough to at least get it working.
First off I decided to disable Teredo tunneling because whilst provide IPv6 capability I didn't want it to interfere with the Plusnet trial as there's a very real danger that IPv6 connectivity may well appear to be working but it'd actually be the Teredo tunnel providing it and not Plusnet's native IPv6. I couldn't find a way to do this with the GUI however entering the following in a command prompt (run as administrator) works:

netsh interface teredo set state disable

(You may wish to disable 6to4 tunneling with netsh interface 6to4 set state disable if you find that's kicking in too)
Again I wanted to use autoconfiguration for the IPv6 address but ensure that DHCPv6 was used to obtain an IPv6-enabled DNS server. To do this I first had to find the 'Idx' identifier for my wireless adapter:

C:\>netsh interface ipv6 show interfaces
Idx    Met        MTU          State                Name
---  ----------  ----------  ------------  ---------------------------
  1          50  4294967295  connected    Loopback Pseudo-Interface 1
12          25        1500  connected    Wireless Network Connection
16          50        1280  disconnected  isatap.{C5817D38-DC03-4DA8-89E5-2318E2AFFCE4}
11          20        1500  disconnected  Local Area Connection

...and then enable DHCPv6 for this interface:
netsh interface ipv6 set interface 12 advertise=disable managed=enable

(Further details of DHCPv6 on Windows can be found here)
The config can now be confirmed working:

C:\>ipconfig /all
Wireless LAN adapter Wireless Network Connection:
  Connection-specific DNS Suffix  . :
  Description . . . . . . . . . . . : Atheros AR5005G Wireless Network Adapter
  Physical Address. . . . . . . . . : 00-19-7D-47-E5-86
  DHCP Enabled. . . . . . . . . . . : Yes
  Autoconfiguration Enabled . . . . : Yes
  IPv6 Address. . . . . . . . . . . : 2a02:16c8:2000:6000:f820:b600:64c2:f2cd(Preferred)
  Temporary IPv6 Address. . . . . . : 2a02:16c8:2000:6000:287c:b3a3:c594:2183(Preferred)
  Link-local IPv6 Address . . . . . : fe80::f820:b600:64c2:f2cd%12(Preferred)
  IPv4 Address. . . . . . . . . . . :
  Subnet Mask . . . . . . . . . . . :
  Lease Obtained. . . . . . . . . . : 30 May 2011 14:15:43
  Lease Expires . . . . . . . . . . : 30 May 2011 21:26:20
  Default Gateway . . . . . . . . . : fe80::212:d9ff:fed8:b2ee%12
  DHCP Server . . . . . . . . . . . :
  DHCPv6 IAID . . . . . . . . . . . : 218110333
  DHCPv6 Client DUID. . . . . . . . : 00-01-00-01-12-B1-83-96-00-16-36-D1-05-36
  DNS Servers . . . . . . . . . . . : 2001:470:20::2
  NetBIOS over Tcpip. . . . . . . . : Enabled

So you can see that global IPv6 addresses have been assigned through autoconfiguration (one using the MAC address, another randomly generated), a link-local address (again via autoconfiguration), the link-local address of the gateway (obtained via the router advertisement) and the IPv6-enabled DNS server included in the DNS server lineup. A packet trace confirmed that this server was indeed being used (over IPv6).
I've got an IPv4/IPv6 dual-stack server in Telehouse (London) and so used this as a test reference as I can rule out a number of external variables that may otherwise impact on performance tests such as server load, distance from Plusnet's peering point, etc.
Firstly, ICMP pings showed comparable results (~40ms):

mathew@rugrat:~$ ping -c 5
PING ( 56(84) bytes of data.
64 bytes from ( icmp_seq=1 ttl=54 time=39.2 ms
64 bytes from ( icmp_seq=2 ttl=54 time=34.6 ms
64 bytes from ( icmp_seq=3 ttl=54 time=39.8 ms
64 bytes from ( icmp_seq=4 ttl=54 time=41.0 ms
64 bytes from ( icmp_seq=5 ttl=54 time=37.1 ms
--- ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 4014ms
rtt min/avg/max/mdev = 34.635/38.377/41.041/2.267 ms
mathew@rugrat:~$ ping6 -c 5
PING 56 data bytes
64 bytes from 2001:ba8:1f1:f137::2: icmp_seq=1 ttl=55 time=40.2 ms
64 bytes from 2001:ba8:1f1:f137::2: icmp_seq=2 ttl=55 time=39.7 ms
64 bytes from 2001:ba8:1f1:f137::2: icmp_seq=3 ttl=55 time=39.3 ms
64 bytes from 2001:ba8:1f1:f137::2: icmp_seq=4 ttl=55 time=41.9 ms
64 bytes from 2001:ba8:1f1:f137::2: icmp_seq=5 ttl=55 time=40.4 ms
--- ping statistics ---
5 packets transmitted, 5 received, 0% packet loss, time 6333ms
rtt min/avg/max/mdev = 39.353/40.337/41.920/0.887 ms

Whereas traceroutes showed that the IPv6 path was a couple of hops shorter:

mathew@rugrat:~$ traceroute
traceroute to (, 30 hops max, 40 byte packets
1 (  1.538 ms  1.477 ms  1.440 ms
2 (  45.569 ms  40.505 ms  37.733 ms
3 (  40.463 ms  35.753 ms  78.430 ms
4 (  42.998 ms  39.137 ms  36.721 ms
5  * * *
6 (  38.153 ms  103.258 ms  37.881 ms
7 (  42.972 ms
(  40.637 ms  40.631 ms
8 (  39.963 ms  43.046 ms  38.500 ms
9 (  41.410 ms  43.332 ms  40.395 ms
10 (  38.183 ms  41.575 ms  39.601 ms
mathew@rugrat:~$ traceroute6
traceroute to (2001:ba8:1f1:f137::2) from 2a02:16c8:2000:6000:240:f4ff:fe54:7310, 30
hops max, 16 byte packets
1  2a02:16c8:2000:6000:212:d9ff:fed8:b2ee (2a02:16c8:2000:6000:212:d9ff:fed8:b2ee)  1.597 ms  1.271 ms  1.128 ms
2  2a02:16c8:0:1::d (2a02:16c8:0:1::d)  49.208 ms  45.303 ms  40.646 ms
3  2a02:16c8:1:8018::1 (2a02:16c8:1:8018::1)  43.581 ms  42.079 ms  38.507 ms
4 (2001:7f8:17::1b1b:1)  39.029 ms  50.168 ms  38.502 ms
5 (2001:7f8:4::22ef:1)  39.337 ms  41.416 ms  48.074 ms
6 (2001:ba8:0:1f1::2)  41.018 ms  39.814 ms  43.729 ms
7 (2001:ba8:0:1f1:2e0:81ff:fe47:1d16)  40.763 ms  44.476 ms  39.449 ms
8  2001:ba8:1f1:f137::2 (2001:ba8:1f1:f137::2)  49.213 ms  45.636 ms  41.738 ms

Plusnet's peering (to my server on the Jump network) in Telehouse can be seen to be provided for separately for IPv4 (Level3) and IPv6 (Hurricane Electric) but it didn't seem to affect the latency despite the different hop count (there will of course be many differences, particularly at the underlying levels so it's not worth dwelling on too much).
Downstream throughput was tested using iperf by running a TCP stream for 20s over IPv4 then IPv6:

mathew@targur:~$ iperf -t 20 -c
Client connecting to, TCP port 5001
TCP window size: 16.0 KByte (default)
[  3] local port 33649 connected with port 5001
[ ID] Interval      Transfer    Bandwidth
[  3]  0.0-20.1 sec  7.77 MBytes  3.24 Mbits/sec
mathew@targur:~$ iperf -V -t 20 -c
Client connecting to, TCP port 5001
TCP window size: 16.0 KByte (default)
[  3] local 2001:ba8:1f1:f137::2 port 45936 connected with 2a02:16c8:2000:6000::50 port 5001
[ ID] Interval      Transfer    Bandwidth
[  3]  0.0-20.2 sec  8.67 MBytes  3.60 Mbits/sec

Note that whilst the IPv6 transfer may have seemed quicker (3.6 Mbps compared with 3.24 Mbps) repeated tests showed there was quite a lot of variance and so I will rerun the tests overnight rather than mid-afternoon on a bank holiday! I also tested upload which again was comparable (and maxed out my connection at ~400kbps).
Finally, I have attached the obligatory result confirming all is hunkydory:

All in all things are looking good so a big well done and thank you, Plusnet!  Smiley
Rising Star
Posts: 2,305
Thanks: 33
Registered: ‎19-07-2007

Re: Initial feedback/findings for Cisco 837 + Linux/Win7 clients

I modified your config a little to get it working on a Cisco 877W.
Instead of putting ipv6 address pnipv6 ::/64 eui-64 onto Ethernet0 I stuck it onto BVI1, like so:
interface BVI1
description $FW_INSIDE$
ip address
ip access-group 103 in
no ip redirects
no ip unreachables
no ip proxy-arp
ip flow ingress
ip nat inside
ip virtual-reassembly in
ipv6 address pnipv6 ::/64 eui-64
ipv6 enable
ipv6 mtu 1480
ipv6 nd other-config-flag
ipv6 nd ra interval 4
ipv6 dhcp server ipv6pool

By sticking it on BVI1 it gives all devices that attach to my router an IPV6 address (including wireless with newer firmware releases).
First problem I've run into, my IPV6 works but not quite.
Pinging [2a00:1450:8006::68] with 32 bytes of data:
Reply from 2a00:1450:8006::68: time=86ms
Reply from 2a00:1450:8006::68: time=54ms
Reply from 2a00:1450:8006::68: time=66ms
Reply from 2a00:1450:8006::68: time=54ms
Ping statistics for 2a00:1450:8006::68:
   Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
   Minimum = 54ms, Maximum = 86ms, Average = 65ms

The problem being...
Windows IP Configuration

Ethernet adapter Local Area Connection:
  Connection-specific DNS Suffix  . :
  IPv6 Address. . . . . . . . . . . : 2001:470:1f09:611:24fb:8d3e:a871:6e77
  IPv6 Address. . . . . . . . . . . : 2a02:16c8:60c0:5000:24fb:8d3e:a871:6e77
  Temporary IPv6 Address. . . . . . : 2001:470:1f09:611:53d:cec1:8ca8:57b6
  Temporary IPv6 Address. . . . . . : 2a02:16c8:60c0:5000:53d:cec1:8ca8:57b6
  Link-local IPv6 Address . . . . . : fe80::24fb:8d3e:a871:6e77%10
  IPv4 Address. . . . . . . . . . . :
  Subnet Mask . . . . . . . . . . . :
  Default Gateway . . . . . . . . . : fe80::215:2bff:fe30:9516%10
Tunnel adapter isatap.{B7BF63BA-F242-47F0-902B-5797F8E8058B}:
  Media State . . . . . . . . . . . : Media disconnected
  Connection-specific DNS Suffix  . :

I have two different IPV6 addresses, so I'm getting an oddity. (see attached screenshots)  I can access Google ipv6 but the rest results show I'm not using IPV6, it's rather odd.
/edit - fixed, I went into Local Area Connection properties, unchecked IPV6 (to turn it off) then checked it (to turn it back on) and it found PlusNets IPV6, I'm now scoring a perfect 10!
Posts: 1,318
Thanks: 161
Fixes: 5
Registered: ‎26-08-2010

Re: Initial feedback/findings for Cisco 837 + Linux/Win7 clients

Quote from: David
I have two different IPV6 addresses, so I'm getting an oddity. (see attached screenshots)  I can access Google ipv6 but the rest results show I'm not using IPV6, it's rather odd.

The 2001:470:1f09:61:: address is/was a Hurricane Electric address so presumably you've been using one of their tunnels in the past? If the tunnel isn't up the network stack might still try and use the address and fall back to IPv4 if it doesn't work.
Rising Star
Posts: 2,305
Thanks: 33
Registered: ‎19-07-2007

Re: Initial feedback/findings for Cisco 837 + Linux/Win7 clients

Aye, I was using the HE tunnel, I took the config out of the umm, config but Windows was still using that until I disabled and re-enabled IPV6 (ipconfig /release didn't work though I'm guessing a reboot may have).
Out of interest, how is your VMBU looking?  I only switched to IPV6 today (F9 domain so needed fiddling for plusdsl domain) and I'm currently showing 0kb peak which turned to peak 2 hours ago so the VMBU should have caught up and shown a little traffic by now.
Resting Legend
Posts: 10,063
Thanks: 674
Fixes: 75
Registered: ‎06-04-2007

Re: Initial feedback/findings for Cisco 837 + Linux/Win7 clients

Have you logged into the portal using your test credentials (if it will let you)? Otherwise won't VMBU reflect only your normal IPv4 account usage (probably nil for today)?
Plusnet Help Team
Plusnet Help Team
Posts: 12,252
Thanks: 288
Fixes: 4
Registered: ‎04-04-2007

Re: Initial feedback/findings for Cisco 837 + Linux/Win7 clients

You should be able to log in and see VMBU with the test account login, however we aren't currently recording IPv6 traffic in VMBU in the protocol split so you'll just see traffic you do on the test account over IPv4.
Dave Tomlinson
Enterprise Architect - Network & OSS
Plusnet Technology