[Xorp-users] IPv6 intermittent connectivity

Hansi hantongs at gmail.com
Tue Nov 6 00:53:29 PST 2007


Hello Pavlin,

Thank you for your quick response. Allow me to redraw my network.

                             -----------------
------------------
pc--------------------|   Router 1    |------------------|    Router 2
|---------------------pc
                    sk0    ----------------- vr0          vr0
------------------ sk0

Router 1:
vr0: 2001:ec0:4000:beef::1
sk0: 2001:ec1:4001:10af:1

Router 2:
vr0: 2001:ec0:4000:beef::2
sk0: 2001:ec2:4002:fa11::1

My goal is to establish full IPv6 connectivity from pc to pc using static
routes. I'm not sure though but I think I was able to pinpoint the cause of
the problem. Allow me to show it to you.

To isolate the problem, I shutdown XORP and manually added static IPv6
static routes to both routers 1 & 2. IPv6 connectivity was up and running
and I was able to ping the pc's end to end. Here's how I did it.


(4:18:12<root at demo_rtr :/home/hansi>)#route add -inet6
2001:ec2:4002:fa11::/64 2001:ec0:4000:beef::2
 add net 2001:ec2:4002:fa11::/64: gateway 2001:ec0:4000:beef::2


(4:19:52<root at demo_rtr :/home/hansi>)#netstat -rna | more

Routing tables

IInternet6:
Destination                       Gateway                       Flags
Netif
 Expire
::/96                                     ::1
UGRS        lo0
::1                                        ::1
UHL         lo0
::ffff:0.0.0.0/96                     ::1
UGRS        lo0
2001:ec0:4000:beef::/64           link#2                        UC
vr0
2001:ec0:4000:beef::1             00:13:d4:d8:68:08             UHL
lo0
2001:ec0:4000:beef::2             00:15:f2:3d:ac:91             UHLW
vr0
2001:ec1:4001:10af::/64           link#1                        UC
sk0
2001:ec1:4001:10af::1             00:19:5b:85:cf:c7             UHL
lo0
2001:ec1:4001:10af:219:5bff:fe2f:1468 00:19:5b:2f:14:68
UHLW
sk0
2001:ec2:4002:fa11::/64           2001:ec0:4000:beef::2         UGS
vr0
fe80::/10                         ::1                           UGRS
lo0
fe80::%sk0/64                     link#1                        UC
sk0
fe80::219:5bff:fe2f:1468%sk0      00:19:5b:2f:14:68             UHLW
sk0
fe80::219:5bff:fe85:cfc7%sk0      00:19:5b:85:cf:c7             UHL
lo0
fe80::%vr0/64                     link#2                        UC
vr0
fe80::213:d4ff:fed8:6808%vr0      00:13:d4:d8:68:08             UHL
lo0
fe80::215:f2ff:fe3d:ac91%vr0      00:15:f2:3d:ac:91             UHLW
vr0
fe80::%lo0/64                     fe80::1%lo0                   U
lo0
fe80::1%lo0                       link#4                        UHL
lo0
ff01:1::/32                       link#1                        UC
sk0
ff01:2::/32                       link#2                        UC
vr0
ff01:4::/32                       ::1                           UC
lo0
ff02::/16                         ::1                           UGRS
lo0
ff02::%sk0/32                     link#1                        UC
sk0
ff02::%vr0/32                     link#2                        UC
vr0
ff02::%lo0/32                     ::1                           UC
lo0

While using XORP to add static routes would produce:


(4:19:52<root at demo_rtr :/home/hansi>)#netstat -nra | more
Routing tables

Internet6:
Destination                       Gateway                       Flags
Netif
 Expire
::/96                             ::1                           UGRS
lo0
::1                               ::1                           UHL
lo0
::ffff:0.0.0.0/96                 ::1                           UGRS
lo0
2001:ec0:4000:beef::/64           link#2                        UC
vr0
2001:ec0:4000:beef::1             00:13:d4:d8:68:08             UHL
lo0
2001:ec0:4000:beef::2             link#2                        UHLW
vr0
2001:ec0:4000:beef::2             00:15:f2:3d:ac:91             UHLW
vr0
2001:ec1:4001:10af::/64           link#1                        UC
sk0
2001:ec1:4001:10af::1             00:19:5b:85:cf:c7             UHL
lo0
2001:ec1:4001:10af:219:5bff:fe2f:1468 00:19:5b:2f:14:68
UHLW
sk0
2001:ec1:4001:10af::/64/64        2001:ec0:4000:beef::2         UG1
vr0
fe80::/10                         ::1                           UGRS
lo0
fe80::%sk0/64                     link#1                        UC
sk0
fe80::219:5bff:fe2f:1468%sk0      00:19:5b:2f:14:68             UHLW
sk0
fe80::219:5bff:fe85:cfc7%sk0      00:19:5b:85:cf:c7             UHL
lo0
fe80::%vr0/64                     link#2                        UC
vr0
fe80::213:d4ff:fed8:6808%vr0      00:13:d4:d8:68:08             UHL
lo0
fe80::215:f2ff:fe3d:ac91%vr0      00:15:f2:3d:ac:91             UHLW
vr0
fe80::%lo0/64                     fe80::1%lo0                   U
lo0
fe80::1%lo0                       link#4                        UHL
lo0
ff01:1::/32                       link#1                        UC
sk0
ff01:2::/32                       link#2                        UC
vr0
ff01:4::/32                       ::1                           UC
lo0
ff02::/16                         ::1                           UGRS
lo0
ff02::%sk0/32                     link#1                        UC
sk0
ff02::%vr0/32                     link#2                        UC
vr0
ff02::%lo0/32                     ::1                           UC
lo0


Looking closely on the routing table produced by netstat would show:

Manually added routes:

2001:ec2:4002:fa11::/64           2001:ec0:4000:beef::2         UGS
vr0

Routes added by xorp:

2001:ec1:4001:10af::/64/64        2001:ec0:4000:beef::2         UG1
vr0

This is also replicated on the second router:

Manually added routes:

2001:ec1:4001:10af::/64           2001:ec0:4000:beef::1         UGS
vr0

Routes added by xorp:

2001:ec0:4000:beef::/64/64        2001:ec0:4000:beef::1         UG1
vr0

Could this possibly be a bug? Im using FreeBSD6.2 OS and XORP1.4 stable.

Thank you.


On 11/6/07, Pavlin Radoslavov <pavlin at icir.org> wrote:
>
> Hansi <hantongs at gmail.com> wrote:
> > Hello All,
> >
> > I have configured two XORP machines connected to each other using IPv6
> > addresses. IPv6 static routes configuration were successfully entered
> using
> > the XORP CLI. Basically the network topology would look like this:
> >
> >                -----------------                      ------------------
> >  -----------|    Router 1    |----------------|    Router 2
> > |--------------
> > Link1        -----------------      Link
> ------------------    Link3
> >
> > Link1: 2001:ec1:4001:10af::1
> >
> > Link: 2001:ec0:4000:beef::1
> >         2001:ec0:4000:beef::2
> >
> > Link3: 2001:ec2:4002:fa11::1
>
> The above topology drawing was mis-alligned so please redraw it in a
> simpler way and without using any tabs.
>
> > unicast forwarding for IPv4 and IPv6 were added to the configuration.
> After
> > adding the static routes, I was able to successfully ping Link3 from
> Link1.
> > However, I notice that the ping responses were intermittent. Several
> skips
> > occured in the icmp sequence count. I tried configuring static routes
> for
> > IPv4 addresses and didn't encounter such problem. Has anyone encountered
> > this issue? I'm working on an isolated environment. I would appreciate
> if
> > anyone would be willing to lend a hand in helping me resolve this
> > intermittent connectivity issue.
>
> What OS are you running on Router 1 and Router 2?
>
> Are you running the ping command on Router 1 or on another host
> connected to Link1?
> If the latter, what happens if you run ping on Router 1?
>
> Also, what happens if you don't run XORP, but you just install the
> static routes by hand?
>
> Please send a copy of the exact ping command (incl. all
> arguments) and a snapshot of the replies.
>
>
> Regards,
> Pavlin
>
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