[Xorp-users] Problem adding routes to custom devices

[Jeff Mitchell]

On 05/20/2010 10:35 AM, Jeff Mitchell wrote:
> On 05/19/2010 06:04 PM, Ben Greear wrote:
>>> I have a suspicion as to what may be wrong...here's the relevant output
>>> of "ip link":
>>>
>>> 4: eth0.801 at eth0:<BROADCAST,MULTICAST,UP,LOWER_UP>    mtu 1500 qdisc noqueue
>>>         link/ether 00:50:56:9e:1f:7f brd ff:ff:ff:ff:ff:ff
>>> 6: abcd0:<BROADCAST,MULTICAST,NOARP,UP,LOWER_UP>    mtu 1500 qdisc
>>> pfifo_fast qlen 100
>>>         link/void 00:00:00:00:00:00:00:00:00:00:00:00:00:00:00:00 brd
>>> ff:ff:ff:ff:ff:ff:00:00:00:00:00:00:00:00:00:00
>>> 7: pimreg at NONE:<NOARP,UP,LOWER_UP>    mtu 1472 qdisc noqueue
>>>         link/pimreg
>>>
>>> Note the type of "link/void" -- is it possible that XORP refuses to set
>>> routes pertaining to this link because of the link type, even though it
>>> will give the interface an IP address? If so, is there a way to disable
>>> this/fix this/prevent this? Or any other idea what's going wrong?
>>
>> I'd say that's likely.  Can you just fix your network driver so that
>> it claims to be Ethernet?  That's what other virtual drivers, such as 'veth'
>> do...
>
>    From what I hear, the answer is "maybe" -- in that they do have that
> option but it's not working right :-(
>
> One thing the guys here told me is that void is a legit link type in the
> kernel with a configurable link layer address size. The address size
> above is 128-bit; however from poking around at the XORP source code it
> seems that it makes assumptions all over the place that the link layer
> addresses are 48 bit.
>
> However, maybe that's not always the case. I still don't know why it
> successfully sets IP addresses to those interfaces, but won't set a
> route. I suspect that code handling the interfaces is written and/or
> behaving differently in different parts of XORP.

Looks like I spoke a bit too soon on that point. If I change the address 
type:

6: abcd0: <BROADCAST,MULTICAST,NOARP,UP,LOWER_UP> mtu 1500 qdisc 
pfifo_fast qlen 100
     link/ether 00:00:00:00:00:00 brd ff:ff:ff:ff:ff:ff

then still no dice. It's possible that XORP doesn't like the all-zeros 
address in this situation -- or the problem lies elsewhere, perhaps in 
some unsupported call being used when trying to set the routing information?

--Jeff