[Xorp-users] How to change loopback interface?

[Alejandro Berna]

Thanks Bruce,

I found finally some previous conversation where it was explained (with 
less detail than you gave) more or less the loopback problem. I'm just 
performing some tests, nothing important, this is because I'm using RFC 
1918 prefix. I am using Ubuntu server so I performed:

#ip address add 192.168.0.1/24 dev lo

Then I keep 127.0.0.1 as the local loopback address. I am developing 
some code to configure OSPF in a virtual machine with XORP and I wanted 
to automate all the process writing the .boot file or with xorpsh, not 
using Ubuntu cli. But I guess it's not possible, anyway it's not a big 
problem so my code performs a ssh connection to the Ubuntu machine.

Anyway thanks a lot for the reply,

               Alejandro

Bruce Simpson escribió:
> Alejandro Berna wrote:
>> Hi, I am trying to configure OSPF changing the loopback interfaces of 
>> my XORP routers. I have not found how to do with Xorpsh therefore I 
>> have done with ifconfig linux command. But when I try to run my 
>> config.boot file with the OSPF configuration it fails because XORP 
>> still thinks that the loopback address is 127.0.0.1, here is the 
>> trace of the error:
>> ...
>>
>> When I again put with ifconfig the loopback to 127.0.0.1 it doesn't 
>> fail. I want to define my loopback address as the router-id, 
>> 192.168.0.1, how can I change the property my address? And how can I 
>> change the loopback address with XORP? Thanks for everything,
>>   
>
> I can't understand why you want to configure your loopback interface 
> with an RFC 1918 prefix, this is going to break a lot of networking 
> software, not just XORP :-)
>
> You need to do one of these following things:
>
> 1. configure a separate loopback interface instance using your 
> operating system's capabilities to do this, and configure it in the 
> router manager, *OR* :-
> 2. configure *both* the 127.0.0.1 address and another address on the 
> default loopback interface. This is usually named lo or lo0.
>
> It is best not to remove 127.0.0.1 from most IPv4 capable hosts. XORP 
> in particular assumes the existence of 127.0.0.1 and uses TCP sockets 
> bound to this interface address as the default IPC mechanism. It is 
> just one of many pieces of software which do this, so please don't 
> remove this address.
>
> To the best of my knowledge, XORP's OSPF implementation doesn't need 
> the loopback address to be configured with the router ID; as far as I 
> know the router ID is an opaque identifier. It is used for winning DR 
> elections, sure, but XORP doesn't need to see it on the loopback 
> interface. Of course, the normative reference is the code.
>
> cheers,
> BMS
>
>
>


-- 
Alejandro Berna Juan

Network Technologies Cluster (CTX)
Fundació i2Cat, Internet i Innovació Digital a Catalunya
C/ Gran Capità 2 - 4, Nexus I building, 2nd floor, office 203
08034 Barcelona, Catalonia, Spain


P: +34 93 553 2522
F: +34 93 553 2520