[Xorp-hackers] {Disarmed} Re: xorp: enable IGMP/PIM-SM over a VLAN interface on Linux

[Ray Soucy]

To be fair, I haven't been able to migrate to the current XORP yet, so
these bugs are from 1.6 with patches; I may be speaking based on old
information.

If they've since been fixed then that's great.

With 1.6 we do perform multicast (using IGMP, PIM-SM) just fine on
802.1Q interfaces in production for several connections.

One note on VLANs and Linux; you will likely want to avoid using the
native (untagged) interface for anything if you setup sub-interfaces;
depending on your driver, and the way an application is implemented
(raw sockets for example), the untagged interface may also see the
tagged traffic as untagged.

Also avoid the use of 31-bit prefixes for point-to-point networks like
the plague.  You can configure them, but they are _not_ supported (use
a 30-bit prefix instead); otherwise you will see some very odd (and
hard to troubleshoot) breakage.

On Thu, Dec 8, 2011 at 12:03 AM, Ben Greear <greearb at candelatech.com> wrote:
> On 12/07/2011 07:13 PM, Ray Soucy wrote:
>>
>> I haven't had good luck with default-system-configuration and VLAN
>> interfaces; especially where PIM is concerned.
>>
>> You likely need to specify the addresses manually (in addition to
>> creating the VLAN interfaces manually with vconfig).
>>
>> The XORP handling of VLANs has never been great; recent patches have
>> been made to try an improve it; but it's still has work to be done
>> before it's up to user expectations.
>
>
> I don't ever test using default-system-config, but if you find
> problems when using config from within Xorp, please report the
> bug.
>
> In general, I'd suggest you drive all changes through xorp..ie,
> tell it to set the IP instead of hoping it will figure things out
> when you set it outside of xorp.
>
> You can script xorpsh using multiple -c 'command 1' -c 'command 2' ....
>
> It's not exactly user-friendly, but it works (for my uses, at least).
>
> And as always, patches are welcome, as are detailed bug reports
> with xorp logs, OS & kernel version, etc.  Please submit such
> bug reports to the bugzilla so we don't loose track of it.
>
>
>
>>> Being familiar with the Cisco routing CLI, these caveats seem quite
>>> counter-intuitive... Could anybody help me understand if XORP was
>>> deployed
>>> outside the research/academia community?
>
>
> Probably not so much.  We use it in our LANforge product, but we drive
> xorp from our program (which builds networks with a GUI) using
> programatically
> created xorpsh commands and xorp config files.  Those
> code paths are pretty well tested, but I'm certain bugs remain
> to be uncovered.
>
> Thanks,
> Ben
>
> --
> Ben Greear <greearb at candelatech.com>
> Candela Technologies Inc  http://www.candelatech.com



-- 
Ray Soucy

Epic Communications Specialist

Phone: +1 (207) 561-3526

Networkmaine, a Unit of the University of Maine System
http://www.networkmaine.net/