[Xorp-hackers] linux VRRP svn xorp

[Li Zhao]

1. "show vrrp" did not use "10.0.0.100" as the master IP.

This is the correct behavior actually. It is telling who is the master. 
But perhaps it is better to show the virtual IP address too.

--- On Thu, 3/11/10, Li Zhao <lizhaous2000 at yahoo.com> wrote:

> From: Li Zhao <lizhaous2000 at yahoo.com>
> Subject: Re: [Xorp-hackers] linux VRRP svn xorp
> To: xorp-hackers at icir.org, "Eric S. Johnson" <esj at cs.fiu.edu>
> Date: Thursday, March 11, 2010, 1:26 PM
> I tested configuring virtual IP addr
> thr "... vrid 100 ip 10.0.0.100". What happened was not what
> I expected:
> 1. "show vrrp" did not use "10.0.0.100" as the master IP.
> 2. I can not ping 10.0.0.100 from a neighbor.
> 
> This is different from cisco behavior as far as I can
> remember. Not only 
> virtual IP can be a next-hop, it can be a destination too.
> So I guess this 
> is bug.
> 
> I traced Vrrp::add_ip once, but did not have any clue yet.
> I will try to 
> do it again later.
> 
> --- On Thu, 3/11/10, Eric S. Johnson <esj at cs.fiu.edu>
> wrote:
> 
> > From: Eric S. Johnson <esj at cs.fiu.edu>
> > Subject: [Xorp-hackers] linux VRRP svn xorp
> > To: xorp-hackers at icir.org
> > Date: Thursday, March 11, 2010, 11:13 AM
> > 
> > So I am kind feeling silly this morning. Ive been
> chasing a
> > bug 
> > that nearly  does not exist.
> > 
> > On and off for the last two weeks I have been trying
> to
> > debug
> > why xorp svn (checked out 20100217, i dont think much
> has
> > changed
> > since then) VRRP didn't work.
> > 
> > The behavior I saw was that when xorp became master
> for a
> > router
> > it would correctly change the mac address on the
> interface,
> > but
> > yet pinging the virtual IP would not work. I thought
> VRRP
> > was 
> > broken and spent some time tracing through the code
> to
> > figure
> > out what was going on and going wrong.
> > 
> > It was not until I was deep in the depths of
> vrrp/arpd.cc 
> > that I realized that the code was *mostly* working.
> Well,
> > all the code I could find was working, but there is
> one 
> > behavior that is far from what I expected.
> > 
> > I  found that indeed I could ping THROUGH the xorp
> > VRRP master 
> > router, just not ping the virtual address it self.
> > 
> > And that seems to be the way the code is designed to
> > work?!?
> > 
> > Vrrp::become_master()
> > {
> >     _state = MASTER;
> >            
> >         // my comments
> >     _vif.add_mac(_source_mac);   
> >     // this changes the mac on the interface
> >     send_advertisement();   
> >     // start sending vrrp master
> > announcements
> >     send_arps();   
> >         // send gratuitous
> > arps
> >     setup_timers();   
> >         // start timers
> >     _arpd.start();   
> >         // start an pseudo arp
> > deamon
> >            
> >         // that responds to
> > arp requests for the virtual
> >            
> >         // IP address with the
> > virtual mac
> > }
> > 
> > 
> > but no where does it seem to add the virtual IP as a
> IP on
> > the interface/vif..
> > 
> > So a station sending a packet to the an address that
> is not
> > the 
> > virtual IP but that has a next hop of the virtual IP
> will
> > make a 
> > arp request for the Virtual IP, and get back (from
> the
> > pseudo arp 
> > deamon) the virtual MAC and when that IP packet
> arrives at
> > the xorp 
> > router, it is processed normally and forwarded.
> > 
> > But an IP packet with a DESTINATION of the virtual IP
> > address will get
> > to the xorp router too. But the virtual router does
> not
> > recognize the
> > virtual IP as being one of it's IP address and
> doesn't
> > accept it.
> > 
> > 
> > soooo 
> > 
> > Is/was this just unfinished code?
> > 
> > Am I missing somewhere the Virtual address would be
> added
> > to the
> > VIF and something is broken in the code I can't find?
> > 
> > Or am I miss-understanding how VRRP should work
> (though
> > EVERY other 
> > implementation I have seen (vendor C, J, and open
> source
> > vrrpd) all
> > accept IP packets destined for the virtual IP
> address?)
> > 
> > 
> > 
> > Would a correct solution be to have xorp set the
> virtual IP
> > 
> > as a secondary IP on that VIF? If so, what would be
> the
> > correct
> > way to do this.. IfTreeVif::add_addr method?
> > 
> > 
> > Thoughts?
> > 
> > linux centos 5 kernel 2.6.18-164.6.1.el5
> > E
> > 
> > _______________________________________________
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> > Xorp-hackers at icir.org
> > http://mailman.ICSI.Berkeley.EDU/mailman/listinfo/xorp-hackers
> > 
> 
> 
>       
> 
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