* GRE devices and MULTICAST flag.
@ 2011-09-23 19:56 Ben Greear
2011-09-23 20:42 ` Ben Greear
0 siblings, 1 reply; 3+ messages in thread
From: Ben Greear @ 2011-09-23 19:56 UTC (permalink / raw)
To: netdev
I was under the impression that GRE tunnels could support MULTICAST
traffic, but the MULTICAST flag is not set. This is making the xorp
router crap out because it checks the MULTICAST flag and will
not start multicast on the interface if it's not set....
Is it supposed to be set?
7: gre0: <NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
link/gre 0.0.0.0 brd 0.0.0.0
8: netb: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
link/gre 192.168.100.223 peer 192.168.100.138
inet 10.0.1.1/32 scope global netb
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: GRE devices and MULTICAST flag.
2011-09-23 19:56 GRE devices and MULTICAST flag Ben Greear
@ 2011-09-23 20:42 ` Ben Greear
2011-09-23 21:16 ` David Lamparter
0 siblings, 1 reply; 3+ messages in thread
From: Ben Greear @ 2011-09-23 20:42 UTC (permalink / raw)
To: netdev
On 09/23/2011 12:56 PM, Ben Greear wrote:
> I was under the impression that GRE tunnels could support MULTICAST
> traffic, but the MULTICAST flag is not set. This is making the xorp
> router crap out because it checks the MULTICAST flag and will
> not start multicast on the interface if it's not set....
>
> Is it supposed to be set?
>
> 7: gre0: <NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
> link/gre 0.0.0.0 brd 0.0.0.0
> 8: netb: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
> link/gre 192.168.100.223 peer 192.168.100.138
> inet 10.0.1.1/32 scope global netb
Well, ifconfig netb multicast seems to add the flag,
so maybe all is as it should be.
Thanks,
Ben
--
Ben Greear <greearb@candelatech.com>
Candela Technologies Inc http://www.candelatech.com
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: GRE devices and MULTICAST flag.
2011-09-23 20:42 ` Ben Greear
@ 2011-09-23 21:16 ` David Lamparter
0 siblings, 0 replies; 3+ messages in thread
From: David Lamparter @ 2011-09-23 21:16 UTC (permalink / raw)
To: Ben Greear; +Cc: netdev
On Fri, Sep 23, 2011 at 01:42:53PM -0700, Ben Greear wrote:
> On 09/23/2011 12:56 PM, Ben Greear wrote:
> > I was under the impression that GRE tunnels could support MULTICAST
> > traffic, but the MULTICAST flag is not set. This is making the xorp
> > router crap out because it checks the MULTICAST flag and will
> > not start multicast on the interface if it's not set....
> >
> > Is it supposed to be set?
> >
> > 7: gre0: <NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
> > link/gre 0.0.0.0 brd 0.0.0.0
> > 8: netb: <POINTOPOINT,NOARP,UP,LOWER_UP> mtu 1476 qdisc noqueue state UNKNOWN
> > link/gre 192.168.100.223 peer 192.168.100.138
> > inet 10.0.1.1/32 scope global netb
>
> Well, ifconfig netb multicast seems to add the flag,
> so maybe all is as it should be.
I distinctively remember that the MULTICAST flag is supposed to be an
input to the kernel, not a feature-indication flag output. I'm quite
unsure where I picked this up, but I remember using it in that way that
xorp does and then finding out it's wrong.
-David
^ permalink raw reply [flat|nested] 3+ messages in thread
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