iproute2 neighboring

iproute2 neighboring

[Kevin Wilson]

Hi,
It seems to me that "ip -6 neigh show" does not show multicast entries from
IPv6 neighboring  table. Is there a reason for this ?
rgs,
Kevin

Re: iproute2 neighboring

[Eric Dumazet]

Le vendredi 04 novembre 2011 à 13:11 +0200, Kevin Wilson a écrit :
> Hi,
> It seems to me that "ip -6 neigh show" does not show multicast entries from
> IPv6 neighboring  table. Is there a reason for this ?
> rgs,

What would be a neighbour entry for multicast ipv4 or ipv6 ?

Could you describe your need ?

Re: iproute2 neighboring

[David Stevens]

> From: Kevin Wilson <wkevils@gmail.com>

> Hi,
> It seems to me that "ip -6 neigh show" does not show multicast entries 
from
> IPv6 neighboring  table. Is there a reason for this ?

Multicast memberships aren't in the neighbor table. The
neighbor table is for translating protocol addresses to
MAC addresses and that translation is fixed for multicast
destinations.

You can see group memberships with "netstat -g". There are also
some data in /proc/net/{dev_mcast,igmp6,mcfilter6} depending on
what you're looking for.

                                                +-DLS

Re: iproute2 neighboring

[François-Xavier Le Bail]

----- Original Message -----
> From: David Stevens <dlstevens@us.ibm.com>
> To: Kevin Wilson <wkevils@gmail.com>
> Cc: netdev@vger.kernel.org; netdev-owner@vger.kernel.org
> Sent: Friday, November 4, 2011 4:46 PM
> Subject: Re: iproute2 neighboring
> 
>>  From: Kevin Wilson <wkevils@gmail.com>
> 
>>  Hi,
>>  It seems to me that "ip -6 neigh show" does not show multicast 
> entries 
> from
>>  IPv6 neighboring  table. Is there a reason for this ?
> 
> Multicast memberships aren't in the neighbor table. The
> neighbor table is for translating protocol addresses to
> MAC addresses and that translation is fixed for multicast
> destinations.
> 
> You can see group memberships with "netstat -g". There are also
> some data in /proc/net/{dev_mcast,igmp6,mcfilter6} depending on
> what you're looking for.
> 
>                                                 +-DLS

Hi,

You can also see group memberships with "ip m".

François-Xavier

Re: iproute2 neighboring

[Kevin Wilson]

Hi,
Thanks all responses!
The answer that there is a fixed mapping in case of multicast is reasonable,
and I assume this is the reason for not seeing multicast addresses in
neigh table.
>You can also see group memberships with "ip m".
I wonder whether I can know from "ip -m" which multicast addresses
are attached to which ip addresses.
For example,
"ip -m" shows:
2:	em1
...     ip1
...     ip2
...     ip3
	inet  224.0.0.1
	inet6 ff02::1:ffcf:c821
	inet6 ff02::1

is the order important here?
namely, is  ip1 belongs to  224.0.0.1,
ip2 belongs to ff02::1:ffcf:c821, and ip3 belong to ff02::1?

rgs,
Kevin


2011/11/4 François-Xavier Le Bail <fx.lebail@yahoo.com>:
>
>
>
>
> ----- Original Message -----
>> From: David Stevens <dlstevens@us.ibm.com>
>> To: Kevin Wilson <wkevils@gmail.com>
>> Cc: netdev@vger.kernel.org; netdev-owner@vger.kernel.org
>> Sent: Friday, November 4, 2011 4:46 PM
>> Subject: Re: iproute2 neighboring
>>
>>>  From: Kevin Wilson <wkevils@gmail.com>
>>
>>>  Hi,
>>>  It seems to me that "ip -6 neigh show" does not show multicast
>> entries
>> from
>>>  IPv6 neighboring  table. Is there a reason for this ?
>>
>> Multicast memberships aren't in the neighbor table. The
>> neighbor table is for translating protocol addresses to
>> MAC addresses and that translation is fixed for multicast
>> destinations.
>>
>> You can see group memberships with "netstat -g". There are also
>> some data in /proc/net/{dev_mcast,igmp6,mcfilter6} depending on
>> what you're looking for.
>>
>>                                                 +-DLS
>
> Hi,
>
> You can also see group memberships with "ip m".
>
> François-Xavier
>
>