Re: SCTP Multihoming Always sending primary interface ip I

[VARUN BHATIA <varuninbharti@gmail.com>]

Hi Vlad,

This is my configuration eth2 and eth3 of 2 machines are connected
through my office network.
                 Host A                                      Host B
Primary    10.204.200.200                          10.205.200.200
Secondary 10.204.100.100                         10.205.100.100

When my both interfaces are up then:

  0.903456 10.204.200.200 -> 10.204.100.100 SCTP 100 INIT
  0.905510 10.204.100.100 -> 10.204.200.200 SCTP 356 INIT_ACK
  0.905565 10.204.200.200 -> 10.204.100.100 SCTP 312 COOKIE_ECHO
  0.907578 10.204.100.100 -> 10.204.200.200 SCTP 62 COOKIE_ACK

  3.099986 10.205.100.100 -> 10.205.200.200 SCTP 100 HEARTBEAT
  3.106487 10.204.200.200 -> 10.205.100.100 SCTP 100 HEARTBEAT_ACK
  6.889510 10.204.200.200 -> 10.204.100.100 SCTP 100 HEARTBEAT
  6.891533 10.204.100.100 -> 10.204.200.200 SCTP 100 HEARTBEAT_ACK
  9.257506 10.204.200.200 -> 10.205.100.100 SCTP 100 HEARTBEAT
  9.258420 10.204.100.100 -> 10.204.200.200 SCTP 100 HEARTBEAT_ACK
 12.248829 10.204.100.100 -> 10.204.200.200 SCTP 100 HEARTBEAT
 12.248869 10.204.200.200 -> 10.204.100.100 SCTP 100 HEARTBEAT_ACK
 57.372808 10.204.200.200 -> 10.204.100.100 SCTP 56 SHUTDOWN
 57.374730 10.204.100.100 -> 10.204.200.200 SCTP 62 SHUTDOWN_ACK
 57.374767 10.204.200.200 -> 10.204.100.100 SCTP 52 SHUTDOWN_COMPLETE


Now I make my interface down eth2 which is primary of Host A:

At A:

107.729047 10.204.200.200 -> 10.204.100.100 SCTP 100 INIT
110.740242 10.204.200.200 -> 10.205.100.100 SCTP 100 INIT
113.744168 10.204.200.200 -> 10.204.100.100 SCTP 100 INIT


At B:
 69.842169 10.204.200.200 -> 10.204.100.100 SCTP 100 INIT
 69.842234 10.204.100.100 -> 10.204.200.200 SCTP 356 INIT_ACK


It is dropping INIT ACK because the ip address on which it is sending
is down, I have made the changes recommended by you but yet the result
is same:

ip neigh list
fe80::224:13ff:fe45:ced4 dev eth3 lladdr 00:24:13:45:ce:d4 router STALE
fe80::224:13ff:fe45:ced5 dev eth0 lladdr 00:24:13:45:ce:d5 router REACHABLE
10.205.100.100 dev eth3 lladdr 00:0b:ab:55:57:01 DELAY
10.201.100.22 dev eth3 lladdr 00:24:13:45:ce:d4 DELAY
10.206.0.1 dev eth0 lladdr 00:24:13:45:ce:d5 REACHABLE


Thanks,
Varun

On Wed, Sep 24, 2014 at 10:03 PM, Vlad Yasevich <vyasevich@gmail.com> wrote:
> On 09/24/2014 11:42 AM, Varun Bhatia wrote:
>> Thanks Vlad for your response but they are already on different subnets :(
>
> Look at your neighbor cache (ip neigh list).  If it shows the peer
> on the wrong interface, then you need arg_ignore|arp_announce changes.
>
> -vlad
>
>>
>> Sent from Iphone,
>> Varun
>>
>>> On 24-Sep-2014, at 18:36, Vlad Yasevich <vyasevich@gmail.com> wrote:
>>>
>>>> On 09/24/2014 08:56 AM, VARUN BHATIA wrote:
>>>> Hi,
>>>>
>>>> We have developed multihomed application now while testing my setup is:
>>>>
>>>> Eth4  as primary interface connected back to back to another machine.
>>>> Eth5 as secondary interface connected back to back to another machine.
>>>>
>>>> I make my porimary interface down now when the INIT is been sent it
>>>> reaches to peer machine seems using secondary interface but the source
>>>> ip address kept is of primary interface only due to which when peer
>>>> machine tries to respond INIT_ACK it tries to send on primary
>>>> interface ip which is down and due to ICMP it drops the packet.
>>>>
>>>> I am not too good in Routing but it seems that some routing has not
>>>> been configuered properly, why is it always using primary ip ?
>>>>
>>>> I have tested the same part when I have connected my primary &
>>>> secondary interface through router but facrd the same issue.
>>>>
>>>> Any inputs are appreciated as I am stuck in it since last 2 days.
>>>>
>>>
>>> Try to put the 2 interfaces into 2 different subnets.  That should fix
>>> your issue.  If you can't do that,  then you'd have to play with arp_ignore
>>> and arp_announce sysctl values to make it do what you want.
>>>
>>> -vlad
>



-- 
Regards,
Varun Bhatia