Message-ID: <529DF73E.7060604@gmail.com>
Date:	Tue, 03 Dec 2013 10:22:38 -0500
From:	Vlad Yasevich <vyasevich@...il.com>
To:	Sun Paul <paulrbk@...il.com>
CC:	netdev@...r.kernel.org, linux-sctp@...r.kernel.org,
	Karl Heiss <kheiss@...il.com>,
	Neil Horman <nhorman@...driver.com>,
	linux-kernel@...r.kernel.org
Subject: Re: Supporting 4 way connections in LKSCTP

On 12/03/2013 08:11 AM, Sun Paul wrote:
> But how about the HB and HB_ACK?  Still valid?

As long as the source address is part of the association, then yes
it is perfectly valid.

-vlad

> On Dec 3, 2013 8:32 PM, "Vlad Yasevich" <vyasevich@...il.com> wrote:
> 
>> On 12/02/2013 09:19 PM, Sun Paul wrote:
>>> so in this case, says
>>>
>>> (NODE-A) IP-B send INIT to IP-X (NODE-B), and then IP-Y (NODE-B)
>>> returns INIT_ACK to IP-B (NODE-A)
>>>
>>> this is also treated as a valid, am I correct?
>>
>> As long as IP-X (Node-B) is present in the address list of the INIT-ACK
>> chunk, yes.
>>
>> There is the code in __sctp_rcv_lookup_harder() that looks for other
>> adddresses in the INIT and INIT-ACK chunks.
>>
>> -vlad
>>>
>>>
>>> On Tue, Dec 3, 2013 at 10:03 AM, Vlad Yasevich <vyasevich@...il.com>
>> wrote:
>>>> On 12/02/2013 08:39 PM, Sun Paul wrote:
>>>>> Another question
>>>>>
>>>>> if a wrong source IP is used, does the association still classified as
>> normal?
>>>>
>>>> What do you mean my wrong source IP?  As long as the address is part of
>>>> the association, it can be used.
>>>>
>>>> -vlad
>>>>
>>>>>
>>>>> On Tue, Dec 3, 2013 at 9:31 AM, Sun Paul <paulrbk@...il.com> wrote:
>>>>>> Thanks Vlad
>>>>>>
>>>>>> I checked on the route, and it looks correct.
>>>>>>
>>>>>> [root@...alhost ~]# ip route get 11.1.1.1 from 110.1.1.1
>>>>>> 11.1.1.1 from 110.1.1.1 via 110.1.1.254 dev eth1
>>>>>>     cache  mtu 1500 advmss 1460 hoplimit 64
>>>>>>
>>>>>> [root@...alhost ~]# ip route get 11.1.1.1 from 120.1.1.1
>>>>>> 11.1.1.1 from 120.1.1.1 via 120.1.1.254 dev eth2
>>>>>>     cache  mtu 1500 advmss 1460 hoplimit 64
>>>>>>
>>>>>> [root@...alhost ~]# ip route get 12.1.1.1 from 120.1.1.1
>>>>>> 12.1.1.1 from 120.1.1.1 via 120.1.1.254 dev eth2
>>>>>>     cache  mtu 1500 advmss 1460 hoplimit 64
>>>>>>
>>>>>> [root@...alhost ~]# ip route get 12.1.1.1 from 110.1.1.1
>>>>>> 12.1.1.1 from 110.1.1.1 via 110.1.1.254 dev eth1
>>>>>>     cache  mtu 1500 advmss 1460 hoplimit 64
>>>>>>
>>>>>> so, if this is not being handled in LKSCTP, is it possible to suggest
>>>>>> a way how we can achieve it?
>>>>>>
>>>>>> On Tue, Dec 3, 2013 at 12:42 AM, Vlad Yasevich <vyasevich@...il.com>
>> wrote:
>>>>>>> On 12/02/2013 10:45 AM, Karl Heiss wrote:
>>>>>>>> On Mon, Dec 2, 2013 at 9:38 AM, Vlad Yasevich <vyasevich@...il.com>
>> wrote:
>>>>>>>>> On 11/27/2013 11:03 PM, Sun Paul wrote:
>>>>>>>>>> How LKSCTP select which source address to use for the INIT_ACK or
>>>>>>>>>> HB_ACK? below is the testing result where a router is located in
>> the
>>>>>>>>>> middle.
>>>>>>>>>>
>>>>>>>>>> Before starting the application. the packet on eth1 and eth2 are
>>>>>>>>>>
>>>>>>>>>> eth1
>>>>>>>>>> 0 packets dropped by kernel
>>>>>>>>>> [root@...alhost ~]# tcpdump -i eth1 -s 0 -nn
>>>>>>>>>> tcpdump: verbose output suppressed, use -v or -vv for full
>> protocol decode
>>>>>>>>>> listening on eth1, link-type EN10MB (Ethernet), capture size
>> 65535 bytes
>>>>>>>>>> 11:24:14.262489 IP 12.1.1.1.2905 > 110.1.1.1.2905: sctp (1) [INIT]
>>>>>>>>>> [init tag: 28362903] [rwnd: 102400] [OS: 16] [MIS: 16] [init TSN:
>> 0]
>>>>>>>>>> 11:24:14.262522 IP 110.1.1.1.2905 > 12.1.1.1.2905: sctp (1)
>> [ABORT]
>>>>>>>>>> 11:24:14.539486
>>>>>>>>>> 11:24:16.262488 IP 12.1.1.1.2905 > 110.1.1.1.2905: sctp (1) [INIT]
>>>>>>>>>> [init tag: 29391734] [rwnd: 102400] [OS: 16] [MIS: 16] [init TSN:
>> 0]
>>>>>>>>>> 11:24:16.262520 IP 110.1.1.1.2905 > 12.1.1.1.2905: sctp (1)
>> [ABORT]
>>>>>>>>>>
>>>>>>>>>> eth2
>>>>>>>>>> [root@...alhost ~]# tcpdump -i eth2 -s 0 -nn
>>>>>>>>>> tcpdump: verbose output suppressed, use -v or -vv for full
>> protocol decode
>>>>>>>>>> listening on eth2, link-type EN10MB (Ethernet), capture size
>> 65535 bytes
>>>>>>>>>>
>>>>>>>>>> When starting the application. the packet show as below.
>>>>>>>>>>
>>>>>>>>>> eth1
>>>>>>>>>> 11:26:02.261511 IP 12.1.1.1.2905 > 110.1.1.1.2905: sctp (1) [INIT]
>>>>>>>>>> [init tag: 26256828] [rwnd: 102400] [OS: 16] [MIS: 16] [init TSN:
>> 0]
>>>>>>>>>> 11:26:02.263513 IP 12.1.1.1.2905 > 110.1.1.1.2905: sctp (1)
>> [COOKIE ECHO]
>>>>>>>>>> 11:26:02.264518 IP 12.1.1.1.2905 > 110.1.1.1.2905: sctp (1) [HB
>> REQ]
>>>>>>>>>> 11:26:02.563511 IP 12.1.1.1.2905 > 110.1.1.1.2905: sctp (1) [HB
>> REQ]
>>>>>>>>>>
>>>>>>>>>> eth2
>>>>>>>>>> 11:26:02.261604 IP 120.1.1.1.2905 > 12.1.1.1.2905: sctp (1) [INIT
>> ACK]
>>>>>>>>>> [init tag: 3478239387] [rwnd: 131072] [OS: 5] [MIS: 5] [init TSN:
>>>>>>>>>> 2330749678]
>>>>>>>>>> 11:26:02.263583 IP 120.1.1.1.2905 > 12.1.1.1.2905: sctp (1)
>> [COOKIE ACK]
>>>>>>>>>> 11:26:02.264548 IP 120.1.1.1.2905 > 12.1.1.1.2905: sctp (1) [HB
>> ACK]
>>>>>>>>>> 11:26:02.264652 IP 11.1.1.1.2905 > 120.1.1.1.2905: sctp (1) [HB
>> REQ]
>>>>>>>>>> 11:26:02.264705 IP 120.1.1.1.2905 > 11.1.1.1.2905: sctp (1) [HB
>> ACK]
>>>>>>>>>> 11:26:02.563543 IP 120.1.1.1.2905 > 12.1.1.1.2905: sctp (1) [HB
>> ACK]
>>>>>>>>>>
>>>>>>>>>> From the above result, you can see that the INIT, COOKIE ECHO and
>>>>>>>>>> HB_REQ originated from 12.1.1.1 on eth1, but the ACK (INIT_ACK,
>>>>>>>>>> COOKIE_ACK, HB_ACK) are returned on eth2 using source address
>>>>>>>>>> 120.1.1.1 instead of 110.1.1.1.
>>>>>>>>>>
>>>>>>>>>> Why LKSCTP use 120.1.1.1 as source instead of 110.1.1.1?
>>>>>>>>>>
>>>>>>>>>> For simple ICMP ping test, it is normal, but not for SCTP.
>>>>>>>>>>
>>>>>>>>>> eth1
>>>>>>>>>> 11:30:02.824548 IP 12.1.1.1 > 110.1.1.1: ICMP echo request, id
>> 37178,
>>>>>>>>>> seq 12, length 64
>>>>>>>>>> 11:30:02.824559 IP 110.1.1.1 > 12.1.1.1: ICMP echo reply, id
>> 37178,
>>>>>>>>>> seq 12, length 64
>>>>>>>>>> 11:30:03.825551 IP 12.1.1.1 > 110.1.1.1: ICMP echo request, id
>> 37178,
>>>>>>>>>> seq 13, length 64
>>>>>>>>>> 11:30:03.825561 IP 110.1.1.1 > 12.1.1.1: ICMP echo reply, id
>> 37178,
>>>>>>>>>> seq 13, length 64
>>>>>>>>>>
>>>>>>>>>> eth2
>>>>>>>>>> 11:30:34.027687 IP 11.1.1.1 > 120.1.1.1: ICMP echo request, id
>> 46138,
>>>>>>>>>> seq 2, length 64
>>>>>>>>>> 11:30:34.027697 IP 120.1.1.1 > 11.1.1.1: ICMP echo reply, id
>> 46138,
>>>>>>>>>> seq 2, length 64
>>>>>>>>>> 11:30:35.027686 IP 11.1.1.1 > 120.1.1.1: ICMP echo request, id
>> 46138,
>>>>>>>>>> seq 3, length 64
>>>>>>>>>> 11:30:35.027694 IP 120.1.1.1 > 11.1.1.1: ICMP echo reply, id
>> 46138,
>>>>>>>>>> seq 3, length 64
>>>>>>>>>>
>>>>>>>>>> Below is the route information
>>>>>>>>>> #route -n
>>>>>>>>>> Kernel IP routing table
>>>>>>>>>> Destination     Gateway         Genmask         Flags Metric Ref
>>    Use Iface
>>>>>>>>>> 110.1.1.0       0.0.0.0         255.255.255.0   U     0      0
>>      0 eth1
>>>>>>>>>> 120.1.1.0       0.0.0.0         255.255.255.0   U     0      0
>>      0 eth2
>>>>>>>>>>
>>>>>>>>>> # ip route show
>>>>>>>>>> 110.1.1.0/24 dev eth1  proto kernel  scope link  src 110.1.1.1
>>>>>>>>>> 120.1.1.0/24 dev eth2  proto kernel  scope link  src 120.1.1.1
>>>>>>>>>>
>>>>>>>>>> Since we are using iproute2, so we will have dedicate routing
>> table
>>>>>>>>>> per interface
>>>>>>>>>>
>>>>>>>>>> # ip route show table SCTP1
>>>>>>>>>> default via 110.1.1.254 dev eth1
>>>>>>>>>>
>>>>>>>>>> # ip route show table SCTP2
>>>>>>>>>> default via 120.1.1.254 dev eth2
>>>>>>>>>>
>>>>>>>>>> # ip rule ls
>>>>>>>>>> 0: from all lookup local
>>>>>>>>>> 101: from 110.1.1.1 lookup SCTP1
>>>>>>>>>> 102: from 120.1.1.1 lookup SCTP2
>>>>>>>>>> 32766: from all lookup main
>>>>>>>>>> 32767: from all lookup default
>>>>>>>>>>
>>>>>>>>>> How LKSCTP select source address to reply? If we know how it
>> works,
>>>>>>>>>> then we may know what is going wrong.
>>>>>>>>>
>>>>>>>>> LKSCTP will prefer the address returned from the routing table as
>> long
>>>>>>>>> as it is one of the addresses that is bound by the socket and are
>> usable
>>>>>>>>> by the association.
>>>>>>>>>
>>>>>>>>> If the address returned from the route lookup is not part of the
>>>>>>>>> association, then lksctp attempts to lookup routes using one of the
>>>>>>>>> source addresses it has available.  Usually the first lookup
>> succeeds
>>>>>>>>> due to the host-model implementation in linux.
>>>>>>>>>
>>>>>>>>> You may want to change your rule set to be destination based.  Then
>>>>>>>>> in the table associated with the rule, specify the source address
>>>>>>>>> you want to be used.
>>>>>>>>>
>>>>>>>>> -vlad
>>>>>>>>
>>>>>>>> I have had similar qualms myself about this behavior, and I honestly
>>>>>>>> don't know what the correct answer should be...
>>>>>>>>
>>>>>>>> In my opinion, shouldn't the source address "just work" for
>>>>>>>> acknowledgements? If the spec explicitly states that the ACK should
>>>>>>>> have a source address that matches the destination of the chunk
>> being
>>>>>>>> ACKed, why should someone have to configure this behavior outside of
>>>>>>>> the SCTP stack by default? Is it a technical limitation, or is this
>>>>>>>> done for a particular reason?  I can understand needing to override
>>>>>>>> the behavior, but why isn't the default "sane"?
>>>>>>>
>>>>>>> I think the results are sane, they simply may not match expectations.
>>>>>>> SCTP spec doesn't say anything about source address selection.  It
>>>>>>> says that a response should be send back to the source of the
>> request.
>>>>>>> This is being done in both cases, i.e. the destination address in
>>>>>>> INIT-ACK matches the source of the INIT.
>>>>>>>
>>>>>>> The spec does contain the MAY text that allows finer control of
>> source
>>>>>>> addresses, but lksctp doesn't seem to implement that.  Whenever we've
>>>>>>> tried, we couldn't get the generic mechanism working to please
>> everyone,
>>>>>>> as everyone had slightly different configurations and expectations.
>>  So
>>>>>>> we left it to the rules engine.
>>>>>>>
>>>>>>> In this setup, it just appears that the default routing is not what
>> you
>>>>>>> expect.  You can easily check this with 'ip route get' command.  If
>> it
>>>>>>> is not what you want linux allows you to change that via ip rules.
>>>>>>>
>>>>>>> -vlad
>>>>>>>
>>>>>>>>
>>>>>>>> Karl
>>>>>>>>
>>>>>>>>>>
>>>>>>>>>> On Wed, Nov 27, 2013 at 8:45 PM, Neil Horman <
>> nhorman@...driver.com> wrote:
>>>>>>>>>>> On Wed, Nov 27, 2013 at 07:10:49AM +0800, Sun Paul wrote:
>>>>>>>>>>>> Hi Vlad
>>>>>>>>>>>>
>>>>>>>>>>>> Thank for your reply. If it is based on the destination IP to
>> find the
>>>>>>>>>>>> best route, why the problem didn't happen on single-homing
>> sample?
>>>>>>>>>>>>
>>>>>>>>>>> Because You only ever use one address from NODE A (12.1.1.1)
>>>>>>>>>>>
>>>>>>>>>>>> In the single-homing sample that provided in the original
>> email, both
>>>>>>>>>>>> of the interfaces (eth1 and eth2) are presented on NODE-B
>> during the
>>>>>>>>>>>> test. However, the LKSCTP library know to use the interface
>> eth1 to
>>>>>>>>>>>> respond to the SCTP request.
>>>>>>>>>>>>
>>>>>>>>>>> Yes, because it does a route lookup to each of the two ip
>> addresses to NODE B,
>>>>>>>>>>> and in both lookups, the route indicates that only one source
>> address should be
>>>>>>>>>>> used (12.1.1.1).  If you issue a ip route show command, you'll
>> see that routes
>>>>>>>>>>> to both address on NODE B match on a rule that specifies the
>> same src address
>>>>>>>>>>> and interface be used.
>>>>>>>>>>>
>>>>>>>>>>> Neil
>>>>>>>>>>>
>>>>>>>>>>>> - PS
>>>>>>>>>>>>
>>>>>>>>>>>> On Wed, Nov 27, 2013 at 7:09 AM, Sun Paul <paulrbk@...il.com>
>> wrote:
>>>>>>>>>>>>> Hi Vlad
>>>>>>>>>>>>>
>>>>>>>>>>>>> Thank for your reply. If it is based on the destination IP to
>> find the
>>>>>>>>>>>>> best route, why the problem didn't happen on single-homing
>> sample?
>>>>>>>>>>>>>
>>>>>>>>>>>>> In the single-homing sample that provided in the original
>> email, both
>>>>>>>>>>>>> of the interfaces (eth1 and eth2) are presented on NODE-B
>> during the
>>>>>>>>>>>>> test. However, the LKSCTP library know to use the interface
>> eth1 to
>>>>>>>>>>>>> respond to the SCTP request.
>>>>>>>>>>>>>
>>>>>>>>>>>>> - PS
>>>>>>>>>>>>>
>>>>>>>>>>>>> On Tue, Nov 26, 2013 at 11:19 PM, Vlad Yasevich <
>> vyasevich@...il.com> wrote:
>>>>>>>>>>>>>> On 11/25/2013 08:03 PM, Sun Paul wrote:
>>>>>>>>>>>>>>> Hi
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> we have a problem on using LKSCTP to form a 4 ways
>> multi-homing network.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Configuration
>>>>>>>>>>>>>>> - Node-A has 2 IP addresses in different subnets, known as
>> IP-A (eth1),
>>>>>>>>>>>>>>> IP-B (eth2)
>>>>>>>>>>>>>>> - Node-B has 2 IP addresses in different subnets, known as
>> IP-X (eth1),
>>>>>>>>>>>>>>> IP-Y (eth2)
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> First of all, this is not a 4 way multi-homed network.  As
>> far as each
>>>>>>>>>>>>>> SCTP association is concerned, it has only 2 destinations to
>> send to
>>>>>>>>>>>>>> so it has only 2 ways to get there.  The fact that you have
>> multiple
>>>>>>>>>>>>>> local addresses doesn't mean that every local address can and
>> should
>>>>>>>>>>>>>> be used to connect to the remote.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> the four way paths are shown below.
>>>>>>>>>>>>>>> 1. IP-A (11.1.1.1) to IP-X (11.1.1.11)
>>>>>>>>>>>>>>> 2. IP-B (12.1.1.1) to IP-Y (12.1.1.11)
>>>>>>>>>>>>>>> 3. IP-A (11.1.1.1) to IP-Y (12.1.1.11)
>>>>>>>>>>>>>>> 4. IP-B (12.1.1.1) to IP-X (11.1.1.11)
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> No, actually you only have 2 paths:  one to IPX and one to
>> IP-Y.
>>>>>>>>>>>>>> Which source address you choose is based on routing policy
>>>>>>>>>>>>>> decisions and is outside the scope of SCTP.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> the HB/HB_ACK is normal for the paths " IP-A to IP-X" and
>> "IP-B to
>>>>>>>>>>>>>>> IP-Y", but it is not correct for the rest of two.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> Right, because linux is using a host addressing model, not an
>> interface
>>>>>>>>>>>>>> addressing model.  SCTP stack simply finds the best source
>> address
>>>>>>>>>>>>>> that can be used to reach IP-X and it happens to be IP-A.  So
>> that
>>>>>>>>>>>>>> is what it is going to use.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> The above explains why you are seeing what you describe below.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> In the end, linux SCTP implementation determines paths solely
>> based
>>>>>>>>>>>>>> on the destination address.
>>>>>>>>>>>>>>
>>>>>>>>>>>>>> -vlad
>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> First of all, we are using iproute2 to form 2 table such
>> that when
>>>>>>>>>>>>>>> IP-B arrives on IP-X, it will know how to route back to IP-B
>> on the
>>>>>>>>>>>>>>> same interface, i.e (eth1). Same logic for the path "IP-A to
>> IP-X".
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> What we observed here is that when 12.1.1.1 sends INIT to
>> 11.1.1.11,
>>>>>>>>>>>>>>> LKSCTP will send back the INIT_ACK to 12.1.1.1 using
>> 12.1.1.11 but not
>>>>>>>>>>>>>>> using the IP 11.1.1.11.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> The above operation makes the subsequence HB/HB_ACK in using
>> wrong IP address.
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> TCP trace on eth1
>>>>>>>>>>>>>>> 18:02:41.058640 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [INIT]
>>>>>>>>>>>>>>> [init tag: 19933036] [rwnd: 102400] [OS: 16] [MIS: 16] [init
>> TSN: 0]
>>>>>>>>>>>>>>> 18:02:41.061634 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [COOKIE ECHO]
>>>>>>>>>>>>>>> 18:02:41.062642 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:02:41.062846 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1)
>> [HB ACK]
>>>>>>>>>>>>>>> 18:02:41.361811 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1)
>> [HB ACK]
>>>>>>>>>>>>>>> 18:02:41.661791 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1)
>> [HB ACK]
>>>>>>>>>>>>>>> 18:02:41.961791 IP 11.1.1.11.2905 > 11.1.1.1.2905: sctp (1)
>> [HB ACK]
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> TCP trace on eth2
>>>>>>>>>>>>>>> 18:02:41.058755 IP 12.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [INIT ACK]
>>>>>>>>>>>>>>> [init tag: 424726157] [rwnd: 131072] [OS: 5] [MIS: 5] [init
>> TSN:
>>>>>>>>>>>>>>> 3340756356]
>>>>>>>>>>>>>>> 18:02:41.061696 IP 12.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [COOKIE ACK]
>>>>>>>>>>>>>>> 18:02:41.062663 IP 12.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [HB ACK]
>>>>>>>>>>>>>>> 18:02:41.062791 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:02:41.361777 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:02:41.661772 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:02:41.961772 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:02:42.161771 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:02:42.461770 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:02:42.675770 IP 11.1.1.1.2905 > 12.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> If we are using single homing, there is no problem on the
>> SCTP
>>>>>>>>>>>>>>> communication. Below is the TCP trace on eth1 using sctp_test
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> 18:09:55.356727 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [INIT]
>>>>>>>>>>>>>>> [init tag: 32516609] [rwnd: 102400] [OS: 16] [MIS: 16] [init
>> TSN: 0]
>>>>>>>>>>>>>>> 18:09:55.356811 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [INIT ACK]
>>>>>>>>>>>>>>> [init tag: 3168861995] [rwnd: 131072] [OS: 10] [MIS: 16]
>> [init TSN:
>>>>>>>>>>>>>>> 1877695021]
>>>>>>>>>>>>>>> 18:09:55.357727 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [COOKIE ECHO]
>>>>>>>>>>>>>>> 18:09:55.357788 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [COOKIE ACK]
>>>>>>>>>>>>>>> 18:09:55.358724 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:09:55.358740 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [HB ACK]
>>>>>>>>>>>>>>> 18:09:55.379715 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [DATA]
>>>>>>>>>>>>>>> (B)(E) [TSN: 0] [SID: 0] [SSEQ 0] [PPID 0x3]
>>>>>>>>>>>>>>> 18:09:55.379735 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [SACK]
>>>>>>>>>>>>>>> [cum ack 0] [a_rwnd 131064] [#gap acks 0] [#dup tsns 0]
>>>>>>>>>>>>>>> 18:09:55.657716 IP 12.1.1.1.2905 > 11.1.1.11.2905: sctp (1)
>> [HB REQ]
>>>>>>>>>>>>>>> 18:09:55.657732 IP 11.1.1.11.2905 > 12.1.1.1.2905: sctp (1)
>> [HB ACK]
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> From the observations, it seems that the LKSCTP library is
>> not able to
>>>>>>>>>>>>>>> use the original local address when multi-homing is being
>> used. Is
>>>>>>>>>>>>>>> there anyway can be resolved it?
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> Thanks
>>>>>>>>>>>>>>>
>>>>>>>>>>>>>>> PS
>>>>>>>>>>>>>>> --
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>>>>>>>>>>>>>>
>>>>>>>>>>>> --
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>>>>>>>>>>>>
>>>>>>>>>
>>>>>>>>> --
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>>>>
>>
>>
> 

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