OpenFlow 1.3.1 remove all flows and flow_stats about linc-switch

[konradkaplita]

After fixing ofp_flow_stats response message when I run delete all flows scenario introduced in this commit: 806e95a
I see such results:

1. After adding two flows and before deleting them, ofp_flow_stats returns:

Openflow Protocol
    Header
        Version: 0x04
        Type: Multipart reply (CSM) - OFPT_MULTIPART_REPLY (19)
        Length: 240
        Transaction ID: 4062250353
    Multipart reply
        Type: Individual flow statistics - OFPMP_FLOW (1)
        Flags: 0x0000
            .... .... .... ...0 = More replies to follow: Not set
        Padding
    Individual Flow Stats
        Length: 112
        Table ID: 0
        Padding
        Duration (sec): 0
        Duration (nsec): 202135000
        Priority: 1
        Idle Timeout: 0
        Hard Timeout: 0
        Flags: 0x0000
            0000 0000 0000 0... = Reserved: Not set
            .... .... .... ...0 = Send flow removed message when flow expires or is deleted: Not set
            .... .... .... ..0. = Check for overlapping entries first: Not set
            .... .... .... .0.. = Reset flow packet and byte counts: Not set
        Padding
        Cookie: 0x0000000000000000
        Packet count: 0
        Byte count: 0
        Match
            Type: OpenFlow Extensible Match - OFPMT_OXM (0x0001)
            Length: 23
            OXM field
                Class: Basic class for OpenFlow - OFPXMC_OPENFLOW_BASIC (0x8000)
                0000 101. = Field: Ethernet frame type - OFPXMT_OFB_ETH_TYPE (0x05)
                0 = Has mask: No
                Length: 2
                Value: 0800
            OXM field
                Class: Basic class for OpenFlow - OFPXMC_OPENFLOW_BASIC (0x8000)
                0001 010. = Field: IP protocol - OFPXMT_OFB_IP_PROTO (0x0a)
                0 = Has mask: No
                Length: 1
                Value: 06
            OXM field
                Class: Basic class for OpenFlow - OFPXMC_OPENFLOW_BASIC (0x8000)
                0001 011. = Field: IPv4 source address - OFPXMT_OFB_IPV4_SRC (0x0b)
                0 = Has mask: No
                Length: 4
                Value: 192.168.0.79 (192.168.0.79)
            Padding
        Instruction
            Type: Applies the action(s) immediately - OFPIT_APPLY_ACTIONS (0x0004)
            Length: 40
            Padding
            Action
                Type: Set a header field using OXM TLV format - OFPAT_SET_FIELD (0x0019)
                Length: 16
                OXM field
                    Class: Basic class for OpenFlow - OFPXMC_OPENFLOW_BASIC (0x8000)
                    0001 110. = Field: TCP destination port - OFPXMT_OFB_TCP_DST (0x0e)
                    0 = Has mask: No
                    Length: 2
                    Value: 1f2b
                Padding
            Action
                Type: Output to switch port - OFPAT_OUTPUT (0x0000)
                Length: 16
                Port: 2
                Max Length: 65535
                Padding
    Individual Flow Stats
        Length: 112
        Table ID: 0
        Padding
        Duration (sec): 0
        Duration (nsec): 405510000
        Priority: 1
        Idle Timeout: 0
        Hard Timeout: 0
        Flags: 0x0000
            0000 0000 0000 0... = Reserved: Not set
            .... .... .... ...0 = Send flow removed message when flow expires or is deleted: Not set
            .... .... .... ..0. = Check for overlapping entries first: Not set
            .... .... .... .0.. = Reset flow packet and byte counts: Not set
        Padding
        Cookie: 0x0000000000000000
        Packet count: 0
        Byte count: 0
        Match
            Type: OpenFlow Extensible Match - OFPMT_OXM (0x0001)
            Length: 18
            OXM field
                Class: Basic class for OpenFlow - OFPXMC_OPENFLOW_BASIC (0x8000)
                0000 101. = Field: Ethernet frame type - OFPXMT_OFB_ETH_TYPE (0x05)
                0 = Has mask: No
                Length: 2
                Value: 0800
            OXM field
                Class: Basic class for OpenFlow - OFPXMC_OPENFLOW_BASIC (0x8000)
                0001 011. = Field: IPv4 source address - OFPXMT_OFB_IPV4_SRC (0x0b)
                0 = Has mask: No
                Length: 4
                Value: 192.168.0.68 (192.168.0.68)
            Padding
        Instruction
            Type: Applies the action(s) immediately - OFPIT_APPLY_ACTIONS (0x0004)
            Length: 40
            Padding
            Action
                Type: Set a header field using OXM TLV format - OFPAT_SET_FIELD (0x0019)
                Length: 16
                OXM field
                    Class: Basic class for OpenFlow - OFPXMC_OPENFLOW_BASIC (0x8000)
                    0001 100. = Field: IPv4 destination address - OFPXMT_OFB_IPV4_DST (0x0c)
                    0 = Has mask: No
                    Length: 4
                    Value: 10.0.0.68 (10.0.0.68)
                Padding
            Action
                Type: Output to switch port - OFPAT_OUTPUT (0x0000)
                Length: 16
                Port: 2
                Max Length: 65535
                Padding

Flow mod that deletes all flows:

Openflow Protocol
    Header
        Version: 0x04
        Type: Flow mod (CSM) - OFPT_FLOW_MOD (14)
        Length: 56
        Transaction ID: 2153886217
    Flow Mod
        Cookie: 0x0000000000000000
        Cookie Mask: 0x0000000000000000
        Table ID: 255
        Command: Delete all matching flows - OFPFC_DELETE (0x03)
        Idle Timeout: 0
        Hard Timeout: 0
        Priority: 0
        Buffer ID: 0xffffffff
        Output Port: 4294967295
        Output Group: 4294967295
        Flags: 0x0000
            0000 0000 0000 0... = Reserved: Not set
            .... .... .... ...0 = Send flow removed message when flow expires or is deleted: Not set
            .... .... .... ..0. = Check for overlapping entries first: Not set
            .... .... .... .0.. = Reset flow packet and byte counts: Not set
        Padding
        Match
            Type: OpenFlow Extensible Match - OFPMT_OXM (0x0001)
            Length: 4
            Padding

Flow stats response after deletion of all flows:

Openflow Protocol
    Header
        Version: 0x04
        Type: Multipart reply (CSM) - OFPT_MULTIPART_REPLY (19)
        Length: 16
        Transaction ID: 1337138230
    Multipart reply
        Type: Individual flow statistics - OFPMP_FLOW (1)
        Flags: 0x0000
            .... .... .... ...0 = More replies to follow: Not set
        Padding

@mihailtudoran Can you confirm that it behaves the same for your controller?

[mihailtudoran]

@konradkaplita:

I still can't remove all flows with my controller, I think it is a problem on the match_field length:

The flow_mod my controller send have a match_field length of 8:

Openflow Protocol
Header
Flow Mod
Cookie: 0x0000000000000000
Cookie Mask: 0x0000000000000000
Table ID: 255
Command: Delete all matching flows - OFPFC_DELETE (0x03)
Idle Timeout: 0
Hard Timeout: 0
Priority: 32768
Buffer ID: 0xffffffff
Output Port: 4294967295
Output Group: 4294967295
Flags: 0x0000
Padding
Match
Type: OpenFlow Extensible Match - OFPMT_OXM (0x0001)
Length: 8
Padding

Your test scenario flow_mod have a match_field length of 4:

Openflow Protocol
Header
Flow Mod
Cookie: 0x0000000000000000
Cookie Mask: 0x0000000000000000
Table ID: 255
Command: Delete all matching flows - OFPFC_DELETE (0x03)
Idle Timeout: 0
Hard Timeout: 0
Priority: 0
Buffer ID: 0xffffffff
Output Port: 4294967295
Output Group: 4294967295
Flags: 0x0000
Padding
Match
Type: OpenFlow Extensible Match - OFPMT_OXM (0x0001)
Length: 4
Padding

According to OF1.3 spec the match_field length should be 8.

Regarding the flow_stats_request it works now.

[konradkaplita]

@mihailtudoran

You are right that total lenght of encoded ofp_match structure without any match fields will be 8 bytes, but the value of field length in this structure will be 4 bytes.

According to OFP 1.3 and 1.3.1 specs:

/* Fields to match against flows */
struct ofp_match {
    uint16_t type;             /* One of OFPMT_* */
    uint16_t length;           /* Length of ofp_match (excluding padding) */
    /* Followed by:
     * - Exactly (length - 4) (possibly 0) bytes containing OXM TLVs, then
     * - Exactly ((length + 7)/8*8 - length) (between 0 and 7) bytes of
     *   all-zero bytes
     * In summary, ofp_match is padded as needed, to make its overall size
     * a multiple of 8, to preserve alignement in structures using it.
     */
    uint8_t oxm_fields[4];     /* OXMs start here - Make compiler happy */
};
OFP_ASSERT(sizeof(struct ofp_match) == 8);

According to spec field lenght is calculated without padding. When match is empty lenght value is 4 and we have:

     * - Exactly (length - 4) (possibly 0) bytes containing OXM TLVs, then\

0 bytes of OXM TLVs (this is correct, we don't have any match fields)

and

     * - Exactly ((length + 7)/8*8 - length) (between 0 and 7) bytes of

(4+7)/8 is rounded to 1, multiplied by 8 gives 8 and when lenght is substracted this gives us padding of size 4. Hence overall size of ofp_match is 8 bytes.

[mihailtudoran]

@konradkaplita:

Correct, I fixed my flow_mod, now the messages are identical but I did not manage to remove the flows, the switch seems to ignore the command.

Sending the flow_mod from your controller ( of_controller_v4.erl ) is working correctly but sending the exact same flow_mod from my controller it doesn't work. With my controller I am able to insert new flows, this is not a connection issue.

How could I enable debugging mode on the switch ? It will help me a lot to see how the messages are processed this way I could identify the problem faster.

Thanks !

[konradkaplita]

@mihailtudoran

First of all you can increase loglevel by editing file rel/files/sys.config and changing:

{lager_console_backend, info},

to

{lager_console_backend, debug},

You have to rebuild switch by running make afterwards.

Please run LINC switch with console attached by: rel/linc/bin/linc console

As an effect you should see packets received by the switch like this:

13:25:07.796 [debug] Received message from the controller: {ofp_message,4,flow_mod,1905181425,{ofp_flow_mod,<<0,0,0,0,0,0,0,0>>,<<0,0,0,0,0,0,0,0>>,0,add,0,0,1,no_buffer,any,any,[],{ofp_match,[{ofp_field,openflow_basic,eth_type,false,<<8,0>>,undefined},{ofp_field,openflow_basic,ipv4_src,false,<<192,168,0,68>>,undefined}]},[{ofp_instruction_apply_actions,2,[{ofp_action_set_field,13,{ofp_field,openflow_basic,ipv4_dst,false,<<10,0,0,68>>,undefined}},{ofp_action_output,16,2,65535}]}]}}
13:25:07.997 [debug] Received message from the controller: {ofp_message,4,flow_mod,3105434037,{ofp_flow_mod,<<0,0,0,0,0,0,0,0>>,<<0,0,0,0,0,0,0,0>>,0,add,0,0,1,no_buffer,any,any,[],{ofp_match,[{ofp_field,openflow_basic,eth_type,false,<<8,0>>,undefined},{ofp_field,openflow_basic,ip_proto,false,<<6>>,undefined},{ofp_field,openflow_basic,ipv4_src,false,<<192,168,0,79>>,undefined}]},[{ofp_instruction_apply_actions,2,[{ofp_action_set_field,13,{ofp_field,openflow_basic,tcp_dst,false,<<31,43>>,undefined}},{ofp_action_output,16,2,65535}]}]}}
13:25:08.199 [debug] Received message from the controller: {ofp_message,4,multipart_request,4062250353,{ofp_flow_stats_request,[],all,any,any,<<0,0,0,0,0,0,0,0>>,<<0,0,0,0,0,0,0,0>>,{ofp_match,[]}}}
13:25:08.400 [debug] Received message from the controller: {ofp_message,4,flow_mod,2153886217,{ofp_flow_mod,<<0,0,0,0,0,0,0,0>>,<<0,0,0,0,0,0,0,0>>,all,delete,0,0,0,no_buffer,any,any,[],{ofp_match,[]},[]}}

above you have two flow mods, one flow stats request and final flow mod that deletes all flows.

Please make sure that switch does not report any errors when processing your OFP messages.

You can inspect flow tables installed on the switch by running from the console:

linc_us4_flow:get_flow_table(0, 0).

First zero indicates logical switch number, second zero indicates flow table number.
For example when you have two flow mods installed by my scenario(delete_all_flows) from of_controller_v4.erl you will see (before they are deleted of course :)

(linc@riesling)2> linc_us4_flow:get_flow_table(0,0).
[{flow_entry,{1,#Ref<0.0.0.613>},
             1,
             {ofp_match,[{ofp_field,openflow_basic,eth_type,false,
                                    <<8,0>>,
                                    undefined},
                         {ofp_field,openflow_basic,ip_proto,false,<<6>>,undefined},
                         {ofp_field,openflow_basic,ipv4_src,false,
                                    <<192,168,0,79>>,
                                    undefined}]},
             <<0,0,0,0,0,0,0,0>>,
             [],
             {1369,222749,847996},
             {infinity,0,0},
             {infinity,0,0},
             [{ofp_instruction_apply_actions,2,
                                             [{ofp_action_set_field,13,
                                                                    {ofp_field,openflow_basic,tcp_dst,false,
                                                                               <<31,43>>,
                                                                               undefined}},
                                              {ofp_action_output,16,2,65535}]}]},
 {flow_entry,{1,#Ref<0.0.0.610>},
             1,
             {ofp_match,[{ofp_field,openflow_basic,eth_type,false,
                                    <<8,0>>,
                                    undefined},
                         {ofp_field,openflow_basic,ipv4_src,false,
                                    <<192,168,0,68>>,
                                    undefined}]},
             <<0,0,0,0,0,0,0,0>>,
             [],
             {1369,222749,647322},
             {infinity,0,0},
             {infinity,0,0},
             [{ofp_instruction_apply_actions,2,
                                             [{ofp_action_set_field,13,
                                                                    {ofp_field,openflow_basic,ipv4_dst,false,
                                                                               <<10,0,0,68>>,
                                                                               undefined}},
                                              {ofp_action_output,16,2,65535}]}]}]

After sending flow mod that deletes all flows you shall see empty list:

(linc@riesling)3> linc_us4_flow:get_flow_table(0,0).
[]

Last but not least thing is tracing. You can set up a dynamic tracer, to show you what functions are executed on the live environment.
We are interested with function linc_us4_flow:delete_matching_flows/7. You can enable tracer by pasting this lines into LINC console:

dbg:tracer().
dbg:p(all,c).
dbg:tpl(linc_us4_flow, delete_matching_flows, x).

as an effect, when switch receives flow mod that should delete flows, you will see this function calls printed on the console.

Hope this can help you debug this issue.

[mihailtudoran]

@konradkaplita:

I can confirm this issue is fixed. I identified a problem on my side, on the last padding ( match padding ).

Thank you!

[konradkaplita]

Great news! I'm closing this issue then.

Thanks for your effort and feedback.