Question

Cannot discover topology of switches


I have a lab setup where the controller is connected to the management ports of three OF switches through another L2 switch (another X440). The three switches are able to connect to the controller but the connection between them isn't discovered by the Topology manager in OpenDaylight. I see an empty topology through the REST API and the web view shows three isolated switches. I suspect this is because the L2 switch isn't forwarding the LLDP packet sent by the controller to the three OF switches. I may be completely wrong though. Do I need to enable some LLDP related feature/setting on the X440s to forward LLDPs? Or disable some feature on the one I'm using as a simple L2 switch? Kindly help me figure out why the topology isn't discovered by the controller.

7 replies

Userlevel 4
I guess extreme switches have EDP enabled by default.
And LLDP must be enabled manually.
Please try enabling LLDP.
Communication between controller and switches is via Open Flow protocol. LLDP packets get encapsulated in Open Flow protocol and send to controller. So L2 switch is not a problem here.

Output of below commands from all switches may give idea on what's going on in the switches.

1. show openflow
2. show openflow flows
Masadi, Ravi wrote:

Communication between controller and switches is via Open Flow protocol. LLDP packets get encapsulated in Open Flow protocol and send to controller. So L2 switch is not a problem here.

Output of below commands from all switches may give idea on what's going on in the switches.

1. show openflow
2. show openflow flows

The output of these commands looks okay. Switch one ----------------- X440-8p.1 # show openflow OpenFlow: Enabled Versions: OpenFlow10, OpenFlow13 Mode: Standard FDB: Off Access-list width: Single Controller : Primary Status : ACTIVE Datapath ID : 000000049697c679 VR : VR-Mgmt Mode : out-of-band Active Target : tcp:10.10.1.10:6633 Uptime(secs) : 1152 Controller : Secondary Not configured. Total number of VLAN(s): 0 X440-8p.2 # show openflow flows Total number of OpenFlow flows : 0 Total number of default flows : 2 Flow name Type Duration (secs) Prio Packets ---------------- ---- ------------------- ----- -------------------- ofDefault_0 ACL 1326 0 0 Match : Actions: CONTROLLER ofDefault_2 ACL 1326 0 0 Match : Ethernet Type : 0x88cc (LLDP) Actions: CONTROLLER Packets: (*) Cumulative packet count for all FDB flows X440-8p.3 # X440-8p.3 # X440-8p.3 # show openflow flows Total number of OpenFlow flows : 0 Total number of default flows : 2 Flow name Type Duration (secs) Prio Packets ---------------- ---- ------------------- ----- -------------------- ofDefault_0 ACL 1365 0 0 Match : Actions: CONTROLLER ofDefault_2 ACL 1365 0 0 Match : Ethernet Type : 0x88cc (LLDP) Actions: CONTROLLER Packets: (*) Cumulative packet count for all FDB flows Switch two -------------- X440-8p.1 # show openflow OpenFlow: Enabled Versions: OpenFlow10, OpenFlow13 Mode: Standard FDB: Off Access-list width: Single Controller : Primary Status : ACTIVE Datapath ID : 0000000496979b95 VR : VR-Mgmt Mode : out-of-band Active Target : tcp:10.10.1.10:6633 Uptime(secs) : 838 Controller : Secondary Not configured. Total number of VLAN(s): 0 X440-8p.2 # X440-8p.2 # show openflow flows Total number of OpenFlow flows : 0 Total number of default flows : 2 Flow name Type Duration (secs) Prio Packets ---------------- ---- ------------------- ----- -------------------- ofDefault_0 ACL 1314 0 0 Match : Actions: CONTROLLER ofDefault_2 ACL 1314 0 0 Match : Ethernet Type : 0x88cc (LLDP) Actions: CONTROLLER Packets: (*) Cumulative packet count for all FDB flows
Masadi, Ravi wrote:

Communication between controller and switches is via Open Flow protocol. LLDP packets get encapsulated in Open Flow protocol and send to controller. So L2 switch is not a problem here.

Output of below commands from all switches may give idea on what's going on in the switches.

1. show openflow
2. show openflow flows

Hi Ankit,

From the above show openflow - (Total number of VLAN(s): 0), I could see that you have not enabled OpenFlow on ports/VLANs that connecting the switches that is the reason for not seeing the topology. Open Flow process processes the packets that ingress on open flow enabled ports only.

Since EXOS doesn't allow to enable open flow on port directly, you need create a VLAN in all the switches and add the connecting ports and then enable open flow on the VLAN. Here is an example configuration

create vlan "v11"
configure vlan v11 tag 11
configure vlan v11 add ports 22, 25-26 tagged
enable openflow vlan "v11"

Regards,
Ravi Masadi
Masadi, Ravi wrote:

Communication between controller and switches is via Open Flow protocol. LLDP packets get encapsulated in Open Flow protocol and send to controller. So L2 switch is not a problem here.

Output of below commands from all switches may give idea on what's going on in the switches.

1. show openflow
2. show openflow flows

Thanks Ravi! I see the topology as expected on the controller now.
Ankit

Can you try enabling the following on the switch

configure openflow default-rule lldp controller
configure openflow default-rule miss controller

controller uses OF packet_in and packet_out messages to figure out the topolology. If the default action is set to drop on the switch the LLDP packets might get dropped and will never be sent to controller.

Regards
Sathish
Srinivasan, Satishkumar wrote:

Ankit

Can you try enabling the following on the switch

configure openflow default-rule lldp controller
configure openflow default-rule miss controller

controller uses OF packet_in and packet_out messages to figure out the topolology. If the default action is set to drop on the switch the LLDP packets might get dropped and will never be sent to controller.

Regards
Sathish

The config is already present on the switches. I think I'm missing something else. X440-8p.5 # show configuration "openflow" # # Module openflow configuration. # configure openflow default-rule lldp controller configure openflow default-rule miss controller enable openflow configure openflow controller primary out-of-band active ipaddress 10.10.1.10 vr VR-Mgmt

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