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How topology manager work for OVS switchs and connected client to that switch

asked 2015-03-04 08:50:18 -0700

deepak660d gravatar image

updated 2015-03-04 08:58:52 -0700

ODL learn LLDP messages come from OVS ports and draws the line and for clients it learn from grat ARP .

This is my understanding . Please correct me if i am wrong .

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answered 2015-03-08 21:43:15 -0700

Vishal Thapar gravatar image

Yes, you're correct.

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answered 2015-03-09 07:34:48 -0700

harshahelium gravatar image

updated 2015-03-09 07:36:15 -0700

Thanks alot Vishal . Appreciate it !!! I have a small query regarding the topology discovery . Following is my setup . The SWITCH here is actual hardware running openflow agent .

                    SWITCH ------eth0(openflow enabled)------- HOST

So in this case , i have to run the LLDP protocol on eth0(openflow enabled) interface or the interface eth1 (connecting the controller) to discover the topology ??? Appreciate your help !!

Thanks Harsha

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LLDP is normally sent from the controller to the switch to be broadcast out all switch ports and most switch will automation will send LLDP to the controller. For it to discover the connection between the HOST and the switch you need to have the host send an ARP message out

Chris O'Shea ( 2015-03-09 15:25:42 -0700 )edit

Thanks Chris !!! Since I am newbie in this domain , i am still not clear about how the topology discovery happens . 1. Are LLDP packets exchanged between controller and switch using openfow ?? 2 . How does the link between two switches is detected by the controller ? Thanks

harshahelium ( 2015-03-09 22:23:11 -0700 )edit

Topology discovery uses LLDP to find out how different switches are connected. Host Tracker uses grat ARP packets from hosts to determine which hosts are connected to which switch ports. Controller will send an LLDP Packet Out with Flood action on a switch. Then it will receive same pkt as pkt_in

Vishal Thapar ( 2015-03-09 23:32:18 -0700 )edit

from other switches. This way it knows that switch2 is connected to switch1 over whichever port pkt came in on switch2. Repeat this for every switch in network and you get your topology. In your case, LLDP will be sent out over eth0 but will never come to controller as pkt_in.

Vishal Thapar ( 2015-03-09 23:34:07 -0700 )edit
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Asked: 2015-03-04 08:50:18 -0700

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Last updated: Mar 09 '15