Hello Sakib,
Yes that is correct regarding LLDP. As far as measuring of the detection time 
is required. I suggest the following:
1) Build a Mininet topology2) Run Wireshark and capture  packets on the 
controller interfaces 3) Use a Mininet command to remove a link4) A link down 
event is generated and you can stop the Wireshark now5) Apply OpenFlow filters 
on the Wireshark and analyse the data. It will tell you the time it took to 
generate the link down event once the controller did not receive the specific 
LLDP packets (You can identify the sequence number and the specific link 
details in the LLDP packet). The data will also tell you the frequency and hold 
time of LLDP packet.
Regards,Zubair
  

Date: Tue, 26 May 2015 19:37:29 +0000
From: [email protected]
To: [email protected]; [email protected]
Subject: Re: [Ryu-devel] How the Link delete events is detected?

Hello Zubair,
Thank you for your reply. So if I understand it correct, controller waits for 
specific LLDP sequence number for each link. When timeout of LLDP occurs for a 
link, controller considers that the link is down and when it receives a LLDP 
packet from a new link it consider that there is a link add.

As my final goal is to find the time required for detection of this event, can 
I say that the detection time depends on the setting of frequency and hold time 
of LLDP packet in mininet( as I am using mininet currently)? It will be great 
if you could share some idea about how can I measure this time?
Thanks in advance.
RegardsSakib
  


     On Tuesday, 26 May 2015, 21:07, Zubair Hafeez <[email protected]> 
wrote:
     

 Hello Sakib,Ryu uses LLDP to detect link failure/ add events.  When the 
controller is unable to receive the specified number of LLDP packets, these 
events are generated.Regards,ZubairDate: Tue, 26 May 2015 18:43:06 +0000From: 
[email protected]: [email protected]: Re: [Ryu-devel] 
How the Link delete events is detected?Hello Iwase,Thank you for your answer. I 
am extremely sorry that I asked you a different question from the subject. As 
my mail bounced from the mailing list two times, by mistake I copy pasted 
different question. My actual question was actually about the mechanism ryu 
used to detect link failure/ add event. I used LinkAdd and LinkDelete handler 
in my application as follows-@set_ev_cls(EventLinkAdd, MAIN_DISPATCHER)    def 
_link_add_handler(self, ev):@set_ev_cls(EventLinkDelete, MAIN_DISPATCHER)    
def _link_del_handler(self, ev)Now
 I want to evaluate the performance of this handlers in different link 
condition(how much time 
requires to detect the event). Before that I need to know actually how this 
handlers detect this events and how fast the controller knows about this
 events after this events actually happened. But
 unfortunately I was not able to find it. Can you please tell me how 
this event are discovered by the decorator function? Thanking youSakib       On 
Tuesday, 26 May 2015, 7:46, Yusuke Iwase <[email protected]> wrote:      
Hi Sakib,On 2015年05月26日 02:28, MD.Badruzzaman Shakib wrote:> Hello everyone,> > 
I want to get the port information from the link_add event. I couldn't find any 
getter function for port number.> for the code below-> > 
@set_ev_cls(EventLinkAdd, MAIN_DISPATCHER)> def _link_add_handler(self, ev):>   
      link = ev.link>         #print "type of links:", type(link)>         
print link> > it prints-       > Link: Port<dpid=4, port_no=5, LIVE> to 
Port<dpid=6, port_no=3, LIVE>> > So now I am getting the source port_no by 
using>         src_port = int(str(link)[27:28])You can get the port number from 
EventLinkAdd/EventLinkDelete as follow.    @set_ev_cls(EventLinkAdd, 
MAIN_DISPATCHER)    def _link_add_handler(self, ev):            link = ev.link  
          self.logger.info('link.src.port_no = %d', link.src.port_no)           
 # e.g.)            # link.src.port_no = 2FYI,'ev.link' is an instance of 
'class Link' in ryu/topology/switches.py. 
<https://github.com/osrg/ryu/blob/master/ryu/topology/switches.py#L135>And 
'ev.link.src/dst' is an instance of 'class Port'. 
<https://github.com/osrg/ryu/blob/master/ryu/topology/switches.py#L57>Thanks,Iwase>
 > But I am interested to know is there any standard method to get the port 
number from the link_add/ link_delete event?> > Thanking you> Sakib> 
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