This does not happen when a host is added to the network. This happens the first time a host sends a packet, which could be any time. A host could be hooked up and just not sending anything for an arbitrarily long time before this happens.
-- Murphy On Jul 24, 2012, at 12:36 AM, 王健 wrote: > The followings are NOX debug information when a host joins in. (its IP > address is set to 192.168.1.16 and MAC address is c8:60:00:b9:c1:50 ). > 00090|openflow-event|DBG:received packet-in event from 001bcd03006c (len:82) > 00091|authenticator|DBG:Automatically authing c8:60:00:b9:c1:50 192.168.1.16. > 00092|authenticator|DBG:Binding for host doesnt exist, using default. > 00093|authenticator|DBG:Host auth event received. > 00094|authenticator|DBG:authenticated added location authenticated to > c8:60:00:b9:c1:50. > 00095|authenticator|DBG:Added c8:60:00:b9:c1:50 192.168.1.16 to host > authenticated. > 00096|sp_routing|DBG:Broadcasting 1bcd03006c port0002:vlanffff:pcp:0 > macc8:60:00:b9:c1:50->ff:ff:ff:ff:ff:ff proto0800 > ip192.168.1.16->255.255.255.255 port3601->3600 > ..... > I think the host must report its information to NOX in some way. Then the > topology or host table(maintain in NOX) will update, and if there is no > route calculated by routing component according to topology information, it > means no path existed. So no need to flood. > Well, maybe i make a misunderstanding in some places, please help me. > > > Wang JIan > > > 2012-7-24 > > > > At 2012-07-24 13:49:12,"Murphy McCauley" <[email protected]> wrote: > (Hah, looks like maybe my mobile had a misfire there.) > > I'm not sure what information you think the host is sending when it joins, > but... a host is not required to send anything. It may send stuff. Hosts > often do. But there's no host-joining-a-network protocol or anything. > > NOX learns about a host's presence whenever that host sends *anything*. But > if a host is quiet, NOX will never learn about it. Thus, it can easily be > the case that a host is on the network and NOX has no idea. Thus, if someone > wants to send to that host... NOX has no idea where it should be sending it. > The two main options at this point would be: A) Drop (because you don't know > where the destination is, or even if it exists at all), or B) Flood (which, > if the destination exists, will definitely get the packet there). > > -- Murphy > > On Jul 23, 2012, at 7:37 PM, 王健 wrote: > >> But a host reports its own information when joins in the network, which I >> observe according to NOX debug information. Does the topology will be >> updated? If not, how does it update? Thank you very much. >> >> 在 2012-07-24 10:23:39，"Murphy McCauley" <[email protected]> 写道： >> On Jul 23, 2012, at 7:19 PM, 王健 wrote: >> >>> Thank Murphy and Kyriakos for your patient reply, i am sorry that maybe i >>> don't express my meaning clearly. When a host joins in the network, it >>> receives the peridictly LLPP packet and reply its own information such as >>> IP, MAC, access point to the NOX. Then the NOX update the topology >>> immediately when it receives the host join in event, isn't it? If the >>> toology is update immediately, then there is a quetion I can't think >>> clealy. If host A sends an ICMP request to host B, the >>> path_calculation_module says there is no route, it means there is no path >>> between A and B, isn't it? If so, I think there is no need to broadcast. >>> This confuses me a lot. I think maybe I was wrong somewhere, can you help >>> me? >> >> I think you're saying that you expect the hosts to be receiving the LLDP >> from the switch and then responding. This isn't the case. The hosts are >> not expected to participate in the LLDP conversation -- it is strictly >> between switches. >> >> >> -- Murphy >> >> > > >
