ARP and DHCP requests are not affected by forward-bpdu (they are not considered BPDUs). ARP and DHCP treatment would go through the normal paths in the flow table.
ARPs should not have a destination MAC of 00:00:00:00:00:00; they are normally broadcast or unicast. On Tue, Mar 31, 2015 at 07:23:45AM +0000, Graham, Mark wrote: > Does disabling "forward-bpdu" also explain why ARP and DHCP request are not > captured, or is this more to do with the dst MAC being 00:00:00:00:00:00 for > ARP and source IP addressing being 0.0.0.0 for DHCP? > > -----Original Message----- > From: discuss [mailto:[email protected]] On Behalf Of Ben Pfaff > Sent: 30 March 2015 17:43 > To: Field, Brian > Cc: [email protected] > Subject: Re: [ovs-discuss] CDP (cisco discovery protocol) packets being > dropped by OVS > > On Sun, Mar 29, 2015 at 01:44:58PM +0000, Field, Brian wrote: > > I’ve noticed the CDP frames are being dropped by OVS: > > > > > > # ovs-dpctl dump-flows > > > > skb_priority(0),in_port(2),eth(src=52:54:00:d7:50:8e,dst=01:00:0c:cc:c > > c:cc),eth_type(0/0xffff), packets:0, bytes:0, used:never, actions:drop > > > > > > > > In http://benpfaff.org/~blp/ovs-fields.pdf, it mentions “OpenFlow and Open > > vSwitch only support LLC headers with DSAP and SSAP 0xaa and control byte > > 0x03, which indicate that a SNAP header follows the LLC header. In turn, > > OpenFlow and Open vSwitch only support a SNAP header with organization > > 0x000000." > > > > > > CDP frames use LLC/SNAP encapsulation with an organization code of (0xc). > > So it would appear this is why CDP frames are being dropped by OVS. > > No. I expect it's because forward-bpdu is disabled. Please see > ovs-vswitchd.conf.db(5) for details. > > > Is the limitation to only support LLC/SNAP with org values of 0x0 a > > limitation imposed on OVS because OpenFlow doesn’t support or… ? > > It is true that OpenFlow does not support this, but the reason is primarily > that no one has found this important enough to implement. > > For CDP, for example, you can alternatively match on the destination Ethernet > address, which is 01:00:0c:cc:cc:cc for CDP. > _______________________________________________ > discuss mailing list > [email protected] > http://openvswitch.org/mailman/listinfo/discuss > > -- > > In the official 2014 government assessment of our research the following 12 > areas were found to have world-leading research: Allied Health Professions; > Architecture & Built Environment; Art & Design; Business & Management > Studies; Communication, Cultural & Media Studies; English Language & > Literature; Geography & Environmental Studies; History; Law; Music, Drama & > Dance; Psychology; and Social Work & Social Policy. > > This e-mail and any attachments are intended for the above named > recipient(s)only and may be privileged. If they have come to you in > error you must take no action based on them, nor must you copy or show > them to anyone please reply to this e-mail to highlight the error and > then immediately delete the e-mail from your system. Any opinions > expressed are solely those of the author and do not necessarily > represent the views or opinions of Anglia Ruskin University. > Although measures have been taken to ensure that this e-mail and attachments > are > free from any virus we advise that, in keeping with good computing > practice, the recipient should ensure they are actually virus free. > Please note that this message has been sent over public networks which > may not be a 100% secure communications _______________________________________________ discuss mailing list [email protected] http://openvswitch.org/mailman/listinfo/discuss
