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
