Hello, thank you very much, I have applied the patch. I am now trying to
install a rule on switch startup to match all ip packets and decrement
ttl or drop all IP packets who have TTL=0
Is this code correct? Because I only have these two rules on ovs startup
when i dump flows:
sudo ovs-ofctl dump-flows 0_0_1 -O OpenFlow14
OFPST_FLOW reply (OF1.4) (xid=0x2):
cookie=0x0, duration=18.703s, table=0, n_packets=10, n_bytes=600,
priority=65535,dl_dst=01:80:c2:00:00:0e,dl_type=0x88cc
actions=CONTROLLER:65535
cookie=0x0, duration=18.705s, table=0, n_packets=2, n_bytes=140,
priority=0 actions=CONTROLLER:65535
*_
_*
*_My code:_*
@set_ev_cls(ofp_event.EventOFPSwitchFeatures, CONFIG_DISPATCHER)
def switch_features_handler(self, ev):
datapath = ev.msg.datapath
ofproto = datapath.ofproto
parser = datapath.ofproto_parser
# install table-miss flow entry
#
# We specify NO BUFFER to max_len of the output action due to
# OVS bug. At this moment, if we specify a lesser number, e.g.,
# 128, OVS will send Packet-In with invalid buffer_id and
# truncated packet data. In that case, we cannot output packets
# correctly. The bug has been fixed in OVS v2.1.0.
match = parser.OFPMatch()
actions = [parser.OFPActionOutput(ofproto.OFPP_CONTROLLER,
ofproto.OFPCML_NO_BUFFER)]
self.add_flow(datapath, 0, match, actions)
match = parser.OFPMatch(eth_type_nxm=0x0800,nw_ttl = 0)
actions = []
self.add_flow(datapath,10,match,actions)
match = parser.OFPMatch(eth_type_nxm=0x0800)
actions = [parser.OFPActionDecNwTtl()]
self.add_flow(datapath,5,match,actions)
Thank you in advance.
On 09/08/16 17:37, Iwase Yusuke wrote:
Hi,
How about using NXM "nw_ttl" match field to drop packets with TTL=0?
But, currently, Ryu does not support this filed,
please apply the following patch.
$ git diff
diff --git a/ryu/app/simple_switch_13.py b/ryu/app/simple_switch_13.py
index 3e7c598..baa732c 100644
--- a/ryu/app/simple_switch_13.py
+++ b/ryu/app/simple_switch_13.py
@@ -48,6 +48,10 @@ class SimpleSwitch13(app_manager.RyuApp):
ofproto.OFPCML_NO_BUFFER)]
self.add_flow(datapath, 0, match, actions)
+ match = parser.OFPMatch(eth_type_nxm=0x0800, nw_ttl=0)
+ actions = [] # Drop
+ self.add_flow(datapath, 1, match, actions)
+
def add_flow(self, datapath, priority, match, actions,
buffer_id=None):
ofproto = datapath.ofproto
parser = datapath.ofproto_parser
diff --git a/ryu/ofproto/nicira_ext.py b/ryu/ofproto/nicira_ext.py
index e2fca47..7487b3b 100644
--- a/ryu/ofproto/nicira_ext.py
+++ b/ryu/ofproto/nicira_ext.py
@@ -435,6 +435,10 @@ ip_proto_nxm Integer 8bit IP protocol.
Needed to support Nicira
extensions that require the ip_proto to
be set. (i.e. tcp_flags_nxm)
tunnel_id_nxm Integer 64bit Tunnel identifier.
+nw_ttl Integer 8bit IP TTL or IPv6 hop limit value ttl
+ (between 0 and 255).
+ Requires setting fields:
+ eth_type_nxm = [0x0800 (IP)|0x86dd
(IPv6)]
tun_ipv4_src IPv4 address Tunnel IPv4 source address.
tun_ipv4_dst IPv4 address Tunnel IPv4 destination address.
pkt_mark Integer 32bit Packet metadata mark.
@@ -484,6 +488,7 @@ oxm_types = [
oxm_fields.NiciraExtended0('eth_type_nxm', 3, type_desc.Int2),
oxm_fields.NiciraExtended0('ip_proto_nxm', 6, type_desc.Int1),
oxm_fields.NiciraExtended1('tunnel_id_nxm', 16, type_desc.Int8),
+ oxm_fields.NiciraExtended1('nw_ttl', 29, type_desc.Int1),
oxm_fields.NiciraExtended1('tun_ipv4_src', 31, type_desc.IPv4Addr),
oxm_fields.NiciraExtended1('tun_ipv4_dst', 32, type_desc.IPv4Addr),
oxm_fields.NiciraExtended1('pkt_mark', 33, type_desc.Int4),
e.g.)
$ sudo mn --controller remote
...(snip)
mininet> sh ovs-ofctl dump-flows s1
NXST_FLOW reply (xid=0x4):
cookie=0x0, duration=4.616s, table=0, n_packets=0, n_bytes=0,
idle_age=4, priority=1,ip,nw_ttl=0 actions=drop
cookie=0x0, duration=4.616s, table=0, n_packets=4, n_bytes=280,
idle_age=36, priority=0 actions=CONTROLLER:65535
Thanks,
Iwase
On 2016年09月08日 13:29, Warsang wrote:
Hello all,
I am running a fat-tree topology. When I ping a host x with h1 it first
send arp discovery with ff:ff:ff:ff:ff:ff as destination. Hence
everytime a switch gets this packet it floods it. Having no TTL these
packets are immortal. My question is the following. What is the proper
way of getting rid of these packets? I thought of decrementing the TTL
every time a packet hits a switch. However I can only drop the packet
with TTL = 0 at my controller and I can't create an OpenFlow rule that
matches all packets with TTL = 0 hence I lose performance having to send
the packets to my controller everytime I want to drop them. What is the
proper way to get rid of these packets?
Thank you in advance.
-Warsang
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