Dpctl Flow Mod Cases

Contents

• Match Fields List
• Instructions List
• Actions List
• [Flow mod Cases] (#Mod)

Flow-mod is the most variable command of dpctl. The number of match fields, instructions and actions, always raise doubts on how to add some specific flow. So this page aims to be a reference for people starting to get used with the wide range of possibilities that flow mod brings.

We will start start with lists of all match fields, instructions and actions, because the first doubt is always: How is that field named?

## Match Fields

Field name	Description
in_port	Switch input port
meta	Metadata passed between tables
eth_dst	Ethernet destination address
eth_type	Ethernet source address
eth_src	Ethernet frame type
vlan_vid	VLAN id
vlan_pcp	VLAN priority
ip_dscp	IP DSCP
ip_ecn	IP ECN
ip_proto	IP protocol
ip_src	IPv4 source address
ip_dst	IPv4 destination address
tcp_src	TCP source port
tcp_dst	TCP destiny port
udp_src	UDP source port
udp_dst	UDP destiny port
sctp_src	SCTP source port
sctp_dst	SCTP destination port
icmp_code	ICMP type
icmp_type	ICMP code
arp_op	ARP opcode
arp_spa	ARP source IPv4 address
arp_tpa	ARP target IPv4 address
arp_sha	ARP source hardware address
arp_tha	ARP target hardware address
ipv6_src	IPv6 source address
ipv6_dst	IPv6 destination address
ipv6_flabel	IPv6 Flow Label
icmpv6_code	ICMPv6 type
icmpv6_type	ICMPv6 code
ipv6_nd_target	Target address for ND
ipv6_nd_sll	Source link-layer for ND
ipv6_nd_tll	Target link-layer for ND
mpls_label	MPLS label
mpls_tc	MPLS TC
pbb_isid	PBB I-SID
tunn_id	Logical Port Metadata
ext_hdr	IPv6 Extension Header pseudo-field

## Instructions

Field name	Description
goto	Go to the next flow table
meta	Write on the metadata field
write	Write actions in the action set
apply	Applies the action(s) immediately
clear	Clear the action set
meter	Apply meter

## Actions

Field name	Description
output	Output packet to a port
ttl_out	Copy TTL from the next to outermost header to the outermost
ttl_in	Copy TLL from the outermost header to the next to outermost
mpls_ttl	Set MPLS TTL
mpls_dec	Decrease MPLS TTL
push_vlan	Push VLAN tag
pop_vlan	Pop VLAN tag
push_pbb	Push PBB I-TAG tag
pop_pbb	Pop PBB I-TAG tag
push_mpls	Push MPLS tag
pop_mpls	Pop MPLS tag
queue	Set queue id
group	Apply group entry
nw_ttl	Set IP TTL
nw_dec	Decrement IP TTL
set_field	Set one packet field

## Flow Mod Cases

• Inport
• Ethernet header
• Vlan

The simplest flow mod is the one which matches all fields. To create this flow just omit the match fields.

dpctl unix:/tmp/ofd flow-mod cmd=add,table=0  apply:output=2

SENDING:
flow_mod{table="0", cmd="add", cookie="0x0", mask="0x0", idle="0", hard="0", prio="32768", buf="none",       
port="any", group="any", flags="0x0", match=oxm{all match}, insts=[apply{acts=[out{port="2"}]}]}

OK.

#### Inport

Inport is one of the most common fields to match. In our example we will see how easy is to establish connection between two hosts attached to the ports 1 and 2.

dpctl unix:/tmp/ofd flow-mod cmd=add,table=0 in_port=1  apply:output=2

SENDING:
flow_mod{table="0", cmd="add", cookie="0x0", mask="0x0", idle="0", hard="0", prio="32768", buf="none",     port="any", group="any", flags="0x0", match=oxm{in_port="1"}, insts=[apply{acts=[out{port="2"}]}]}

OK.

dpctl unix:/tmp/ofd flow-mod cmd=add,table=0 in_port=2  apply:output=1

SENDING:
flow_mod{table="0", cmd="add", cookie="0x0", mask="0x0", idle="0", hard="0", prio="32768", buf="none",    port="any", group="any", flags="0x0", match=oxm{in_port="2"}, insts=[apply{acts=[out{port="1"}]}]}

OK.

After the addition of these flows, packets should be forwarded in both ways. Pretty easy.

#### Ethernet header

The fields to match in the Ethernet header are the source and destination MAC and the Ethernet type. The Ethernet type is should be a very common field, as it is a pre-requisite for upper layer fields.

In the first example, we will install flows that usually installed by a learning switch application.

dpctl unix:/tmp/ofd flow-mod cmd=add,table=0 in_port=1,eth_dst=00:00:00:00:00:01  apply:output=2

SENDING:
flow_mod{table="0", cmd="add", cookie="0x0", mask="0x0", idle="0", hard="0", prio="32768", buf="none",    port="any", group="any", flags="0x0", match=oxm{in_port="1",eth_src=00:00:00:00:00:01, eth_dst="00:00:00:00:00:01"}, insts=[apply{acts=[out{port="2"}]}]}

OK.

dpctl unix:/tmp/ofd flow-mod cmd=add,table=0 in_port=2,eth_dst=00:00:00:00:00:01  apply:output=1

SENDING:
flow_mod{table="0", cmd="add", cookie="0x0", mask="0x0", idle="0", hard="0", prio="32768", buf="none", port="any", group="any", flags="0x0", match=oxm{in_port="2",eth_src=00:00:00:00:00:02, eth_dst="00:00:00:00:00:01"}, insts=[apply{acts=[out{port="1"}]}]}

OK.

In our second example, we will install a flow that will forward only IPv4 packets between two hosts, adding the ethernet type 0x800 to the match fields of our previous example.

dpctl unix:/tmp/ofd flow-mod cmd=add,table=0 in_port=2,eth_type=0x800,eth_src=00:00:00:00:00:02,eth_dst=00:00:00:00:00:01  apply:output=1

SENDING:
flow_mod{table="0", cmd="add", cookie="0x0", mask="0x0", idle="0", hard="0", prio="32768", buf="none", port="any", group="any", flags="0x0", match=oxm{eth_dst="00:00:00:00:00:01", in_port="2", eth_src="00:00:00:00:00:02", eth_type="0x800"}, insts=[apply{acts=[out{port="1"}]}]}

OK.

dpctl unix:/tmp/ofd flow-mod cmd=add,table=0 in_port=1,eth_type=0x800,eth_src=00:00:00:00:00:01,eth_dst=00:00:00:00:00:02  apply:output=2

SENDING:
flow_mod{table="0", cmd="add", cookie="0x0", mask="0x0", idle="0", hard="0", prio="32768", buf="none", port="any", group="any", flags="0x0", match=oxm{eth_dst="00:00:00:00:00:02", in_port="1", eth_src="00:00:00:00:00:01", eth_type="0x800"}, insts=[apply{acts=[out{port="2"}]}]} 

OK.

#### Vlan

match push pop

IPv4

output, dec ttl, set ttl

IPv6

MPLS

match on label, push, pop, set ttl, dec ttl