Control Plane Policing

Control Plane Policing or Policies (CoPP) ensures the CPU and control plane are not over-utilized which is essential for the robustness of the switch. CoPP limits the number of control plane packets. NVIDIA Onyx implements several CoPP mechanisms:

ACLs may be used to limit the rate of packets or bytes of a certain type, including L3 control packets (L2 control packets are forwarded to the CPU before the ACL)
Policers on traffic going to the CPU—these policers are configured by NVIDIA Onyx and cannot be modified by the user
IP filter tables limit the traffic to the CPU coming in from the management ports

IP Table Filtering

IP table filtering is a mechanism that allows the user to apply actions to a specific control packet flow identified by a certain flow key.

This mechanism is used in order to protect switch control traffic against attacks. For example, it could allow traffic coming from a specific trusted management subnet only, block the SNMP UDP port from receiving traffic, and force ping rate to be lower than a specific threshold.
Each IP table rule is defined by key, priority, and action:

Key—the key is a combination of physical port and layer 3 parameters (e.g. SIP, DIP, SPORT, DPORT, etc.), and other fields. Each part of the key, can be set to a specific value or masked.
Priority—each rule in the IP table is assigned a priority, and the rule with the highest priority whose key matches the packet executes the action.
Action—the action describes the behavior of packets which match the key. The action type may be drop, accept, rate limit, etc.

An IP-table rule is bound to an IP interface that can be a management out-of-band interface, VLAN interface, or router port interface. Once bound, all traffic received (ingress rule) or transmitted (egress rule) in this direction is being verified with all bounded rules.

Once a match was found, the rule action is executed. If no match is found, the default policy of the chain shall apply.

Warning

IP table rules get a lower priority than ACL mechanism.

Warning

In the rare case that IP filter is used while the input policy is "drop" (i.e., ip filter chain input policy drop) and an NTP server or an MLAG switch is used, then the following rule needs to be added that allows src-ip 127.0.0.1 (which is a requirement for any clustered application (e.g., mlag-vip) and NTP):

ip filter chain input rule append tail target accept dup-delete source-addr 127.0.0.1 /32

Configuring IP Table Filtering

Prerequisite for IPv6:

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            switch (config) # ipv6 enable

To configure IPv4 table filtering:

Select the policy that applies to the input/output chain (default is “accept”). Run:

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            switch (config)# ip filter chain input policy drop
switch (config)# ip filter chain output policy accept

Append filtering rules to the list or set a specific rule number, select a target, and (optional) any additional filter conditions. For example, run:

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            switch (config)# ip filter chain input rule append tail target rate-limit 2 protocol udp
switch (config)# ip filter chain input rule set 2 target drop protocol icmp in-intf mgmt1
switch (config)# ip filter chain output rule append tail target drop protocol icmp

Enable IP table filtering. Run:

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            switch (config) # ip filter enable

Verify IP table filtering configuration. Run:

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            switch (config) # show ip filter configured
 
Packet filtering for IPv4: enabled
 
IPv4 configuration:
  Chain 'input' Policy 'accept':
    Rule 1:
      Target      : rate-limit 2 pps
      Protocol    : udp
      Source      : all
      Destination : all
      Interface   : all
      State       : any
      Other Filter:  - 
 
    Rule 2:
      Target      : drop
      Protocol    : icmp
      Source      : all
      Destination : all
      Interface   : mgmt1 (ingress)
      State       : any
      Other Filter:  - 
 
  Chain 'output' Policy 'accept':
    Rule 1:
      Target      : drop
      Protocol    : icmp
      Source      : all
      Destination : all
      Interface   : all
      State       : any
      Other Filter: -

Modifying IP Table Filtering

To modify IP table filtering configuration:

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            switch (config) # ip filter chain input rule modify 3 target reject-with icmp6-adm-prohibited source-addr 10::0 /126

To delete an existing IP table filtering rule:

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            switch (config) # no ip filter chain input rule 2

To delete all existing IP table filtering rules:

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            switch (config) # no ip filter chain output rule all

To insert an IP table filtering rule in a chain:

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            switch (config) # ip filter chain input rule 2 set target drop protocol tcp dest-port 22 in-intf mgmt1

Rate-Limit Rule Configuration

Using a rate-limit target allows to create a rule to limit the rate of certain traffic types. The limit is specified in packets per second (pps) and can be anywhere between 1-1000 pps. When enabled, the system takes the user specified rate and converts it into units of 1/10000 of a second. Therefore, any value greater than 100 can have a slight difference when the rule is displayed using the show command.

Unlike other rules which are a match type of rule, limiting packets should be followed by a rule that drops additional packets of the same “type”. Alternatively, this can be implicitly achieved by setting the chain policy to “drop” so that it drops packets not processed by matching rules. Otherwise, no effect of the rule is observed as the remaining traffic simply gets accepted.

Warning

Rate-limit is implemented with an average rate and a burst-limit. Rate values are specified in pps and take a range from 1-1000 pps. For rate values in the range 1-100, the burst value is set equal to the rate value. For rate values in the range 101-1000, the burst limit is set to 100.

Control Plane Policing Commands

ip filter enable | ipv6 filter enable

	{ip \| ipv6} filter enable no {ip \| ipv6} filter enable Enables IP filtering. The no form of the command disables IP filtering.
Syntax Description	N/A
Default	Disabled
Configuration Mode	config
History	3.5.1000
Example	switch (config) # ip filter enable
Related Commands
Notes	It is recommended to run this command only after configuring all of the IP table filter parameters.

ip filter chain policy | ipv6 filter chain policy

	{ip \| ipv6} filter chain <chain_name> policy {accept \| drop} no {ip \| ipv6} filter chain <chain_name> policy Configures default policy for a specific chain (if no rule matches this default policy action shall apply). The no form of the command resets default policy for a specific chain.
Syntax Description	chain_name	Selects a chain for which to add or modify a filter: input –input chain or ingress interfaces output –output chain or egress interfaces
	accept	Accepts all traffic by default for this chain
	drop	Drops all traffic by default for this chain
Default	Accept for input and output chains
Configuration Mode	config
History	3.5.1000
Example	switch (config) # ipv6 filter chain input policy accept
Related Commands
Notes

ip filter chain rule target | ipv6 filter chain rule target

	{ip \| ipv6} filter chain <chain_name> rule <oper> target <target> [<param>] no {ip \| ipv6} filter chain <chain_name> rule {<number> \| all} Inserts rule before specified rule number. The no form of the command deletes rule for a specific chain.
Syntax Description	chain_name	A chain to which to add or modify a filter: input –input chain or ingress interfaces output –output chain or egress interfaces
	rule	append tail –appends operation to the bottom of operation list insert <oper_num> –inserts operation at specified position (existing operation at that position moves back in the list) modify <oper_num> –modifies existing operation at specified position. Only the parameters specified in this invocation are altered; everything else is left untouched. move <oper_num1> to <oper_num2> –moves one operation to another place in the operation list set <oper_num> –sets operation at specified position (overwrites existing)
	target	accept –allows the packets that match the rule into the management plane drop –drops packets that match the rule rate-limit –allows with rate limiting in packets per sec (PPS) reject-with –drops the packet and replies with an ICMP error message
	param	comment <text> –specifies description string for this rule (60 chars max) dest-addr <ip> –IP matching a specific destination address or address range. A specific IPv4 address can be provided or an entire subnet by giving an address along with netmask in dot notation or as a CIDR notation (e.g. /24). not-dest-addr <ip> –IP not matching a specific destination address range dest-port <port(s)> –matching a specific destination port or port range not-dest-port <port(s)> –port not matching a specific destination port or port range dup-delete –deletes any preexisting duplicates of this rule in-intf –interface matching a specific inbound interface not-in-intf <if_name> –interface not matching a specific inbound interface out-intf <if_name> –matches a specific outbound interface not-out-intf <if_name> –interface not matching a specific outbound interface
	param4 (cont.)	protocol <if_name> –matches a specific protocol tcp udp icmp all not-protocol <protocol> –does not match a specific protocol tcp udp icmp all source-addr <ip> –matches a specific source address range not-source-addr <ip> –does not match a specific source address range source-port <port(s)> –matches a specific source port or port range not-source-port <port(s)> –does not match a specific source port or port range state –matches packets in a particular state. Possible values: established –packet associated with an established connection which has seen traffic in both directions related –packet that starts a new connection but is related to an existing connection new –packet that starts a new, unrelated connection A combination can be entered separated by commas
Default	N/A
Configuration Mode	config
History	3.5.1000
Example	switch (config) # ipv6 filter enable chain input rule append tail target drop state related protocol all dup-delete
Related Commands
Notes	The source and destination ports may each be either a single number, or a range specified as “<low>-<high>”. For example: “10-20” would specify ports 10 through 20 (inclusive). The port parameter only works in conjunction with TCP and UDP Setting a “positive” rule removes any corresponding “not-” rules, and vice-versa The “state” parameter is a classification of the packet relative to existing connections If TCP or UDP are selected for the “protocol” parameter, source and/or destination ports may be specified. If ICMP is selected, these options are either ignored, or an error is produced.

ip filter options include-bridges

	{ip \| ipv6} filter options include-bridges no {ip \| ipv6} filter options include-bridges Applies IP filters to bridges
Syntax Description	N/A
Default	Disabled
Configuration Mode	config
History	3.5.1000
Example	switch (config) # ip filter options include-bridges
Related Commands
Notes

show ip filter

	show ip filter Displays IPv4 filtering state.
Syntax Description	N/A
Default	N/A
Configuration Mode	config
History	3.6.6000
Example	switch (config) # show ip filter Packet filtering for IPv4: enabled Active IPv4 filtering rules (omitting any not from configuration): Chain 'input' Policy 'accept': Rule 1: Target : accept Protocol : all Source : all Destination : 1.1.1.0/24 Interface : all State : any Other Filter: - Chain 'output' Policy 'accept': Rule 1: Target : reject-with icmp-net-unreachable Protocol : tcp Source : all Destination : all Interface : all State : any Other Filter: dest-port 1000
Related Commands
Notes

show ip filter all

	show ip filter all Displays IPv4 filtering state (including un-configured rules).
Syntax Description	N/A
Default	N/A
Configuration Mode	config
History	3.6.6000
Example	Destination : 1.1.1.0/24 Interface : all State : any Other Filter: - Chain 'output' Policy 'accept': Rule 1: Target : reject-with icmp-net-unreachable Protocol : tcp Source : all Destination : all Interface : all State : any Other Filter: dest-port 1000
Related Commands
Notes

show ip filter configured

	show ip filter configured Displays IPv4 filtering configuration.
Syntax Description	N/A
Default	N/A
Configuration Mode	config
History	3.6.6000
Example	switch (config) # show ip filter configured Packet filtering for IPv4: enabled IPv4 configuration: Chain 'input' Policy 'accept': Rule 1: Target : accept Protocol : all Source : all Destination : 1.1.1.0/24 Interface : all State : any Other Filter: - Chain 'output' Policy 'accept': Rule 1: Target : reject-with icmp-net-unreachable Protocol : tcp Source : all Destination : all Interface : all State : any Other Filter: dest-port 1000
Related Commands
Notes

show ipv6 filter

	show ipv6 filter Displays IPv6 filtering state.
Syntax Description	N/A
Default	N/A
Configuration Mode	config
History	3.6.6000
Example	switch (config) # show ipv6 filter Packet filtering for IPv6: enables Active IPv6 filtering rules (omitting any not from configuration): Chain 'input' Policy 'accept': Rule 1: Target : accept Protocol : all Source : all Destination : 1.1.1.0/24 Interface : all State : any Other Filter: - Chain 'output' Policy 'accept': Rule 1: Target : reject-with icmp-net-unreachable Protocol : tcp Source : all Destination : all Interface : all State : any Other Filter: dest-port 1000
Related Commands
Notes

show ipv6 filter all

	show ipv6 filter all Displays IPv6 filtering state (including un-configured rules).
Syntax Description	N/A
Default	N/A
Configuration Mode	config
History	3.6.6000
Example	switch (config) # show ipv6 filter all Packet filtering for IPv6: enables All active IPv6 filtering rules: Chain 'input' Policy 'accept': Rule 1: Target : accept Protocol : all Source : all Destination : 1.1.1.0/24 Interface : all State : any Other Filter: - Chain 'output' Policy 'accept': Rule 1: Target : reject-with icmp-net-unreachable Protocol : tcp Source : all Destination : all Interface : all State : any Other Filter: dest-port 1000
Related Commands
Notes

show ipv6 filter configured

	show ipv6 filter configured Displays IPv6 filtering configuration.
Syntax Description	N/A
Default	N/A
Configuration Mode	config
History	3.6.6000
Example	switch (config) # show ipv6 filter configured Packet filtering for IPv6: enables IPv6 configuration: Chain 'input' Policy 'accept': Rule 1: Target : accept Protocol : all Source : all Destination : 1.1.1.0/24 Interface : all State : any Other Filter: - Chain 'output' Policy 'accept': Rule 1: Target : reject-with icmp-net-unreachable Protocol : tcp Source : all Destination : all Interface : all State : any Other Filter: dest-port 1000
Related Commands
Notes

Control Plane Policing

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