User Defined Keys

User defined keys (UDKs) allow defining custom byte keys—that is, groups of bytes that can be matched to a predefined point in the packet (an extraction point, e.g. the start of a MAC header, or an IP header)—which is useful when wanting to make a match with a part of the packet which does not have a dedicated key.

Warning

The maximum number of UDKs is 4.

An extraction point may be defined for each packet type in a UDK. For each extraction point, an offset (from the beginning of the extraction) is defined.

To be able to modify a UDK after attaching it to an ACL rule, it is first necessary to un-match the UDK from the ACL, and then change the match mode of the UDK to none using the command “no udk match mode”.

Warning

Defining a UDK affects the throughput for packets equal or smaller than 128 bytes.

Configuring UDK

To set UDK with ACL on a specific field:

Define new user defined key called ipv4_udk. Run:

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            switch (config) # udk ipv4_udk
switch (config udk ipv4_udk) # exit

Set user defined key ipv4_udk to match on IPV4 header in offset 4 bytes from start of header. Run:

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            switch (config) # udk ipv4_udk extraction point mode l3 packet type ipv4 extraction point start-of-header offset 4

Set the len (in bytes) of the field to match on. Run:

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            switch (config) # udk ipv4_udk len 2

Set the user defined key to work with access list. Run:

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            switch (config) # udk ipv4_udk match mode acl

Define new access list table called my_acl_table. Run:

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            switch (config) # ipv4-udk access-list my_acl_table

Set new rule on the access list table with the previously defined user defined key to match 0x1234. Run:

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            switch (config) # ipv4-udk access-list my_acl_table permit ip any any udk ipv4_udk 0x1234

Bind the access list table to an ethernet interface. Run:

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            switch (config) # interface ethernet 1/1 ipv4-udk port access-group my_acl_table

UDK Commands

udk

	udk <udk-name> no udk <udk-name> Creates user defined key. The no form of the command deletes user defined key.
Syntax Description	udk-name	String
Default	N/A
Configuration Mode	config
History	3.6.5000
Example	switch (config)# udk udk_name switch (config udk udk_name)#
Related Commands
Notes	Defining UDK affects the throughput for packets equal or smaller than 128 bytes.

match mode

	match mode <match-mode> no match mode Configures user defined key match mode. The no form of the command resets this parameter to its default.
Syntax Description	match-mode	Possible values: acl all ecmp
Default	None
Configuration Mode	config udk
History	3.6.5000
Example	switch (config udk udk_name)# match mode all
Related Commands	udk <udk-name>
Notes

extraction point

	extraction point mode <mode> [packet type <type> [extraction point <point> [offset <offset>]]] Configures user-defined key extraction point mode.
Syntax Description	mode	Possible values: l2 l3 l4
	packet type	Sets user defined key packet type. Possible values: For L2: l2 For L3: arp; ipv4; ipv6 For L4: udp
	extraction point	Sets user defined key extraction point. Possible values for: l2: l2-ether-type; start-of-header arp: start-of-header ipv4; ipv6: start-of-header; start-of-payload udp: start-of-payload
	offset	Sets user defined key extraction point offset Range: 0-126 (even values)
Default	Mode: l3 Default extraction point per packet type: L2: start-of-header ARP; IPv4; IPv6: start-of-header UDP: start-of-payload Offset: 0
Configuration Mode	config udk
History	3.6.5000
Example	switch (config udk udk_name)# extraction point mode l3 packet type ipv4 extraction point start-of-header offset 2
Related Commands	udk <udk-name>
Notes

len

	len <length> Configures user-defined key length.
Syntax Description	length	Range: 1-4
Default	4
Configuration Mode	config udk
History	3.6.5000
Example	switch (config udk udk_name)# len 4
Related Commands	udk <udk-name>
Notes

show udk

	show udk [<udk-name>] Displays summary for user-defined keys.
Syntax Description	udk-name	Displays information about specific UDK
Default	N/A
Configuration Mode	Any command mode
History	3.6.5000
Example	switch (config)# show udk UDK name: udk_name Match mode: none Length: 4 Extraction mode: l3 IPv4 extraction point: start-of-header IPv4 offset: 22 IPv6 extraction point: start-of-header IPv6 offset: 0 ARP extraction point: start-of-header ARP offset: 0
Related Commands	udk <udk-name>
Notes

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