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Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Understanding and Configuring IP Multiplexing
This chapter discusses IP multiplexing for satellite topologies in the following major sections:
- Understanding IP Multiplexing, page 12- - Configuring IP Multiplexing, page 12- - Verifying the IP Multiplexing Configuration, page 12-
Understanding IP Multiplexing
You can use IP multiplexing to optimize IPv4 and IPv6 traffic in environments where packet-per second
transmission limitations cause inefficient bandwidth utilization, such as a satellite network. IP
multiplexing addresses this constraint by bundling smaller packets into one larger UDP packet, known
as a superframe. The router then sends the superframe to the destination router which demultiplexes the
individual packets out of the superframe and routes them to their final destination.
IP multiplexing uses Cisco IOS access control lists (ACLs) to identify outbound packets. You can
configure standard, extended, or named ACLs to use with IP multiplexing. IP multiplexing maintains a
the cache of recent ACL lookup results to optimize traffic classification.
The following interface types support IP multiplexing:
- Ethernet - Fast Ethernet - Gigabit Ethernet - IPv4 GRE tunnel - IPv6 GRE tunnel - Ethernet, Fast Ethernet, and Gigabit Ethernet VLAN - VMI over Ethernet, Fast Ethernet, and Gigabit Ethernet - Virtual-Template on VMI
Both endpoints of the multiplex connection must be configured for multiplexing with corresponding
source and destination addresses. If a superframe arrives at an interface with IP multiplexing not
configured or not configured to receive superframes from the destination router, the superframe is not
demultiplexed, and the superframe is routed normally. If IP multiplexing is not configured, then
outbound packets are routed normally.
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Configuring IP Multiplexing
Configuring IP Multiplexing
When configuring IP multiplexing, you must configure each device before enabling the configuration.
Failure to do so will result in lost packets at the end that is not yet configured.
Configuring IP multiplexing requires the following procedures:
- Configuring ACLs to Identify Traffic, page 12- - Configuring an IP Multiplex Profile, page 12- - Configuring IP Multiplexing on an Interface, page 12-
The following procedures are optional and can be used to optimized IP multiplexing:
- Configuring the Multiplex Lookup Cache Size, page 12- - Configuring the IP Multiplex Policy, page 12-
Configuring ACLs to Identify Traffic
IP multiplexing uses ACL definitions to identify traffic selected for multiplexing treatment. You can
configure standard, extended or named ACLs to define traffic you want to multiplex. Packets that are not
identified by an ACL used for multiplexing are routed normally.
Refer to the following URL on Access Control Lists for more information on how to configure an ACL:
http://www.cisco.com/en/US/docs/ios/sec_data_plane/configuration/guide/sec_acc_list_ov_ps10591_T
SD_Products_Configuration_Guide-Chapter.html.
In general, an ACL statement for IP multiplexing should have the following format:
permit udp any host destination_IP_address UDP_port_number
IP Multiplexing makes caching decisions based on destination IP address, destination port, and protocol
type. Although ACLs can be defined to filter packets based on other attrbutes, using other attributes in
an IP Multiplexing ACL may have unexpected and/or unwanted results.
Configuring an IP Multiplex Profile
The attributes associated with an IP multiplexing connection between two routers are configured in an
IP multiplex profile.
Tip You must configure an IP multiplex profile for each endpoint of an IP multiplex connection in the
network.
You must define the following information for an IP multiplex profile:
- Profile name - Access control list (ACL) used to classify outbound IP packets as IP multiplex traffic - Source and destination IP addresses to be included in the superframe header - Maximum amount of time the router waits to fill a superframe before sending a partial superframe
You can define the following optional information for an IP multiplex profile:
- Maximum size of an outbound IP packet to be considered for multiplexing
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Configuring IP Multiplexing
DETAILED STEPS
Command or Action Purpose
Step 1 enable
Example
Router> enable Router#
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2 configure^ terminal
Example
Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#
Enters global configuration mode.
Step 3 { ip^ |^ ipv6 }^ mux^ profile^ profile_name
Example
Router(config)# ip mux profile routeRTP-SJ Router(config-ipmux-profile)#
Creates an IP multiplex profile with the specified name and
enters IP multiplexing mode profile mode.
Use the ip keyword to create an IPv4 profile. Use the ipv
keyword create an IPv6 profile.
Step 4 access-list^ access-list^ name^ or
number
Example
Router(config-ipmux-profile)# access-list routeRTP-SJ Router(config-ipmux-profile)#
Applies the specified access list to the profile and uses the
statements in the access list to identify outbound traffic for
multiplexing.
Step 5 source^ { ip_address^ |^ interface
interface-type }
Example
Router(config-ipmux-profile)# source 172.16.1. Router(config-ipmux-profile)#
Designates the source IP address for the profile. The source
address is the IP address assigned to the outbound
interface. If you created an IPv4 profile, then use an IPv
address. If you created an IPv6 profile, then use an IPv
address.
If you use the interface keyword, IP multiplexing will use
the IP address configured for that interface. Beware if you
are using the interface keyword for an IPv6 interface with
multiple IP addresses assigned to it. IP multiplexing may
not use the IP address you want for multiplexing.
The profile must be shutdown in order to change the source
address.
Note This source address must be configured as the
destination address in the corresponding profile at
the other end of the IP multiplexing connection.
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Configuring IP Multiplexing
Step 6 destination ip_address
Example
Router(config-ipmux-profile)# destination 172.172.16.2. Router(config-ipmux-profile)#
Designates the IP address to which superframes will be sent
from the particular profile. The destination address must
match the source address of the corresponding profile on
the destination router. If you created an IPv4 profile, then
use an IPv4 address. If you created an IPv6 profile, then use
an IPv6 address.
The profile must be shutdown in order to change the
destination address.
Note This destination address must be configured as the
source address in the corresponding profile at the
other end of the IP multiplexing connection.
Step 7 holdtime^ milliseconds
Example
Router(config-ipmux-profile)# holdtime 150 Router(config-ipmux-profile)#
(Optional) Configures the amount of time in milliseconds
that a multiplex profile waits to fill the superframe before
sending a partial superframe.
Valid values range from 20 to 250 milliseconds
If you do not set a hold time, the profile uses 20
milliseconds as a default
Step 8 maxlength^ bytes
Example
Router(config-ipmux-profile)# maxlength 128 Router(config-ipmux-profile)#
(Optional) Configures the largest packet size that the
multiplex profile can hold for multiplexing. A larger packet
size will not be multiplexed even if it correctly matches the
ACL attached to the profile.
Valid values range from 64 to 1472 bytes.
If you do not configure a maximum packet length, then any
packet that fits into the superframe is multiplexed.
Step 9 mtu^ bytes
Example
Router(config-ipmux-profile)# mtu 1400 Router(config-ipmux-profile)#
(Optional) Configures the maximum size for the outbound
superframe.Valid values range from 256 to 1500 bytes.
If you do not configure a MTU values, the profile uses 1500
bytes as a default.
The superframe size specified in the mtu command
includes the IP and UPD headers for the superframe of 48
bytes for IPv6 and 28 bytes for IPv4 packets. Therefore an
IPv6 mtu configured to 1400 bytes will accept 1352 bytes
of data before sending a full superframe. An IPv4 mtu
configured to 1400 bytes will accept 1372 bytes of data
before sending a full superframe.
Step 10 ttl^ hops
Example
Router(config-ipmux-profile)# ttl 128 Router(config-ipmux-profile)#
(Optional) Configures the superframe time-to-live (ttl) for
the IP header of the superframe.
Valid values range from 1 to 255 hops.
By default, the ttl value is set to 64 hops.
Command or Action Purpose
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Configuring IP Multiplexing
DETAILED STEPS
Configuring UDP Port for Superframe Traffic
The receiving router identifies incoming superframes by destination IP address, protocol type (UDP),
and a UDP port number. A single UDP port number is used for all IP multiplexing traffic in the network.
Note If you do not configure a UDP port for IP multiplexing traffic, the system uses the default value of 6682.
This value is inserted in the UDP header of the outbound superframe. If you use the default UDP port
value, make sure that all routers sending or receiving IP multiplexing traffic use the same value.
Perform this task to configure the UDP port for IP multiplexing traffic.
Command or Action Purpose
Step 1 enable
Example
Router> enable Router#
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2 configure^ terminal
Example
Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#
Enters global configuration mode.
Step 3 interface^ type/slot
Example
Router(config)# interface fastethernet0/ Router(config-if)#
Enters interface configuration mode for the specified
interface.
Step 4 { ip^ |^ ipv6 }^ mux
Example
Router(config-if)# ipv6 mux Router(config-if)#
Enables IP multiplexing on the interface. Use ip mux for an
IPv4 interface and ipv6 mux for an IPv6 interface.
Note You can use the show interface command to verify
that the interface is administratively up and whether
the interface has an IPv4 or IPv6 address configured
for the interface.
Step 5 exit
Example
Router(config-ipmux-policy)# exit Router(config)#
Exits IP multiplex policy mode.
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Configuring IP Multiplexing
SUMMARY STEPS
1. enable
2. configure terminal
3. { ip | ipv6 } mux udpport port_number
DETAILED STEPS
Configuring the Multiplex Lookup Cache Size
The lookup cache maps the destination address, protocol type, and port number to a multiplex profile to
reduce performance overhead related to ACL lookups. You can configure the maximum size of the cache
to manage memory utilization on the router.
The maximum size of the IPv6 cache can range from 1,000,000 to 4,294,967,295 bytes which
corresponds to 10,419 to 44,739,242 entries. The maximum size of the IPv4 cache can range from
1,000,000 to 4,294,967,295 bytes which corresponds to 11,363 to 49,367,440 entries.
Note If you do not configure the cache size, the cache size defaults to 1,000,000 bytes, which will hold 11,
entries for IPv4 multiplex and 10,419 for IPv6 multiplex.
Perform this task to configure the size of the lookup cache.
SUMMARY STEPS
1. enable
2. configure terminal
3. ip mux cache size
Command or Action Purpose
Step 1 enable
Example
Router> enable Router#
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2 configure terminal
Example
Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#
Enters global configuration mode.
Step 3 { ip | ipv6 } mux udpport
port_number
Example
Router(config)#ip mux udpport 5000 Router(config)#
Configures the UDP port for IP multiplexing.
Valid Values range from 1024 to 49151.
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Configuring IP Multiplexing
SUMMARY STEPS
1. enable
2. configure terminal
3. { ip | ipv6 } mux policy policy_name
4. outdscp DSCP_value
5. matchdscp DSCP_value
6. exit
DETAILED STEPS
Command or Action Purpose
Step 1 enable
Example
Router> enable Router#
Enables privileged EXEC mode.
Enter your password if prompted.
Step 2 configure terminal
Example
Router# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Router(config)#
Enters global configuration mode.
Step 3 { ip | ipv6 } mux policy policy-name
Example
Router(config)# ip mux policy RouteRTP-SJ Router(config-ipmux-policy)#
Configures an IP policy with the specified name and enters
IP multiplex policy configuration mode.
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Configuring IP Multiplexing
Step 4 outdscp DSCP_value
Example
Router(config-ipmux-policy)# outdscp 10 Router(config-ipmux-policy)#
Configures the DSCP value for the outbound superframe.
Valid values range from 0 to 63. The following DSCP values
are also valid:
af11 Match packets with AF11 dscp (001010)
af12 Match packets with AF12 dscp (001100)
af13 Match packets with AF13 dscp (001110)
af21 Match packets with AF21 dscp (010010)
af22 Match packets with AF22 dscp (010100)
af23 Match packets with AF23 dscp (010110)
af31 Match packets with AF31 dscp (011010)
af32 Match packets with AF32 dscp (011100)
af33 Match packets with AF33 dscp (011110)
af41 Match packets with AF41 dscp (100010)
af42 Match packets with AF42 dscp (100100)
af43 Match packets with AF43 dscp (100110)
cs1 Match packets with CS1(precedence 1) dscp (001000)
cs2 Match packets with CS2(precedence 2) dscp (010000)
cs3 Match packets with CS3(precedence 3) dscp (011000)
cs4 Match packets with CS4(precedence 4) dscp (100000)
cs5 Match packets with CS5(precedence 5) dscp (101000)
cs6 Match packets with CS6(precedence 6) dscp (110000)
cs7 Match packets with CS7(precedence 7) dscp (111000)
default Match packets with default dscp (000000)
ef Match packets with EF dscp (101110)
Command or Action Purpose
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Verifying the IP Multiplexing Configuration
The following example shows how to display IPv4 multiplex statistics:
router# show ip mux Superframe UDP Port: 6682
Multiplex Policies muxpol Outbound DSCP: 19 Match DSCP values: af21 19 muxpol2 Outbound DSCP: af Match DSCP values: 11 muxpol3 Outbound DSCP: 2 Match DSCP values: 1
IPv4 Multiplex Cache Statistics Current Entries: 3 Maximum Number of Entries: 56818 Cache High Water Mark: 3 Total Stale Entries: 0 Total Do-Not-Multiplex Entries: 0
router#
Displaying IP Multiplexing Cache Statistics
You can use the show { ip | ipv6 } mux cache command to display IP multiplexing cache statistics.
The following example shows how to display the cache statistics:
router# show ip mux cache
IPv4 Multiplex Cache Statistics Current Entries: 3 Maximum Number of Entries: 56818 Cache High Water Mark: 3 Total Stale Entries: 0 Total Do-Not-Multiplex Entries: 0
IPv4 Multiplex Cache Contents Destination Address Port Protocol Profile
20.20.20.24 0 UDP r 20.20.20.20 1000 UDP r 20.20.20.21 1000 UDP r router#
Displaying IP Multiplex Profiles
You can use the show { ip | ipv6 } mux profile command to display IP multiplex profile statistics. If you
do not enter a profile name, this command displays statistics for all multiplex profiles.
The following example shows how to display the profile statistics for the IPv6 profile r1v6:
router# show ipv6 mux profile rlv
Profile r1v Shutdown: No Destination: 2000:0:1:2:A8BB:CCFF:FE01: Source: 2000:0:1:2:A8BB:CCFF:FE01: Access-list: muxv6acl TTL: 64 Max mux length: 1452
Software Configuration Guide for Cisco IOS Release 15.2(2) GC OL-24065-
Verifying the IP Multiplexing Configuration
MTU: 1500
Hold time(ms): 20 Single packet superframes: Enabled
Inbound (demux) Statistics Superframes received: 0 Packets demultiplexed: 0 Avg. Inbound Multiplex ratio: N/A
Outbound (mux) Statistics Default Policy Packets: 40825 Full Superframes: 0 Partial Superframes: 20293 Avg. Outbound Multiplex ratio: 2.1:1 Mux length exceeded: 0
Policy policy Packets: 1273 Full Superframes: 0 Partial Superframes: 532 Avg. Outbound Multiplex ratio: 2.39:1 Mux length exceeded: 0
router#
Displaying IP Multiplexing Statistics for an Interface
You can use the show { ip | ipv6 } mux interface command to display IP multiplexing statistics for a
specific interface.
If you do not specify a specific interface, this command displays statistics for all interfaces with IP
multiplexing configured.
The following example shows how to display IP multiplex statistics for Ethernet 0/1:
router# show ip mux interface Ethernet0/ IPv4 Multiplexing statistics for Ethernet0/ Transmit IPv4 superframes transmitted: 20430 IPv4 packets multiplexed: 30555 Average TX mux ratio: 1.49: Receive IPv4 super frames received: 22009 IPv4 packets demuxed: 32634 IPv4 superframes rejected: 0 IPv4 format errors: 0 Average RX mux ratio: 1.48: router#
