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Cisco IOS IP Command Reference, Volume 1 of 4: Addressing and Services, Release 12.3 T
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Introduction
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IP Addressing and Services Commands: A through C
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IP Addressing and Services Commands: D through H
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IP Addressing and Services Commands: idle through ip local-proxy-arp
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IP Addressing and Services Commands: ip mask-reply through ip web-cache redirect
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IP Addressing and Services Commands: L through R
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IP Addressing and Services Commands: serverfarm through show ip nat
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IP Addressing and Services Commands: show ip nhrp through synguard
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IP Addressing and Services Commands: T through W
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Table Of Contents
local-ip (IPC transport-SCTP local)
remote-ip (IPC transport-SCTP remote)
lease
To configure the duration of the lease for an IP address that is assigned from a Cisco IOS Dynamic Host Configuration Protocol (DHCP) server to a DHCP client, use the lease command in DHCP pool configuration mode. To restore the default value, use the no form of this command.
lease {days [hours [minutes]] | infinite}
no lease
Syntax Description
Defaults
1 day
Command Modes
DHCP pool configuration
Command History
Examples
The following example shows a 1-day lease:
lease 1The following example shows a 1-hour lease:
lease 0 1The following example shows a 1-minute lease:
lease 0 0 1The following example shows an infinite (unlimited) lease:
lease infiniteRelated Commands
ip dhcp pool
Configures a DHCP address pool on a Cisco IOS DHCP server and enters DHCP pool configuration mode.
local-ip (IPC transport-SCTP local)
To define at least one local IP address that is used to communicate with the local peer, use the local-ip command in IPC transport-SCTP local configuration mode. To remove one or all IP addresses from your configuration, use the no form of this command.
local-ip device-real-ip-address [device-real-ip-address2]
no local-ip device-real-ip-address [device-real-ip-address2]
Syntax Description
Defaults
No IP addresses are defined; thus, peers cannot communicate with the local peer.
Command Modes
IPC transport-SCTP local configuration
Command History
Usage Guidelines
Use the local-ip command to help associate Stream Control Transmission Protocol (SCTP) as the transport protocol between the local and remote peer.
This command is part of a suite of commands used to configure the Stateful Switchover (SSO) protocol. SSO is necessary for IP Security (IPSec) and Internet Key Exchange (IKE) to learn about the redundancy state of the network and to synchronize their internal application state with their redundant peers.
Examples
The following example shows how to enable SSO:
!redundancy inter-devicescheme standby HA-in!!ipc zone defaultassociation 1no shutdownprotocol sctplocal-port 5000local-ip 10.0.0.1remote-port 5000remote-ip 10.0.0.2Related Commands
local-port
To define the local Stream Control Transmission Protocol (SCTP) port that is used to communicate with the redundant peer, use the local-port command in SCTP protocol configuration mode. .
local-port local-port-number
Syntax Description
local-port-number
Local port number, which should be the same as the remote port number on the peer router (which is specified via the remote-port command).
Defaults
A local SCTP port is not defined.
Command Modes
SCTP protocol configuration
Command History
Usage Guidelines
The local-port command enters IPC transport-SCTP local configuration mode, which allows you to specify at least one local IP address (via the local-ip command) that is used to communicate with the redundant peer.
Examples
The following example shows how to enable Stateful Switchover (SSO):
!redundancy inter-devicescheme standby HA-in!!ipc zone defaultassociation 1no shutdownprotocol sctplocal-port 5000local-ip 10.0.0.1remote-port 5000remote-ip 10.0.0.2Related Commands
logging server-arp
To enable the sending of Address Resolution Protocol (ARP) requests for syslog server address during system initialization bootup, use the logging server-arp command in global configuration mode. To disable the sending of ARP requests for syslog server addresses, use the no form of this command.
logging server-arp
no logging server-arp
Syntax Description
This command has no arguments or keywords.
Command Default
This command is disabled by default.
Command Modes
Global configuration.
Command History
12.3
This command was introduced.
12.3(4)T
This command was integrated into Cisco IOS Release 12.3(4)T.
12.3(5)B
This command was integrated into Cisco IOS Release 12.3(5)B.
Usage Guidelines
The logging server-arp global configuration command allows the sending of ARP requests for syslog server address during system initialization bootup.
When this CLI command is configured and saved to the startup configuration file, the system will send an ARP request for remote syslog server address before sending out the first syslog message.
The command should only be used when the remote syslog server is in the same subnet as the system router sending the ARP request.
Note
Use this command even if a static ARP has been configured with the syslog server address.
Examples
The following example shows how to enable an ARP request for syslog server addresses:
Router# configure terminalRouter(config)# logging server-arpRouter(config)# exitThe following example shows how to disable an ARP request for syslog server addresses:
Router# configure terminalRouter(config)# no logging server-arpRouter(config)# exitRelated Commands
arp (global)
Adds a permanent entry in the Address Resolution Protocol (ARP) cache, use the arp command in global configuration mode.
manager (DFP agent)
This command has been replaced by the following commands:
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maxconns (server farm)
To limit the number of active connections to the real server, use the maxconns command in SLB server farm configuration mode. To restore the default of 4294967295, use the no form of this command.
maxconns maximum-number [sticky-override]
no maxconns
Syntax Description
Defaults
The default maximum number of simultaneous active connections on the real server is 4294967295.
Command Modes
SLB server farm configuration
Command History
Examples
The following example limits the real server to a maximum of 1000 simultaneous active connections:
Router(config)# ip slb serverfarm PUBLICRouter(config-slb-sfarm)# real 10.10.1.1Router(config-slb-real)# maxconns 1000Related Commands
nat
To configure IOS SLB Network Address Translation (NAT) and specify a NAT mode, use the nat SLB server farm configuration command. To remove a NAT configuration, use the no form of this command.
nat server
no nat server
Syntax Description
server
Specifies that the destination address in load-balanced packets sent to the real server is the address of the real server chosen by the server farm load-balancing algorithm.
Defaults
No default behavior or values.
Command Modes
SLB server farm configuration
Command History
12.1(1)E
This command was introduced.
12.1(5)T
This command was integrated into Cisco IOS Release 12.1(5)T.
Usage Guidelines
The no nat command is allowed only if the virtual server was removed from service with the no inservice command.
Examples
The following example changes to IOS SLB server farm configuration mode and configures NAT mode as server address translation on the server farm named FARM2:
ip slb serverfarm FARM2nat serverRelated Commands
netbios-name-server
To configure NetBIOS Windows Internet Naming Service (WINS) name servers that are available to Microsoft Dynamic Host Configuration Protocol (DHCP) clients, use the netbios-name-server command in DHCP pool configuration. To remove the NetBIOS name server list, use the no form of this command.
netbios-name-server address [address2...address8]
no netbios-name-server
Syntax Description
Command Modes
DHCP pool configuration
Command History
Usage Guidelines
One IP address is required, although you can specify up to eight addresses in one command line. Servers are listed in order of preference (address1 is the most preferred server, address2 is the next most preferred server, and so on).
Examples
The following example specifies the IP address of a NetBIOS name server available to the client:
netbios-name-server 10.12.1.90Related Commands
netbios-node-type
To configure the NetBIOS node type for Microsoft Dynamic Host Configuration Protocol (DHCP) clients, use the netbios-node-type command in DHCP pool configuration mode. To remove the NetBIOS node type, use the no form of this command.
netbios-node-type type
no netbios-node-type
Syntax Description
type
Specifies the NetBIOS node type. Valid types are:
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Command Modes
DHCP pool configuration
Command History
Usage Guidelines
The recommended type is h-node (hybrid).
Examples
The following example specifies the client's NetBIOS type as hybrid:
netbios node-type h-nodeRelated Commands
network (DHCP)
To configure the subnet number and mask for a Dynamic Host Configuration Protocol (DHCP) address pool on a Cisco IOS DHCP server, use the network command in DHCP pool configuration mode. To remove the subnet number and mask, use the no form of this command.
network network-number [mask | prefix-length]
no network
Syntax Description
Defaults
No default behavior or values.
Command Modes
DHCP pool configuration
Command History
Usage Guidelines
This command is valid for DHCP subnetwork address pools only. If the mask or prefix length is not specified, the class A, B, or C natural mask is used. The DHCP Server assumes that all host addresses are available. The system administrator can exclude subsets of the address space by using the ip dhcp excluded-address command.
You cannot configure manual bindings within the same pool that is configured with the network command.
Examples
The following example configures 172.16.0.0/16 as the subnetwork number and mask of the DHCP pool:
network 172.16.0.0/16Related Commands
next-server
To configure the next server in the boot process of a Dynamic Host Configuration Protocol (DHCP) client, use the next-server command in DHCP pool configuration. To remove the boot server list, use the no form of this command.
next-server address [address2...address8]
no next-server address
Syntax Description
Defaults
If the next-server command is not used to configure a boot server list, the DHCP Server uses inbound interface helper addresses as boot servers.
Command Modes
DHCP pool configuration
Command History
Usage Guidelines
You can specify up to eight servers in the list. Servers are listed in order of preference (address1 is the most preferred server, address2 is the next most preferred server, and so on).
Examples
The following example specifies 10.12.1.99 as the IP address of the next server in the boot process:
next-server 10.12.1.99Related Commands
no ip gratuitous-arps
To disable the transmission of gratuitous Address Resolution Protocol (ARP) messages for an address in a local pool, use the no ip gratuitous-arps command in global configuration mode.
no ip gratuitous-arps
Syntax Description
This command has no keywords or arguments.
Defaults
Disabled
Command Modes
Global configuration
Command History
Usage Guidelines
A Cisco router will send out a gratuitous ARP message when a client connects and negotiates an address over a PPP connection. This transmission occurs even when the client receives the address from a local address pool.
Examples
The following example disables gratuitous arp messages from being sent:
no ip gratuitous-arpsobject (tracking)
To specify an object for a tracked list, use the object command in tracking configuration mode. To remove the object from the tracked list, use the no form of this command.
object object-number [not] [weight weight-number]
no object object-number [not] [weight weight-number]
Syntax Description
Defaults
The object is removed from the tracked list.
Command Modes
Tracking configuration
Command History
Examples
The following example shows two serial interfaces (objects) that are in tracked list 100. The Boolean "not" negates state of object 2 , which means when object 2 is up, the tracked list regards the object as down.
track 1 interface serial2/0 line-protocoltrack 2 interface serial2/1 line-protocoltrack 100 list boolean andobject 1object 2 notRelated Commands
option
To configure Cisco IOS Dynamic Host Configuration Protocol (DHCP) server options, use the option command in DHCP pool configuration mode. To remove the options, use the no form of this command.
option code [instance number] {ascii string | hex string | ip address}
no option code [instance number]
Syntax Description
Defaults
The default instance number is 0.
Command Modes
DHCP pool configuration
Command History
Usage Guidelines
DHCP provides a framework for passing configuration information to hosts on a TCP/IP network. Configuration parameters and other control information are carried in tagged data items that are stored in the options field of the DHCP message. The data items themselves are also called options. The current set of DHCP options are documented in RFC 2131, Dynamic Host Configuration Protocol.
Examples
The following example configures DHCP option 19, which specifies whether the client should configure its IP layer for packet forwarding. A value of 0 means disable IP forwarding; a value of 1 means enable IP forwarding. IP forwarding is enabled in the following example:
option 19 hex 01The following example configures DHCP option 72, which specifies the World Wide Web servers for DHCP clients. World Wide Web servers 172.16.3.252 and 172.16.3.253 are configured in the following example:
option 72 ip 172.16.3.252 172.16.3.253Related Commands
ip dhcp pool
Configures a DHCP address pool on a Cisco IOS DHCP server and enters DHCP pool configuration mode.
origin
To configure an address pool as an on-demand address pool (ODAP) or static mapping pool, use the origin command in DHCP pool configuration mode. To disable the ODAP, use the no form of this command.
origin {dhcp | aaa | ipcp | file url} [subnet size initial size [autogrow size]]
no origin {dhcp | aaa | ipcp | file url} [subnet size initial size [autogrow size]]
Syntax Description
Defaults
The default size value is /0.
Command Modes
DHCP pool configuration
Command History
Usage Guidelines
If you do not configure the pool as an autogrow pool, the pool will not request additional subnets if one subnet is already in the pool.
Use the dhcp keyword to obtain subnets from DHCP, the aaa keyword to obtain subnets from the AAA server, and the ipcp keyword to obtain subnets from IPCP negotiation. If you expect that the utilization of the pool may grow over time, use the autogrow size option.
If a pool has been configured with the autogrow size option, ensure that the source server is capable of providing more than one subnet to the same pool. Even though the Cisco IOS software specifies the requested subnet size, it can accept any offered subnet size from the source server.
Examples
The following example shows how to configure an address pool named green to use DHCP as the subnet allocation protocol with an initial subnet size of 24 and an autogrow subnet size of 24:
ip dhcp pool greenvrf greenorigin dhcp subnet size initial /24 autogrow /24utilization mark high 80utilization mark low 20The following example shows how to configure the location of the external text file:
ip dhcp pool abcpoolorigin file tftp://10.1.0.1/staticbindingfileRelated Commands
password (DFP agent)
To configure a DFP agent password for MD5 authentication, use the password command in DFP agent configuration mode. To remove the DFP agent password, use the no form of this command.
password [0 | 7] password [timeout]
no password
Syntax Description
Defaults
No password is enabled.
Command Modes
DFP agent configuration
Command History
Usage Guidelines
The timeout option allows you to change the password without stopping messages between the DFP agent and its manager. The default value is 180 seconds.
During the timeout, the agent sends packets with the old password (or null, if there is no old password), and receives packets with either the old or new password. After the timeout expires, the agent sends and receives packets only with the new password; received packets that use the old password are discarded.
If you are changing the password for an entire load-balanced environment, set a longer timeout. This allows enough time for you to update the password on all agents and servers before the timeout expires. It also prevents mismatches between agents and servers that have begun running the new password and agents, and servers on which you have not yet changed the old password.
Examples
The following example shows how to set the DFP agent password (unencrypted by default) to Cookies and the timeout to 360 seconds:
Router(config)# ip dfp agent slbRouter(config-dfp)# password Cookies 360Related Commands
permit (IP)
To set conditions to allow a packet to pass a named IP access list, use the permit command in access list configuration mode. To remove a permit condition from an access list, use the no form of this command.
[sequence-number] permit source [source-wildcard]
[sequence-number] permit protocol source source-wildcard destination destination-wildcard [option option-name] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]
no sequence-number
no permit source [source-wildcard]
no permit protocol source source-wildcard destination destination-wildcard [option option-name] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]
Internet Control Message Protocol (ICMP)
[sequence-number] permit icmp source source-wildcard destination destination-wildcard [icmp-type [icmp-code] | icmp-message] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]
Internet Group Management Protocol (IGMP)
[sequence-number] permit igmp source source-wildcard destination destination-wildcard [igmp-type] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]
Transmission Control Protocol (TCP)
[sequence-number] permit tcp source source-wildcard [operator [port]] destination destination-wildcard [operator [port]] [established | {match-any | match-all} {+ | -} flag-name] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]
User Datagram Protocol (UDP)
[sequence-number] permit udp source source-wildcard [operator [port]] destination destination-wildcard [operator [port]] [precedence precedence] [tos tos] [log] [time-range time-range-name] [fragments]
Syntax Description
sequence-number
(Optional) Sequence number assigned to the permit statement. The sequence number causes the system to insert the statement in that numbered position in the access list.
source
Number of the network or host from which the packet is being sent. There are three alternative ways to specify the source:
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source-wildcard
Wildcard bits to be applied to source. There are three alternative ways to specify the source wildcard:
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protocol
Name or number of an Internet protocol. The protocol argument can be one of the keywords eigrp, gre, icmp, igmp, ip, ipinip, nos, ospf, tcp, or udp, or an integer in the range from 0 to 255 representing an Internet protocol number. To match any Internet protocol (including ICMP, TCP, and UDP), use the ip keyword.
Note
icmp
Permits only ICMP packets. When you enter the icmp keyword, you must use the specific command syntax shown for the ICMP form of the permit command.
igmp
Permits only IGMP packets. When you enter the igmp keyword, you must use the specific command syntax shown for the IGMP form of the permit command.
tcp
Permits only TCP packets. When you enter the tcp keyword, you must use the specific command syntax shown for the TCP form of the permit command.
udp
Permits only UDP packets. When you enter the udp keyword, you must use the specific command syntax shown for the UDP form of the permit command.
destination
Number of the network or host to which the packet is being sent. There are three alternative ways to specify the destination:
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destination-wildcard
Wildcard bits to be applied to the destination. There are three alternative ways to specify the destination wildcard:
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option option-name
(Optional) Packets can be filtered by IP Options, as specified by a number from 0 to 255, or by the corresponding IP Option name, as listed in Table 3 in the "Usage Guidelines" section.
precedence precedence
(Optional) Packets can be filtered by precedence level, as specified by a number from 0 to 7 or by a name.
tos tos
(Optional) Packets can be filtered by type of service (ToS) level, as specified by a number from 0 to 15, or by a name as listed in the "Usage Guidelines" section of the access-list (IP extended) command.
log
(Optional) Causes an informational logging message about the packet that matches the entry to be sent to the console. (The level of messages logged to the console is controlled by the logging console command.)
time-range time-range-name
(Optional) Name of the time range that applies to this permit statement. The name of the time range and its restrictions are specified by the time-range and absolute or periodic commands, respectively.
fragments
(Optional) The access list entry applies to noninitial fragments of packets; the fragment is either permitted or denied accordingly. For more details about the fragments keyword, see the "Access List Processing of Fragments" and "Fragments and Policy Routing" sections in the "Usage Guidelines" section.
icmp-type
(Optional) ICMP packets can be filtered by ICMP message type. The type is a number from 0 to 255.
icmp-code
(Optional) ICMP packets that are filtered by ICMP message type can also be filtered by the ICMP message code. The code is a number from 0 to 255.
icmp-message
(Optional) ICMP packets can be filtered by an ICMP message type name or an ICMP message type and code name. The possible names are listed in the "Usage Guidelines" section of the access-list (IP extended) command.
igmp-type
(Optional) IGMP packets can be filtered by IGMP message type or message name. A message type is a number from 0 to 15. IGMP message names are listed in the "Usage Guidelines" section of the access-list (IP extended) command.
operator
(Optional) Compares source or destination ports. Operators include lt (less than), gt (greater than), eq (equal), neq (not equal), and range (inclusive range).
If the operator is positioned after the source and source-wildcard arguments, it must match the source port. If the operator is positioned after the destination and destination-wildcard arguments, it must match the destination port.
The range operator requires two port numbers. Up to ten port numbers can be enter
