Table Of Contents
Ports on the Catalyst LRE Switch
Environmental Guidelines for LRE Links
Guidelines for Using LRE Profiles
Considerations for Connected Cisco 575 LRE CPEs
Considerations for Connected Cisco 585 LRE CPEs
Assigning a Public Profile to All LRE Ports
Assigning a Private Profile to an LRE Port
Using Rate Selection to Automatically Assign Profiles
Link Qualification and SNR Margins
Configuring for an LRE Upgrade
Global Configuration of LRE Upgrades
Controller Configuration of LRE Upgrades
Configuring LRE
This chapter describes how to configure the Long-Reach Ethernet (LRE) features on your switch. This chapter consists of these sections:
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Ports on the Catalyst LRE Switch
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Ports on the Catalyst LRE Switch
The Catalyst LRE switches use LRE technology to transfer data, voice, and video traffic over categorized and non-categorized unshielded twisted-pair cable (Category 1, 2, and 3 structured and unstructured cable such as existing telephone lines).
Connecting a switch LRE port to a remote Ethernet device (such as a PC) requires two types of connections:
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The actual line speed in either direction between a switch LRE port and remote Ethernet device depends on the LRE link speed and the CPE Ethernet link speed. For example, if a PC Ethernet port is configured to 100 Mbps and the LRE port is configured with an upstream link speed of 5.69 Mbps, the actual upload rate provided to the PC user is 5.69 Mbps, not 100 Mbps.
For LRE troubleshooting information, see the "Troubleshooting LRE Port Configuration" section. Additional LRE details are provided in the switch command reference.
LRE Links and LRE Profiles
The LRE link settings define the connection between the switch LRE port and the CPE RJ-11 wall port. The LRE link provides symmetric and asymmetric data transfer rate for data, voice, and video traffic. Symmetric transmission is when the downstream and upstream data transfer rates are the same. Asymmetric transmission is when the downstream and the upstream bandwidths differ. Downstream transmission refers to the traffic traveling from the LRE switch to the CPE device. Upstream transmission refers to the traffic traveling from the CPE device to the LRE switch.
The switch controls upstream and downstream rates on the LRE link by using configurations called profiles. Depending on the profile, the upstream and downstream bands on an LRE link can range from approximately 1 Mbps to 18.750 Mbps.
This section discusses these topics:
LRE Profiles
You can assign profiles on a per-port or switch-wide basis. When the LRE switch establishes a link with the CPE device, the switch downloads its profile settings to the CPE device so that the switch and CPE device operate with the same configuration.
The LRE switches are shipped with predefined profiles categorized as public (global) mode and private (per-port) mode profiles (Table 8-1). Only the Public-ANSI and Public-ETSI profiles are public; all other system-defined profiles are private. By default, all LRE ports on the switch are enabled with the LRE-10 private profile. This default profile allows the upstream and downstream transmission rate on the LRE link to be 10 Mbps.
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The standards for spectral profiles have not yet been ratified. The PUBLIC-ANSI profile corresponds to ANSI Plan 998. The PUBLIC-ETSI profile corresponds to ETSI Plan 997. Both plans are draft standards. Contact Cisco Systems for the latest information about standards ratification or for updates to the public profiles.
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Your data rates will always be less than the gross data rate listed in table. A small percentage of the link rate is used by Catalyst LRE switch for supervisory functions with the CPE device connected remotely.
In general, profiles are named for the data rate you expect to achieve, and not the gross data rate as given in the table. All system-defined profiles have the prefix LRE, followed by the downstream user data rate, and then the upstream user data rate. If the profile is symmetric, only one data rate is given. The two profiles defined to comply with Public frequency usage plans 998 and 997 (Public-ANSI and Public-ETSI) are exceptions to this. These two uniquely named profiles will work in any private deployment.
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When you assign a different profile to a switch LRE port, the port immediately resets and uses the newly assigned profile.
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All other profiles, port and global, have the interleaver feature enabled and the LL feature disabled. The interleaver feature provides maximum protection against small interruptions on the LRE link but delays data transmission.
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LRE Profile Sequences
The LRE switches are shipped with predefined profile sequences. Sequences are sets of profiles and are used with the rate selection feature so that you can allow the switch to automatically select profiles. You can also define your own sets of sequences by using commands or CMS.
Table 8-2 outlines the predefined profile sequences for rate selection contained in Cisco IOS. When executing rate selection, the switch uses these sequences to choose an appropriate profile for a given LRE interface.
Beginning with the first profile in a sequence, the switch attempts to apply each profile within that sequence to the LRE interface. Convergence time refers to the time required for the switch to settle on an appropriate profile for the LRE interface. If a link cannot be established by any of the profiles in the sequence, the link is declared as DOWN.
For additional information on rate selection, see the "Using Rate Selection to Automatically Assign Profiles" section.
CPE Ethernet Links
The CPE Ethernet link settings define the connection between the CPE Ethernet port and a remote Ethernet device, such as a PC.
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Keep these considerations in mind when you have CPE devices connected to the LRE ports:
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Use the show controllers ethernet-controller privileged EXEC command to display the internal switch statistics, the statistics collected by the LRE switch interface, and the statistics collected by the CPE LRE interface. For information about this command, refer to the switch command reference.
Configuring LRE Ports
These sections describe configuration guidelines and how to assign a profile to all or individual LRE ports. These sections contain more information about LRE links, ports, and profiles:
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Environmental Guidelines for LRE Links
The requirements of your LRE environment are based on these factors:
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Each terminated bridge tap in a room can further reduce LRE link distances by 300 feet. The quality of the cable, the size of the cable bundles, and cross talk within the bundle also can affect overall reach.
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If your site is a single building (or is a connected set of buildings), consult a qualified electrician to ensure that the wiring conforms to the appropriate regulations for indoor circuits.
If your site has separate buildings, you must determine how the buildings are cabled to each other. Where the wiring between the LRE switch and CPE device leaves the building (or the armored conduits certified for inside wiring standards), it must be protected against lightning and shorts to high-voltage power. This protection might be provided by fuses or overvoltage protectors that comply with local regulations for outside wiring protection. Consult an expert in local telecommunications regulations for the details of this protection.
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The greatest impact on LRE performance is from the frequency response of the cable at the higher frequencies. LRE signals are more susceptible to interference at higher frequencies. The LRE upstream signal operates at the high end of the frequency spectrum. Cables have higher attenuation at higher frequencies and also interfere with other pairs in the bundle at higher frequencies. This interference or cross talk can significantly impact the signal quality.
Guidelines for Using LRE Profiles
When assigning a profile to a switch LRE port, keep these considerations in mind:
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If a public profile is configured on the switch and you want the switch LRE ports to use private profiles, you must first disable the public profile by using the no lre profile SS configuration command.
When you assign a different profile to a switch LRE port, the port immediately resets and uses the newly assigned profile.
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A cluster can have a mix of LRE switches using different private profiles. For more information about clusters, see "Clustering Switches."
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To maintain the quality of the LRE connection, use the asymmetric port profiles. These profiles use a low upstream rate but provide a high downstream rate.
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Use the show controllers lre status profile and show controllers lre status link privileged EXEC commands to display the LRE link statistics and profile information on the LRE ports. For information about these commands, refer to the switch command reference.
CPE Ethernet Link Guidelines
The CPE Ethernet link settings define the connection between the CPE Ethernet port and a remote Ethernet device, such as a PC.
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Keep these considerations in mind when you have CPE devices connected to the LRE ports:
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Use the show controllers ethernet-controller privileged EXEC command to display the internal switch statistics, the statistics collected by the LRE switch interface, and the statistics collected by the CPE LRE interface. For information about this command, refer to the switch command reference.
Considerations for Connected Cisco 575 LRE CPEs
You can configure the Cisco 575 LRE CPE Ethernet port to operate at 10 or 100 Mbps and at half- or full-duplex mode, depending on the capability of the remote Ethernet device. Autonegotiation for port speed and duplex mode is supported.
The default speed for the CPE Ethernet port is auto. The default duplex mode is half duplex with back pressure.
The speeds on the LRE links and CPE Ethernet links do not need to match. However, to prevent the possible loss of data when the LRE link is slower than the CPE Ethernet link, make sure that the CPE Ethernet port is set to half-duplex mode. Use duplex autonegotiation only if the remote device supports 802.1X full-duplex flow control. The PC user should notice no significant difference in performance between 100-Mbps half duplex and 100-Mbps full duplex. Use the duplex and speed interface configuration commands, respectively, to change the duplex and speed settings on the Cisco 575 LRE CPE Ethernet port.
Considerations for Connected Cisco 585 LRE CPEs
You cannot configure the Cisco 585 LRE CPE Ethernet ports.
The default speed for the CPE Ethernet ports is auto. The default duplex mode is half duplex with back pressure. Duplex autonegotiation is not supported on the Cisco 585 LRE CPE.
You cannot enable or disable the CPE Ethernet ports on a per-port basis. For example, using the shutdown interface configuration command on an LRE port disables all Ethernet ports on the connected CPE device.
The loopback interface configuration command is not supported on the LRE ports. External loopback on the LRE ports is also not supported. Connecting a CPE Ethernet port to another Ethernet port on the same CPE device can create a loop. If this happens, the switch stops sending to the CPE device and blocks Ethernet traffic coming from the CPE device.
Assigning a Public Profile to All LRE Ports
Public profiles are set on a switch-wide (global) basis. The public profile you select should be compatible with the PSTN to which the LRE switch is connected.
Public profiles have priority over private profiles. If you assign a public profile to the switch, the switch ignores the private profile settings and uses the public profile settings on all LRE ports. To disable the public profile on the switch, use the no lre profile global global configuration command.
Changes to the public profile settings are immediately put in effect, and the public mode automatically becomes the active mode.
Beginning in privileged EXEC mode, follow these steps to assign a public profile to the LRE ports:
Use the show controllers lre status profile and show controllers lre status link privileged EXEC commands to display the LRE link statistics and profile information on the LRE ports. For information about these commands, refer to the switch command reference.
Assigning a Private Profile to an LRE Port
Private profiles are set on a per-port basis. You can assign the same private profile or different private profiles to the LRE ports on the switch. The default active private profile on all LRE ports is LRE-10.
The switch resets the ports with the updated profile settings.
Beginning in privileged EXEC mode, follow these steps to assign a private profile to an LRE port:
Step 1
configure terminal
Enter global configuration mode.
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interface LRE-interface
Enter interface configuration mode, and enter the number of the LRE port to be configured.
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lre profile profile_name
Enter the private profile name (see Table 8-1 for a complete list).
The default profile is LRE-10.
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end
Return to privileged EXEC mode.
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show controllers lre profile mapping
Verify the change.
Use the show controllers lre privileged EXEC commands to display the LRE link statistics and profile information on the LRE ports. For information about these commands, refer to the switch command reference.
Using Rate Selection to Automatically Assign Profiles
An LRE network requires a profile to be configured for each LRE port that is connected to a CPE device (the default is LRE-10). The rate selection feature lets you allow the switch to automatically choose a profile from a set of profiles that the switch port uses to establish an LRE link (a link between an LRE switch port and an attached CPE device). The chosen profile might or might not be the optimal link or the most appropriate profile.
Rate selection is enabled by default, but you must choose a sequence for rate selection to start (in other words, there is no default sequence defined). When rate selection is running, the switch chooses the most appropriate profile for the LRE interface from a sequence, or predefined series of profiles, that are configured for that interface. The rate-selection algorithm begins with the first profile in the sequence and successively tries the next profiles (in descending order) until a link is established with the CPE device. The final profile in each sequence ends with the port attempting to establish link with the LRE-4-1 profile. This profile provides the minimum upstream and downstream rates at which the LRE port and CPE device can establish link.
When enabled, the LRE switch executes rate selection in these scenarios:
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In any of these cases, rate selection is used to obtain the optimal profile for your line conditions.
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The switch chooses the appropriate profile for an LRE interface at the time it executes rate selection. If line conditions of the LRE interface change, rate selection must be executed again.
The rate selection feature can be applied at both the port level and at the switch level. Profiles and sequences have a system-defined priority level which work in conjunction with rate selection to determine the rate for a port or the entire switch. The priority levels, from highest to lowest, are the following:
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See Table 8-1 for the list of profiles, and Table 8-2 for the list of system-defined sequences. You can also use IOS commands or CMS to define your own sequences.
Profile Locking
You can also use rate selection as an installation tool to lock in a particular profile. In this case, you execute rate selection only once at installation time; afterwards, rate selection is never executed, even if one of the above four events occur. You use the config command in privileged EXEC mode to lock the profile chosen by rate selection. (You can enter a special EXEC command to rerun rate selection on the interfaces that have locked the profiles, as needed.)
An advantage to profile locking is that the convergence time during bootup is faster if a profile is locked on an LRE port rather than having to go through a profile sequence.
Beginning in privileged EXEC mode, follow these steps to lock a profile in an LRE port that has rate selection enabled:
Link Qualification and SNR Margins
When rate selection is running, the signal-to-noise ratio (SNR) is used as an indicator of link quality. The switch does not provide any internal mechanism to assure link quality. There can be different requirements for link quality, depending on the required bit-error rate and the noise level of the environment. A noisier environment would require a higher SNR to be able to provide a stable link. A lower bit-error rate would require a higher SNR. Typically a 6-dB margin provides an error rate of 10-21 bits.
In order to provide link stability, you should add a margin to the required SNR. You can configure your margins to an amount that is appropriate for the noise level of your environment. Increasing the margin requirement can cause the system to choose a lower profile, which would in turn translate to a lower data rate but with a higher reach.
The switch does not guarantee any margins after a link is activated; margins are only guaranteed only when the link is established. When a link is activated, if the SNR requirements do not match the configured margin level, the link is not established.
Downstream indicates the remote end of the link, and upstream the local end. The link has to satisfy both the local and remote margin requirements. If either one is not met, the link is advertised as down. This command has no significance if rate selection is disabled on the interface.
Table 8-3 lists the SNR requirements for downstream rates for different profiles.
Table 8-4 lists the SNR requirements for upstream rates for different profiles.
The margin range for link qualification is from 1 to 10 dB. The recommended value in a low noise environment is 2 dB. The recommended value for medium noise environment is 4 dB. The recommended value in a high noise environment is 6 dB.
If a profile has a theoretical minimum of 25 dB and you configure a margin of 3 dB, when the link is established, the SNR should at the least be 28 dB to show a successful link. If a link is established and if the SNR value at link time is 27 dB, the link is advertised as down, and the next profile in the sequence is attempted. If you configure a margin of 0 (the default value), IOS does not check for the SNR value when the link is established.
Beginning in privileged EXEC mode, follow these steps to assign a margin to a specific LRE port:
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LRE Link Persistence
A brief LRE link down and up transition can cause the rest of the IOS modules to react immediately, for example, the Dynamic MAC addresses are removed from that ports table. You can use the link persistence feature to configure a delay duration on the Catalyst LRE switch of up to 20 seconds before link failure is reported.
See the lre persistence reference pages in the Catalyst 2900 XL and Catalyst 3500 XL Desktop Switch Command Reference for further details.
Upgrading LRE Switch Firmware
The Catalyst LRE switch has the capacity to store and properly apply LRE binaries in case there are updates required to the firmware on the switches' local LRE controllers or connected customer premises quipment (CPE) devices.
Other upgrade-related features include:
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You perform an upgrade with the command
hw-module slot x upgrade lre [force][local lo n | remote lo x/y]
Automatic upgrading is not supported. You can upgrade in one these ways:
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Configuring for an LRE Upgrade
In the absence of any LRE upgrade configurations, an LRE upgrade attempts to upgrade all local LRE controllers and CPE devices to the most recent compatible versions of the LRE binaries required for each LRE target device. LRE upgrade configurations should rarely be required. The primary purpose of LRE upgrade configuration commands is to provide for downgrades of LRE binaries.
If you wish to override the switch's automatic selection of LRE binaries, you have two methods available:
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Global config commands allow you to specify the LRE binary or binaries to use on a specified target type. (A target type is the family [and optionally the model or model revision] of a device containing one or more upgradable hardware elements.) A target can be a local LRE controller on the switch or a remote CPE device.
The following describes how global LRE upgrade configurations are performed:
LRE upgrade controller configuration commands are performed from the controller configuration submode. The upgrade configuration command in the controller submode allows the user to override the system default selection of an LRE binary to be applied on a particular remote CPE device or local LRE controller. Controller configurations take precedence over global upgrade configurations.
The preserve keyword is used to cause the LRE upgrade mechanism to NOT upgrade the local controller on which preserve is configured, or any of the CPE devices connected to that controller. If you want to preserve (in other words, not upgrade) some of the CPE devices connected to a particular controller but allow upgrades to others, you can enter controller upgrade configuration commands for the links you want to upgrade.
The no form of the command removes the command for applying a particular LRE binary. In order to resume default upgrade behavior for a given controller, no upgrade commands should be configured on that controller
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See the reference pages for the upgrade commands in the Catalyst 2900 XL and Catalyst 3500 XL Desktop Switch Command Reference for further details.
Performing an LRE Upgrade
You can upgrade either on a system-wide basis (in other words, upgrading the software on all connected CPE devices and local LRE chipsets), or on individual CPE device or LRE controllers. By default, a system wide upgrade applies the most recent versions of LRE binaries that are most compatible with each upgradable hardware module. The system-wide upgrade method is the one that you use in almost all situations.
When executing upgrades, you can elect to upgrade a single CPE device or local controller using the following command:
hw-module slot <x> upgrade lre [local lo n | remote lo x/y]
If no local or remote option is given, a system-wide upgrade is performed.
Global Configuration of LRE Upgrades
Beginning in privileged EXEC mode, follow these steps to use perform a system-wide upgrade to configure the LRE binary to apply to a target device and upgradable hardware element combination:
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Controller Configuration of LRE Upgrades
Beginning in privileged EXEC mode, follow these steps to explicitly direct the LRE binaries to be applied to either the local controller or a specific VDSL link:
The upgrade configuration command in the controller submode allows the user to override the system default selection of an LRE binary that will be applied on either end of a particular LRE link. Controller configurations take precedence over global upgrade configurations.
The preserve keyword is used to cause the LRE upgrade mechanism to NOT upgrade the local controller on which preserve is configured or any of the CPE devices connected to that controller. If you want to preserve (in other words, not upgrade) some of the CPE devices connected to a particular controller but allow upgrades to others, you can enter controller upgrade configuration commands for the links you want to upgrade.
The no form of the command removes the command for applying a particular LRE binary. In order to resume default upgrade behavior for a given controller, no custom upgrade commands should be configured on that controller.
LRE Upgrade Behavior Details
This is what you see on the console when you initiate an upgrade:
Switch>enSwitch#hw-module slot 0 upgrade lreYou are about to start an LRE upgrade on all LRE interfaces.Users on LRE links being upgraded will experience a temporary disruption of Ethernet connectivity.Start LRE upgrade ? [yes]:If you answer yes or press the Enter key, the upgrade starts. If you answer no, you get the EXEC prompt.
You expect the following link behavior of the CPE device during an upgrade:
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LRE Upgrade Example
The following is an example of how an LRE upgrade can proceed:
Switch#hw-module slot 0 upgrade lre force remote lo 0/1You are about to start an LRE upgrade on CPE Lo0/1.Users on LRE links being upgraded will experience a temporarydisruption of Ethernet connectivity.Start LRE upgrade ? [yes]:Starting remote upgrade on CPE Lo0/1Switch#00:21:51: %LINEPROTO-5-UPDOWN: Line protocol on InterfaceLongReachEthernet0/1, changed state to downThe CPE device resets and the link is down. Ethernet connectivity is unavailable.
00:22:37: %LINK-3-UPDOWN: Interface LongReachEthernet0/1, changed state to up00:22:39: %LINEPROTO-5-UPDOWN: Line protocol on InterfaceLongReachEthernet0/1, changed state to upThe CPE device comes out of reset. Ethernet connectivity is available but at low speeds. Upgrade data transfer begins.
00:23:55: %LINEPROTO-5-UPDOWN: Line protocol on InterfaceLongReachEthernet0/1, changed state to downUpgrade data transfer is complete. Reset the CPE device.
00:23:56: %LINK-3-UPDOWN: Interface LongReachEthernet0/1, changed state to upThe CPE device has come out of reset. The desired profile is applied.
00:23:58: %LRE_LINK-3-UPDOWN: Interface Lo0/1, changed state to UP00:23:59: %LINK-3-UPDOWN: Interface LongReachEthernet0/1, changed state to up00:24:02: %LINEPROTO-5-UPDOWN: Line protocol on InterfaceLongReachEthernet0/1, changed state to upOperation resumes in the profile link up state.
Switch#
