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This chapter describes basic hardware and service provision considerations such as system environment requirements, physical infrastructure checklists, IP service considerations, and system upgrade procedures for the Cisco AS5800.
For details on the following, refer to the information on preparing for installation in the Cisco AS5800 Access Server Hardware Installation Guide, available online at
http://www.cisco.com/univercd/cc/td/doc/product/access/acs_serv/as5800/hw_inst/
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Note House the Cisco AS5800 in an area with constant temperature and humidity. Cooler environments are ideal for stabilizing hardware temperatures. Humidity should be high enough to prevent accumulation of static electricity, yet low enough to prevent condensation. Relative humidity up to 90% is acceptable. |
This section describes how to set up and provision basic modem IP services using a Cisco AS5800 network access server. It is tailored for network engineers who work with dialup access technologies, and assumes the reader is Cisco certified or familiar with Cisco IOS routers and technologies.
Corporate users and Internet service providers (ISP) install dialup services to facilitate e-mail, e-commerce, and application/database access for employees, roaming sales personnel, household consumers, and students. As a corporate user or ISP, you want to:
The following section discusses:
The network-service definition for a corporate user generally differs from that for an ISP, as shown in Table 6-1.
Table 6-1 Network-Service-Definition Perspectives
Begin your implementation of basic IP UPC services by establishing a network service definition. Use the perspectives described in Table 6-1 preceding and in the following list of design and configuration considerations as a guide. A conservative approach is to project your current deployment and design into a three-month, one-year, and five-year timeline.
Step 2 Determine user-to-line ratio during busy hours.
Step 3 Determine access media to be used for dial services:
Step 4 Determine types of remote devices to support:
Step 5 Determine operating systems to support:
Step 6 Determine if dial-in modem services will be supported.
Step 7 Rank technology priorities:
Step 8 Determine which access service will be used for connecting to modems:
Step 9 Determine if multilink will be supported. If yes, indicate whether you will scale to a stacked multichassis solution.
Step 10 Determine if PPP timeouts (accounting) will be supported.
Step 11 Determine where user passwords will be stored in the short term:
Step 12 Determine if an AAA server will be used in the long term. If yes, specify which protocol will be used:
Step 13 Determine if users will be allowed to change their own passwords. If yes, specify how:
Step 14 Determine if the access network will use an external authentication database such as SecureID, Windows NT, or Novell NDS.
Step 15 Determine if per-user attribute definitions (authorization) will be supported.
Step 16 Indicate whether an existing accounting system to monitor call-detail records is in place.
Step 17 Indicate whether you are running an existing network-management system. If no, determine whether a network-element management server is needed
This section describes Cisco IOS upgrade procedures for the Cisco AS5800. The following tasks are detailed.
A Cisco IOS upgrade requires a compatible Cisco IOS image upgrade on both the dial-shelf controller (DSC) cards and router-shelf (RS) components of the system. Two distinct upgrade procedures are necessary, one for each component.
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Note Sufficient memory (available bytes) is required to accommodate any new image file size on the RS and DSC! Contact your Cisco Sales Representative for memory upgrades. |
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Note Cisco IOS software is feature specific and licensed on an "as is" basis without warranty of any kind, either expressed or implied. The version of Cisco IOS software used in this manual varies depending on configuration requisites for presentation purposes, and should not be construed as the Cisco IOS software version of choice for your system or internetwork environment. Consult your Cisco Sales Representative regarding your Cisco IOS requirements. |
To upgrade a Cisco IOS software image you need the following:
Before installing new software, first determine the amount of available memory in RAM and Flash.
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Note You must have sufficient memory available on your Access Server to accommodate the file size memory requirements for new software you want to load. |
Step 2 Determine the amount of available flash memory for storage purposes.
Step 3 Record this memory values for future reference.
To obtain a recent version of the Cisco IOS software, you need access to the Cisco.com website.
Cisco IOS software is version specific bundled software that includes the following compatible components:
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Note Images much match the specific version of Cisco IOS software being installed. Example: If attempting to run 12.0.7T, you must run the 12.0.7T dial-shelf (DSC) image (dsc-c5800-mz.XXX) and the 12.0.7T router-shelf image (C5800-p4-mz.XXX) to secure proper system functionality. |
Step 2 After verifying that you have sufficient memory, download the router shelf, dial shelf, and boot image to your TFTP server.
Cisco recommends backing up all existing Cisco IOS images and configurations from privileged exec mode.
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Note Back up current Cisco IOS images (boot, router-shelf, dial-shelf) and configurations to your TFTP server before upgrading. By default, files are copied to and from the Cisco TFTP root directory. |
Step 2 Back up your existing running configuration. Use a distinct file name for the running configuration. This makes it easy to distinguish from other running configurations previously saved on your TFTP Server.
Step 3 Save your running-configuration to your startup configuration in NVRAM.
Step 4 Determine the current boot image.
Step 5 Back up the boot image (c7200-boot-mz.XXX) from bootflash to your TFTP server. Use the file name obtained in Step 4.
Step 6 Determine the router shelf's current flash image.
Step 7 Back up the current router-shelf Cisco IOS image (C5800-p4-mz.XXX) stored in flash memory. Use the file name obtained in Step 6.
Step 8 On your TFTP Server, verify that files were copied (backed up).
A Cisco IOS upgrade requires a compatible Cisco IOS image upgrade on both the dial-shelf controller (DSC) cards and router-shelf (RS) components of the system. Two distinct upgrade procedures are necessary, one for each component.
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Note Cisco recommends upgrading the dial-shelf controllers first, since all upgrades are performed through the router shelf. Once DSCs are upgraded, the router shelf is not be able to communicate with the DSCs until a compatible Cisco IOS image is installed on the RS. |
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Note Do not modify your running configuration during the Cisco IOS upgrade process. |
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Note Upgrade verifications are performed after all necessary upgrades are complete, and all system components are reloaded. |
The following procedure outlines commands used to perform a Cisco 5814 dial-shelf controller (DSC) software upgrade from the router shelf.
Step 2 Identify Cisco IOS images in the DSC bootflash.
Step 3 Delete the current Cisco IOS images from bootflash.
Step 4 Squeeze the DSC bootflash.
Step 5 Identify Cisco IOS images in the DSC flash.
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Note Remember, sufficient memory (available bytes) is required to accommodate any new image file size on the RS and DSC! Compare memory size obtained in "Memory Requirements". |
Step 6 Delete images or files no longer required.
Step 7 Squeeze the DSC flash to remove deleted files.
Step 8 Download the new DSC image from your TFTP server to the DSC flash.
The following Warning message appears.
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Note Do not abort the copy process. This message implies that the file being downloaded is not router-shelf compatible, which is true. However, the router assumes the file being downloaded will be executed on the router shelf, when, in fact, the file is a dial-shelf controller file, being downloaded to the dial shelf through the router, that will ultimately be executed on the dial shelf. |
Step 9 Enter n to proceed with the download.
Step 10 Copy the new DSC image to the DSC bootflash:
Step 11 Reload the DSC to load the new image.
Step 12 Repeat this procedure if you have a second DSC card to ensure both cards are running the same software release. The only change to the commands will be the slot number ("13" instead of "12").
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Note At this juncture, the DSCs and router shelf are not running the same Cisco IOS image, so you will not be able to communicate with the DSC through the router shelf. |
The following procedure outlines commands used to perform a Cisco 7206 router-shelf (RS) software upgrade from the router shelf.
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Note Unless you installed new port adapters in the router shelf, do not upgrade the boot image. See the "Upgrading the Router-Shelf Boot Image" section. |
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Note Remember, sufficient memory (available bytes) is required to accommodate any new image file size on the RS and DSC! Compare memory size obtained in "Memory Requirements". |
Step 2 Delete images or files no longer required.
Step 3 Squeeze the flash to remove all deleted files.
Step 4 Download the new image from your TFTP server to the RS flash.
Step 5 Upgrade the bootflash, if applicable. See the "Upgrading the Router-Shelf Boot Image" section.
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Note Unless you are installing new port adapters in the router shelf, do not upgrade the boot image. See the "Upgrading the Router-Shelf Boot Image" section. |
Step 6 Reload the router shelf to load the new image.
The following procedure outlines commands used to perform a Cisco 7206 router-shelf (RS) boot image software upgrade from the router shelf.
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Note Unless you installed new port adapters in the router shelf, do not upgrade the boot image. |
Step 2 Delete the current boot image from bootflash.
Step 3 Squeeze the bootflash to remove all deleted files.
Step 4 Copy the boot image from your TFTP server (c7200-boot-mz.XXX) to bootflash.
Perform the following steps to verify that the router shelf and DSCs are running new Cisco IOS images, and the Bootflash is running a new boot image.
Step 2 Check the router shelf for a new Cisco IOS image.
Step 3 Check the Bootflash for a new boot image.
Compatible modem firmware is included in each Cisco IOS bundled software version and upgraded as part of the installation process.
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Note Do not install a separate version of modem firmware independent of the Cisco IOS software it accompanies. See the "Modem Upgrades" section 6-14. |
This section describes basic debugging and modem commands used for upgrading modem module firmware as well as modem activation considerations. The show modem version command output is displayed to verify a successful download.
Use the following commands for debugging a modem or group of modems.
From the Cisco IOS privileged mode AS5800-1# .
Each modem card installed in your Cisco AS5800 access server contains 12 MICA modems, each with six modem SIMMs. This allows you to upgrade firmware for each group of six modem SIMMs.
The default firmware image is loaded on the modem card during system boot-up. Normally, you do not need to change the firmware image; however, you can override the default image with another firmware image.
A valid pool range must exist (that is, the pool-range modem pool configuration command must have been configured) for modem overrides to occur. Modem pooling allows you to define, select, and use separate modem pools within a single access server or router to enable different dial-in services for different customers. In this case, the modem pool specifies which modems are loaded with the new firmware image.
The specified firmware image is loaded on every modem for every slot specified in the pool range. If the modem is busy, the firmware change is deferred until the modem is available. When the modem is available, the firmware change takes place immediately.If you specify a firmware image that does not exist, the information is stored so that, in the event that the modem card is updated with that firmware image, it will be loaded when the modem card image boots.
At boot-up time, the default firmware image is loaded first. If there is a firmware image specified by the firmware command, it is then loaded onto the modem card.
Table 6-2 lists modem firmware upgrade commands to override the default modem firmware image with another specified firmware image.
Table 6-2 Modem Firmware Upgrade Commands
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To deactivate a modem command, type no before the command:
To verify that a download has succeeded, use the show modem version command.
When the Cisco 7206 router shelf boots up and parses its NVRAM, the modem cards will not be up. As a result, the override firmware name is stored in the modem pool structures and no action is taken.
When a modem card becomes active, it sends a startup message to the router shelf. The router shelf then triggers a search in the various modem pools to see if any modem modules on the modem card have a specified firmware override. If yes, the firmware override request is relayed to the modem card, which will load the specified override firmware image on the indicated modem modules.
As a result, the modem modules that are destined to run an override firmware image will experience two firmware downloads at bootup time. The default modem firmware image is loaded first, followed by the override modem firmware image.
Error messages result if the following circumstances exist:
The split mode is intended to support two router shelves connected to a single dial shelf. To use this arrangement as intended, both router shelves need a split dial shelf configured. However, a second router is not required; a single router can run in split mode with all slots owned by that router.
Split-dial-shelf configuration is implemented by connecting two router shelves to a single dial shelf. You allocate the slots in the dial shelf between the two router shelves to achieve the desired configuration. The two router shelves are configured to run in split mode by a new top-level router configuration command:
where slot-numbers is a list of the dial-shelf slot numbers (from 0 to 11) that the router owns, with the slot numbers separated by spaces. Slot ownership for each of the two router shelves is configured individually using the dial-shelf split slots command.
When you configure a Cisco AS5800 to operate in split mode, it is the same as having two Cisco AS5800s, each having a separate set of feature boards assigned to its router that happen to be sharing a single dial shelf. Modem pooling, for example, is the same as if you had two separate Cisco AS5800s. Router shelf 1 has a modem pool that consists of all the modem cards that reside in slots owned by router shelf 1. The same situation applies to router shelf 2.
This section describes the procedure required to transition a router from normal mode to split mode, and change the set of slots a router owns while it is in split mode. The process of switching the ownership of a slot from one router to the other is potentially disruptive. When a feature board is restarted, all calls through that card are lost. Therefore, a router shelf cannot take over a slot until ownership is relinquished by the router that currently claims ownership, either by reconfiguring the router or disconnecting that router or its associated DSC.
The dial shelf is split by dividing the ownership of the feature boards between the two router shelves. You must configure the division of the dial-shelf slots between the two router shelves so that each router controls an appropriate mix of trunk and modem cards. Each router shelf controls its set of feature boards as if those were the only boards present. There is no interaction between feature boards owned by either router.
Split mode is entered when the dial-shelf split slots command is parsed on the router shelf. This can occur when the router is starting up and parsing the stored configuration or when the command is entered when the router is already up. On parsing the dial-shelf split slots command, the router frees any resources associated with cards in the slots that it no longer owns, as specified by exclusion of slot numbers from the slot-numbers argument. The router should be in the same state as if the card had been removed from the slot; all calls through that card will be terminated. The configured router then informs its connected DSCs that it is in split mode, and which slots it claims to own.
In split mode, a router shelf uses only half of the 1,792 available TDM timeslots. (See the "TDM Resource Allocation" section.) If a dial-shelf split slots command is entered when the calls using timeslots exceed the number that would be available to the router in split mode, the command is rejected. (This should occur only when a change to split mode is attempted where the dial shelf has more than 896 calls in progress, or more than half of the 1,792 available timeslots. Otherwise, a transition from normal mode to split mode can be made without disturbing the cards in the slots that remain owned, and calls going through those cards will stay up.)
Trunk cards and modem cards are tied together across a time-division multiplexing (TDM) bus on the dial-shelf backplane. Timeslots for the TDM bus are allocated by the router shelf on a call-by-call basis. This is implemented by initializing a queue at start-up with one element for each usable timeslot (currently 14*128 = 1,792 timeslots are used). Timeslots for a call are allocated from the front of the queue and replaced at the end of the queue when the call is completed. For split-dial-shelf operation, timeslots are added to the queue dynamically, as needed. When a TDM slot is required and the queue is empty, a chunk of TDM slots is allocated to the queue.
In normal mode, the router shelf connected to the DSC in slot 12 allocates timeslots starting from 0 going up, and the router shelf connected to the DSC in slot 13 allocates timeslots starting from 1,791 going down. For split-dial-shelf operation each router is assigned half of the usable set of timeslots. The router shelf connected to the DSC in slot 12 controls the first half of the timeslots (0 to 895). The router shelf connected to the DSC in slot 13 controls the second half of the timeslots (896 to 1791).
To transition from normal mode to split mode, complete the following steps:
Having the same version of Cisco IOS software running on both DSCs and both router shelves is not mandatory; however, it is a good idea. There is no automatic check to ensure that the versions are the same.
Step 2 Schedule a time when the Cisco AS5800 universal access server can be taken out of service without unnecessarily terminating calls in progress.
The entire procedure for transitioning from normal mode to split mode should require approximately one hour if the hardware is already installed.
Step 3 Busy out all feature boards and wait for your customers to log off.
Step 4 Reconfigure the existing router shelf to operate in split mode.
Enter the dial-shelf split slots {slot-numbers} command, specifying the slot numbers that are to be owned by the existing router shelf.
Step 5 Configure the new router shelf to operate in split mode on other feature boards.
Enter the dial-shelf split slots {slot-numbers} command, specifying the slot numbers that are to be owned by the new router shelf. Do not specify any of the slot numbers that you specified in Step 4. The range of valid slot numbers is 0 to 11.
Step 6 Install the second DSC, if it has not already been installed.
Step 7 Connect the dial-shelf interconnect cable from the second DSC to the new router shelf.
Step 8 Ensure that split mode is operating properly.
Enter the show dial-shelf command for each router. This command has been extended so that the response indicates that the router shelf is running in split mode, and which slots the router shelf owns. The status of any cards in any owned slots is shown, just as they are in the present show dial-shelf command.
Step 9 Enable all feature boards to accept calls again.
You can change the sets of slots owned by the two router shelves while they are in split mode. First remove slots from the set owned by one router, then add them to the slot set owned by the other router. The changed slot-set information is sent to the respective DSCs, and the DSCs determine which slots have been removed and which added. Moving a slot in this manner will disconnect all calls that were going through the card in that slot.
To move a slot from one router shelf's control to the others, first modify the router releasing the slot by entering the dial-shelf split slots remove command specifying the slot numbers to be released. The released slots can then be added to the slot set of the other router by entering the dial-shelf split slots command including the new slot numbers.
When a slot is removed, the router shelf that is losing the slot frees any resources and clears any state associated with the card in the slot it is relinquishing. The DSC reconfigures its hub to ignore traffic from that slot, and if there is a card in the slot it will be reset. This ensures that the card frees up any TDM resources it might be using, and allows it to restart under control of the router shelf that is subsequently configured to own the slot.
When a slot is added, if there are no configuration conflicts, and there is a card present in the added slot, a dial-shelf OIR insertion event is sent to the router shelf. The router shelf processes the event as a normal event. The card in the added slot is reset by the DSC to ensure a clean state, and the card downloads its image from the router shelf that now owns it. If the other router shelf (and the other DSC) claim ownership of the same slot, the command adding the slot should be rejected. However, should a configuration conflict exist, error messages are sent to both routers. The card is not reset until one of the other router shelves and its DSC stop claiming ownership of the slot. Normally this will not happen until you issue a dial-shelf split slots remove command surrendering the ownership claim on the slot by one of the routers.
Split mode is exited when the dial-shelf configuration is changed by a no dial-shelf split slots command. When the split dial-shelf line is removed, the router shelf will start using all of the TDM timeslots. Feature boards that were not owned in split mode and are not owned by the other router will be reset. Cards in slots that are owned by the other router will be reset, but only after the other DSC has been removed or is no longer claiming the slots. The split-dial-shelf configuration should not be removed while the second router shelf is still connected to the dial shelf.
When a router configured in split mode fails, all calls associated with the failed router are lost. Users cannot connect back in until the failed router recovers and is available to accept new incoming calls. However, the other split mode router shelf will continue to operate normally.
The system will behave as configured as soon as the configuration is changed. The exception is when there is a misconfiguration, such as when one router is configured in split mode and the other router is configured in normal mode, or when both routers are configured in split mode and both claim ownership of the same slots.
Problems can arise if one of the two routers connected to a dial shelf is not configured in split mode, or if both are configured in split mode and both claim ownership of the same slots. If the state of the second router is known when the dial-shelf split slots command is entered and the command would result in a conflict, the command is rejected.
If a conflict in slot ownership does arise, both routers receive warning messages until the conflict is resolved. Any card in a slot that is claimed by both routers remains under the control of the router that claimed it first, until you resolve the conflict by correcting the configuration of one or both routers.
Note that there can be slots that are not owned by either router (orphan slots). Cards in orphan slots cannot boot up until one of the two routers claims ownership of the slot, because neither DSC will download bootstrap images to cards in orphan slots.
In normal mode, all show commands look and behave as they do in the current system. In split mode, most show commands look and behave as they would in the current system if there were no cards in the slots for which the other router has configured ownership. This is consistent with the view of a split-dial-shelf configuration being basically two separate Cisco AS5800 universal access servers. A router shelf cannot manage or even recognize cards in slots that it does not own. For example, DSIP console and execute-on commands work only in owned slots.
There are, however, the following exceptions:
When in split mode, the show dial-shelf output is extended. For example:
Note that only the first two lines of output are new. The remaining information is exactly the same as what would currently be displayed if there were no cards in the slots that are not owned (1 and 7 to 12).
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Note Note that the show dial-shelf split command also shows the slots and corresponding feature boards for orphan slots (those slots not owned by either router shelf). This means that OIR events on all slots in the dial shelf are detected by both DSCs, and the feature boards are added to or deleted from the list of boards physically present in the dial shelf. When a feature board is inserted into an orphan slot, a message is sent to both router shelves indicating that a feature board was just inserted. This message differs from an OIR event message, OIR event processing is done only for owned slots. |
If you are installing split-dial-shelf systems, a system controller is available that provides a single system view of multiple POPs. The system controller for the Cisco AS5800 includes the Cisco 3640 router running Cisco IOS software. The system controller can be installed at a remote facility so that you can access multiple systems through a console port or Web interface.
There are no new Management Information Bases (MIBs) or MIB variables required for the split-dial-shelf configuration. A split dial shelf appears to Simple Network Management Protocol (SNMP) management applications as two separate Cisco AS5800s. You cannot use one console to manage the whole system—you must have a console session for each router shelf (two console sessions) to configure each split. The system controller must manage a split-dial-shelf configuration as two separate Cisco AS5800 universal access servers.
The normal mode configuration of the Cisco AS5800 requires the dial-shelf and router-shelf IDs to be different. In a split system, four unique shelf IDs are desirable; one for each router shelf and one for each of the slot sets. However, a split system will function satisfactorily if the router-shelf IDs are the same. If a system controller is used to manage a split-dial-shelf configuration, then the two routers must have distinct shelf IDs, just as they must when each router has its own dial shelf.
You can download software configurations to any Cisco AS5800 using SNMP or a Telnet connection. The system controller also provides performance monitoring and accounting data collection and logging.
In addition to the system controller, a network management system with a graphical user interface (GUI) runs on a UNIX SPARC station and includes a database management system, polling engine, trap management, and map integration.
To configure a router for split-dial-shelf operation, use the following commands in global configuration mode 5800(config)#
Normal mode: This command changes the router shelf to split mode with ownership of the slots listed.
In case of conflicting slot assignments, the command is rejected and a warning message is issued. Issue a show dial-shelf split slots command to the other router shelf to display its list of owned dial-shelf slots.
OIR events on all slots are detected by both DSCs and added to the list of feature boards physically present in the dial shelf. However, OIR event processing is done only for assigned slots.
Split mode: This command adds the dial-shelf slots listed to the router shelf's list of owned slots.
Normal mode: This command is invalid.
Split mode: This command displays the slots assigned to each of the router shelves and the corresponding feature boards in orphan slots (slots not currently assigned to either router).
Normal mode: This command puts the router shelf in split mode; however, it does not assign ownership of any dial-shelf slots.
To prevent accidentally entering the dial-shelf split slots command, at least one valid dial-shelf slot number (0-11) or the keyword none must be specified.
If the dial-shelf split slots command is entered in normal mode without valid slot numbers or the keyword none, the command is rejected.
Split mode: This command will change dial-shelf slot ownership. The router will no longer have ownership of any dial-shelf slots.
Normal mode: This command has no effect. If the router shelf is in normal mode, it stays that way.
Split mode: This command changes the router shelf to normal mode if it is in split mode, and the other router shelf has already relinquished control of all dial-shelf slots or is switched off.
Normal mode: This command changes the router shelf to split mode with ownership of the slots listed. Valid slot numbers are 0 through 11.
Split mode: This command adds the dial-shelf slots listed to the router shelf's list of owned dial-shelf slots. The effect of multiple commands is cumulative.
Normal mode: This command has no effect.
Split mode: This command removes the dial-shelf slots listed from the router shelf's list of owned dial-shelf slots. The effect of multiple commands is cumulative.
New error messages for various split-dial-shelf conditions include:
Duplicate priority clock source configured on other router shelf.
Explanation The configuration commands for the master clock specify the clock sources and a priority for each source. Together, these commands define a prioritized list of the clock sources used to generate the master clock. This list, configured on the router shelf, is passed to and stored by the DSC providing the active clock. In the event of failure of the highest priority clock source, the DSC switches to the source with the next highest priority.
With a split dial shelf, clock sources can be configured on either of the router shelves from the slots that each shelf owns. All valid clock source configurations are known to the DSC providing the clock, including the clock sources configured on the other router or DSC.
This error condition results when a clock source input on one router is configured to have the same priority as one configured on the other router. The original configuration command is not rejected; however, these error messages are issued to both routers. The two inputs, with identical priorities, both go into the ordered list of clock sources, but the one received first by the DSC providing the active clock is assigned a higher priority.
Action Reconfigure the clock sources on the two routers so that they have different priorities.
Other router shelf is in split mode when this one is not.
Explanation Split mode is intended to support two router shelves connected to a single dial shelf. To use this arrangement, both connected router shelves should be configured for split dial shelves. Problems can arise if two routers are connected to the dial shelf, but one router is not configured in split mode.
Action Issue a dial-shelf split slots command to this router or a no-dial-shelf split slots command to the other router.
Other router shelf is not in split mode when this one is.
Explanation Split mode is intended to support two router shelves connected to a single dial shelf. To use this arrangement, both connected router shelves should be configured for split dial shelves. Problems can arise if two routers are connected to the dial shelf, but one router is not configured in split mode.
Action Issue a dial-shelf split slots command to this router or a no-dial-shelf split slots command to the other router.
Other router shelf has overlapping slot ownership specified in its split dial shelf
configuration.
Explanation Each router shelf connects to one of the DSCs in the dial shelf. The dial-shelf feature boards are divided between the two router shelves. Each router controls its own set of feature boards as if those were the only boards present. There is no interaction between the routers or between feature boards owned by one router and feature boards owned by the other router.
This error message indicates that both routers are configured in split mode, but there is an overlap in the set of slots each router claims. While the conflict in slot ownership continues, both router shelves will periodically receive this error message.
Action Correct the configuration of one of the routers by issuing a dial-shelf split slots command with a list of slot numbers that does not include the slot that is reporting as having overlapping ownership. You must configure the division of the dial-shelf slots between the two router shelves so that each router controls an appropriate mix of trunk and modem cards. Any card in a slot that is claimed by both routers remains under the control of the router that claimed it first until you resolve the conflict by correcting the configuration.
Your Cisco 7206 router went through extensive testing before leaving the factory. However, if you encounter problems starting the routers, do the following:
If you are unable to solve the problem, contact a customer service representative for assistance and further instructions. Be prepared to provide the representative with the following information:
Figure 6-2 shows the general troubleshooting strategy for Cisco 7206 routers. Refer to this chart to isolate problems to a specific subsystem; then attempt to resolve the problem.
When an active router shelf in a Cisco AS5800 loses communication with the dial shelf, a backup router shelf can be automatically invoked to take over dial-shelf resources controlled by the lost router shelf. This backup method, called redundancy, is provided on the Cisco AS5800 to prevent a single point of failure, subsequent downtime, and user intervention to resolve unrecoverable hardware faults.
Router-shelf redundancy uses a second router shelf that automatically assumes resource responsibility (dial-shelf card and traffic control) of the primary, or active router, if it fails. This disruptive failover makes no attempt to retain established calls on the failed router. All calls are dropped when dial-shelf cards, controlled by the failing router, are automatically restarted by the secondary or backup router, which becomes the controlling router after restart.
Redundancy on a Cisco AS5800 is two router shelves connected, in parallel, to a single dial shelf (as in split-dial-shelf mode), except only one router is active, or engaged, at any given time. Each router shelf contains user specific configurations for normal mode operations, as opposed to split mode. The active router controls all the dial-shelf cards, while the secondary router functions purely as a standby backup. In the event the active router fails, all dial-shelf cards are restarted by the backup router that automatically assumes active router functionality.
External interfaces do not share the same IP address between redundant routers or duplicate IP address errors occur. One (active) router shelf maintains control of dial-shelf cards at a time. However unsuccessful, it does not interfere with the operation of the primary active router. If the active router shelf crashes, the link between it and it's DSC will go down, relinquishing control of all dial-shelf cards to the other DSC which is connected to the secondary or backup router shelf. This surviving router shelf restarts the cards and commences normal operations. If the router shelf that crashed recovers, or is restarted, it will not regain control of the cards, but becomes the backup, serving as the standby router shelf for the new active router, should it fail.
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Note A failover is triggered if the active DSC (i.e. the DSC connected to the active router) goes down and doesn't recover within ninety seconds. Any router-shelf failure that does not result in the DSC link going down would not cause a failover (for example, the active router's egress interface going down would not trigger failover). Conversely any temporary loss of the link between the active router and its DSC would cause a failover, even if the router shelf itself had not crashed and connectivity was quickly re-established (for example, if the BIC cable was knocked out and then quickly replaced). |
There is no load sharing between routers. Calls can not be routed through the active and backup routers simultaneously. Consequently, you cannot split the load between the routers to reduce granularity of failure, or the number of calls that are lost, when a router crashes. Conversely, failover conditions, that would otherwise occur, such as overwhelming traffic volume on the surviving router after failover, under load sharing, will not degrade service.
Hitless redundancy is not supported. When a router-shelf failover occurs, all calls associated with that router shelf are lost. Cisco AS5800 redundancy ensures that resources (particularly trunk lines) do not remain unusable while the controlling router is down.
Redundancy management via SNMP is not supported. However, an SNMP trap will be issued by the backup router when the router failover event occurs. The trap "ccrSwitchStatusChange" defined in the CISCO-C8500-REDUNDANCY-MIB as well as the SNMP variables "ccrCpuMode" and "ccrCpuStatus" are used for issuing a failover.
Enabling failover has no significant (greater than 1%) impact on system performance, both before and after failover has occurred. With a redundant router, of the same model as the active router, acting purely as a standby, the load capacity threshold is unchanged, thereby not affecting performance.
A single active router is conceptually simpler, and makes it easier to support failover when dealing with external servers, such as signalling controllers for RPMS server, SS7.
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Note RPMS server must be configured with the same information for both router shelves to ensure full functionality before and after a switchover. |
In an SS7 environment, call signalling comes via an external SC2200 rather than directly from the switch over the trunk line (as for CAS and ISDN). After a switchover has occurred, both routers must be connected to the SC2200. Use SS7's redundant link manager (RLM) to provide redundant links between a single router and the signalling controller. Configure RLM links from both the active and standby routers so a change of routers will look like a change from one redundant link to another.
Router-shelf failover is a simple configuration command on the two router shelves in split-dial-shelf configuration mode. The command is issued in "redundancy" configuration submode:
This command must be configured on both routers. The parameter group-code is used by the system controller and must be the same for both routers forming the redundant pair. It identifies both routers as the same set of dial-shelf resources.
For successful failover to occur, both router-shelf configurations need to be synchronized. Configure each router separately, as active and backup, respectively, with the same configuration, except for the IP address on egress interfaces.
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Note Test the backup router's configuration for errors discovery before production environment deployment. |
The show redundancy command indicates when failover is enabled. The show redundancy history command logs failover events (where the router has changed from ACTIVE to BACKUP or vice-versa).
Posted: Fri Oct 17 13:42:56 PDT 2003
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