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The IPX SAP-after-RIP feature links Service Advertising Protocol (SAP) updates to Routing Information Protocol (RIP) updates so that SAP broadcast and unicast updates automatically occur immediately after the completion of the corresponding RIP update. It ensures that no service information will be rejected by a remote router because it lacks a valid route to the service. As a result of this feature, periodic SAP updates are sent at the same interval as RIP updates.
The default behavior of the router is to send RIP and SAP periodic updates with each using its own update interval, depending on the configuration. In addition, RIP and SAP periodic updates are jittered slightly, such that they tend to diverge from each other over time. This feature synchronizes SAP and RIP updates.
In addition, it is now possible to disable the sending of general RIP and/or SAP queries on a link when it first comes up.
Sending all SAP and RIP information in a single update reduces bandwidth demands and eliminates erroneous rejections of SAP broadcasts.
Linking SAP and RIP updates populates the service table at the remote router more quickly, because services will not be rejected due to the lack of a route to the service. This can be especially useful on WAN circuits where the update intervals have been greatly increased to reduce the overall level of periodic update traffic on the link.
RIP and SAP general queries are normally sent by remote routers when a circuit first comes up. On WAN circuits, two full updates of each kind are often sent across the link. The first update is a full broadcast update, triggered locally by the link-up event. The second update is a specific (unicast) reply triggered by the general query received from the remote router. By disabling the sending of general queries when the link first comes up, it is possible to reduce traffic to a single update, and save bandwidth.
This feature is supported on these platforms:
This section describes the following configuration tasks associated with the IPX SAP-after-RIP feature:
To configure the router to send a SAP update following a RIP broadcast, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
| Configure the router to send a SAP broadcast immediately following a RIP broadcast. | ipx update sap-after-rip |
To disable the sending of a general RIP and/or SAP query when an interface comes up, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
| Disable the sending of a general RIP and/or SAP Query when an interface comes up. | no ipx linkup-request {rip | sap} |
To re-enable the sending of a general RIP and/or SAP query, use the positive form of the command.
Prior to Release 11.2(4)F, RIP and SAP updates were set using two different commands. The ipx update-time and ipx sap-interval commands are replaced by one command, ipx update interval.
To adjust the SAP or RIP update intervals, perform the following task in interface configuration mode:
| Task | Command |
|---|---|
| Adjust the interval at which RIP or SAP updates are sent. | ipx update interval {rip | sap} {value | changes-only} |
This section provides sample configurations for configuring the IPX SAP-after-RIP feature.
The following example configures the router to issue a SAP broadcast immediately following a RIP broadcast on serial interface 0.
interface serial 0 ipx update sap-after-rip
The following example configures the router to disable the general query for both RIP and SAP on serial interface 0.
interface serial 0 no ipx linkup-request rip no ipx linkup-request sap
The following example configures the update timers for RIP updates on two interfaces in a router:
interface serial 0 ipx update interval rip 40 interface ethernet 0 ipx update interval rip 20
The following example configures SAP updates to be sent (and expected) on serial interface 0 every 300 seconds (5 minutes) to reduce periodic update overhead on a slow-speed link:
interface serial 0 ipx update interval sap 300
This section documents new commands. All other commands used with this feature are documented in the Cisco IOS Release 11.2 command references. The following commands have been added as a result of feature enhancements:
To enable the sending of a general RIP and/or SAP query when an interface comes up, use the ipx linkup-request interface configuration command. To disable the sending of a general RIP and/or SAP query when an interface comes up, use the no form of this command.
ipx linkup-request {rip | sap}| rip | Enables the sending of a general RIP query when an interface comes up. |
| sap | Enables the sending of a general SAP query when an interface comes up. |
General RIP and SAP queries are sent.
Interface configuration
This command first appeared in Cisco IOS Release 11.2 F.
Under normal operation, when using serial or other point-to-point links, the router sends RIP and SAP information twice when an interface comes up. The RIP and SAP information is sent as soon as the link is up and is sent again when the router receives a general RIP query from the other end of the connection. By disabling the ipx linkup-request command, the router sends the RIP and SAP information once, instead of twice.
The following example configures the router to disable the general query for both RIP and SAP on serial interface 0.
interface serial 0 no ipx linkup-request rip no ipx linkup-request sap
ipx update interval
ipx update sap-after-rip
To adjust the RIP or SAP update interval, use the ipx update interval interface configuration command. To restore the default values, use the no form of this command.
ipx update interval {rip | sap} {value | changes-only}| rip | Adjusts the interval at which RIP updates are sent. The minimum interval is 10 seconds. |
| sap | Adjusts the interval at which SAP updates are sent. The minimum interval is 10 seconds. |
| value | The interval specified in seconds. |
| changes-only | Specifies the sending of a SAP update only when the link comes up, when the link is downed administratively, or when service information changes. This parameter is supported for SAP updates only. |
The default interval is 60 seconds for both IPX routing updates and SAP updates.
Interface configuration
This command first appeared in Cisco IOS Release 11.2 F.
This command replaces two commands found in previous releases of the Cisco IOS software: ipx sap-interval and ipx update-time.
Routers exchange information about routes by sending broadcast messages when they are started up and shut down, and periodically while they are running. The ipx update interval command enables you to modify the periodic update interval. By default, this interval is 60 seconds (this default is defined by Novell).
You should set RIP timers only in a configuration in which all routers are Cisco routers or in which all other IPX routers allow configurable timers. The timers should be the same for all devices connected to the same cable segment.
The update value you choose affects the internal IPX timers as follows:
Setting the interval at which SAP updates are sent is most useful on limited-bandwidth links, such as slower-speed serial interfaces.
You should ensure that all IPX servers and routers on a given network have the same SAP interval. Otherwise, they may decide that a server is down when it is really up.
It is not possible to change the interval at which SAP updates are sent on most PC-based servers. This means that you should never change the interval for an Ethernet or Token Ring network that has servers on it.
You can set the router to send an update only when changes have occurred. Using the changes-only keyword specifies the sending of a SAP update only when the link comes up, when the link is downed administratively, or when the databases change. The changes-only keyword causes the router to do the following:
The following example configures the update timers for RIP updates on two interfaces in a router:
interface serial 0 ipx update interval rip 40 interface ethernet 0 ipx update interval rip 20
The following example configures SAP updates to be sent (and expected) on serial interface 0 every 300 seconds (5 minutes) to reduce periodic update overhead on a slow-speed link:
interface serial 0 ipx update interval sap 300
ipx linkup-request
ipx output-sap-delay
ipx update sap-after-rip
show ipx interface
To configure the router to send a SAP update immediately following a RIP broadcast, use the
ipx update sap-after-rip interface configuration command. To restore the default value, use the no form of this command.
This command has no arguments or keywords.
RIP and SAP updates are sent every 60 seconds.
Interface configuration
This command first appeared in Cisco IOS Release 11.2 F.
The ipx update sap-after-rip command causes the router to issue a SAP update immediately following a RIP broadcast. This ensures that the SAP update follows the RIP broadcast, and that the SAP update is sent using the RIP update interval. It also ensures that the receiving router has learned the route to the service interface via RIP prior to getting the SAP broadcast.
The following example configures the router to issue a SAP broadcast immediately following a RIP broadcast on serial interface 0.
interface serial 0 ipx update sap-after-rip
ipx linkup-request
ipx update interval
For more information on RIP timers and SAP broadcasts, see the Cisco IOS Release 11.2 Network Protocols Configuration Guide, Part 2.
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