This chapter describes how to configure and monitor the Next Hop Resolution Protocol (NHRP). For a description of this protocol, refer to "Next Hop Resolution Protocol (NHRP) Overview".
This chapter contains the following sections:
To access the NHRP configuration:
This section explains all of the NHRP configuration commands as shown in Table 64. Enter the commands at the NHRP config>
prompt.
Table 64. NHRP Configuration Command Summary
Command | Function |
---|---|
? (Help) | Displays all the commands available for this command level or lists the options for specific commands (if available). See "Getting Help". |
Enable NHRP | Turns on NHRP for all interfaces that are not explicitly defined. |
Disable NHRP | Turns off NHRP for all interfaces that are not explicitly defined. |
List | Displays the NHRP configuration. |
Advanced config | Gets you to the NHRP Advanced config> prompt, from which you can enter other commands as described in NHRP Advanced Configuration Commands. |
Exit | Returns you to the previous command level. See "Exiting a Lower Level Environment". |
Use the enable command to enable NHRP on all interfaces not explicitly defined using an NHRP advanced config command. It is a simple way to get NHRP up and running with default parameters.
Syntax:
Use the disable command to disable NHRP on all interfaces not explicitly defined using an NHRP advanced config command.
Syntax:
Example:
NHRP config> disable Disable NHRP for the router [No]:
Use the advanced command to get to the NHRP advanced configuration prompt, NHRP Advanced config>. From this prompt, you can enter the commands described in "NHRP Advanced Configuration Commands".
Syntax:
Example:
NHRP config> advanced NHRP Advanced config>
Note: | Most installations will not need to use this "advanced" command. The enable NHRP command is sufficient to enable NHRP with recommended default options. |
Use the list command to list the NHRP configuration.
Syntax:
Example:
NHRP config> list Box level NHRP enabled Explicit interface definitions override box level setting Interfaces explicitly defined for NHRP -------------------------------------- Interface 0: ATM NHRP enabled NHRP LANE Shortcut Interface: -------------------------------------------------- Interface: 1 ESI: burned-in Sel: auto Use Best Effort: no (Data) Cell Rate(kbps): Peak: 155000 Sustained: 155000 ATM adapter's burned-in MAC address is used as source address General Parameters ------------------ Holding time: 20 minutes Protocol Access Controls: Use source and destination address When should NHC attempt shortcuts?: Based on datarate Data-rate threshold: 10 packets/second NHS allows shortcuts to ATMARP clients?: Yes Cache Sizes ----------- Resolution cache: 10000 entries Server purge cache: 10000 entries Server registrations cache: 10000 entries Extension Usage --------------- Use NHRP Forward transit NHS record client extension: No Use NHRP Reverse transit NHS record client extension: No Use Responder Address client extension: No Use LANE shortcuts extension: Yes List of NHRP IP exclude records ------------------------------- # Address Mask 1 6.6.6.6 255.255.255.255 2 5.5.5.0 255.255.255.0 Disallowed router-to-router shortcuts for IP -------------------------------------------- None
This section explains all of the NHRP advanced configuration commands as
shown in Table 65. Enter the commands from the NHRP Advanced
config> prompt.
Table 65. NHRP Advanced Configuration Command Summary
Command | Function |
---|---|
? (Help) | Displays all the commands available for this command level or lists the options for specific commands (if available). See "Getting Help". |
Add | Adds an NHRP interface, exclude list, or disallowed R2R shortcuts. |
Change | Changes an NHRP interface, or changes a LANE shortcut interface definition. |
Delete | Deletes an NHRP interface, exclude list, or disallowed R2R shortcuts. |
List | Displays the NHRP configuration. |
Set | Sets NHRP parameters. |
Exit | Returns you to the previous command level. See "Exiting a Lower Level Environment". |
Use the add command to add an explicit interface definition, an exclude list entry, or disallowed router-to-router shortcuts.
Syntax:
Note: | Any explicit interface definitions override the "NHRP enabled/disabled" box-level setting. |
Interface Number [0]? Enable NHRP [Yes]:
Valid values: IP address and mask.
Default: Empty.
IP Address [0.0.0.0]? 6.6.6.5 Address Mask [255.255.255.255]? Deny Shortcuts[Yes]? Record added to Disallowed Router-to-Router Shortcuts Record added to Exclude List
See "Disallowed Router-to-Router Shortcuts" for more information.
IP ADDRESS [0.0.0.0]? 8.8.8.1 Address Mask [255.255.255.255]?
Valid values: IP address and mask.
Default: Empty.
Use the delete command to delete an interface definition for NHRP, an exclude list entry, or disallowed router-to-router shortcuts.
Syntax:
Interface Number [0]?
You must specify an index which must be deleted. Use the list exclude command to determine the right index.
Enter index of access control to be deleted [1]? # Address Mask 1 6.6.6.6 255.255.255.255 Are you sure this the record you want to delete [Yes]? Record deleted from Exclude List Delete from Disallowed Router-to-Router Shortcuts [Yes]? Record deleted from Disallowed Router-to-Router Shortcuts
Disallowed shortcuts index [1]?
Use the change command to modify NHRP interface definitions.
Syntax:
Interface Number [0]? Enable NHRP [Yes]:
Interface Number of NHRP LANE Shortcut Interface [0]? ( 1) Use burned in ESI Select ESI [1]? Use internally assigned selector? [Yes]: Use Best Effort Service for Data VCCs? [Yes]: Peak Cell Rate of outbound Data VCCs (Kbps) [0]? Sustained Cell Rate of outbound Data VCCs (Kbps) [0]? Use ATM adapter's burned-in MAC address for source?
See "ATM and LAN Emulation" in Software User's Guide for further information.
Note: | It is recommended that you use the default values until you have determined the specific processing options required by your environment. |
Use the list command to display the NHRP configuration information.
Syntax:
Output is the same as for the list command. See "List".
List of NHRP IP exclude records ------------------------------- # Address Mask 1 7.7.7.7 255.255.255.255
Disallowed router-to-router shortcuts for IP -------------------------------------------- 1 8.8.8.1 255.255.255.255 2 6.6.6.1 255.255.255.255
Interfaces explicitly defined for NHRP -------------------------------------- None NHRP LANE Shortcut Interface: -------------------------------------------------- Interface: 3 ESI: burned-in Sel: auto Use Best Effort: yes (Data) Cell Rate(kbps): Peak: 0/ 0 Sustained: 1000/538764944 MAC address supplied by NHS is used as source address
Cache Sizes ----- ----- Resolution cache: 10000 entries Server purge cache: 10000 entries Server registrations cache: 10000 entries
Use the set command for the following:
Syntax:
Use (Destination, Source & Destination, None) [None]?
Valid Values: None, Source and Destination, Destination
Default Value: None
Valid values: Y, N, Data-rate.
Note: | This setting can prevent the creation of VCCs for "one-time" traffic, such as SNMP traps that are sent to an SNMP manager. |
Try shortcut VCs? (Yes, No, Data-rate) [Data-rate]?
The holding time parameter is used for these functions:
Valid values: 1 - 60 minutes.
Holding time (in minutes) [20]?
The datarate threshold is used when the attempt shortcuts parameter is set to Data-rate.
When traffic is destined for a particular station, but the rate is less than this threshold, then the router does not attempt to establish shortcuts. (In other words, it does not generate Next Hop Resolution Requests and send them to the next hop along the routed path.) Once the traffic rate exceeds the threshold, the router tries to establish a shortcut. If it can successfully create a shortcut path, the path is used even if the traffic drops below the threshold. The path continues to be used until the traffic stops for a period of time. This is done to avoid going back and forth from the routed path to the shortcut path if traffic is sporadic.
Valid values: Minimum 1 packet/second. Maximum is 5120 packets/second.
Default: 10 packets/second.
Data-rate threshold in packets/second [10]?
Valid Values: yes or no
Use LANE shortcuts extension [Yes]?
Cache sizes can be selected for any of the following:
When the cache size is exceeded, no new attempts are made to resolve protocol addresses to NBMA addresses (in other words, no new Next Hop Resolution Requests are sent) until existing entries are purged, either because the holding time has expired or a specific purge request has been received from the originator of the information. Also, when cache size is exceeded, Registration Requests from new clients are rejected.
Valid values: 256 - 65535 entries.
Number of cache entries [10000]?
Valid values: 256 - 16384 entries.
Number of cache entries [10000]?
The destination address may represent the server itself, devices on subnetworks to which the server is attached, NHRP clients that have registered with the server, or routers for which a R2R shortcut has been advertised. The router uses the information in these cache entries to notify clients to purge address information that becomes invalid before the holding time expires.
When the server purge cache size is exceeded, the server rejects Authoritative Next Hop Resolution Requests.
Valid values: 256 - 65535 entries.
Default: 10000 entries.
Number of cache entries [10000]?
This parameter can be used to allow or disallow the server from giving out shortcuts to native ATMARP clients that do not support NHRP. This may be required if these clients are not capable of supporting large number of VCs. Use the "Exclude List" option if shortcuts need to be disallowed selectively to certain clients or subnets.
Allow shortcuts to Classical IP clients? [Yes]:
To access the NHRP monitoring prompt:
This section explains all of the NHRP monitoring commands as shown in Table 66. Enter the commands from the NHRP>
prompt.
Table 66. NHRP Monitoring Command Summary
Command | Function |
---|---|
? (Help) | Displays all the commands available for this command level or lists the options for specific commands (if available). See "Getting Help". |
Box Status | Displays NHRP enable/disable status. |
Interface Status | Displays NHRP interface status. |
Statistics | Displays NHRP interface statistics. |
Cache | Displays NHRP resolution cache entries. |
Server_purge_cache | Displays NHRP server_purge_cache entries. |
MIB | Displays MIB information. |
LANE Shortcuts | Displays LANE shortcut entries. |
CONFIG Parameters | Displays, changes or resets NHRP configuration information. |
Reset | Dynamically reconfigure NHRP interfaces or protocol. |
Exit | Returns you to the previous command level. See "Exiting a Lower Level Environment". |
Use the box status command to display NHRP status as configured for the box (for example, all interfaces not explicitly defined).
Syntax:
Example:
box status Box level NHRP is ON by config
Use the interface status command to display NHRP status on interfaces.
Syntax:
Example:
interface status Interface 0: UP (NHRP enabled) Interface 1: UP (NHRP disabled) Interface 2: DOWN Interface 3: UP (NHRP LANE Shortcut Interface)
Use the statistics command to display NHRP statistics for all interfaces or for a specific interface.
Syntax:
Output is the same as that for the statistics interface command as shown in the following example.
Interface number [0]? 0 Statistics for Interface 0 -------------------------- Field Description Value ----------------- ----- Inbound Requests 5 Outbound Requests 3 Inbound Replies 3 Outbound Replies 5 Inbound Registers 0 Outbound Registers 0 Inbound Error Packets 0 Inbound Error Indication Packets 0 Outbound Error Indication Packets 0 Reply Forwards 0 Unrecognized Options 0 Registration Overflows 0 ProtocolErrors 0 Negative Outbound Replies 0 Inbound Packets on NHRP disabled interface 0 'Send_to_me' Outbound Replies 0 Inbound Purges 0 Outbound Purges 2
Use the cache command to display all NHRP resolution cache entries or a specific cache entry identified by a destination address.
Syntax:
Examples:
cache list Total Client Cache Entries = 3 NHRP Client Cache Entries ========================= Dest Address NextHop Address State Htime MTU Net ------------ --------------- ----- ----- --- --- 5.5.5.1 5.5.5.1 Act 1121 4490 1 5.5.5.2 5.5.5.2 Inact 1185 4490 1 6.6.6.1 6.6.6.1 Act 602 9180 0
cache entry Enter destination address [0.0.0.0]? 6.6.6.1 Destination: 6.6.6.1 NextHop: 6.6.6.1 ATM Address: 39840F0000000000000000000410005A00DEADCA State: Act Net: 0 HoldingTime: 433 seconds MTU size: 9180 Flags: 0x00420000
Use the server_purge_cache command to list all NHRP server purge cache entries.
Syntax:
Use the MIB command to display NHRP MIB related information.
Syntax:
MIB Server Table List ===================== Index Server Address State ATM Addr ----- -------------- ----- -------- 0 6.6.6.2 UP 39840F0000000000000000000210005A00DEADC8
Index [0]? 0 Index : 0 Protocol : 1x0800 Protocol Address: 6.6.6.2 ATM Address type: 0x0 (NSAP) ATM Address : 39840F000.... SubnetworkId : 0 Authentication : 1 Current Clients : 0 Max Clients : 512 State : 1 Net : 1
Use the lane shortcuts command to display all or specific entries using LANE shortcuts. You can also display any ATM addresses for which LANE shortcuts are disallowed due to operational problems.
Syntax:
LANE Shortcut Interface #: 1, ATM Network Interface #: 0 =========================================================== Next Hop Prot @ Dest Mac @ VPI/VCI ---------------- ----------------- -------- 5.5.5.1 04-AA-AA-AA-AA-01 0/34 Current MTU being used: 4490
LANE Shortcut Interface number [0]? 1 Enter IP address of next hop [0.0.0.0]? 5.5.5.1 Next Hop Addr: 5.5.5.1 Dest Mac Addr: 04-AA-AA-AA-AA-01 ATM Address: 39840F0000000000000000000310005A00DEAD02 Media type: Token Ring VPI/VCI: 0/34 Holding Time: 20 minutes MTU size: 4490 RI Field:064001020203
Any ATM address listed in this display means that the NHRP LANE Shortcut Interface received data from that ATM address. This is not allowed since all NHRP LANE Shortcut Interface VCCs will be used only to transmit data to a LEC at the other end. If the LEC attempts to send data over a VCC set up by an NHRP LANE Shortcut Interface, then the VCC will be brought down and no further LANE shortcuts will be set up to that LEC.
Once the condition which caused the NHRP LANE Shortcut Interface to receive data has been corrected, then the device must be restarted in order to allow that ATM address to be again used for NHRP LANE shortcuts.
LAN Shortcut Interface #: 2, ATM Network Interface #: 0 ======================================================= Atm Address -------------------------------------------- 39840F0000000000000000000310005A00DEAD02
Use the config parameters command to access the command
menus for display, change, or reset NHRP
configuration parameters.
Table 67. NHRP Config Parameter Summary
Command | Function |
---|---|
? (Help) | Displays all the commands available for this command level or lists the options for specific commands (if available). See "Getting Help". |
Display | Displays the current NHRP and Route-switching configuration parameters. |
Change | Allows NHRP configuration parameters to be dynamically changed without affecting the static configuration. |
Reset | Reads the configuration parameter from the static configuration and uses it during the router's runtime. |
Use the display command to display the current NHRP and Route-Switching configuration parameters.
Syntax:
Use the change command to change the current NHRP configuration parameters. See "Set" for a description of these configuration parameters.
Syntax:
Use the reset command to reset the dynamic configuration parameter value to the value in the static configuration. See "Set" for a description of these configuration parameters.
Syntax:
Use the reset command to dynamically reconfigure NHRP protocol or an interface. A reset causes the applicable static configuration values to be used.
Syntax:
NHRP packet traces can be activated from the Event Logging System (ELS) which is an integral part of the router operating system. See "Using and Configuring the Event Logging System" and "Monitoring the Event Logging System" in Software User's Guide
The NHRP packet tracing mechanism supports the "set trace decode on" option. This option enables the NHRP packet trace output to be interpreted for viewing. The control frames over the LSI can also be traced apart from the NHRP protocol packets. For details on using the trace facility see the description of the trace command in "Monitoring the Event Logging System" in Software User's Guide
The NHRP protocol packets are identified by event 19 and the LSI control packets are identified by event 113.
Sample trace output #1:
Dir:OUTGOING Time:0.0.48.88 Trap:6035 Comp:NHRP Type:UNKNOWN Port:1 Circuit:0x000000 Size:160 ----------------------------------------------------------------- ** NHRP/MPOA Frame ** AddressFamily:ATM_NSAP ProtocolType:IPv4 HopCount:64 PacketSize:160 Checksum:0x03F4 ExtensionOffset:0x0038 Version:1 PktType:ResolutionRequest SrcAddrTL:20 SrcSubAddrTL:0 SrcProtoLen:4 DstProtoLen:4 Flags:requester is a router Flags:want authoritative only Flags:want unique only ReqID:1 Src NBMA:39840F0000000000000000000610005A019600C9 Src Protocol Addr: 6.6.6.1 Dest Protocol Addr: 3.3.3.2 0038: 00 08 00 1C 08 00 5A 00 00 01 00 0A 00 00 00 00 | ......Z......... | 0048: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | ................ | 0058: 00 08 00 34 08 00 5A 00 00 01 00 0C 00 00 00 00 | ...4..Z......... | 0068: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | ................ | 0078: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 | ................ | 0088: 00 00 00 00 00 00 00 00 00 08 00 08 08 00 5A 00 | ..............Z. | 0098: 00 01 00 06 80 00 00 00 | ................ |
Sample trace output #2:
Dir:INCOMING Time:0.0.50.69 Trap:6035 Comp:NHRP Type:UNKNOWN Port:1 Circuit:0x000000 Size:202 ----------------------------------------------------------------- ** NHRP/MPOA Frame ** AddressFamily:ATM_NSAP ProtocolType:IPv4 HopCount:63 PacketSize:202 Checksum:0xEC88 ExtensionOffset:0x005C Version:1 PktType:ResolutionReply SrcAddrTL:20 SrcSubAddrTL:0 SrcProtoLen:4 DstProtoLen:4 Flags:requester is a router Flags:authoritative info Flags:requested info unique ReqID:1 Src NBMA:39840F0000000000000000000610005A019600C9 Src Protocol Addr: 6.6.6.1 Dest Protocol Addr: 3.3.3.2 1483 VCC Shortcut Information (CIE) follows: CIE Code:0 Prefix:32 MTU:4376 Htime:180 Preference:254 CIE NBMA:39840F0000000000000000000310005A01950103 CIE Protocol Addr: 3.3.3.1 005C: 00 08 00 1C 08 00 5A 00 00 01 00 0B 00 00 00 01 | ......Z......... | 006C: 97 00 01 04 03 03 03 02 11 18 90 00 5A 01 94 00 | ............Z... | 007C: 00 08 00 34 08 00 5A 00 00 01 00 0D 00 B4 14 00 | ...4..Z......... | 008C: 39 84 0F 00 00 00 00 00 00 00 00 00 03 10 00 5A | 9..............Z | 009C: 01 95 01 03 00 00 00 00 00 00 00 00 00 00 00 00 | ................ | 00AC: 00 00 00 00 00 00 00 00 00 08 00 0E 08 00 5A 00 | ..............Z. | 00BC: 00 01 00 07 06 A0 00 80 00 20 80 00 00 00 | ................ |