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Digital Equipment Corporation (Digital) developed the DECnet protocol to provide a way for its computers to communicate with one another. DECnet is currently in its fifth major product release called Phase V. DECnet Phase V is a superset of the OSI protocol suite, supports all OSI protocols, and is compatible with the previous release, Phase IV.
Use the commands in this chapter to configure and monitor DECnet networks. For DECnet protocol configuration information and examples, refer to the "Configuring DECnet" chapter of the Router Products Configuration Guide.
To create a standard access list, use the access-list global configuration command. Use the no form of this command to delete the entire access list.
access-list access-list-number {permit | deny} source source-mask| access-list-number | Integer you choose between 300 and 399 that uniquely identifies the access list. |
| permit | Permits access when there is an address match. |
| deny | Denies access when there is an address match. |
| source | Source address. DECnet addresses are written in the form area.node. For example, 50.4 is node 4 in area 50. All addresses are in decimal. |
| source-mask | Mask to be applied to the address of the source node. Bits are set wherever the corresponding bits in the address should be ignored. All masks are in decimal. |
None
Global configuration
In contrast with IP masks, a DECnet mask specification of "all ones" is entered as the decimal value 1023. In IP, the equivalent is 255.
The following example sets up access list 300 to deny packets coming from node 4.51 and permit packets coming from 2.31:
!
access-list 300 deny 4.51 0.0
access-list 300 permit 2.31 0.0
!
access-list (extended)
access-list (filter connect initiate packets)
decnet access-group
decnet in-routing-filter
decnet out-routing-filter
show decnet interface
To create an extended access list, use the access-list global configuration command. Use the no form of this command to delete the entire access list.
access-list access-list-number {permit | deny} source source-mask [destination]| access-list-number | Integer you choose between 300 and 399 that uniquely identifies the access list. |
| permit | Permits access when there is an address match. |
| deny | Denies access when there is an address match. |
| source | Source address. DECnet addresses are written in the form area.node. For example, 50.4 is node 4 in area 50. All addresses are in decimal. |
| source-mask | Mask to be applied to the address of the source node. All masks are in decimal. |
| destination | (Optional.) Destination node's DECnet address in decimal format. DECnet addresses are written in the form area.node. For example, 50.4 is node 4 in area 50. |
| destination-mask | (Optional.) Destination mask. DECnet addresses are written in the form area.node. For example, 50.4 is node 4 in area 50. All masks are in decimal. |
None
Global configuration
In the following example, access list 301 is configured to allow traffic from any host in networks 1 and 3. It implies no other traffic will be permitted. (The end of a list contains an implicit "deny all else" statement.)
!
access-list 301 permit 1.0 0.1023 0.0 63.1023
access-list 301 permit 3.0 0.1023 0.0 63.1023
!
access-list (standard)
access-list (filter connect initiate packets)
decnet access-group
decnet in-routing-filter
decnet out-routing-filter
show decnet interface
To create an access list that filters connect initiate packets, use the access-list global configuration command. Use the no form of this command to disable the access list.
access-list access-list-number {permit | deny} source source-maskThe optional argument source-object consists of the following string:
src [{eq | neq | gt | lt} object-number] [exp regular expression] [uic [group, user]]The optional argument destination-object consists of the following string:
dst [{eq | neq | gt | lt} object-number] [exp regular expression] [uic [group, user]]The optional argument identification consists of the following string:
[id regular expression] [password regular expression] [account regular expression]| access-list-number | Integer you choose between 300 and 399 that uniquely identifies the access list. |
| permit | Permits access when there is an address match. |
| deny | Denies access when there is an address match. |
| source | Source address. DECnet addresses are written in the form area.node. For example, 50.4 is node 4 in area 50. All addresses are in decimal. |
| source-mask | Mask to be applied to the address of the source node. All masks are in decimal. |
| destination | (Optional.) Destination node's DECnet address in decimal format. DECnet addresses are written in the form area.node. For example, 50.4 is node 4 in area 50. All addresses are in decimal. |
| destination-mask | (Optional.) Destination mask. DECnet addresses are written in the form area.node. For example, 50.4 is node 4 in area 50. All masks are in decimal. |
| eq | neq | Use either of these keywords:
neq--item matches the packet if any of the specified parts do not match the corresponding entry in the packet. |
| source-object | (Optional.) Contains the mandatory keyword src and one of the following optional keywords:
exp--stands for expression; followed by a regular expression that matches a string.
uic--stands for user identification code; followed by a numeric user ID (UID) expression.The argument [group, user] is a numeric UID expression. In this case, the bracket symbols are literal; they must be entered. The group and user parts can either be specified in decimal, in octal by prefixing the number with a 0, or in hex by prefixing the number with 0x. The uic expression is displayed in show displays as an octal number. |
| destination-object | (Optional.) Contains the mandatory keyword dst and one of the following optional keywords:
eq | neq | lt | gt--equal to, not equal to, less than, or greater than. These keywords must be followed by the argument object-number, a numeric DECnet object number.
exp--stands for expression; followed by a regular expression that matches a string.
uic--stands for user identification code; followed by a numeric user ID (UID) expression. In this case, the bracket symbols are literal; they must be entered. The group and user parts can either be specified in decimal, in octal by prefixing the number with a 0, or in hex by prefixing the number with 0x. The uic expression is displayed in show displays as an octal number. |
| identification | (Optional.) Uses any of the following three keywords:
id--regular expression; refers to user ID.
password--regular expression; the password to the account.
account--regular expression; the account string. |
| any | Item matches if any of the specified parts do match the corresponding entries for source-object, destination-object, or identification. |
See Appendix C for a description of regular expressions.
None
Global configuration
Depending upon the arguments you use, you can define access lists in three ways:
Table 1-1 lists the DECnet object numbers.
| Name | Number | Description |
|---|---|---|
| FAL | 17 | File Access Listener |
| HLD | 18 | Host Loader |
| NML | 19 | Network Monitor Link/NICE |
| MIRROR | 25 | Loopback mirror |
| EVL | 26 | Event logger |
| 27 | ||
| PHONE | 29 | Phone |
| NOTES | 33 | VAX Notes |
| CTERM | 42 | Terminal sessions |
| DTR | 63 | DECnet Test Sender/Receiver |
The following example illustrates an access list for matching all connect packets for object number 27:
access-list 300 permit 0.0 63.1023 eq dst eq 27
The following example illustrates an access list for matching all connect packets except for the object number 17:
access-list 300 permit 0.0 63.1023 neq dst eq 17
The following example illustrates an access list for matching all connect packets where the access identification was SYSTEM:
access-list 300 permit 0.0 63.1023 eq id ^SYSTEM$
The following example illustrates an access list for matching all connect packets from area 1 to object number 27 (27 = VAX/VMS Personal Utility or MAIL) where SYSTEM is the originating user:
access-list 300 permit 1.0 0.1023 eq src exp ^SYSTEM$ dst eq 27
The following example illustrates an access list for matching any connect packet and can be used at the end of a list to permit any packets not already matched:
access-list 300 permit 0.0 63.1023 eq any
access-list (standard)
access-list (extended)
decnet access-group
decnet in-routing-filter
decnet out-routing-filter
show decnet interface
To clear DECnet counters that are shown in the output of the show decnet traffic EXEC command, use the clear decnet counters EXEC command.
clear decnet countersThis command has no arguments or keywords.
None
EXEC
The following example provides sample output of the clear decnet counters EXEC command:
Router# clear decnet counters
Router# show decnet traffic
Total: 3 received, 0 format errors, 0 unimplemented
0 not a gateway, 0 no memory, 0 no routing vector
0 congestion encountered
Hellos: 3 received, 0 bad, 0 other area, 4 sent
Level 1 routing: 0 received, 0 bad, 0 other area, 4 sent
Level 2 routing: 0 received, 0 not primary router, 2 sent
Data: 0 received, 0 not long format, 0 too many visits
0 forwarded, 0 returned, 0 converted, 0 local destination
0 access control failed, 0 no route, 0 encapsulation failed
0 inactive network, 0 incomplete map
Router#
show decnet traffic
To create a DECnet access group, use the decnet access-group interface configuration command.
decnet access-group access-list-number| access-list -number | Either a standard or extended DECnet access list. A standard DECnet access list applies to destination addresses. The value (or values in the case of extended lists) can be in the range 300 through 399. |
None
Interface configuration
The following example applies access list 389 to interface Ethernet 1:
!
interface ethernet 1
decnet access-group 389
!
access-list
show decnet interface
To configure border routers to propagate Phase IV areas through an OSI backbone, use the decnet advertise global configuration command. To disable this feature, use the no decnet advertise command.
decnet advertise decnet-area hops cost| decnet-area | Phase IV area that you want propagated. |
| hops | Hop count to be associated with the route being advertised. Default is 0. |
| cost | Cost to be associated with the route being advertised. Default is 0. |
Disabled
Global configuration
The output from the show decnet route EXEC command shows the cost and hop count for routes.
The following example shows a partial use of the decnet advertise command:
!
decnet conversion 49
decnet advertise 4
clns route 49.0001 discard
!
A dagger (+) indicates that the command is documented in another chapter.
clns route discard +
show decnet route
To set the maximum cost specification value for interarea routing, use the decnet area-max-cost global configuration command.
decnet [network-number] area-max-cost value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | Maximum cost for a route to a distant area that the router may consider usable; the router treats as unreachable any route with a cost greater than the value you specify. A valid range for cost is from 1 through 1022. This parameter is only valid for area routers. The default is 1022. |
1022
Global configuration
Make sure you have used the decnet node-type area global configuration command before using this command.
In the following example, the node type is specified as area and the maximum cost is set to 500. Any route with a cost exceeding 500 will be considered unreachable by this router.
!
decnet node-type area
decnet area-max-cost 500
!
decnet area-max-hops
decnet node-type
show decnet interface
To set the maximum hop count value for interarea routing, use the decnet area-max-hops global configuration command.
decnet [network-number] area-max-hops value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | Maximum number of hops for a usable route to a distant area. The router treats as unreachable any route with a count greater than the value you specify. A valid range for the hop count is from 1 through 30. The default is 30. |
30 hops
Global configuration
This command is only valid for area routers. Make sure you have issued the decnet node-type area global configuration command before using this command.
The following example sets the router to be a Level 2 router, then sets a maximum hop count of 21:
!
decnet node-type area
decnet area-max-hops 21
!
decnet area-max-cost
decnet node-type
show decnet interface
Use the decnet congestion-threshold interface configuration command to set the congestion- experienced bit if the output queue has more than the specified number of packets in it. A number value of zero or the no form of the command prevents this bit from being set. Use the no decnet congestion-threshold command to remove the parameter setting and set it to 0.
decnet congestion-threshold number| number | Number of packets that are allowed in the output queue before the system will set the congestion experience bit. This value is an integer between 0 and 0x7fff. The value zero prevents this bit from being set. Only relatively small integers are reasonable. The default is 1. |
1
Interface configuration
If a router configured for DECnet experiences congestion, it sets the congestion-experienced bit. An error PDU is sent to the sending router and the packet is dropped if the number of packets exceeds the threshold.
The following example sets the congestion threshold to 10:
interface Ethernet 0
decnet congestion-threshold 10
To allow Phase IV routers (running Software Release 9.1 or higher) to run in a Phase V network and vice versa, enable conversion with the decnet conversion global configuration command. To disable conversion, use the no form of this command.
decnet conversion nsap-prefix| nsap-prefix | Value used for the IDP field when constructing NSAPs from a Phase IV address. |
None
Global configuration
To enable DECnet conversion, you must configure both DECnet and ISO CLNS on your router.
DECnet Phase V is OSI-compatible and conforms to the ISO 8473 (CLNP/CLNS) and
ISO 9542 (ES-IS) standards. Digital has defined algorithms for mapping a subset of the Phase V address space onto the Phase IV address space and for converting Phase IV and Phase V packets back and forth. This allows a network administrator to support both Phase IV hosts in Phase V networks and Phase V hosts in Phase IV networks.
Our implementation differs from Digital's in how reachability information is advertised. Our implementation allows you to add Phase V support without modifying your existing Phase IV support. It also delays converting packets from Phase IV to Phase V, while Digital's implementation converts as soon as possible.
It is essential that the area you specify in the decnet routing global configuration command is the same as the local area you specified with the net router configuration command for the CLNS network.
Make sure that the area you specify in the decnet conversion command is the same as the area you specified for the CLNS network. Also note that the DECnet area is specified in decimal, and the CLNS area is specified in hexadecimal.
The decnet routing command is specified with a decimal address, while the net command address is specified in hexadecimal. In addition, the nsap-prefix specified on the decnet conversion command must match one of the NETs for this router.
The following guidelines apply:
The following example enables DECnet conversion on a router with the area tag xy and Phase IV address 20.401 using an ISO IGRP router:
!
clns routing
decnet routing 20.401
decnet max-address 600
!
router iso-igrp xy
net 47.0004.004d.0014.aa00.0400.9151.00
!
decnet conversion 47.0004.004d
!
interface ethernet 0
decnet cost 4
clns router iso-igrp xy
!
A dagger (+) indicates that the command is documented in another chapter.
net +
show decnet interface
show decnet routing
To set a cost value for an interface, use the decnet cost interface configuration command. Use the no form of this command to disable DECnet routing for an interface.
decnet cost cost-value| cost-value | Integer from 1 through 63. There is no default cost for an interface, although a suggested cost for FDDI is 1, for Ethernet is 4, and for serial links is greater than 10. |
None
Interface configuration
After DECnet routing has been enabled, you must assign a cost to each interface over which you want DECnet to run. Assigning a cost in effect enables DECnet routing for an interface. Most DECnet installations have an individualized routing strategy for using costs. Therefore, check the routing strategy used at your installation to ensure that costs you specify are consistent with those set for other hosts on the network.
The following example establishes a DECnet routing process for the router and sets the router's DECnet address to 21.456, then sets a cost of 4 for the Ethernet 0 interface:
decnet routing 21.456
interface ethernet 0
decnet cost 4
decnet encapsulation
decnet node-type
decnet routing
show decnet interface
show decnet routing
To provide DECnet encapsulation over Token Ring, use the decnet encapsulation interface configuration command.
decnet encapsulation {pre-dec | dec}| pre-dec | Configures routers for operation on the same Token Ring with routers running software versions prior to 9.1. In this mode, Cisco routers cannot communicate with non-Cisco equipment. Referred to as Cisco-style encapsulation. |
| dec | Provides encapsulation that is compatible with other Digital equipment. All Cisco routers must be running Software Release 9.1 or later. |
dec
Interface configuration
If you have both 9.0 and 9.1 routers in the same network, you must use the pre-dec encapsulation type on the 9.1 routers.
The following example sets Cisco-style encapsulation for DECnet routing, which means that Cisco and Digital equipment will not interoperate over Token Ring:
!
interface tokenring 0
decnet encapsulation pre-dec
decnet cost 4
!
decnet cost
show decnet interface
To change the interval for sending broadcast Hello messages, use the decnet hello-timer interface configuration command. To restore the default value, use the no form of this command.
decnet hello-timer value| value | Interval at which the router sends Hello messages. It can be a decimal number in the range 1 through 8191 seconds; the default is 15 seconds. |
15 seconds
Interface configuration
The router broadcasts Hello messages on all interfaces with DECnet enabled. Other hosts on the network use the Hello messages to identify the hosts with which they can communicate directly. On extremely slow serial lines, you may want to increase the default value to reduce overhead on the line.
The following example increases the Hello interval to 2 minutes (120 seconds) on interface serial 1:
interface serial 1
decnet hello-timer 120
show decnet interface
To provide access control to Hello messages or routing information received on an interface, use the decnet in-routing-filter interface configuration command. Use the no form of this command to remove access control.
decnet in-routing-filter access-list-number| access-list-number | Standard DECnet access list. This list applies to destination addresses. The value can be in the range 300 through 399. |
None
Interface configuration
In the following example, interface Ethernet 0 is set up with a DECnet in-routing filter of 321, which means that any Hello messages sent from addresses that are denied in list 321 will be ignored. Additionally, all node addresses listed in received routing messages on this interface will be checked against the access list, and only routes passing the filter will be considered usable.
!
interface ethernet 0
decnet in-routing-filter 321
!
access-list
decnet out-routing-filter
show decnet interface
To establish an address translation for selected nodes, use the decnet map global configuration command.
decnet first-network map virtual-address second-network real-address| first-network | DECnet network numbers in the range 0 through 3. |
| virtual-address | Numeric DECnet address (10.5, for example). |
| second-network | DECnet network number you map to; DECnet numbers range from 0 through 3. |
| real-address | Numeric DECnet address (10.5, for example). |
None
Global configuration
Keep the following limitations in mind when configuring the Address Translation Gateway (ATG):
As an additional feature and security caution, DECnet "Poor Man's Routing" can be used between nodes outside of the translation map as long as those nodes have access to nodes that are in the map, so that a user on node B could issue the following VMS command:
$ dir A::D::E::
When a Poor Man's Routing connection is made between two networks, only the two adjacent nodes between the networks will have any direct knowledge about the other network. Application-level network access may then be specified to route through the connection.
In the following example, packets in Network 0 sent to address 19.5 will be routed to Network 1, and the destination address will be translated to 50.1. Packets sent to address 47.1 in Network 1 will be routed to Network 0 as 19.1.
decnet 0 map 19.5 1 50.1
decnet 1 map 47.1 0 19.1
show decnet map
To configure the router with a maximum number of node addresses, use the decnet max-address global configuration command.
decnet [network-number] max-address value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | A number less than or equal to 1023 that represents the maximum node address possible on the network. In general, all routers on the network should use the same value for this argument. The default is 1023. |
1023
Global configuration
DECnet routers do not have the concept of aging out a route. Therefore, all possible areas or nodes must be advertised as unreachable if they cannot be reached. Since it is best to keep routing updates small, you need to indicate the default maximum possible node and area numbers that can exist in the network.
The following example configures a small network to a maximum address value of 300:
!
decnet max-address 300
!
decnet max-area
To set the largest number of areas that the router can handle in its routing table, use the decnet max-area global configuration command.
decnet [network-number] max-area value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | Area number from 1 through 63. Like the decnet max-address global configuration command value, this argument controls the sizes of internal routing tables and of messages sent to other nodes. All routers on the network should use the same maximum address value. The default is 63. |
63
Global configuration
In the following example, the largest area to be stored in the routing table is 45:
!
decnet max-area 45
!
decnet max-address
show decnet interface
To set the maximum cost specification for intra-area routing, use the decnet max-cost global configuration command.
decnet [network-number] max-cost value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | Cost from 1 through 1022. The default is 1022. |
1022
Global configuration
The router ignores routes within its local area that have a cost greater than the value you specify.
In the following example, the node type is specified as a Level 1 router and the maximum cost is set to 335. Any route whose cost exceeds 335 will be considered unreachable by this router.
!
decnet node-type routing-iv
decnet max-cost 335
!
decnet max-hops
decnet max-paths
decnet node-type routing-iv
decnet path-split-mode
show decnet interface
To set the maximum hop count specification value for intra-area routing, use the decnet max-hops global configuration command.
decnet [network-number] max-hops value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | Hop count from 1 through 30. The router ignores routes that have a hop count greater than the corresponding value of this parameter. The default is 30. |
30 hops
Global configuration
The following example sets the router to be a Level 1 router, then sets a maximum hop count of 2:
!
decnet node-type routing-iv
decnet max-hops 2
!
decnet max-cost
decnet max-paths
decnet max-visits
decnet node-type routing-iv
To define the maximum number of equal-cost paths to a destination that the router will keep in its routing table, use the decnet max-paths global configuration command.
decnet [network-number] max-paths value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | Decimal number equal to the maximum number of equal-cost paths the router will save. The valid range is from 1 through 31. The default is 1. |
1
Global configuration
Limiting the number of equal-cost paths can save memory on routers with limited memory or very large configurations. Additionally, in networks with a large number of multiple paths and end-systems with limited ability to cache out-of-sequence packets, performance may suffer when traffic is split between many paths.
Limiting the size of the routing table will not affect your router's ability to recover from network failures transparently, provided that you do not make the maximum number of paths too small. If more than the specified number of equal-cost paths exist, and one of those paths suddenly becomes unusable, the router will discover an additional path from the paths it has been ignoring.
In the following example, the router will save no more than three equal-cost paths:
!
decnet max-paths 3
!
decnet max-cost
decnet max-hops
decnet path-split-mode
show decnet interface
show decnet route
To set the limit on the number of times a packet can pass through a router, use the decnet max-visits global configuration command.
decnet [network-number] max-visits value| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| value | Number of times a packet can pass through a router. It can be a decimal number in the range 1 through 63. If a packet exceeds value, the router discards the packet. Digital recommends that the value of the max-visits parameter be at least twice that of the max-hops parameter, to allow packets to still reach their destinations when routes are changing. The default is 63. |
63
Global configuration
The following example of intra-area routing configuration specifies Level 1 routing, a maximum hop count of 28, and maximum number of visits of 62 (which is more than twice 28).
!
decnet node-type routing-iv
decnet max-hops 28
decnet max-visits 62
!
decnet max-hops
show decnet interface
show decnet traffic
To specify the node type, use the decnet node-type global configuration command.
decnet [network-number] node-type {area | routing-iv}| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| area | Router participates in the DECnet routing protocol with other area routers, as described in the Digital documentation, and routes packets from and to routers in other areas. This is sometimes referred to as Level 2, or interarea, routing. An area router does not just handle interarea routing; it also acts as an intra-area or Level 1 router in its own area. |
| routing-iv | Router acts as an intra-area (standard DECnet Phase IV, Level 1 router) and ignores Level 2 routing packets. In this mode, it routes packets destined for other areas to a designated interarea router, exchanging packets with other end-nodes and routers in the same area. |
None
Global configuration
In the following example, the router node type is specified as area, or Level 2:
decnet node-type area
decnet cost
decnet routing
show decnet interface
To provide access control to routing information being sent out on an interface, use the decnet out-routing-filter interface configuration command. Use the no form of this command to remove access control.
decnet out-routing-filter access-list-number| access-list-number | Standard DECnet access list applying to destination addresses. The value can be in the range 300 through 399. |
None
Interface configuration
Addresses that fail this test are shown in the update message as unreachable.
In the following example, interface Ethernet 1 is set up with a DECnet out-routing filter of 351. This filter is applied to addresses in the transmitted routing updates. Transmitted Hello messages are not filtered.
!
interface ethernet 1
decnet out-routing-filter 351
!
access-list
decnet in-routing-filter
show decnet interface
To specify how the router will split the routable packets between equal-cost paths, use the decnet path-split-mode global configuration command with the appropriate keyword.
decnet path-split-mode {normal | interim}| normal | Normal mode, where equal-cost paths are selected on a round-robin basis. This is the default. |
| interim | Traffic for any particular (higher-layer) session is always routed over the same path. This mode supports older implementations of DECnet (VMS Versions 4.5 and earlier) that do not support out-of-order packet caching. Other sessions may take another path, thus using equal-cost paths that a router may have for a particular destination. |
Normal
Global configuration
In the following example, the router will split routable packets between equal-cost paths using the round-robin (or first-come, first-served) basis:
decnet path-split-mode normal
decnet max-cost
decnet max-paths
To enable fast-switching, use the decnet route-cache interface configuration command. To turn off fast switching, use the no form of this command.
decnet route-cacheThis command has no arguments or keywords.
Enabled
Interface configuration
By default, our DECnet routing software implements fast switching of DECnet datagrams. There are times when it makes sense to disable fast switching. This is especially important when using rates slower than T1.
Fast switching uses memory space on interface cards. In situations where a high-bandwidth interface is writing large amounts of information to a low-bandwidth interface, additional memory could help avoid congestion on the slow interface.
In the following example, fast switching is disabled:
no decnet route-cache
To elect a designated router to which packets will be sent when no destination is specified, use the decnet router-priority interface configuration command.
decnet router-priority value| value | Priority of the router. This can be a number in the range 0 through 127. The larger the number the higher the priority. The default priority is 64. |
64
Interface configuration
The designated router is the router to which all end nodes on an Ethernet communicate if they do not know where else to send a packet. The designated router is chosen through an election process in which the router with the highest priority gets the job. When two or more routers on a single Ethernet in a single area share the same highest priority, the unit with the highest node number is elected. You can reset a router's priority to help ensure that it is elected designated router in its area.
DECnet end systems use the designated router only when they have no other information about how to reach a particular system. The end systems maintain a cache of how to reach other systems on the network. The cache contains the following information:
<remote system DECnet address> <next hop DECnet address>
When an end system receives a packet, it examines three pieces of information: the intra-LAN bit, the source address, and the previous hop. If the intra-LAN bit is set, indicating that the packet has never left this wire (and thus the remote system is reachable without a router), a cache entry is created as follows:
<remote system DECnet address> = <source address>
<next hop DECnet address> = <source address>
If the intra-LAN bit is not set, indicating that the packet has come from another network, the cache entry is created as follows:
<remote system DECnet address> = <source address>
<next hop DECnet address> = <previous hop>
If there is no cache entry, then the designated router is used. This means that when starting a session, the designated router is used, but the reverse traffic will populate a cache entry so that the router can later communicate directly.
In the following example, DECnet priority for this router is set to 110 on Ethernet 1:
!
interface ethernet 1
decnet router-priority 110
!
To enable DECnet routing, use the decnet routing global configuration command. To disable DECnet routing, use the no form of this command.
decnet [network-number] routing decnet-address| network-number | (Optional.) Network number in the range 0 through 3. Specified when using Address Translation Gateway (ATG). If not specified, the default is network 0. |
| decnet-address | Address in DECnet format X.Y, where X is the area number and Y is the node number. |
Disabled
Global configuration
Enabling DECnet changes the MAC addresses of the router's interfaces. This is not a problem on routers equipped with nonvolatile memory. On systems that attempt to get their IP network addresses from network servers rather than from nonvolatile memory, there may be a problem with the hardware addresses changing and confusing other IP-speaking hosts. If you are attempting to use DECnet on such a configuration, be sure to set all global DECnet parameters before enabling DECnet routing on the interfaces.
In the following example, DECnet routing is enabled for the router in area 21 with node number 456:
decnet routing 21.456
decnet cost
decnet node-type
To specify how often the router sends routing updates that list the hosts that the router can reach, use the decnet routing-timer interface configuration command. Use the no form of this command to disable the routing update timer.
decnet routing-timer value| value | Time from 1 through 65535 seconds. The default is 40. |
40 seconds
Interface configuration
Other routers use this information to construct local routing tables. In a network where changes occur infrequently or do not need to be responded to immediately (it is small and uncomplicated, applications are not particularly sensitive to delays or occasional packet loss, slow serial links, and so on), increasing the time between routing updates reduces the amount of unnecessary network traffic. Digital calls this argument the broadcast routing timer because they use a different timer for serial lines; our DECnet implementation does not make this distinction.
In the following example, a serial interface is set to broadcast routing updates every 2 minutes (120 seconds):
interface serial 0
decnet routing-timer 120
Use the DECnet ping privileged EXEC command to send DECnet echo packets to test the reachability of a remote host over a DECnet network.
pingThis command has no arguments or keywords.
Privileged EXEC
To abort a ping session, type the escape sequence (by default, Ctrl-^ X, which is done by simultaneously pressing the Ctrl, Shift, and 6 keys, letting go, then pressing the X key).
Table 1-2 describes the test characters that the ping facility sends.
| Char | Description |
|---|---|
| ! | Each exclamation point indicates receipt of a reply. |
| . | Each period indicates the network server timed out while waiting for a reply. |
| U | A destination unreachable error PDU was received. |
| C | A congestion-experienced packet was received. |
| I | User interrupted test. |
| ? | Unknown packet type. |
| & | Packet lifetime exceeded. |
The following display shows a sample DECnet ping session that uses a DECnet address to specify the source:
Router# ping
Protocol [ip]: decnet
Target DECnet address: 2.16
Repeat count [5]:
Datagram size [100]:
Timeout in seconds [2]:
Type escape sequence to abort.
Sending 5, 100-byte DECnet Echos to 2.16,
timeout is 2 seconds:
!!!!!
Success rate is 100 percent, round-trip min/avg/max = 1/4/8 ms
Table 1-3 describes the fields shown in the display.
| Field | Description |
|---|---|
| Protocol [ip]: | Default is IP. |
| Target DECnet address: | Prompts for the DECnet address of the destination node you plan to ping. |
| Repeat count [5]: | Number of ping packets that will be sent to the destination address. Default: 5. |
| Datagram size [100]: | Size of the ping packet (in bytes). Default: 100 bytes. |
| Timeout in seconds [2]: | Timeout interval. Default: 2 (seconds). |
ping (user)
Use the DECnet ping EXEC command to send DECnet echo packets to test the reachability of a remote host over a DECnet network.
ping decnet {host | address}| decnet | DECnet protocol keyword. |
| host | DECnet host of system to ping. |
| address | DECnet address of system to ping. |
EXEC
The ping Exec command provides a basic user ping facility for DECnet users who do not have system privileges. This feature allows the router to perform the simple default ping functionality for the DECnet protocol. Only the nonverbose form of the ping command is supported for user-level pings.
To abort a ping session, type the escape sequence (by default, Ctrl-^ X, which is done by simultaneously pressing the Ctrl, Shift, and 6 keys, letting go, then pressing the X key).
Table 1-4 describes the test characters that the ping facility sends.
| Char | Description |
|---|---|
| ! | Each exclamation point indicates receipt of a reply. |
| . | Each period indicates the network server timed out while waiting for a reply. |
| U | A destination unreachable error PDU was received. |
| C | A congestion-experienced packet was received. |
| I | User interrupted test. |
| ? | Unknown packet type. |
| & | Packet lifetime exceeded. |
The following display shows sample ping output when you ping the DECnet address of 2.16:
router> ping decnet 2.16
Sending 5, 100-byte DECnet Echos to 2.16,
timeout is 2 seconds:
!!!!!
Success rate is 100 percent, round-trip min/avg/max = 1/4/8 ms
ping (privileged)
Use the show decnet EXEC command to display the global DECnet parameters.
show decnetThis command has no arguments or keywords.
EXEC
The following is sample output from the show decnet command:
Router# show decnet
Global DECnet parameters for network 0:
Local address is 19.15, node type is area
Maximum node is 350, maximum area is 63, maximum visits is 63
Maximum paths is 1, path split mode is normal
Local maximum cost is 1022, maximum hops is 30
Area maximum cost is 1022, maximum hops is 30
Table 1-5 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Global DECnet parameters for network 0: | Indicates the DECnet network number of the network being described. |
| Local address is 19.15 | DECnet address of the router. |
| node type is area | Indicates the DECnet node type with which the interface has been configured. Possible values include area (area router) or routing-iv (intra-area router). |
| Maximum node is 350 | Highest node number that the router will recognize. |
| maximum area is 63 | Indicates the maximum DECnet area number, which is used to control the size of internal routing tables and messages sent to other routers. Range: 1 through 63. Default: 63. |
| maximum visits is 63 | Indicates the maximum number of times (visits) a packet can pass through a router. Range: 1 through 63. Default: 63. |
| Maximum paths is 1 | Indicates the maximum number of equal-cost paths the router will save. Range: 1 through 31. Default: 1. |
| path split mode is normal | Indicates how the router will split the routable packets among equal-cost paths. Possible values: normal (default) or interim. |
| Local maximum cost is 1022 | For intra-area routes. Router ignores routes in its area that have a cost greater than this value. |
| maximum hops is 30 | Indicates the maximum number of hops for a usable route within the local area. The router ignores routes within the local area that use more than this number of hops. |
| Area maximum cost is 1022 | Indicates the maximum cost specification for interarea routing. The router ignores routes to other areas that have a cost greater than this value. Range: 1 through 1022: Default: 1022. |
| maximum hops is 30 | Indicates the maximum number of hops for a usable route to other areas. The router ignores routes to other areas that use more than this number of hops. |
Use the show decnet interface EXEC command to display the global DECnet status and configuration for all interfaces, or the status and configuration for a specified interface.
show decnet interface [interface unit]| interface unit | (Optional.) Displays information for a particular interface. For example, e0 specifies the first Ethernet interface; e1 specifies the second Ethernet interface. You must specify both the interface type and unit number. If you do not specify an interface, information on all DECnet interfaces and global DECnet status are displayed. |
EXEC
The following is sample output from the show decnet interface command when you do not specify an interface:
Router# show decnet int
Global DECnet parameters for network 0:
Local address is 19.15, node type is area
Maximum node is 350, maximum area is 63, maximum visits is 63
Maximum paths is 1, path split mode is normal
Local maximum cost is 1022, maximum hops is 30
Area maximum cost is 1022, maximum hops is 30
Ethernet0 is up, line protocol is up, encapsulation is ARPA
Interface cost is 4, priority is 64, DECnet network: 0
The designated router is 1.3
Sending HELLOs every 15 seconds, routing updates 40 seconds
Smallest router blocksize seen is 1498 bytes
Routing input list is not set, output list is not set
Access list is not set
DECnet fast switching is enabled
Number of L1 router adjacencies is : 1
Table 1-6 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Global DECnet parameters for network 0: | Indicates the DECnet network number of the network being described. |
| Local address is 19.15 | DECnet address of the router. |
| node type is area | Indicates the DECnet node type with which the interface has been configured. Possible values include area (area router) or routing-iv (intra-area router). |
| Maximum node is 350 | Highest node number that the router will recognize. |
| maximum area is 63 | Indicates the maximum DECnet area number, which is used to control the size of internal routing tables and messages sent to other routers. Range: 1 through 63. Default: 63. |
| maximum visits is 63 | Indicates the maximum number of times (visits) a packet can pass through a router. Range: 1 through 63. Default: 63. |
| Maximum paths is 1 | Indicates the maximum number of equal-cost paths the router will save. Range: 1 through 31. Default: 1. |
| path split mode is normal | Indicates how the router will split the routable packets among equal-cost paths. Possible values: normal (default) or interim. |
| Local maximum cost is 1022 | For intra-area routes. Router ignores routes in its area that have a cost greater than this value. |
| maximum hops is 30 | Indicates the maximum number of hops for a usable route within the local area. The router ignores routes within the local area that use more than this number of hops. |
| Area maximum cost is 1022 | Indicates the maximum cost specification for interarea routing. The router ignores routes to other areas that have a cost greater than this value. Range: 1 through 1022: Default: 1022. |
| maximum hops is 30 | Indicates the maximum number of hops for a usable route to other areas. The router ignores routes to other areas that use more than this number of hops. |
| Ethernet 0 is up | Indicates whether the interface hardware is currently active and if it has been taken down by an administrator. |
| line protocol is up | Indicates whether the software processes that handle the line protocol believe the interface is usable (that is, whether keepalives are successful). |
| encapsulation is ARPA | Indicates the encapsulation type. |
| Interface cost is 4 | Indicates the cost that has been assigned to this interface using the decnet cost interface configuration command. If there are multiple paths to a destination, the one with the lowest cost is selected. |
| priority is 64 | Indicates the priority that has been assigned to this router on this interface. End systems will select the router with the highest priority as their designated router. |
| DECnet network: 0 | Indicates that this interface is on DECnet network 0. This fact is significant only if Address Translation Gateway (ATG) is turned on. |
| The designated router is 1.3 | Indicates the designated router on this particular LAN. |
| Sending HELLOs every 15 seconds | Indicates the frequency of HELLO packets. |
| routing updates 40 seconds | Indicates the frequency of routing updates. |
| Smallest router blocksize seen is 1498 bytes | Indicates the largest size of packets being sent on all routers on the LAN. |
| Routing input list is not set, output list is not set | Indicates that no access restrictions on incoming (or outgoing) router update or Hello messages have been set for this interface. |
| Access list is not set | Indicates that no access lists have been configured for the interface. |
| DECnet fast switching is enabled | Indicates that fast switching is enabled. |
| Number of L1 router adjacencies is : 1 | Indicates how many Level 1 adjacencies the router has on this interface. |
The following is sample output from the show decnet interface command when you specify an interface:
Router# show decnet int e 0
Ethernet0 is up, line protocol is up, encapsulation is ARPA
Interface cost is 4, priority is 64, DECnet network: 0
The designated router is 1.3
Sending HELLOs every 15 seconds, routing updates 40 seconds
Smallest router blocksize seen is 1498 bytes
Routing input list is not set, output list is not set
Access list is not set
DECnet fast switching is enabled
Number of L1 router adjacencies is : 1
Table 1-7 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Ethernet 0 is up | Indicates whether the interface hardware is currently active and if it has been taken down by an administrator. |
| line protocol is up | Indicates whether the software processes that handle the line protocol believe the interface is usable (that is, whether keepalives are successful). |
| encapsulation is ARPA | Indicates the encapsulation type. |
| Interface cost is 4 | Indicates the cost that has been assigned to this interface using the decnet cost interface configuration command. If there are multiple paths to a destination, the one with the lowest cost is selected. |
| priority is 64 | Indicates the priority that has been assigned to this router on this interface. End systems will select the router with the highest priority as their designated router. |
| DECnet network: 0 | Indicates that this interface is on DECnet network 0. This fact is significant only if Address Translation Gateway (ATG) is turned on. |
| The designated router is 1.3 | Indicates the designated router on this particular LAN. |
| Sending HELLOs every 15 seconds | Indicates the frequency of HELLO packets. |
| routing updates 40 seconds | Indicates the frequency of routing updates. |
| Smallest router blocksize seen is 1498 bytes | Indicates the largest size of packets being sent on all routers on the LAN. |
| Routing input list is not set, output list is not set | Indicates that no access restrictions on incoming (or outgoing) router update or Hello messages have been set for this interface. |
| Access list is not set | Indicates that no access lists have been configured for the interface. |
| DECnet fast switching is enabled | Indicates that fast switching is enabled. |
| Number of L1 router adjacencies is : 1 | Indicates how many Level 1 adjacencies the router has on this interface. |
Use the show decnet map EXEC command to display the address mapping information used by the DECnet Address Translation Gateway.
show decnet mapThis command has no arguments or keywords.
EXEC
The following is sample output from the show decnet map command:
Router# show decnet map
Net Node -> Net Node Uses Cost Hops
0 1.100 1 2.100 0
Table 1-8 describes significant fields shown in the display.
| Field | Description |
|---|---|
| Net Node - Net Node | Net number and node address. |
| Uses | Number of times this map was used. |
| Cost | Cost associated with route. |
| Hop | Number of hops to destination mode. |
Use the show decnet route EXEC command to display the DECnet routing table.
show decnet route [decnet-address]| decnet-address | (Optional.) DECnet address and, when specified, the first hop route to that address is displayed. |
EXEC
The following is sample output from the show decnet route command when a DECnet address name was not specified, so the entire routing table is displayed:
Router# show decnet route
Area Cost Hops Next Hop to Node Expires Prio
1 4 1 Ethernet1 -> 1.300 26 64 A
*1 4 1 Ethernet1 -> 1.400 37 64 A
*2 8 2 Ethernet1 -> 1.400
*5 0 0 (Local) -> 5.5
*10 4 1 Ethernet2 -> 10.1 36 64 A
*13 11 3 Ethernet1 -> 1.400
*44 22 6 Ethernet1 -> 1.400
*51 18 4 Ethernet1 -> 1.400
*61 1 1 (OSI) -> 5.5
*62 1 1 (OSI) -> 5.5
Node Cost Hops Next Hop to Node Expires Prio
*(Area) 0 0 (Local) -> 5.5
*5.5 0 0 (Local) -> 5.5
Router#
As the display shows, the show decnet route command can display more than one route for a destination when equal-cost paths have been set with the decnet max-paths global configuration command, and when there is more than one equal-cost path to a destination. The display also shows that this node is an area router.
Table 1-9 describes significant fields shown in the display.
| Field | Description |
|---|---|
| * | Currently selected route for a particular destination. In interim mode, the selected route will never appear to change. |
| Node | DECnet address of this (reachable) destination. |
| Cost | Assigned cost for the interface, based on a recommended value for the underlying media. Range: 1 through 63. No default. |
| Hops | Number of hops to this node from the router being monitored. |
| Next Hop to Node | DECnet address of the next hop a packet will take to get to the final destination as well as the interface. |
| Expires | Displays how many seconds from now this entry expires. |
| Prio | Router priority of this node. |
| V | Adjacent Level 1 router; VA or A indicates that this is an adjacent Level 2 (area) router. |
The show decnet traffic EXEC command shows the DECnet traffic statistics, including datagrams sent, received, and forwarded.
show decnet trafficThis command has no arguments or keywords.
EXEC
The following is sample output from the show decnet traffic command:
Router# show decnet traffic
Total: 42 received, 0 format errors, 0 unimplemented
0 not a gateway, 0 no memory, 0 no routing vector
0 congestion encountered
Hellos: 21 received, 0 bad, 0 other area, 16 sent
Level 1 routing: 14 received, 0 bad, 0 other area, 16 sent
Level 2 routing: 7 received, 0 not primary router, 8 sent
Data: 0 received, 0 not long format, 0 too many visits
0 forwarded, 0 returned, 0 converted, 0 local destination
0 access control failed, 0 no route, 0 encapsulation failed
0 inactive network, 0 incomplete map
Table 1-10 describes the fields shown in the display.
| Field | Description |
|---|---|
| Total: | Displays the totals of packet types received. |
| received | Total of all types of DECnet packets received. |
| format errors | Lists the number of packets that appeared to be DECnet, but were formatted incorrectly. The number in the received field includes these packets. |
| 0 unimplemented | Reports the number of incoming packets that are DECnet control packets, and how many specify a service that the router does not implement. This includes services implemented to forward Level 1 and Level 2 routing information, and router and end-system Hello packets. |
| 0 not a gateway | Reports the total number of packets received while not routing DECnet. |
| 0 no memory | Records transaction attempts when the system has run out of memory. |
| 0 no routing vector | Indicates that either a routing update came in from another router when the router did not have an adjacency for it, or it had no routing vector for the type of routing update. Use the debug decnet-routing EXEC command for more information. |
| 0 congestion encountered | Number of times the underlying physical layer detected congestion. |
| HELLOs: | Displays the number of Hello messages received and sent. |
| received | Displays the total number of Hello messages received. All protocol types are included. |
| bad | Displays the total number of "bad" Hello messages received. Invoke the EXEC command debug decnet to display more information about why the Hello message was judged as bad. |
| other area | Displays the total number of Hello messages received from nodes on other areas when the router is a Level 1 router only. |
| sent | Displays the total number of Hello messages sent. |
| Level 1 routing: | Displays the Level 1 routing updates received and sent. |
| received | Displays the total number of Level 1 routing updates received. |
| bad | Displays the total number of Level 1 updates received that were judged to be bad. |
| other area | Displays the total number of Level 1 updates from nodes in other areas. |
| sent | Displays the total number of Level 1 updates sent. |
| Level 2 routing: | Displays the Level 2 routing updates received and sent. |
| received | Displays the total number of Level 2 updates received. |
| not primary router | Should always be zero. |
| sent | Displays the total number of Level 2 updates sent. |
| Data: | Displays the number of data packets received and sent. |
| received | Displays the total number of noncontrol (data) packets received. |
| not long format | Displays the number of packets received which are not in the long DECnet format. This number should always be zero. If it is not, investigate the source of the improperly formatted packets. |
| too many visits | Lists the number of packets received which have visited too many routers and have been flushed. |
| forwarded | Lists the total number of packets forwarded. |
| returned | Lists the total number of packets returned to the sender at the senders' request. |
| converted | Displays the number of Phase IV packets converted to Phase V packets. |
| local destination | Packets received that are destined for this router. |
| access control failed | Lists the packets dropped because access control required it. |
| no route | Lists the total packets dropped because the router did not know where to forward them. |
| encapsulation failed | Lists the number of packets that could not be encapsulated. This usually happens where there are entries missing in a map for a public data network, such as X.25 or Frame Relay. This can also occur if an interface is set for an encapsulation for which there is no defined DECnet encapsulation (such as PPP on serial interfaces). |
| inactive network | Displays the number of packets that appear to come from a known interface, or that ATG returned because they did not make sense. |
| incomplete map | Counts the number of packets that failed address translation. This usually means a node that is not in the ATG map is trying to access a node in another network advertised by the ATG. |
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