- IS-IS Overview and Basic Configuration
- Reducing Failure Detection Times in IS-IS Networks
- Enhancing Security in an IS-IS Network
- Configuring Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- IS-IS Support for Route Tags
- IS-IS Multiarea Support
- IS-IS Support for an IS-IS Instance per VRF for IP
- IPv6 Routing: IS-IS Multitopology Support for IPv6
- IPv6 Routing: IS-IS Support for IPv6
- IPv6 Routing: Route Redistribution
- Finding Feature Information
- Prerequisites for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- Information About Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- How to Create, Monitor and Make Changes to Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
Configuring Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
The Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters feature allows you to disable the Integrated Intermediate System-to-Intermediate System (IS-IS) protocol at the interface level or at the global IS-IS process level without removing the IS-IS configuration parameters.
This module describes the tasks to configure and monitor a basic Intermediate System-to-Intermediate System (IS-IS) network. The IS-IS process and adjacency formation are also explained. IS-IS is link-state protocol that allows the network designer to organize the network into a group of flooding domains. Often deployed as the Interior Gateway Protocol (IGP) for an ISP network backbone, IS-IS is capable of handling large topologies and large numbers of routing changes.
- Finding Feature Information
- Prerequisites for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- Information About Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- How to Create, Monitor and Make Changes to Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- Configuration Examples for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- ““Where to Go Next
- Additional References for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
- Feature Information for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
Finding Feature Information
Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to www.cisco.com/go/cfn. An account on Cisco.com is not required.
Prerequisites for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
Before performing the tasks in this module, you should be familiar with the concepts described in the “Integrated IS-IS Routing Protocol Overview” module.
You should know your network design and how you want traffic to flow through it before configuring IS-IS. Define areas, prepare an addressing plan for the devices (including defining the NETs), and determine the interfaces that will run Integrated IS-IS. To facilitate verification, a matrix of adjacencies should be prepared before you configure your devices, showing what neighbors should be expected in the adjacencies table. For more information about verifying IS-IS configuration and formed adjacencies, see “Monitoring IS-IS”.
Information About Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
IS-IS Process and Adjacencies
IS-IS requires some configuration on both the device and the interface. An IS-IS process is created when you enable IS-IS on a device and define a specific tag to identify that routing process. Interfaces configured with a specific tag will be part of the corresponding device process. More than one IS-IS process can run on a device for Connectionless Network Service (CLNS), but only one IS-IS process can run for IP.
Small IS-IS networks are built as a single area that includes all the devices in the network. As the network grows larger, it is usually reorganized into a backbone area made up of the connected set of all Level 2 devices from all areas. The areas are connected to local areas. Within a local area, devices know how to reach all system IDs. Between areas, devices know how to reach the backbone, and the backbone devices know how to reach other areas.
Devices establish Level 1 adjacencies to perform routing within a local area (intra-area routing). Devices establish Level 2 adjacencies to perform routing between Level 1 areas (inter-area routing).
If the network administrator does not specify Level 1 or Level 2 routing for the routing process being configured, the default routing behavior for the routing process will be Level 1-2.
If Level 2 routing is configured on any process, additional processes are automatically configured as Level 1, with the exception of previously configured Level 2 process, which will remain Level 2. You can have only one Level-2 process. You can configure the Level-2 process to perform Level-1 routing at the same time. If Level-2 routing is not desired for a device instance, use the is-type command in device configuration mode to remove the Level-2 capability. You can also use the is-type command to configure a different device instance as a Level-2 device.
Some networks use legacy equipment that supports only Level 1 routing. These devices are typically organized into many small areas that cannot be aggregated due to performance limitations. Cisco devices are used to interconnect each area to the Level 2 backbone.
Network entity titles (NETs) define the area addresses and the system ID of the device. See the “Configuring ISO CLNS” module in the Cisco IOS ISO CLNS Configuration Guide for a more detailed discussion of NETs.
PDU Packet Types in IS-IS Routing
The OSI stack defines a unit of data as a protocol data unit (PDU). A frame therefore is regarded by OSI as a data-link PDU, and a packet is regarded as a network PDU. There are four types of PDU packets, and each type can be Level 1 or Level 2:
LSP—Link-state PDU. Used to distribute link-state information.
IIH PDU—For IS-IS this is called the IS-IS Hello PDU. Used to establish and maintain adjacencies.
Note | On point-to-point links, IIH PDUs will be the same for Level 1 and Level 2. Both Level-1 and Level-2 IIH use the same type of PDU, but they carry different circuit types. |
PSNP—Partial sequence numbers protocol data unit (PDU). Used to acknowledge and request link-state information.
CSNP—Complete sequence number protocol data unit (PDU). Used to distribute the complete link-state database of a device.
IS-IS LSPs include specific information about the device’s attachments. The following information is included in multiple Type Length Value (TLV) fields in the main body of the LSP:
How to Create, Monitor and Make Changes to Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
Enabling IS-IS as an IP Routing Protocol on the Device
1.
enable
2.
configure
terminal
3.
router
isis
[area-tag]
4.
net
network-entity-title
5.
end
DETAILED STEPS
Enabling IS-IS as an IP Routing Protocol on the Interface
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
ip
address
ip-address
mask
[secondary]
5.
ip
router
isis
[area-tag]
6.
end
DETAILED STEPS
Monitoring IS-IS
1.
enable
2.
configure
terminal
3.
isis
display
delimiter
[return
count
|
character
count]
4.
exit
5.
show
ip
protocols
6.
show
clns
area-tag
is-neighbors
[type
number] [detail]
7.
show
clns
interface
[type
number]
8.
show
clns
area-tag
neighbors
[type
number]
[area] [detail]
9.
show
clns
area-tag
traffic
10.
show
ip
route
[ip-address
[mask]]
[[longer-prefixes] |
protocol
[process-id] |
list [access-list-number |
access-list-name] |
static
download]]
11.
show
isis
[process-tag]
database
[level-1]
[level-2]
[l1] [l2] [detail] [lspid]
12.
show
isis
database
verbose
13.
show
isis
lsp-log
14.
show
isis
[area-tag]
[ipv6 |
*]
spf-log
15.
show
isis
[process-tag]
[ipv6 |
*]
topology
16.
show
isis
[area-tag]
neighbors [detail]
DETAILED STEPS
Example
When the show isis neighbors command is entered with the detail keyword, the output provides information about the IS-IS adjacencies that have formed.
Device1# show isis neighbors detail System Id Type Interface IP Address State Holdtime Circuit Id Device2 L2 Et1/0 10.1.1.0 UP 255 Circuit3.01 Area Address(es): 32 SNPA: aabb.cc00.2001 State Changed: 00:00:14 LAN Priority: 64 Format: Phase V
Troubleshooting Tips
You can use the following two system debugging commands to check your IS-IS IPv4 implementation.
If adjacencies are not coming up properly, use the debug isis adj-packets command.
To display a log of significant events during an IS-IS SPF calculation, use the debug isis spf-events command.
Shutting Down IS-IS to Make Changes to Your IS-IS Network
You can shut down IS-IS (placing it in an administrative down state) to make changes to the IS-IS protocol configuration, without losing your configuration parameters. You can shut down IS-IS at the interface level or at the global IS-IS process level. If the device was rebooted when the protocol was turned off, the protocol would be expected to come back up in the disabled state. When the protocol is set to the administrative down state, network administrators are allowed to administratively turn off the operation of the IS-IS protocol without losing the protocol configuration, to make a series of changes to the protocol configuration without having the operation of the protocol transition through intermediate—and perhaps undesirable—states, and to then reenable the protocol at a suitable time.
Before the introduction of the Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters feature, there was no nondestructive way to disable IS-IS operation. The only way to disable IS-IS at the device level was to issue the no router isis command, which removes the IS-IS configuration. At the interface level there are two ways to disable IS-IS operation. You can enter the no ip router isis command to remove IS-IS from the specified interface, or you can put the interface into passive mode such that the IP address of the specified interface will still be advertised. In either case, the current IS-IS configuration will be removed.
Shutting Down IS-IS in Interface Mode
1.
enable
2.
configure
terminal
3.
interface
type
number
4.
isis
protocol
shutdown
5.
end
DETAILED STEPS
Shutting Down IS-IS in Router Mode
1.
enable
2.
configure
terminal
3.
router
isis
area-tag
4.
protocol
shutdown
5.
end
DETAILED STEPS
Configuration Examples for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
Example: Configuring a Basic IS-IS Network
The following example shows how to configure three devices to run IS-IS as an IP routing protocol.
Device A Configuration
router isis net 49.0001.0000.0000.000a.00 interface ethernet0/0 ip address 10.1.1.1 255.255.255.0 ip router isis interface serial 2/0 ip router isis ip address 192.168.1.2 255.255.255.0
Device B Configuration
router isis net 49.0001.0000.0000.000b.00 interface ethernet0/0 ip router isis ip address 172.17.1.1 255.255.255.0 interface serial2/0 ip router isis ip address 192.168.1.1 255.255.255.0 interface serial5/0 ip router isis ip address 172.21.1.1 255.255.255.0
Device C Configuration
router isis net 49.0001.0000.0000.000c.00 interface ethernet2/0 ip router isis ip address 172.21.1.2 255.255.255.0 interface serial5/0 ip router isis ip address 172.22.1.1 255.255.255.0
The show isis topology command displays the following information about how the devices are connected within the IS-IS network:
DeviceB# show isis topology IS-IS paths to level-1 routers System Id Metric Next-Hop Interface SNPA DeviceA 10 DeviceA Se2/0 *HDLC* DeviceB -- DeviceC 10 DeviceC Se5/0 *HDLC* IS-IS paths to level-2 routers System Id Metric Next-Hop Interface SNPA DeviceA 10 DeviceA Se2/0 *HDLC* DeviceB -- DeviceC 10 DeviceC Se5/0 *HDLC*
The show isis database command displays following information for the Level 1 and Level 2 LSPs for each device in the IS-IS network.
DeviceB# show isis database IS-IS Level-1 Link State Database: LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL DeviceA.00-00 0x00000005 0x1A1D 1063 0/0/0 DeviceB.00-00 * 0x00000006 0xD15B 1118 0/0/0 DeviceC.00-00 0x00000004 0x3196 1133 1/0/0 IS-IS Level-2 Link State Database: LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OL DeviceA.00-00 0x00000008 0x0BF4 1136 0/0/0 DeviceB.00-00 * 0x00000008 0x1701 1137 0/0/0 DeviceC.00-00 0x00000004 0x3624 1133 0/0/0
The show ip route command displays information about the interfaces of each device, including their IP addresses and how they are connected to Device B:
DeviceB# show ip route Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2 E1 - OSPF external type 1, E2 - OSPF external type 2 i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2 ia - IS-IS inter area, * - candidate default, U - per-user static route o - ODR, P - periodic downloaded static route Gateway of last resort is not set 172.17.0.0/24 is subnetted, 1 subnets C 172.17.1.0 is directly connected, Ethernet0/0 172.16.0.0/24 is subnetted, 1 subnets C 172.16.1.0 is directly connected, Serial4/0 172.21.0.0/24 is subnetted, 1 subnets C 172.21.1.0 is directly connected, Serial5/0 172.22.0.0/24 is subnetted, 1 subnets i L1 172.22.1.0 [115/20] via 172.21.1.2, Serial5/0 10.0.0.0/24 is subnetted, 1 subnets i L1 10.1.1.0 [115/20] via 192.168.1.2, Serial2/0 C 192.168.1.0/24 is directly connected, Serial2/0 C 192.168.3.0/24 is directly connected, Serial3/0
The show isis spf-log command displays logs of Level 1 and Level 2 LSPs including time of occurrence, duration, count, and the event that triggered the LSP.
DeviceC## show isis spf-log level 1 SPF log When Duration Nodes Count First trigger LSP Triggers 00:01:30 0 3 7 DeviceB.00-00 PERIODIC NEWADJ NEWLSP TLVT level 2 SPF log When Duration Nodes Count First trigger LSP Triggers 00:01:31 0 3 7 DeviceB.00-00 PERIODIC NEWADJ NEWLSP TLVT
The figure below illustrates the sample configuration.
Example: Shutting Down IS-IS in Interface Mode
The following device output shows that the device has two IS-IS adjacencies:
Device# show clns neighbors System Id Interface SNPA State Holdtime Type Protocol first Et3/1 0002.7dd6.1c21 Up 25 L1L2 IS-IS second Et3/2 0004.6d25.c056 Up 29 L1L2 IS-IS
When the isis protocol shutdown command is entered for Ethernet interface 3/1, the IS-IS protocol will be disabled for the specified interface:
Device# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Device(config)# Interface Gigabitethernet 0/0 Device(config-if)# isis protocol shutdown Device(config-if)# end
The following device output shows that the adjacency for Ethernet interface 3/1 has not formed:
Device# show clns neighbors System Id Interface SNPA State Holdtime Type Protocol second Et3/2 0004.6d25.c056 Up 27 L1L2 IS-IS
Example: Shutting Down IS-IS in Router Mode
The following device output shows that the device has two IS-IS adjacencies:
Device# show clns neighbors System Id Interface SNPA State Holdtime Type Protocol south Et3/1 0002.7dd6.1c21 Up 29 L1L2 IS-IS north Et3/2 0004.6d25.c056 Up 28 L1L2 IS-IS
The protocol shutdown command is entered so that IS-IS is disabled and no adjacencies will be formed on any interface:
Device# configure terminal Enter configuration commands, one per line. End with CNTL/Z. Device(config)# router isis area1 Device(config-router)# protocol shutdown Device(config-router)# end
The following device output now shows that both adjacencies are gone.
Device# show clns neighbors System Id Interface SNPA State Holdtime Type Protocol
When the no protocol shutdown command is entered, the adjacencies will again be formed on both interfaces:
Device(config)# router isis area1 Device(config-router)# no protocol shutdown Device(config-router)# end Device# show clns neighbors System Id Interface SNPA State Holdtime Type Protocol south Et3/1 0002.7dd6.1c21 Up 24 L1L2 IS-IS north Et3/2 0004.6d25.c056 Up 24 L1L2 IS-IS
““Where to Go Next
Additional References for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
Related Documents
Related Topic |
Document Title |
---|---|
IS-IS commands: complete command syntax, command mode, defaults, command history, usage guidelines, and examples |
Cisco IOS IP Routing: ISIS Command Reference |
Overview of IS-IS concepts |
“Integrated IS-IS Routing Protocol Overview” module |
Customizing IS-IS for achieving fast convergence and scalability |
“Overview of IS-IS Fast Convergence” module |
Standards
Standard |
Title |
---|---|
No new or modified standards are supported, and support for existing standards has not been modified. |
— |
MIBs
MIB |
MIBs Link |
---|---|
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL: |
RFCs
RFC |
Title |
---|---|
RFC 1195 |
Use of OSI IS-IS for Routing in TCP/IP and Dual Environments Use of OSI IS-IS for Routing in TCP/IP and Dual Environments (http://www.ietf.org/rfc/rfc1195.txt) |
Technical Assistance
Description |
Link |
---|---|
The Cisco Support and Documentation website provides online resources to download documentation, software, and tools. Use these resources to install and configure the software and to troubleshoot and resolve technical issues with Cisco products and technologies. Access to most tools on the Cisco Support and Documentation website requires a Cisco.com user ID and password. |
Feature Information for Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters
The following table provides release information about the feature or features described in this module. This table lists only the software release that introduced support for a given feature in a given software release train. Unless noted otherwise, subsequent releases of that software release train also support that feature.
Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to . An account on Cisco.com is not required.
Feature Name |
Releases |
Feature Information |
---|---|---|
Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters |
Cisco IOS XE Release 3.3SE |
The Integrated IS-IS Protocol Shutdown Support Maintaining Configuration Parameters feature allows you to disable the Integrated Intermediate System-to-Intermediate System (IS-IS) protocol at the interface level or at the global IS-IS process level without removing the IS-IS configuration parameters. In Cisco IOS XE Release 3.3SE , support was added for the Cisco Catalyst 3650 Series Switches and Cisco Catalyst 3850 Series Switches. |