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Table Of Contents
Prerequisites to Using IS-IS Route Tags
Information About IS-IS Route Tags
IS-IS Route Tag Characteristics
IS-IS Route Leaking Based on a Route Tag
Tagging Routes for Networks Directly Connected to an Interface
Tagging Routes Using a Route Map
Using the Tag to Set Values and/or Redistribute Routes
Configuration Examples for IS-IS Support for Route Tags
Tagging Routes for Networks Directly Connected to an Interface and Redistributing Them: Example
Redistributing IS-IS Routes Using a Route-Map: Example
Tagging a Summary Address and Applying a Route Map: Example
Filtering and Redistributing IS-IS Routes Using an Access List and a Route Map: Example
IS-IS Support for Route Tags
The IS-IS Support for Route Tags feature provides the capability to tag IS-IS route prefixes and use those tags in a route map to control Intermediate System-to-Intermediate System (IS-IS) route redistribution or route leaking.
History for the IS-IS Support for Route Tags Feature
Finding Support Information for Platforms and Cisco IOS Software Images
Use Cisco Feature Navigator to find information about platform support and Cisco IOS software image support. Access Cisco Feature Navigator at http://www.cisco.com/go/fn. You must have an account on Cisco.com. If you do not have an account or have forgotten your username or password, click Cancel at the login dialog box and follow the instructions that appear.
Contents
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Prerequisites to Using IS-IS Route Tags
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Prerequisites to Using IS-IS Route Tags
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Information About IS-IS Route Tags
You should understand at least the first two concepts before implementing IS-IS route tags, and you should understand the third concept if you plan to configure route leaking:
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Benefits of IS-IS Route Tags
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IS-IS Route Tag Characteristics
An IS-IS route tag number can be up to 4 bytes long. The tag value is set into a sub-TLV 1 for TLV (Type Length Value) Type 135. For more information about TLV Type 135, refer to the "Intermediate System-to-Intermediate System (IS-IS) TLVs" document referenced in the "Additional References" section.
Only one tag can be set to an IS-IS IP route (prefix).The tag is sent out in link-state packets (LSPs) advertising the route. Setting a tag to a route alone does nothing for your network. You can use the route tag at area or Level 1/Level 2 boundaries by matching on the tag and then applying administrative policies such as redistribution, route summarization, or route leaking.
Configuring a tag for an interface (with the isis tag command) triggers the generation of new LSPs from the router because the tag is new information for the packets.
IS-IS Route Leaking Based on a Route Tag
The IS-IS Support for Route Tags feature provides a new way to configure route leaking (redistribution). If you configure route leaking and you want to match on a tag, use a route map (not a distribute list). For more information on route leaking, refer to IS-IS Route Leaking Overview at:
http://www.cisco.com/warp/public/97/route-leak.htmlHow to Use IS-IS Route Tags
There are two general steps to using IS-IS route tags: tagging routes and referencing the tag to set values for the routes and/or redistribute routes. This section describes the following tasks:
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Tagging IS-IS Routes
There are three ways to tag IS-IS routes: tag routes for networks directly connected to an interface, set a tag in a route map, or tag a summary route. All three methods are described in this section. The tagging method is independent of how you use the tag.
After you tag the routes, you can use the tag to set values (such as a metric or next hop, and so on) and/or redistribute routes. You might tag routes on one router, but reference the tag on other routers, depending on what you want to achieve. For example, you could tag the interface on Router A with a tag, match the tag on Router B to set values, and redistribute routes on Router C based on values using a route map.
Prerequisites
Before you tag any IS-IS routes, you need to decide on the following:
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After you know which tagging method suits your need, proceed to one of the following tasks:
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Tagging Routes for Networks Directly Connected to an Interface
Perform this task if you want to tag routes for networks directly connected to an interface.
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DETAILED STEPS
What to Do Next
Applying the tag does nothing for your network until you use the tag by referencing it in a route map, either to set values, to redistribute routes, or to do both. Proceed to the "Using the Tag to Set Values and/or Redistribute Routes."
Tagging Routes Using a Route Map
Perform this task when you want to redistribute connected routes, static routes or routes from other routing protocols using a route map. You can optionally set some new values for the redistributed routes. You should create the route map first, and then reference the tag (shown in a separate task).
It is possible that you might configure some commands on one router and other commands on another router. For example, you might have a route map that matches on a tag and sets a different tag on a router at the edge of a network, and on different routers configure the redistribution of routes based on the route map.
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DETAILED STEPS
What to Do Next
Applying the tag does nothing for your network until you use the tag by referencing it in a route map, either to set values, to redistribute routes, or to do both. Proceed to the "Using the Tag to Set Values and/or Redistribute Routes."
Tagging a Summary Address
Perform this task if you want to summarize IS-IS routes at an area boundary or level boundary and tag the summarized route. You will later use the tag to set values for the summarized route.
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What to Do Next
Applying the tag does nothing for your network until you use the tag by referencing it in a route map to set value. It is unlikely that you will redistribute summary routes. Proceed to the ""Using the Tag to Set Values and/or Redistribute Routes" section."
Using the Tag to Set Values and/or Redistribute Routes
Now that you have applied a tag to one or more routes, you can use that tag to set various values for routes or to redistribute the routes, or both. This task shows you how to set values and redistribute routes. Note that it is likely you are using the tag on a different router from the router on which you applied the tag.
Prerequisites
You must have already applied a tag either on the interface, in a route map, or on a summary route. See the section "Tagging IS-IS Routes."
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Configuration Examples for IS-IS Support for Route Tags
This section provides the following examples:
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Tagging Routes for Networks Directly Connected to an Interface and Redistributing Them: Example
In this example, two interfaces are tagged with different tag values. By default, these two IP addresses would have been put into the IS-IS Level 1 and Level 2 database. However, by using the redistribute command with a route map to match tag 110, only IP address 20.1.1.1 255.255.255.0 is put into the Level 2 database.
interface ethernet 1/0ip address 10.1.1.1 255.255.255.0ip router isisisis tag 120interface ethernet 1/1ip address 20.1.1.1 255.255.255.0ip router isisisis tag 110router isisnet 49.0001.0001.0001.0001.00redistribute isis ip level-1 into level-2 route-map match-tagroute-map match-tag permit 10match tag 110Redistributing IS-IS Routes Using a Route-Map: Example
In a scenario using route tags, you might configure some commands on one router and other commands on another router. For example, you might have a route map that matches on a tag and sets a different tag on a router at the edge of a network, and on different routers configure the redistribution of routes based on a tag in a different route map.
Figure 1 Example of Redistributing IS-IS Routes Using a Route Tag
Figure 1 illustrates a flat Level 2 IS-IS area. On the left edge are static routes from Router A to reach some IP prefixes. Router A redistributes the static routes into IS-IS. Router B runs BGP and redistributes IS-IS routes into BGP and then uses the tag to apply different administrative policy based on different tag values.
Router A
router isisnet 49.0000.0000.0001.00metric-style wideredistribute static ip route-map set-tag!route-map set-tag permit 5set tag 10Router B
router bgp 100redistribute isis level-2 route-map tag-policyroute-map tag-policy permit 20match tag 10set metric 1000Tagging a Summary Address and Applying a Route Map: Example
Figure 2 illustrates two Level 1 areas and a Level 2 area between them. Router A and Router B are Level 1/Level 2 edge routers in the Level 2 area. On edge Router A, a summary address is configured to reduce the number of IP addresses put into the Level 2 IS-IS database. Also, a tag value of 100 is set to the summary address.
On Router B, the summary address is leaked into the Level 1 area and administrative policy is applied based on the tag value.
Figure 2 Tag on a Summary Address
Router A
router isisnet 49.0001.0001.0001.00metric-style widesummary-address 10.0.0.0 255.0.0.0 tag 100Router B
router isisnet 49.0002.0002.0002.0002.0metric-style wideredistribute isis ip level-2 into level-1 route-map match-tagroute-map match-tag permit 10match tag 100Filtering and Redistributing IS-IS Routes Using an Access List and a Route Map: Example
In this example, the first redistribute isis ip command controls the redistribution of Level 1 routes into Level 2. Only the routes with the tag of 90 and whose IP prefix is not 3.3.3.3/32 will be redistributed from Level 1 into Level 2.
The second redistribute isis ip command controls the route leaking from Level 2 into Level 1 domain. Only the routes tagged with 60 or 50 will be redistributed from Level 2 into Level 1.
interface ethernet 1ip address 3.3.3.3 255.255.255.0ip router isisisis tag 60!interface ethernet 2ip address 10.10.10.1 255.255.255.0ip router isisisis tag 90!interface ethernet 3ip address 20.20.20.20 255.255.255.0ip router isisisis tag 50!router isisnet 49.0001.0001.0001.0001.00metric-style wideredistribute isis ip level-1 into level-2 route-map redist1-2redistribute isis ip level-2 into level-1 route-map leak2-1!access-list 102 deny ip host 3.3.3.3 host 255.255.255.255access-list 102 permit ip any any!route-map leak2-1 permit 10match tag 60!route-map leak2-1 permit 20match tag 50!route-map redist1-2 permit 10match ip address 102match tag 90Additional References
The following sections provide references related to IS-IS Support for Route Tags.
Related Documents
MIBs
None
To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:
Technical Assistance
Command Reference
This section documents new and modified commands only.
isis tag
To set a tag on the IP address configured for an interface when this IP prefix is put into an Intermediate System-to-Intermediate System (IS-IS) link-state packet (LSP), use the isis tag command in interface configuration mode. To stop tagging the IP address, use the no form of this command.
isis tag tag-number
no isis tag tag-number
Syntax Description
Defaults
No route tag is associated for IP addresses configured for the interface.
Command Modes
Interface configuration
Command History
12.3(2)T
This command was introduced.
12.2(27)SBC
This command was integrated into Cisco IOS Release 12.2(27)SBC.
Usage Guidelines
Tagging a route does nothing for you until you use the tag, for example, to redistribute routes or summarize routes.
Configuring the isis tag command triggers the router to generate new LSPs because the tag is a new piece of information in the packet.
Examples
In this example, two interfaces are tagged with different tag values. By default, these two IP addresses would have been put into the IS-IS Level 1 and Level 2 database. However, by using the redistribute command with a route map to match tag 110, only IP address 20.1.1.1 255.255.255.0 is put into the Level 2 database.
interface ethernet 1/0ip address 10.1.1.1 255.255.255.0ip router isisisis tag 120interface ethernet 1/1ip address 20.1.1.1 255.255.255.0ip router isisisis tag 110router isisnet 49.0001.0001.0001.0001.00redistribute isis ip level-1 into level-2 route-map match-tagroute-map match-tag permit 10match tag 110redistribute isis
To redistribute Intermediate System-to-Intermediate System (IS-IS) routes specifically from Level 1 into Level 2 or from Level 2 into Level 1, use the redistribute isis command in router configuration mode. To disable the redistribution, use the no form of this command.
redistribute isis ip {level-1 | level-2} into {level-2 | level-1} [[distribute-list list-number] | [route-map map-tag]]
no redistribute isis ip {level-1 | level-2} into {level-2 | level-1}{[distribute-list list-number] | [route-map map-tag]}
Syntax Description
Defaults
There are no default values for this command.
Command Modes
Router configuration
Command History
12.0(5)T
This command was introduced.
12.3(2)T
The route-map map-tag keyword and argument were added.
12.2(27)SBC
This command was integrated into Cisco IOS Release 12.2(27)SBC.
Usage Guidelines
Specify either level-l into level-2 or level-2 into level-1. You may optionally specify either a distribute list or a route map, but not both. You must also specify the metric-style wide command in order for the redistribute isis command to work.
In IS-IS, all areas are stub areas, which means that no routing information is leaked from the backbone (Level 2) into areas (Level 1). Level 1-only routers use default routing to the closest Level 1-Level 2 router in their area. This command enables you to redistribute Level 2 IP routes into Level 1 areas. This redistribution enables Level 1-only routers to pick the best path for an IP prefix to get out of the area. This is an IP-only feature, CLNS routing is still stub routing.
For more control and scalability, a distribute list or a route map can control which Level 2 IP routes can be redistributed into Level 1. This command allows large IS-IS-IP networks to use areas for better scalability.
Examples
In the following example, access list 100 controls the redistribution of IS-IS from Level 1 into Level 2:
router isisnet 49.0000.0000.0001.00metric-style wideredistribute isis ip level-1 into level-2 distribute-list 100access-list 100 permit ip 10.10.10.0 0.0.0.255 anyIn the following example, the route map named "match-tag" controls the redistribution of IS-IS from Level 1 into Level 2 so that only routes tagged with 110 are redistributed:
router isisnet 49.0000.0000.0001.00metric-style wideredistribute isis ip level-1 into level-2 route-map match-tagroute-map match-tag permit 10match tag 110Related Commands
metric-style wide
Configures a router running IS-IS so that it generates and accepts only new-style TLVs.
show ip route
To display the current state of the routing table, use the show ip route command in user EXEC or privileged EXEC mode.
show ip route [ip-address [mask] [longer-prefixes] | protocol [process-id] | list [access-list-number | access-list-name] | static download]
Syntax Description
Command Modes
User EXEC
Privileged EXECCommand History
Usage Guidelines
The show ip route static download command provides a way to display all dynamic static routes with name and distance information, including active and inactive ones. You can display all active dynamic static routes with both the show ip route and show ip route static commands after these active routes are added in the main routing table.
Examples
Routing Table Examples
The following examples show the standard routing tables displayed by the show ip route command. Use the codes displayed at the beginning of each report and the information in Table 1 to understand the type of route.
The following is sample output from the show ip route command when entered without an address:
Router# show ip routeCodes: I - IGRP derived, R - RIP derived, O - OSPF derived,C - connected, S - static, E - EGP derived, B - BGP derived,* - candidate default route, IA - OSPF inter area route,i - IS-IS derived, ia - IS-IS, U - per-user static route,o - on-demand routing, M - mobile, P - periodic downloaded static route,D - EIGRP, EX - EIGRP external, E1 - OSPF external type 1 route,E2 - OSPF external type 2 route, N1 - OSPF NSSA external type 1 route,N2 - OSPF NSSA external type 2 routeGateway of last resort is 10.119.254.240 to network 10.140.0.0O E2 10.110.0.0 [160/5] via 10.119.254.6, 0:01:00, Ethernet2E 10.67.10.0 [200/128] via 10.119.254.244, 0:02:22, Ethernet2O E2 10.68.132.0 [160/5] via 10.119.254.6, 0:00:59, Ethernet2O E2 10.130.0.0 [160/5] via 10.119.254.6, 0:00:59, Ethernet2E 10.128.0.0 [200/128] via 10.119.254.244, 0:02:22, Ethernet2E 10.129.0.0 [200/129] via 10.119.254.240, 0:02:22, Ethernet2E 10.65.129.0 [200/128] via 10.119.254.244, 0:02:22, Ethernet2E 10.10.0.0 [200/128] via 10.119.254.244, 0:02:22, Ethernet2E 10.75.139.0 [200/129] via 10.119.254.240, 0:02:23, Ethernet2E 10.16.208.0 [200/128] via 10.119.254.244, 0:02:22, Ethernet2E 10.84.148.0 [200/129] via 10.119.254.240, 0:02:23, Ethernet2E 10.31.223.0 [200/128] via 10.119.254.244, 0:02:22, Ethernet2E 10.44.236.0 [200/129] via 10.119.254.240, 0:02:23, Ethernet2E 10.141.0.0 [200/129] via 10.119.254.240, 0:02:22, Ethernet2E 10.140.0.0 [200/129] via 10.119.254.240, 0:02:23, Ethernet2The following is sample output that includes IS-IS Level 2 routes learned:
Router# show ip routeCodes: I - IGRP derived, R - RIP derived, O - OSPF derived,C - connected, S - static, E - EGP derived, B - BGP derived,* - candidate default route, IA - OSPF inter area route,i - IS-IS derived, ia - IS-IS, U - per-user static route,o - on-demand routing, M - mobile, P - periodic downloaded static route,D - EIGRP, EX - EIGRP external, E1 - OSPF external type 1 route,E2 - OSPF external type 2 route, N1 - OSPF NSSA external type 1 route,N2 - OSPF NSSA external type 2 routeGateway of last resort is not set10.89.0.0 is subnetted (mask is 255.255.255.0), 3 subnetsC 10.89.64.0 255.255.255.0 is possibly down,routing via 0.0.0.0, Ethernet0i L2 10.89.67.0 [115/20] via 10.89.64.240, 0:00:12, Ethernet0i L2 10.89.66.0 [115/20] via 10.89.64.240, 0:00:12, Ethernet0The following is sample output using the longer-prefixes keyword. When the longer-prefixes keyword is included, the address and mask pair becomes the prefix, and any address that matches that prefix is displayed. Therefore, multiple addresses are displayed.
In the following example, the logical AND operation is performed on the source address 10.0.0.0 and the mask 10.0.0.0, resulting in 10.0.0.0. Each destination in the routing table is also logically ANDed with the mask and compared to that result of 10.0.0.0. Any destinations that fall into that range are displayed in the output.
Router# show ip route 10.0.0.0 10.0.0.0 longer-prefixesCodes: I - IGRP derived, R - RIP derived, O - OSPF derived,C - connected, S - static, E - EGP derived, B - BGP derived,* - candidate default route, IA - OSPF inter area route,i - IS-IS derived, ia - IS-IS, U - per-user static route,o - on-demand routing, M - mobile, P - periodic downloaded static route,D - EIGRP, EX - EIGRP external, E1 - OSPF external type 1 route,E2 - OSPF external type 2 route, N1 - OSPF NSSA external type 1 route,N2 - OSPF NSSA external type 2 routeGateway of last resort is not setS 10.134.0.0 is directly connected, Ethernet0S 10.10.0.0 is directly connected, Ethernet0S 10.129.0.0 is directly connected, Ethernet0S 10.128.0.0 is directly connected, Ethernet0S 10.49.246.0 is directly connected, Ethernet0S 10.160.97.0 is directly connected, Ethernet0S 10.153.88.0 is directly connected, Ethernet0S 10.76.141.0 is directly connected, Ethernet0S 10.75.138.0 is directly connected, Ethernet0S 10.44.237.0 is directly connected, Ethernet0S 10.31.222.0 is directly connected, Ethernet0S 10.16.209.0 is directly connected, Ethernet0S 10.145.0.0 is directly connected, Ethernet0S 10.141.0.0 is directly connected, Ethernet0S 10.138.0.0 is directly connected, Ethernet0S 10.128.0.0 is directly connected, Ethernet010.19.0.0 255.255.255.0 is subnetted, 1 subnetsC 10.19.64.0 is directly connected, Ethernet010.69.0.0 is variably subnetted, 2 subnets, 2 masksC 10.69.232.32 255.255.255.240 is directly connected, Ethernet0S 10.69.0.0 255.255.0.0 is directly connected, Ethernet0The following examples display all downloaded static routes. A P designates which route was installed using AAA route download.
Router# show ip routeCodes: C - connected, S - static, R - RIP, M - mobile, B - BGPD - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter areaN1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2E1 - OSPF external type 1, E2 - OSPF external type 2i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, * - candidate defaultU - per-user static route, o - ODR, P - periodic downloaded static routeT - traffic engineered routeGateway of last resort is 172.21.17.1 to network 0.0.0.0172.31.0.0/32 is subnetted, 1 subnetsP 172.31.229.41 is directly connected, Dialer1 20.0.0.0/24 is subnetted, 3 subnetsP 10.1.1.0 [200/0] via 172.31.229.41, Dialer1P 10.1.3.0 [200/0] via 172.31.229.41, Dialer1P 10.1.2.0 [200/0] via 172.31.229.41, Dialer1Router# show ip route static172.27.4.0/8 is variably subnetted, 2 subnets, 2 masksP 172.1.1.1/32 is directly connected, BRI0P 172.27.4.0/8 [1/0] via 103.1.1.1, BRI0S 172.31.0.0/16 [1/0] via 172.21.114.65, Ethernet0S 10.0.0.0/8 is directly connected, BRI0P 10.0.0.0/8 is directly connected, BRI0172.21.0.0/16 is variably subnetted, 5 subnets, 2 masksS 172.21.114.201/32 is directly connected, BRI0S 172.21.114.205/32 is directly connected, BRI0S 172.21.114.174/32 is directly connected, BRI0S 172.21.114.12/32 is directly connected, BRI0P 10.0.0.0/8 is directly connected, BRI0P 10.1.0.0/8 is directly connected, BRI0P 10.2.2.0/8 is directly connected, BRI0S* 0.0.0.0/0 [1/0] via 172.21.114.65, Ethernet0S 172.29.0.0/16 [1/0] via 172.21.114.65, Ethernet0The following example shows how to use the show ip route static download command to display all active and inactive routes installed using AAA route download:
Router# show ip route static downloadConnectivity: A - Active, I - InactiveA 10.10.0.0 255.0.0.0 BRI0A 10.11.0.0 255.0.0.0 BRI0A 10.12.0.0 255.0.0.0 BRI0A 10.13.0.0 255.0.0.0 BRI0I 10.20.0.0 255.0.0.0 172.21.1.1I 10.22.0.0 255.0.0.0 Serial0I 10.30.0.0 255.0.0.0 Serial0I 10.31.0.0 255.0.0.0 Serial1I 10.32.0.0 255.0.0.0 Serial1A 10.34.0.0 255.0.0.0 103.1.1.1A 10.36.1.1 255.255.255.255 BRI0 200 name remote1I 10.38.1.9 255.255.255.0 104.21.69.1
Specific Route Information
When you specify that you want information about a specific network displayed, more detailed statistics are shown. The following is sample output from the show ip route command when entered with the address 10.0.0.1:
Router# show ip route 10.0.0.1Routing entry for 10.0.0.1/32Known via "isis", distance 115, metric 20, type level-1Redistributing via isisLast update from 10.191.255.251 on Fddi1/0, 00:00:13 agoRouting Descriptor Blocks:* 10.22.22.2, from 10.191.255.247, via Serial2/3Route metric is 20, traffic share count is 110.191.255.251, from 10.191.255.247, via Fddi1/0Route metric is 20, traffic share count is 1When an IS-IS router advertises its link-state information, it includes one of its own IP addresses to be used as the originator IP address. When other routers calculate IP routes, they can store the originator IP address with each route in the routing table.
The example above shows the output from the show ip route command when looking at an IP route generated by IS-IS. Each path that is shown under the Routing Descriptor Blocks report displays two IP addresses. The first address (10.22.22.2) is the next hop address. The second is the originator IP address from the advertising IS-IS router. This address helps you determine where a particular IP route has originated in your network. In the example the route to 10.0.0.1/32 was originated by a router with IP address 10.191.255.247.
Table 2 describes the significant fields shown when using the show ip route command with an IP address (previous displays).
The following is sample output using the longer-prefixes keyword. When the longer-prefixes keyword is included, the address and mask pair becomes the prefix, and any address that matches that prefix is displayed. Therefore, multiple addresses are displayed.
In the following example, the logical AND operation is performed on the source address 10.0.0.0 and the mask 10.0.0.0, resulting in 10.0.0.0. Each destination in the routing table is also logically ANDed with the mask and compared to that result of 10.0.0.0. Any destinations that fall into that range are displayed in the output.
Router# show ip route 10.0.0.0 10.0.0.0 longer-prefixesCodes: I - IGRP derived, R - RIP derived, O - OSPF derived,C - connected, S - static, E - EGP derived, B - BGP derived,* - candidate default route, IA - OSPF inter area route,i - IS-IS derived, ia - IS-IS, U - per-user static route,o - on-demand routing, M - mobile, P - periodic downloaded static route,D - EIGRP, EX - EIGRP external, E1 - OSPF external type 1 route,E2 - OSPF external type 2 route, N1 - OSPF NSSA external type 1 route,N2 - OSPF NSSA external type 2 routeGateway of last resort is not setS 10.134.0.0 is directly connected, Ethernet0S 10.10.0.0 is directly connected, Ethernet0S 10.129.0.0 is directly connected, Ethernet0S 10.128.0.0 is directly connected, Ethernet0S 10.49.246.0 is directly connected, Ethernet0S 10.160.97.0 is directly connected, Ethernet0S 10.153.88.0 is directly connected, Ethernet0S 10.76.141.0 is directly connected, Ethernet0S 10.75.138.0 is directly connected, Ethernet0S 10.44.237.0 is directly connected, Ethernet0S 10.31.222.0 is directly connected, Ethernet0S 10.16.209.0 is directly connected, Ethernet0S 10.145.0.0 is directly connected, Ethernet0S 10.141.0.0 is directly connected, Ethernet0S 10.138.0.0 is directly connected, Ethernet0S 10.128.0.0 is directly connected, Ethernet010.19.0.0 255.255.255.0 is subnetted, 1 subnetsC 10.19.64.0 is directly connected, Ethernet010.69.0.0 is variably subnetted, 2 subnets, 2 masksC 10.69.232.32 255.255.255.240 is directly connected, Ethernet0S 10.69.0.0 255.255.0.0 is directly connected, Ethernet0The following output includes the tag 120 applied to the route 10.22.0.0/16. You must specify an IP prefix in order to see the tag value.
Router# show ip route 10.22.0.0Routing entry for 10.22.0.0/16Known via "isis", distance 115, metric 12Tag 120, type level-1Redistributing via isisLast update from 172.19.170.12 on Ethernet2, 01:29:13 agoRouting Descriptor Blocks:* 172.19.170.12, from 10.3.3.3, via Ethernet2Route metric is 12, traffic share count is 1Route tag 120Static Routes Using a DHCP Gateway Examples
The following example shows that IP route 10.8.8.0 is directly connected to the Internet and is the next-hop (option 3) default gateway. Routes 10.1.1.1 [1/0], 10.3.2.1 [24/0], and 172.2.2.2 [1/0] are static, and route 10.0.0.0/0 is a default route candidate.
Router# show ip routeCodes: C - connected, S - static, R - RIP, M - mobile, B - BGPD - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter areaN1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2E1 - OSPF external type 1, E2 - OSPF external type 2i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2ia - IS-IS inter area, * - candidate default, U - per-user static routeo - ODR, P - periodic downloaded static routeGateway of last resort is 10.0.19.14 to network 0.0.0.010.0.0.0/24 is subnetted, 1 subnetsC 10.8.8.0 is directly connected, Ethernet110.0.0.0/32 is subnetted, 1 subnetsS 10.1.1.1 [1/0] via 10.8.8.110.0.0.0/32 is subnetted, 1 subnetsS 10.3.2.1 [24/0] via 10.8.8.1172.0.0.0/32 is subnetted, 1 subnetsS 172.2.2.2 [1/0] via 10.8.8.110.0.0.0/28 is subnetted, 1 subnetsC 10.0.19.0 is directly connected, Ethernet010.0.0.0/24 is subnetted, 1 subnetsC 10.15.15.0 is directly connected, Loopback0S* 10.0.0.0/0 [1/0] via 10.0.19.14Related Commands
show isis database verbose
To display additional information about the Intermediate System-to-Intermediate System (IS-IS) database, use the show isis database verbose command in user EXEC or privileged EXEC mode.
show isis database verbose
Syntax Description
This command has no arguments or keywords.
Command Modes
User EXEC
Privileged EXECCommand History
12.0(5)S
This command was introduced.
12.2(27)SBC
This command was integrated into Cisco IOS Release 12.2(27)SBC.
Examples
The following is sample output from the show isis database verbose command:
Router# show isis database verboseIS-IS Level-1 Link State DatabaseLSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OLdtp-5.00-00 * 0x000000E6 0xC9BB 1042 0/0/0Area Address:49.0001NLPID: 0xCCHostname:dtp-5Router ID: 5.5.5.5IP Address: 172.21.39.5Metric:10 IP 172.21.39.0/24dtp-5.00-01 * 0x000000E7 0xAB36 1065 0/0/0Metric:10 IS-Extended dtp-5.01Affinity:0x00000000Interface IP Address:172.21.39.5Physical BW:10000000 bits/secReservable BW:1166000 bits/secBW Unreserved[0]: 1166000 bits/sec, BW Unreserved[1]: 1166000 bits/secBW Unreserved[2]: 1166000 bits/sec, BW Unreserved[3]: 1166000 bits/secBW Unreserved[4]: 1166000 bits/sec, BW Unreserved[5]: 1166000 bits/secBW Unreserved[6]: 1166000 bits/sec, BW Unreserved[7]: 1153000 bits/secMetric:0 ES dtp-5Table 3 describes the significant fields shown in the display.
The following example includes a route tag:
Router# show isis database verboseIS-IS Level-1 Link State Database:LSPID LSP Seq Num LSP Checksum LSP Holdtime ATT/P/OLdasher.00-00 0x000000F8 0xE57B 518 1/0/0Area Address: 49.0002NSPID: 0xCCHostname: dasherIP Address: 10.3.0.1Metric: 10 IP 172.19.170.0/24Metric: 10 IP 10.0.3.0/24Metric: 10 IP 10.0.3.3/30Metric: 10 IS-Extended dasher.02172.19.170.0/24Metric: 20 IP-Interarea 10.1.1.1/32Route Admin Tag: 60Metric: 20 IP-Interarea 205.171.0.6/32Route Admin Tag: 50Related Commands
summary-address (IS-IS)
To create aggregate addresses for Intermediate System-to-Intermediate System (IS-IS), use the summary-address command in router configuration mode. To restore the default, use the no form of this command.
summary-address address mask {level-1 | level-1-2 | level-2} [tag tag-number] [metric metric-value]
no summary-address address mask {level-1 | level-1-2 | level-2}[tag tag-number] [metric metric-value]
Syntax Description
Defaults
All routes are advertised individually.
Command Modes
Router configuration
Command History
Usage Guidelines
Multiple groups of addresses can be summarized for a given level. Routes learned from other routing protocols can also be summarized. The metric used to advertise the summary is the smallest metric of all the more specific routes. This command helps reduce the size of the routing table.
This command also reduces the size of the link-state packets (LSPs) and thus the link-state database (LSDB). It also helps network stability because a summary advertisement is depending on many more specific routes. A single route flap does not cause the summary advertisement to flap in most cases.
The drawback of summary addresses is that other routes might have less information to calculate the most optimal routing table for all individual destinations.
Examples
The following example redistributes Routing Information Protocol (RIP) routes into IS-IS. In a RIP network, there are IP routes for 10.1.1, 10.1.2, 10.1.3, 10.1.4, and so on. This example advertises only 10.1.0.0 into the IS-IS Level 1 link-state PDU. The summary address is tagged with 100 and given a metric value of 110.
router isisnet 01.0000.0000.0001.00redistribute rip level-1 metric 40summary-address 10.1.0.0 255.255.0.0 tag 100 metric 110
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