Examples: Configuring IS-IS on Logical Systems
IS-IS Overview
The IS-IS protocol is an interior gateway protocol (IGP) that uses link-state information to make routing decisions.
IS-IS is a link-state IGP that uses the shortest-path-first (SPF) algorithm to determine routes. IS-IS evaluates the topology changes and determines whether to perform a full SPF recalculation or a partial route calculation (PRC). This protocol originally was developed for routing International Organization for Standardization (ISO) Connectionless Network Protocol (CLNP) packets.
Like OSPF routing, IS-IS uses hello packets that allow network convergence to occur quickly when network changes are detected. IS-IS uses the SPF algorithm to determine routes. Using SPF, IS-IS evaluates network topology changes and determines if a full or partial route calculation is required.
 | Note: Because IS-IS uses ISO addresses, the configuration of IP version 6 (IPv6) and IP version 4 (IPv4) implementations of IS-IS is identical. |
This section discusses the following topics:
- IS-IS Terminology
- ISO Network Addresses
- IS-IS Packets
- Persistent Route Reachability
- IS-IS Support for Multipoint Network Clouds
- Installing a Default Route to the Nearest Routing Device That Operates at Both IS-IS Levels
IS-IS Terminology
An IS-IS network is a single autonomous system (AS), also called a routing domain, that consists of end systems and intermediate systems. End systems are network entities that send and receive packets. Intermediate systems send and receive packets and relay (forward) packets. (Intermediate system is the Open System Interconnection [OSI] term for a router.) ISO packets are called network PDUs.
In IS-IS, a single AS can be divided into smaller groups called areas. Routing between areas is organized hierarchically, allowing a domain to be administratively divided into smaller areas. This organization is accomplished by configuring Level 1 and Level 2 intermediate systems. Level 1 systems route within an area; when the destination is outside an area, they route toward a Level 2 system. Level 2 intermediate systems route between areas and toward other ASs. No IS-IS area functions strictly as a backbone.
Level 1 routers share intra-area routing information, and Level 2 routers share interarea information about IP addresses available within each area. Uniquely, IS-IS routers can act as both Level 1 and Level 2 routers, sharing intra-area routes with other Level 1 routers and interarea routes with other Level 2 routers.
The propagation of link-state updates is determined by the level boundaries. All routers within a level maintain a complete link-state database of all other routers in the same level. Each router then uses the Dijkstra algorithm to determine the shortest path from the local router to other routers in the link-state database.
ISO Network Addresses
IS-IS uses ISO network addresses. Each address identifies a point of connection to the network, such as a router interface, and is called a network service access point (NSAP).
IS-IS supports multiple NSAP addresses on the loopback lo0 interface.
An end system can have multiple NSAP addresses, in which case the addresses differ only by the last byte (called the n-selector). Each NSAP represents a service that is available at that node. In addition to having multiple services, a single node can belong to multiple areas.
Each network entity also has a special network address called a network entity title (NET). Structurally, an NET is identical to an NSAP address but has an n-selector of 00. Most end systems and intermediate systems have one NET. Intermediate systems that participate in multiple areas can have multiple NETs.
The following ISO addresses illustrate the IS-IS address format:
NETs take several forms, depending on your network requirements. NET addresses are hexadecimal and range from 8 octets to 20 octets in length. Generally, the format consists of an authority and format Identifier (AFI), a domain ID, an area ID, a system identifier, and a selector. The simplest format omits the domain ID and is 10 octets long. For example, the NET address 49.0001.1921.6800.1001.00 consists of the following parts:
- 49—AFI
- 0001—Area ID
- 1921.6800.1001—System identifier
- 00—Selector
The system identifier must be unique within the network. For an IP-only network, we recommend using the IP address of an interface on the router. Configuring a loopback NET address with the IP address is helpful when troubleshooting is required on the network.
The first portion of the address is the area number, which is a variable number from 1 through 13 bytes. The first byte of the area number (49) is the authority and format indicator (AFI). The next bytes are the assigned domain (area) identifier, which can be from 0 through 12 bytes. In the examples above, the area identifier is 0001.
The next six bytes form the system identifier. The system identifier can be any six bytes that are unique throughout the entire domain. The system identifier commonly is the media access control (MAC) address (as in the first example, 00a0.c96b.c490) or the IP address expressed in binary-coded decimal (BCD) (as in the second example, 2081.9716.9018, which corresponds to IP address 208.197.169.18). The last byte (00) is the n-selector.
| Note: The system identifier cannot be 0000.0000.0000. All 0s is an illegal setting, and the adjacency is not formed with this setting. |
To provide help with IS-IS debugging, the Junos® operating system (Junos OS) supports dynamic mapping of ISO system identifiers to the hostname. Each system can be configured with a hostname, which allows the system identifier-to-hostname mapping to be carried in a dynamic hostname type, length, and value (TLV) tuple in IS-IS link-state PDUs. This enables intermediate systems in the routing domain to learn about the ISO system identifier of a particular intermediate system.
IS-IS Packets
Each IS-IS PDU shares a common header. IS-IS uses the following PDUs to exchange protocol information:
- IS-IS hello (IIH) PDUs—Broadcast to discover the
identity of neighboring IS-IS systems and to determine whether the
neighbors are Level 1 or Level 2 intermediate systems.
IS-IS hello PDUs establish adjacencies with other routers and have three different formats: one for point-to-point hello packets, one for Level 1 broadcast links, and one for Level 2 broadcast links. Level 1 routers must share the same area address to form an adjacency, while Level 2 routers do not have this limitation. The request for adjacency is encoded in the Circuit type field of the PDU.
Hello PDUs have a preset length assigned to them. The IS-IS router does not resize any PDU to match the maximum transmission unit (MTU) on a router interface. Each interface supports the maximum IS-IS PDU of 1492 bytes, and hello PDUs are padded to meet the maximum value. When the hello is sent to a neighboring router, the connecting interface supports the maximum PDU size.
- Link-state PDUs—Contain information about the state
of adjacencies to neighboring IS-IS systems. Link-state PDUs are flooded
periodically throughout an area.
Also included is metric and IS-IS neighbor information. Each link-state PDU must be refreshed periodically on the network and is acknowledged by information within a sequence number PDU.
On point-to-point links, each link-state PDU is acknowledged by a partial sequence number PDU (PSNP), but on broadcast links, a complete sequence number PDU (CSNP) is sent out over the network. Any router that finds newer link-state PDU information in the CSNP then purges the out-of-date entry and updates the link-state database.
Link-state PDUs support variable-length subnet mask addressing.
- Complete sequence number PDUs (CSNPs)—Contain a
complete list of all link-state PDUs in the IS-IS database. CSNPs
are sent periodically on all links, and the receiving systems use
the information in the CSNP to update and synchronize their link-state
PDU databases. The designated router multicasts CSNPs on broadcast
links in place of sending explicit acknowledgments for each link-state
PDU.
Contained within the CSNP is a link-state PDU identifier, a lifetime, a sequence number, and a checksum for each entry in the database. Periodically, a CSNP is sent on both broadcast and point-to-point links to maintain a correct database. Also, the advertisement of CSNPs occurs when an adjacency is formed with another router. Like IS-IS hello PDUs, CSNPs come in two types: Level 1 and Level 2.
When a device receives a CSNP, it checks the database entries against its own local link-state database. If it detects missing information, the device requests specific link-state PDU details using a partial sequence number PDU (PSNP).
- Partial sequence number PDUs (PSNPs)—Sent multicast
by a receiver when it detects that it is missing a link-state PDU
(when its link-state PDU database is out of date). The receiver sends
a PSNP to the system that transmitted the CSNP, effectively requesting
that the missing link-state PDU be transmitted. That routing device,
in turn, forwards the missing link-state PDU to the requesting routing
device.
A PSNP is used by an IS-IS router to request link-state PDU information from a neighboring router. A PSNP can also explicitly acknowledge the receipt of a link-state PDU on a point-to-point link. On a broadcast link, a CSNP is used as implicit knowledge. Like hello PDUs and CSNPs, the PSNP also has two types: Level 1 and Level 2.
When a device compares a CSNP to its local database and determines that a link-state PDU is missing, the router issues a PSNP for the missing link-state PDU, which is returned in a link-state PDU from the router sending the CSNP. The received link-state PDU is then stored in the local database, and an acknowledgment is sent back to the originating router.
Persistent Route Reachability
IPv4 and IPv6 route reachability information in IS-IS link-state PDUs is preserved when you commit a configuration. IP prefixes are preserved with their original packet fragment upon link-state PDU regeneration.
IS-IS Support for Multipoint Network Clouds
IS-IS does not support multipoint configurations. Therefore, when configuring Frame Relay or Asynchronous Transfer Mode (ATM) networks, you must configure them as collections of point-to-point links, not as multipoint clouds.
Installing a Default Route to the Nearest Routing Device That Operates at Both IS-IS Levels
When a routing device that operates as both a Level 1 and Level 2 router (Router B) determines that it can reach at least one area other than its own (for example, in Area Y), it sets the ATTACHED bit in its Level 1 link-state PDU. Thereafter, the Level 1 router (Router A) introduces a default route pointing to the nearest attached routing device that operates as both a Level 1 and Level 2 router (Router B). See Figure 1.
Figure 1: Install Default Route to Nearest Routing Device That Operates at Both Level 1 and Level 2
Example: Configuring IS-IS on Logical Systems Within the Same Router
This example shows how to configure an IS-IS network by using multiple logical systems that are running on a single physical router. The logical systems are connected by logical tunnel interfaces.
Requirements
You must connect the logical systems by using logical tunnel (lt) interfaces. See Example: Connecting Logical Systems Within the Same Router Using Logical Tunnel Interfaces.
Overview
This example shows an IS-IS configuration with three logical systems running on one physical router. Each logical system has its own routing table. The configuration enables the protocol on all logical tunnel interfaces that participate in the IS-IS domain.
Figure 2 shows the sample network.
Figure 2: IS-IS on Logical Systems
Configuration
CLI Quick Configuration
To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure IS-IS on logical systems:
- Configure the logical tunnel interface on Logical System
LS1 connecting to Logical System LS2.[edit logical-systems LS1]user@host# set interfaces lt-0/1/0 unit 2 description LS1->LS2user@host# set interfaces lt-0/1/0 unit 2 encapsulation ethernetuser@host# set interfaces lt-0/1/0 unit 2 peer-unit 1user@host# set interfaces lt-0/1/0 unit 2 family inet address 10.0.0.1/30user@host# set interfaces lt-0/1/0 unit 2 family iso
- Configure the logical tunnel interface on Logical System
LS1 connecting to Logical System LS3.[edit logical-systems LS1]user@host# set interfaces lt-0/1/0 unit 0 description LS1->LS3user@host# set interfaces lt-0/1/0 unit 0 encapsulation ethernetuser@host# set interfaces lt-0/1/0 unit 0 peer-unit 5user@host# set interfaces lt-0/1/0 unit 0 family inet address 10.0.1.2/30user@host# set interfaces lt-0/1/0 unit 0 family iso
- Configure the logical tunnel interface on Logical System
LS2 connecting to Logical System LS1.[edit logical-systems LS2]user@host# set interfaces lt-0/1/0 unit 1 description LS2->LS1user@host# set interfaces lt-0/1/0 unit 1 encapsulation ethernetuser@host# set interfaces lt-0/1/0 unit 1 peer-unit 2user@host# set interfaces lt-0/1/0 unit 1 family inet address 10.0.0.2/30user@host# set interfaces lt-0/1/0 unit 1 family iso
- Configure the logical tunnel interface on Logical System
LS2 connecting to Logical System LS3.[edit logical-systems LS2]user@host# set interfaces lt-0/1/0 unit 4 description LS2->LS3user@host# set interfaces lt-0/1/0 unit 4 encapsulation ethernetuser@host# set interfaces lt-0/1/0 unit 4 peer-unit 3user@host# set interfaces lt-0/1/0 unit 4 family inet address 10.0.2.2/30user@host# set interfaces lt-0/1/0 unit 4 family iso
- Configure the logical tunnel interface on Logical System
LS3 connecting to Logical System LS2.[edit logical-systems LS3]user@host# set interfaces lt-0/1/0 unit 3 description LS3->LS2user@host# set interfaces lt-0/1/0 unit 3 encapsulation ethernetuser@host# set interfaces lt-0/1/0 unit 3 peer-unit 4user@host# set interfaces lt-0/1/0 unit 3 family inet address 10.0.2.1/30user@host# set interfaces lt-0/1/0 unit 3 family iso
- Configure the logical tunnel interface on Logical System
LS3 connecting to Logical System LS1.[edit logical-systems LS3]user@host# set interfaces lt-0/1/0 unit 5 description LS3->LS1user@host# set interfaces lt-0/1/0 unit 5 encapsulation ethernetuser@host# set interfaces lt-0/1/0 unit 5 peer-unit 0user@host# set interfaces lt-0/1/0 unit 5 family inet address 10.0.1.1/30user@host# set interfaces lt-0/1/0 unit 5 family iso
- Configure the ISO address on the loopback interface for
the three logical systems.[edit logical-systems LS1]user@host# set interfaces lo0 unit 1 family iso address 49.0001.1720.1600.1001.00user@host# set protocols isis interface lo0.1 passive[edit logical-systems LS2]user@host# set interfaces lo0 unit 2 family iso address 49.0001.1720.1600.2002.00user@host# set protocols isis interface lo0.2 passive[edit logical-systems LS3]user@host# set interfaces lo0 unit 3 family iso address 49.0001.1234.1600.2231.00user@host# set protocols isis interface lo0.3 passive
- Configure IS-IS on all the interfaces.[edit logical-systems LS1 protocols isis]user@host# set interface lt-0/1/0.0user@host# set interface lt-0/1/0.2[edit logical-systems LS2 protocols isis]user@host# set interface lt-0/1/0.1 user@host# set interface lt-0/1/0.4[edit logical-systems LS3 protocols isis]user@host# set interface lt-0/1/0.5user@host# set interface lt-0/1/0.3
If you are done configuring the device, commit the configuration.
[edit]user@host# commit
Results
From configuration mode, confirm your configuration by issuing the show logical-systems command. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
user@host# show logical-systemsLS1 {
interfaces {
lt-0/1/0 {
unit 0 {
description LS1->LS3;
encapsulation ethernet;
peer-unit 5;
family inet {
address 10.0.1.2/30;
}
family iso;
}
unit 2 {
description LS1->LS2;
encapsulation ethernet;
peer-unit 1;
family inet {
address 10.0.0.1/30;
}
family iso;
}
}
lo0 {
unit 1 {
family iso {
address 49.0001.1720.1600.1001.00;
}
}
}
}
protocols {
isis {
interface lt-0/1/0.0;
interface lt-0/1/0.2;
interface lo0.1 {
passive;
}
}
}
}
LS2 {
interfaces {
lt-0/1/0 {
unit 1 {
description LS2->LS1;
encapsulation ethernet;
peer-unit 2;
family inet {
address 10.0.0.2/30;
}
family iso;
}
unit 4 {
description LS2->LS3;
encapsulation ethernet;
peer-unit 3;
family inet {
address 10.0.2.2/30;
}
family iso;
}
}
lo0 {
unit 2 {
family iso {
address 49.0001.1720.1600.2002.00;
}
}
}
}
protocols {
isis {
interface lt-0/1/0.1;
interface lt-0/1/0.4;
interface lo0.2 {
passive;
}
}
}
}
LS3 {
interfaces {
lt-0/1/0 {
unit 3 {
description LS3->LS2;
encapsulation ethernet;
peer-unit 4;
family inet {
address 10.0.2.1/30;
}
family iso;
}
unit 5 {
description LS3->LS1;
encapsulation ethernet;
peer-unit 0;
family inet {
address 10.0.1.1/30;
}
family iso;
}
}
lo0 {
unit 3 {
family iso {
address 49.0001.1234.1600.2231.00;
}
}
}
}
protocols {
isis {
interface lt-0/1/0.3;
interface lt-0/1/0.5;
interface lo0.3 {
passive;
}
}
}
} Verification
Confirm that the configuration is working properly.
Verifying That the Logical Systems Are Up
Purpose
Make sure that the interfaces are properly configured.
Action
user@host> show interfaces terseInterface Admin Link Proto Local Remote
...
lt-0/1/0 up up
lt-0/1/0.0 up up inet 10.0.1.2/30
iso
lt-0/1/0.1 up up inet 10.0.0.2/30
iso
lt-0/1/0.2 up up inet 10.0.0.1/30
iso
lt-0/1/0.3 up up inet 10.0.2.1/30
iso
lt-0/1/0.4 up up inet 10.0.2.2/30
iso
lt-0/1/0.5 up up inet 10.0.1.1/30
iso
... Verifying Connectivity Between the Logical Systems
Purpose
Make sure that the IS-IS adjacencies are established by checking the logical system routing entries and by pinging the logical systems.
Action
user@host> show route logical-system LS1inet.0: 5 destinations, 5 routes (5 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.0.0/30 *[Direct/0] 3w0d 01:37:52
> via lt-0/1/0.2
10.0.0.1/32 *[Local/0] 3w0d 01:37:52
Local via lt-0/1/0.2
10.0.1.0/30 *[Direct/0] 3w0d 01:37:52
> via lt-0/1/0.0
10.0.1.2/32 *[Local/0] 3w0d 01:37:52
Local via lt-0/1/0.0
10.0.2.0/30 *[IS-IS/15] 3w0d 01:37:13, metric 20
> to 10.0.1.1 via lt-0/1/0.0
to 10.0.0.2 via lt-0/1/0.2
iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
49.0001.1720.1600.1001/72
*[Direct/0] 3w0d 01:37:52
> via lo0.1
user@host> show route logical-system LS2inet.0: 5 destinations, 5 routes (5 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.0.0/30 *[Direct/0] 3w0d 01:38:01
> via lt-0/1/0.1
10.0.0.2/32 *[Local/0] 3w0d 01:38:01
Local via lt-0/1/0.1
10.0.1.0/30 *[IS-IS/15] 3w0d 01:37:01, metric 20
to 10.0.0.1 via lt-0/1/0.1
> to 10.0.2.1 via lt-0/1/0.4
10.0.2.0/30 *[Direct/0] 3w0d 01:38:01
> via lt-0/1/0.4
10.0.2.2/32 *[Local/0] 3w0d 01:38:01
Local via lt-0/1/0.4
iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
49.0001.1720.1600.2002/72
*[Direct/0] 3w0d 01:38:01
> via lo0.2
user@host> show route logical-system LS3inet.0: 5 destinations, 5 routes (5 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
10.0.0.0/30 *[IS-IS/15] 3w0d 01:37:10, metric 20
to 10.0.2.2 via lt-0/1/0.3
> to 10.0.1.2 via lt-0/1/0.5
10.0.1.0/30 *[Direct/0] 3w0d 01:38:10
> via lt-0/1/0.5
10.0.1.1/32 *[Local/0] 3w0d 01:38:11
Local via lt-0/1/0.5
10.0.2.0/30 *[Direct/0] 3w0d 01:38:11
> via lt-0/1/0.3
10.0.2.1/32 *[Local/0] 3w0d 01:38:11
Local via lt-0/1/0.3
iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
49.0001.1234.1600.2231/72
*[Direct/0] 3w0d 01:38:11
> via lo0.3
From LS1, Ping LS3
user@host> set cli logical-system LS1user@host:LS1> ping 10.0.2.1PING 10.0.2.1 (10.0.2.1): 56 data bytes 64 bytes from 10.0.2.1: icmp_seq=0 ttl=63 time=1.264 ms 64 bytes from 10.0.2.1: icmp_seq=1 ttl=63 time=1.189 ms 64 bytes from 10.0.2.1: icmp_seq=2 ttl=63 time=1.165 ms ^C --- 10.0.2.1 ping statistics --- 3 packets transmitted, 3 packets received, 0% packet loss round-trip min/avg/max/stddev = 1.165/1.206/1.264/0.042 ms
From LS3, Ping LS1
user@host> set cli logical-system LS3user@host:LS3> ping 10.0.0.1PING 10.0.0.1 (10.0.0.1): 56 data bytes 64 bytes from 10.0.0.1: icmp_seq=0 ttl=63 time=1.254 ms 64 bytes from 10.0.0.1: icmp_seq=1 ttl=63 time=1.210 ms ^C --- 10.0.0.1 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max/stddev = 1.210/1.232/1.254/0.022 ms
From LS1, Ping LS2
user@host> set cli logical-system LS1user@host:LS1> ping 10.0.2.2PING 10.0.2.2 (10.0.2.2): 56 data bytes 64 bytes from 10.0.2.2: icmp_seq=0 ttl=64 time=1.240 ms 64 bytes from 10.0.2.2: icmp_seq=1 ttl=64 time=1.204 ms 64 bytes from 10.0.2.2: icmp_seq=2 ttl=64 time=1.217 ms ^C --- 10.0.2.2 ping statistics --- 3 packets transmitted, 3 packets received, 0% packet loss round-trip min/avg/max/stddev = 1.204/1.220/1.240/0.015 ms
From LS2, Ping LS1
user@host> set cli logical-system LS2user@host:LS2> ping 10.0.1.2PING 10.0.1.2 (10.0.1.2): 56 data bytes 64 bytes from 10.0.1.2: icmp_seq=0 ttl=64 time=1.308 ms 64 bytes from 10.0.1.2: icmp_seq=1 ttl=64 time=1.235 ms ^C --- 10.0.1.2 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max/stddev = 1.235/1.272/1.308/0.037 ms
From LS2, Ping LS3
user@host> set cli logical-system LS2user@host:LS2> ping 10.0.1.1PING 10.0.1.1 (10.0.1.1): 56 data bytes 64 bytes from 10.0.1.1: icmp_seq=0 ttl=64 time=1.253 ms 64 bytes from 10.0.1.1: icmp_seq=1 ttl=64 time=1.194 ms 64 bytes from 10.0.1.1: icmp_seq=2 ttl=64 time=1.212 ms 64 bytes from 10.0.1.1: icmp_seq=3 ttl=64 time=1.221 ms 64 bytes from 10.0.1.1: icmp_seq=4 ttl=64 time=1.195 ms ^C --- 10.0.1.1 ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max/stddev = 1.194/1.215/1.253/0.022 ms
From LS3, Ping LS2
user@host> set cli logical-system LS3user@host:LS3> ping 10.0.0.2PING 10.0.0.2 (10.0.0.2): 56 data bytes 64 bytes from 10.0.0.2: icmp_seq=0 ttl=64 time=1.240 ms 64 bytes from 10.0.0.2: icmp_seq=1 ttl=64 time=1.217 ms ^C --- 10.0.0.2 ping statistics --- 2 packets transmitted, 2 packets received, 0% packet loss round-trip min/avg/max/stddev = 1.217/1.228/1.240/0.012 ms
Example: Configuring an IS-IS Default Route Policy on Logical Systems
This example shows logical systems configured on a single physical router and explains how to configure a default route on one logical system.
Requirements
No special configuration beyond device initialization is required before configuring this example.
Overview
This example shows a logical system redistributing a default route to other logical systems. All logical systems are running IS-IS. A common reason for a default route is to provide a path for sending traffic destined outside the IS-IS domain.
In this example, the default route is not used for forwarding traffic. The no-install statement prevents the route from being installed in the forwarding table of Logical System LS3. If you configure a route so it is not installed in the forwarding table, the route is still eligible to be exported from the routing table to other protocols. The discard statement silently drops packets without notice.
Figure 3 shows the sample network.
Figure 3: IS-IS Logical Systems with a Default Route to an ISP
Configuration
CLI Quick Configuration
To quickly configure this example, copy the following commands, paste them into a text file, remove any line breaks, change any details necessary to match your network configuration, and then copy and paste the commands into the CLI at the [edit] hierarchy level.
Step-by-Step Procedure
The following example requires you to navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the CLI User Guide.
To configure an IS-IS default route policy on logical systems:
- Configure the logical tunnel interfaces.[edit logical-systems LS3 interfaces lt-1/2/0]user@R1# set unit 3 description LS3->LS2user@R1# set unit 3 encapsulation ethernetuser@R1# set unit 3 peer-unit 4user@R1# set unit 3 family inet address 10.0.2.1/30user@R1# set unit 3 family isouser@R1# set unit 5 description LS3->LS1user@R1# set unit 5 encapsulation ethernetuser@R1# set unit 5 peer-unit 0user@R1# set unit 5 family inet address 10.0.1.1/30user@R1# set unit 5 family iso[edit logical-systems LS3 interfaces lo0 unit 3]user@R1# set family iso address 49.0001.1234.1600.2231.00
- Enable IS-IS on the interfaces.[edit logical-systems LS3 protocols isis]user@R1# set interface lt-1/2/0.3user@R1# set interface lt-1/2/0.5user@R1# set interface lo0.3 passive
Configure the default route on Logical System LS3.
[edit logical-systems LS3 routing-options]user@R1# set static route 0.0.0.0/0 discard user@R1# set static route 0.0.0.0/0 no-installConfigure the default route policy on Logical System LS3.
[edit logical-systems LS3 policy-options]user@R1# set policy-statement isis-default from protocol static user@R1# set policy-statement isis-default from route-filter 0.0.0.0/0 exact user@R1# set policy-statement isis-default then acceptApply the export policy to IS-IS on Logical System LS3.
[edit logical-systems LS3 protocols isis]user@R1# set export isis-defaultIf you are done configuring the device, commit the configuration.
[edit]user@R1# commit
Results
From configuration mode, confirm your configuration by issuing the show logical-systems LS3 command. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
Verification
Confirm that the configuration is working properly.
Verifying That the Static Route Is Redistributed
Purpose
Make sure that the IS-IS policy is working by checking the routing tables.
Action
user@R1> show route logical-system LS3inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
0.0.0.0/0 *[Static/5] 00:00:45
Discard
10.0.0.0/30 *[IS-IS/15] 1w0d 10:14:14, metric 20
to 10.0.2.2 via lt-1/2/0.3
> to 10.0.1.2 via lt-1/2/0.5
10.0.1.0/30 *[Direct/0] 1w0d 10:15:18
> via lt-1/2/0.5
10.0.1.1/32 *[Local/0] 1w0d 10:15:18
Local via lt-1/2/0.5
10.0.2.0/30 *[Direct/0] 1w0d 10:15:18
> via lt-1/2/0.3
10.0.2.1/32 *[Local/0] 1w0d 10:15:18
Local via lt-1/2/0.3
iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
49.0001.1234.1600.2231/72
*[Direct/0] 1w0d 10:17:19
> via lo0.3user@R1> show route logical-system LS2inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
0.0.0.0/0 *[IS-IS/160] 00:01:38, metric 10
> to 10.0.2.1 via lt-1/2/0.4
10.0.0.0/30 *[Direct/0] 1w0d 10:16:11
> via lt-1/2/0.1
10.0.0.2/32 *[Local/0] 1w0d 10:16:11
Local via lt-1/2/0.1
10.0.1.0/30 *[IS-IS/15] 1w0d 10:15:07, metric 20
> to 10.0.0.1 via lt-1/2/0.1
to 10.0.2.1 via lt-1/2/0.4
10.0.2.0/30 *[Direct/0] 1w0d 10:16:11
> via lt-1/2/0.4
10.0.2.2/32 *[Local/0] 1w0d 10:16:11
Local via lt-1/2/0.4
iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
49.0001.1720.1600.2002/72
*[Direct/0] 1w0d 10:18:12
> via lo0.2user@R1> show route logical-system LS1inet.0: 6 destinations, 6 routes (6 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
0.0.0.0/0 *[IS-IS/160] 00:02:01, metric 10
> to 10.0.1.1 via lt-1/2/0.0
10.0.0.0/30 *[Direct/0] 1w0d 10:16:34
> via lt-1/2/0.2
10.0.0.1/32 *[Local/0] 1w0d 10:16:34
Local via lt-1/2/0.2
10.0.1.0/30 *[Direct/0] 1w0d 10:16:34
> via lt-1/2/0.0
10.0.1.2/32 *[Local/0] 1w0d 10:16:34
Local via lt-1/2/0.0
10.0.2.0/30 *[IS-IS/15] 1w0d 10:15:55, metric 20
to 10.0.1.1 via lt-1/2/0.0
> to 10.0.0.2 via lt-1/2/0.2
iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
49.0001.1720.1600.1001/72
*[Direct/0] 1w0d 10:18:35
> via lo0.1Meaning
The routing table on Logical System LS3 contains the default 0.0.0.0/0 route from protocol Static. The routing tables on Logical System LS1 and Logical System LS2 contain the default 0.0.0.0/0 route from protocol IS-IS. If Logical System LS1 and Logical System LS2 receive packets destined for networks not specified in their routing tables, those packets will be sent to Logical System LS3 for further processing. This configuration assumes that Logical System LS3 has a connection to an ISP or another external network.
