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Example: Configuring Segment Routing Global Blocks in SPRING for IS-IS to Increase Network Speed
This example shows how to define the segment routing label block (SRGB) label range for segment packet routing in networking (SPRING) or segment routing (SR) for the IS-IS protocol. This configuration ensures that the labels are more predictable across the segment routing domain and thereby increasing the speed of the network.
Requirements
This example uses the following hardware and software components:
Two MX Series routers
Junos OS Release 17.2 or later running on all devices
Before you configure the SRGB label range for SPRING in the IS-IS domain, be sure you configured the routing and signaling protocols.
Overview
Currently, Junos OS allows you to configure only node segment indices. The value of the start label depends on the dynamic label available in the system. Because there is no predictability of the dynamic label range being allocated to the SRGB, Junos OS allows you to configure the SRGB label range used by SPRING. The labels in the SRGB range are used for SPRING in the IS-IS domain. This means the labels advertised are more predictable and deterministic across the SPRING domain.
Topology
Figure 1 shows SRGB configured on router R1 and router R2.
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,
copy and paste the commands into the CLI at the [edit] hierarchy level, and then enter commit from configuration
mode.
R1
set chassis network-services enhanced-ip set interfaces ge-0/0/0 unit 0 family inet address 192.0.2.1/24 set interfaces ge-0/0/0 unit 0 family iso set interfaces ge-0/0/0 unit 0 family inet6 address 2001:db8:1:1::1/128 set interfaces ge-0/0/0 unit 0 family mpls set interfaces lo0 unit 0 family inet address 198.51.100.1/24 set interfaces lo0 unit 0 family iso address 49.0001.0010.0100.1001.00 set interfaces lo0 unit 0 family inet6 address 2001:db8:10:10::1/128 set protocols mpls interface ge-0/0/0.0 set protocols isis source-packet-routing srgb start-label 400000 set protocols isis source-packet-routing srgb index-range 4000 set protocols isis source-packet-routing node-segment ipv4-index 2001 set protocols isis source-packet-routing node-segment ipv6-index 3001 set protocols isis level 1 disable set protocols isis interface ge-0/0/0.0 set protocols isis interface lo0.0 passive
R2
set chassis network-services enhanced-ip set interfaces ge-0/0/0 unit 0 family inet address 192.0.2.2/24 set interfaces ge-0/0/0 unit 0 family iso set interfaces ge-0/0/0 unit 0 family inet6 address 2001:db8:1:1::2/64 set interfaces ge-0/0/0 unit 0 family mpls set interfaces lo0 unit 0 family inet address 198.51.100.2/24 set interfaces lo0 unit 0 family iso address 49.0001.0020.0200.2001.00 set interfaces lo0 unit 0 family inet6 address 2001:db8:20:20::1/128 set protocols mpls interface ge-0/0/0.0 set protocols isis source-packet-routing srgb start-label 400000 set protocols isis source-packet-routing srgb index-range 4000 set protocols isis source-packet-routing node-segment ipv4-index 2002 set protocols isis source-packet-routing node-segment ipv6-index 3002 set protocols isis level 1 disable set protocols isis interface ge-0/0/0.0 set protocols isis interface lo0.0 passive
Configuring Device R1
Step-by-Step Procedure
The following example requires that you navigate various levels in the configuration hierarchy. For information about navigating the CLI, see Using the CLI Editor in Configuration Mode in the Junos OS CLI User Guide.
To configure device R1:
Repeat this procedure for device R2 after modifying the appropriate interface names, addresses, and other parameters.
Configure enhanced-ip mode on the MX Series because the SRGB functionality is supported on routers with MPCs and MIC interfaces only. A system reboot is required after you commit this configuration.
[edit chassis network-services] user@R1# set enhanced-ip
Configure the interfaces.
[edit interfaces] user@R1# set ge-0/0/0 unit 0 family inet address 192.0.2.1/24 user@R1# set ge-0/0/0 unit 0 family iso user@R1# set ge-0/0/0 unit 0 family inet6 address 2001:db8:1:1::1/128 user@R1# set ge-0/0/0 unit 0 family mpls user@R1# set lo0 unit 0 family inet address 198.51.100.1/24 user@R1# set lo0 unit 0 family iso address 49.0001.0010.0100.1001.00 user@R1# set lo0 unit 0 family inet6 address 2001:db8:10:10::1/128
Configure the MPLS protocol on the interface. For SR to work, you can configure any of the statements under the [
edit protocols mpls] hierarchy. For example,abstract-hop,class-of-service,label-range,optimize-switchover-delay, et cetra.[edit protocols mpls] user@R1# set interface ge-0/0/0.0
Configure the start label and index range of SRGB.
Note:Ensure that the MPLS label for a binding segment ID (SID) is the sum of the SRGB start label and SID index value. In addition, SID index value must be less than or equal to the index-range value specified in the configuration.
Junos does not check whether the SID index is within the SRGB's range when the SID index is assigned through an ISIS export policy. If you configure an index that is out of range of the configured SRGB, you won’t see any error message in the logs or while committing the configuration. Junos OS shows a commit error only when you configure the SID under the [edit protocols isis source-packet-routing] hierarchy level.
[edit protocols isis source-packet-routing] user@R1# set srgb start-label 400000 user@R1# set srgb index-range 4000
Configure the IPv4 index value of the node segment.
[edit protocols isis source-packet-routing] user@R1# set node-segment ipv4-index 2001
Configure the IPv6 index value of the node segment.
[edit protocols isis source-packet-routing] user@R1# set node-segment ipv6-index 3001
Disable level 1, configure the IS-IS protocol on the interface, and configure loopback interface lo0.0 as passive..
[edit protocols isis ] user@R1# set level 1 disable user@R1# set interface ge-0/0/0.0 user@R1# set interface lo0.0 passive
Results
From configuration mode, confirm your configuration by entering the show chassis, show interfaces, and show protocols commands. If the output does not display the intended configuration, repeat the instructions in this example to correct the configuration.
user@R1# show chassis network-services enhanced-ip;
user@R1# show interfaces
ge-0/0/0 {
unit 0 {
family inet {
address 192.0.2.1/24;
}
family iso;
family inet6 {
address 2001:db8:1:1::1/128;
}
family mpls;
}
}
lo0 {
unit 0 {
family inet {
address 198.51.100.1/24;
}
family iso {
address 49.0001.0010.0100.1001.00;
}
family inet6 {
address 2001:db8:10:10::1/128;
}
}
}
user@R1# show protocols
mpls {
interface ge-0/0/0.0;
}
isis {
source-packet-routing {
srgb start-label 400000 index-range 4000;
node-segment {
ipv4-index 2001;
ipv6-index 3001;
}
}
level 1 disable;
interface ge-0/0/0.0;
interface lo0.0 {
passive;
}
}
Verification
Confirm that the configuration is working properly.
- Verifying IS-IS Neighbors
- Verifying the IS-IS Overview Information
- Verifying the IS-IS Configuration
- Verifying the Route Information of SRGB Label
- Verifying the Forwarding Table of SRGB Label 402002
- Verifying the Route of SRGB Label
- Verifying the Forwarding Table of SRGB Label 403002
Verifying IS-IS Neighbors
Purpose
Verify IS-IS neighbors.
Action
From operational mode, run the show isis adjacency command to display the IS-IS neighbor information.
user@R1> show isis adjacency
Interface System L State Hold (secs) SNPA ge-0/0/0.0 R2 2 Up 7 0:5:86:7e:cc:0
Meaning
The output displays the IS-IS neighbor information of device R1.
Verifying the IS-IS Overview Information
Purpose
Verify the IS-IS overview information.
Action
From operational mode, run the show isis overview command to display the IS-IS overview information.
user@R1> show isis overview
Instance: master
Router ID: 198.51.100.1
Hostname: R1
Sysid: 0010.0100.1001
Areaid: 49.0001
Adjacency holddown: enabled
Maximum Areas: 3
LSP life time: 1200
Attached bit evaluation: enabled
SPF delay: 200 msec, SPF holddown: 5000 msec, SPF rapid runs: 3
IPv4 is enabled, IPv6 is enabled, SPRING based MPLS is enabled
Traffic engineering: enabled
Restart: Disabled
Helper mode: Enabled
Layer2-map: Disabled
Source Packet Routing (SPRING): Enabled
SRGB Config Range:
SRGB Start-Label : 400000, SRGB Index-Range : 4000
SRGB Block Allocation: Success
SRGB Start Index : 400000, SRGB Size : 4000, Label-Range: [ 400000, 403999 ]
Node Segments: Enabled
Ipv4 Index : 2001, Ipv6 Index : 3001
Level 1
Internal route preference: 15
External route preference: 160
Prefix export count: 0
Wide metrics are enabled, Narrow metrics are enabled
Source Packet Routing is enabled
Level 2
Internal route preference: 18
External route preference: 165
Prefix export count: 0
Wide metrics are enabled, Narrow metrics are enabled
Source Packet Routing is enabledMeaning
The output displays the IS-IS overview information along with SPRING information.
Verifying the IS-IS Configuration
Purpose
Verify the IS-IS configuration.
Action
From operational mode, run the show route protocol
isis command to display the IS-IS route information.
user@R1> show route protocol isis
inet.0: 9 destinations, 9 routes (9 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
198.51.100.2/32 *[IS-IS/18] 00:17:27, metric 10
> to 192.0.2.2 via ge-0/0/0.0
inet.3: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
198.51.100.2/32 *[L-ISIS/14] 00:17:26, metric 10
> to 192.0.2.2 via ge-0/0/0.0
iso.0: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
mpls.0: 14 destinations, 14 routes (14 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
16 *[L-ISIS/14] 00:21:03, metric 0
> to 192.0.2.2 via ge-0/0/0.0, Pop
16(S=0) *[L-ISIS/14] 00:02:54, metric 0
> to 192.0.2.2 via ge-0/0/0.0, Pop
17 *[L-ISIS/14] 00:21:03, metric 0
> to 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0, Pop
17(S=0) *[L-ISIS/14] 00:02:54, metric 0
> to 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0, Pop
402002 *[L-ISIS/14] 00:17:26, metric 10
> to 192.0.2.2 via ge-0/0/0.0, Pop
402002(S=0) *[L-ISIS/14] 00:02:54, metric 10
> to 192.0.2.2 via ge-0/0/0.0, Pop
403002 *[L-ISIS/14] 00:17:23, metric 10
> to 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0, Pop
403002(S=0) *[L-ISIS/14] 00:02:54, metric 10
> to 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0, Pop
inet6.0: 7 destinations, 8 routes (7 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
2400:1:1:1::/64 *[IS-IS/18] 00:17:23, metric 20
> to 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0
2400:20:20:20::1/128
*[IS-IS/18] 00:17:23, metric 10
> to 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0
inet6.3: 1 destinations, 1 routes (1 active, 0 holddown, 0 hidden)
+ = Active Route, - = Last Active, * = Both
2400:20:20:20::1/128
*[L-ISIS/14] 00:17:23, metric 10
> to 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0
Meaning
The output displays the IS-IS route information along with segment routing information.
Verifying the Route Information of SRGB Label
Purpose
Verify the route information of SRGB label 402002 of IPv4 node 2002.
Action
From operational mode, run the show route label
402002 extensive command to display the route information of
label 402002 of IPv4 node 2002.
user@R1> show route label 402002 extensive
mpls.0: 14 destinations, 14 routes (14 active, 0 holddown, 0 hidden)
402002 (1 entry, 1 announced)
TSI:
KRT in-kernel 402002 /52 -> {Pop }
*L-ISIS Preference: 14
Level: 2
Next hop type: Router, Next hop index: 591
Address: 0xb7a2710
Next-hop reference count: 4
Next hop: 192.0.2.2 via ge-0/0/0.0, selected
Label operation: Pop
Load balance label: None;
Label element ptr: 0xb7a26a0
Label parent element ptr: 0x0
Label element references: 2
Label element child references: 0
Label element lsp id: 0
Session Id: 0x140
State: < Active Int >
Age: 19:24
Metric: 10
Validation State: unverified
ORR Generation-ID: 0
Task: IS-IS
Announcement bits (1): 1-KRT
AS path: I
402002(S=0) (1 entry, 1 announced)
TSI:
KRT in-kernel 402002 /56 -> {Pop }
*L-ISIS Preference: 14
Level: 2
Next hop type: Router, Next hop index: 593
Address: 0xb7a27d0
Next-hop reference count: 4
Next hop: 192.0.2.2 via ge-0/0/0.0, selected
Label operation: Pop
Load balance label: None;
Label element ptr: 0xb7a2760
Label parent element ptr: 0x0
Label element references: 2
Label element child references: 0
Label element lsp id: 0
Session Id: 0x140
State: < Active Int >
Age: 4:52
Metric: 10
Validation State: unverified
ORR Generation-ID: 0
Task: IS-IS
Announcement bits (1): 1-KRT
AS path: I Meaning
The output displays the details of the SRGB label 402002 of IPv4 node 2002.
Verifying the Forwarding Table of SRGB Label 402002
Purpose
Verify the forwarding table information of SRGB label 402002.
Action
user@R1> show route forwarding-table label 402002
Routing table: default.mpls
MPLS:
Destination Type RtRef Next hop Type Index NhRef Netif
402002 user 0 192.0.2.2 Pop 591 3 ge-0/0/0.0
402002(S=0) user 0 192.0.2.2 Pop 593 3 ge-0/0/0.0
Routing table: __mpls-oam__.mpls
MPLS:
Enabled protocols: Bridging, Single VLAN, Dual VLAN,
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 dscd 556 1Meaning
The output displays forwarding table information of SRGB label 402002 of IPv4 node 2002.
Verifying the Route of SRGB Label
Purpose
Verify the route of SRGB label of IPv6 node 3002.
Action
user@R1> show route label 403002 extensive
mpls.0: 14 destinations, 14 routes (14 active, 0 holddown, 0 hidden)
403002 (1 entry, 1 announced)
TSI:
KRT in-kernel 403002 /52 -> {Pop }
*L-ISIS Preference: 14
Level: 2
Next hop type: Router, Next hop index: 594
Address: 0xb7a2830
Next-hop reference count: 4
Next hop: 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0, selected
Label operation: Pop
Load balance label: None;
Label element ptr: 0xb7a26a0
Label parent element ptr: 0x0
Label element references: 2
Label element child references: 0
Label element lsp id: 0
Session Id: 0x141
State: < Active Int >
Age: 21:06 Metric: 10
Validation State: unverified
ORR Generation-ID: 0
Task: IS-IS
Announcement bits (1): 1-KRT
AS path: I
403002(S=0) (1 entry, 1 announced)
TSI:
KRT in-kernel 403002 /56 -> {Pop }
*L-ISIS Preference: 14
Level: 2
Next hop type: Router, Next hop index: 596
Address: 0xb7a2890
Next-hop reference count: 4
Next hop: 2001:db8:0000:205:86ff:fe7e:cc00 via ge-0/0/0.0, selected
Label operation: Pop
Load balance label: None;
Label element ptr: 0xb7a2760
Label parent element ptr: 0x0
Label element references: 2
Label element child references: 0
Label element lsp id: 0
Session Id: 0x141
State: < Active Int >
Age: 6:37 Metric: 10
Validation State: unverified
ORR Generation-ID: 0
Task: IS-IS
Announcement bits (1): 1-KRT
AS path: I
Meaning
The output displays forwarding table information of SRGB label 403002 of IPv6 node 3002.
Verifying the Forwarding Table of SRGB Label 403002
Purpose
Verify the forwarding table information of SRGB label 403002.
Action
user@R1> show route forwarding-table label 403002
Routing table: default.mpls
MPLS:
Destination Type RtRef Next hop Type Index NhRef Netif
403002 user 0 2001:db8:0000:205:86ff:fe7e:cc00
Pop 594 3 ge-0/0/0.0
403002(S=0) user 0 2001:db8:0000:205:86ff:fe7e:cc00
Pop 596 3 ge-0/0/0.0
Routing table: __mpls-oam__.mpls
MPLS:
Enabled protocols: Bridging, Single VLAN, Dual VLAN,
Destination Type RtRef Next hop Type Index NhRef Netif
default perm 0 dscd 556 1Meaning
The output displays forwarding table information of SRGB label 403002 of IPv6 node 3002.