Understanding Label Space
This chapter contains configurations for Label Space. It also provides an overview of Label Space concepts.
Overview
The Label space refers to the scope of labels in a given LSR. It determines assignment and distribution of labels to a given peer. During data flow, it decides the key for looking up MPLS table and takes appropriate action based on the entry. Label space is designated either as platform label space or per-interface label space.
Per-platform label space
In this implementation, a label must be unique for the entire platform. A label will be interpreted the same way at all the interfaces. The FIB entry in the router does not contain incoming interface related information. Thus the incoming traffic will be matched only with the label.
Per-interface label space
In this implementation, a label must be unique for a given input interface. A label will be interpreted Uniquely at different interface which allows us to re-use label for different entries. The FIB entry in router must contain incoming interface information along with label. Thus the incoming traffic will be matched with label and incoming interface.
Topology
LDP Topology
Configuration
Per-Platform Label Space
PE1
PE1#configure terminal | Enter configure mode |
PE1(config)#interface lo | Enter interface mode. |
PE1(config-if)#ip address 1.1.1.1/32 | Configure IP address for the loopback address |
PE1(config-if)#exit | Exit interface mode |
PE1(config)#interface xe6 | Specify the interface (xe6)to be configured |
PE1(config-if)#ip address 10.10.10.1/24 | Configure IP address for the interface |
PE1(config-if)#no shutdown | Administratively bringing up the interface |
PE1(config-if)#exit | Exit interface mode |
PE1(config)#router ospf 100 | Configure the routing process and specify the Process ID (100) |
PE1(config-router)#network 10.10.10.0/ 24 area 0 PE1(config-router)#network 1.1.1.1/32 area 0 | Define the interface on which OSPF runs and associate the area ID(0)with the interface |
PE1(config-router)#exit | Exit configure mode |
PE1(config)#router ldp | Enter router mode for LDP |
PE1(config-router)#exit | Exit router mode for LDP |
PE1(config)#interface xe6 | Specify the interface (xe6)to be configured |
PE1(config-if)#label-switching | Enabling label switching capability on router |
PE1(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
PE1(config-if)#exit | Exit interface mode |
PE1(config)#exit | Exit configure mode |
P
P#configure terminal | Enter configure mode. |
P(config)#interface lo | Enter interface mode. |
P(config-if)#ip address 2.2.2.2/32 | Configure IP address for the loopback address |
P(config-if)#exit | Exit interface mode |
P(config)#interface xe6 | Specify the interface (xe6)to be configured |
P(config-if)#ip address 10.10.10.2/24 | Configure IP address for the interface |
P(config-if)#no shutdown | Administratively bringing up the interface |
P(config)#interface xe1 | Specify the interface (xe1)to be configured |
P(config-if)#ip address 20.20.20.1/24 | Configure IP address for the interface |
P(config)#router ospf 100 | Configure the routing process and specify the Process ID (100) |
P(config-router)#network 10.10.10.0/24 area 0 P(config-router)#network 20.20.20.0/24 area 0 P(config-router)#network 2.2.2.2/32 area 0 | Define the interface on which OSPF runs and associate the area ID (0)with the interface |
P(config-router)#exit | Exit router mode |
P(config)#router ldp | Enter router mode for LDP |
P(config-router)#exit | Exit router mode for LDP |
P(config)#mpls min-label-value 1000 max-label-value 50000 label-space 0 | Configure the minimum label value and maximum label value to be used by Platform label space (Label space 0) |
P(config)#interface xe6 | Specify the interface (xe6)to be configured |
P(config-if)#label-switching | Enabling label switching capability on router |
P(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
P(config-if)#exit | Exit interface mode |
P(config)#interface xe1 | Specify the interface (xe1)to be configured |
P(config-if)#label-switching | Enabling label switching capability on router |
P(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
P(config-if)#exit | Exit interface mode |
P(config)#exit | Exit configure mode |
PE2
PE2#configure terminal | Enter configure mode. |
PE2(config)#interface lo | Enter interface mode. |
PE2(config-if)#ip address 3.3.3.3/32 | Configure IP address for the loopback address |
PE2(config-if)#exit | Exit interface mode |
PE2(config)#interface xe1 | Specify the interface (xe1)to be configured |
PE2(config-if)#ip address 20.20.20.2/24 | Configure IP address for the interface |
PE2(config-if)#no shutdown | Administratively bringing up the interface |
PE2(config-if)#exit | Exit interface mode |
PE2(config)#router ospf 100 | Configure the routing process and specify the Process ID (100) |
PE2(config-router)#network 20.20.20.0/24 area 0 PE2(config-router)#network 3.3.3.3/32 area 0 | Define the interface on which OSPF runs and associate the area ID (0)with the interface |
PE2(config-router)#exit | Exit router mode |
PE2(config)#router ldp | Enter router mode for LDP |
PE2(config-router)#exit | Exit router mode for LDP |
PE2(config)#interface xe1 | Specify the interface (xe1)to be configured |
PE2(config-if)#label-switching | Enabling label switching capability on router |
PE2(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
PE2(config-if)#exit | Exit interface mode |
Validation
P#sh ldp
Router ID : 2.2.2.2
LDP Version : 1
Global Merge Capability : Merge Capable
Label Advertisement Mode : Downstream Unsolicited
Label Retention Mode : Liberal
Label Control Mode : Independent
Instance Loop Detection : Off
Request Retry : Off
Propagate Release : Disabled
Graceful Restart : Disabled
Hello Interval : 5
Targeted Hello Interval : 15
Hold time : 15
Targeted Hold time : 45
Keepalive Interval : 10
Keepalive Timeout : 30
Request retry Timeout : 5
Transport Address data :
Labelspace 0 : 2.2.2.2 (in use)
Import BGP routes : No
P#show mpls label-space 0
Min-label-value : 1000
Max-label-value : 50000
module-static min-label-value : 1000
max-label-value : 15999
module-srgb min-label-value : 16000
max-label-value : 24319
module-rsvp min-label-value : 0
max-label-value : 0
module-ldp min-label-value : 0
max-label-value : 0
module-bgp min-label-value : 0
max-label-value : 0
module-ospf min-label-value : 0
max-label-value : 0
P#sh mpls ilm-table
Codes: > - selected ILM, p - stale ILM, K - CLI ILM, T - MPLS-TP
Code FEC ILM-ID In-Label Out-Label In-Intf Out-Intf Nexthop LSP-Type
> 1.1.1.1/32 1 3840 3 N/A eth1 172.168.25.56 LSP_DEFAULT
> 3.3.3.3/32 2 3841 3 N/A eth2 10.10.20.51 LSP_DEFAULT
Per-Interface Label Space
PE1
PE1#configure terminal | Enter configure mode |
PE1(config)#interface lo | Enter interface mode. |
PE1(config-if)#ip address 1.1.1.1/32 | Configure IP address for the loopback address |
PE1(config-if)#exit | Exit interface mode |
PE1(config)#interface xe6 | Specify the interface (xe6)to be configured |
PE1(config-if)#ip address 10.10.10.1/24 | Configure IP address for the interface |
PE1(config-if)#no shutdown | Administratively bringing up the interface |
PE1(config-if)#exit | Exit interface mode |
PE1(config)#router ospf 100 | Configure the routing process and specify the Process ID (100) |
PE1(config-router)#network 10.10.10.0/ 24 area 0 PE1(config-router)#network 1.1.1.1/32 area 0 | Define the interface on which OSPF runs and associate the area ID(0)with the interface |
PE1(config-router)#exit | Exit configure mode |
PE1(config)#router ldp | Enter router mode for LDP |
PE1(config-router)#exit | Exit router mode for LDP |
PE1(config)#mpls min-label-value 60000 max-label-value 80000 label-space 1 | Configure the minimum label value and maximum label value to be used by interface label space (Label space 1 in this case) |
PE1(config)#interface xe6 | Specify the interface (xe6)to be configured |
PE1(config-if)#label-switching | Enabling label switching capability on router |
PE1(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
PE1(config-if)#exit | Exit interface mode |
PE1(config)#exit | Exit configure mode |
P
P#configure terminal | Enter configure mode. |
P(config)#interface lo | Enter interface mode. |
P(config-if)#ip address 2.2.2.2/32 | Configure IP address for the loopback address |
P(config-if)#exit | Exit interface mode |
P(config)#interface xe6 | Specify the interface (xe6)to be configured |
P(config-if)#ip address 10.10.10.2/24 | Configure IP address for the interface |
P(config-if)#no shutdown | Administratively bringing up the interface |
P(config)#interface xe1 | Specify the interface (xe1)to be configured |
P(config-if)#ip address 20.20.20.1/24 | Configure IP address for the interface |
P(config)#router ospf 100 | Configure the routing process and specify the Process ID (100) |
P(config-router)#network 10.10.10.0/24 area 0 P(config-router)#network 20.20.20.0/24 area 0 P(config-router)#network 2.2.2.2/32 area 0 | Define the interface on which OSPF runs and associate the area ID (0)with the interface |
P(config-router)#exit | Exit router mode |
P(config)#router ldp | Enter router mode for LDP |
P(config-router)#exit | Exit router mode for LDP |
P(config)#mpls min-label-value 60000 max-label-value 80000 label-space 1 | Configure the minimum label value and maximum label value to be used by Interface label space (Label space 1) |
P(config)#interface xe6 | Specify the interface (xe6)to be configured |
P(config-if)#label-switching 1 | Enabling label switching capability on router |
P(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
P(config)#interface xe1 | Specify the interface (xe1)to be configured |
P(config-if)#label-switching 1 | Enabling label switching capability on router |
P(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
P(config-if)#exit | Exit interface mode |
P(config)#exit | Exit configure mode |
PE2
PE2#configure terminal | Enter configure mode. |
PE2(config)#interface lo | Enter interface mode. |
PE2(config-if)#ip address 3.3.3.3/32 | Configure IP address for the loopback address |
PE2(config-if)#exit | Exit interface mode |
PE2(config)#interface xe1 | Specify the interface (xe1)to be configured |
PE2(config-if)#ip address 20.20.20.2/24 | Configure IP address for the interface |
PE2(config-if)#no shutdown | Administratively bringing up the interface |
PE2(config-if)#exit | Exit interface mode |
PE2(config)#router ospf 100 | Configure the routing process and specify the Process ID (100) |
PE2(config-router)#network 20.20.20.0/24 area 0 PE2(config-router)#network 3.3.3.3/32 area 0 | Define the interface on which OSPF runs and associate the area ID (0)with the interface |
PE2(config-router)#exit | Exit router mode |
PE2(config)#router ldp | Enter router mode for LDP |
PE2(config-router)#exit | Exit router mode for LDP |
PE2(config)#mpls min-label-value 60000 max-label-value 80000 label-space 1 | Configure the minimum label value and maximum label value to be used by interface label space (Label space 1) |
PE2(config)#interface xe1 | Specify the interface (xe1)to be configured |
PE2(config-if)#label-switching | Enabling label switching capability on router |
PE2(config-if)#enable-ldp ipv4 | Enabling ldp on interface |
PE2(config-if)#exit | Exit interface mode |
Validation
P#show ldp
Router ID : 2.2.2.2
LDP Version : 1
Global Merge Capability : Merge Capable
Label Advertisement Mode : Downstream Unsolicited
Label Retention Mode : Liberal
Label Control Mode : Independent
Instance Loop Detection : Off
Request Retry : Off
Propagate Release : Disabled
Graceful Restart : Disabled
Hello Interval : 5
Targeted Hello Interval : 15
Hold time : 15
Targeted Hold time : 45
Keepalive Interval : 10
Keepalive Timeout : 30
Request retry Timeout : 5
Transport Address data :
Labelspace 1 : 2.2.2.2 (in use)
Import BGP routes : No
P#show mpls label-space 1
Min-label-value : 60000
Max-label-value : 80000
module-static min-label-value : 60000
max-label-value : 61000
module-rsvp min-label-value : 0
max-label-value : 0
module-ldp min-label-value : 0
max-label-value : 0
module-bgp min-label-value : 0
max-label-value : 0
module-ospf min-label-value : 0
max-label-value : 0
P#sh mpls ilm
Codes: > - selected ILM, p - stale ILM, K - CLI ILM, T - MPLS-TP
Code FEC ILM-ID In-Label Out-Label In-Intf Out-Intf Nexthop LSP-Type
> 3.3.3.3/32 3 61441 3 eth1 eth2 10.10.20.51 LSP_DEFAULT
> 1.1.1.1/32 4 61440 3 eth2 eth1 172.168.25.56 LSP_DEFAULT