OSPF Per-Interface Link-Local Signaling
Last Updated: May 4, 2009
The OSPF Per-Interface Link-Local Signaling feature allows you to selectively enable or disable Link-Local Signaling (LLS) for a specific interface regardless of the global (router level) setting that you have previously configured.
Finding Feature Information
For the latest feature information and caveats, see 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 for OSPF Per-Interface Link-Local Signaling" section.
Use Cisco Feature Navigator to find information about platform support and Cisco IOS XE software image support. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Contents
•Information About OSPF Per-Interface Link-Local Signaling
•How to Configure the OSPF Per-Interface Link-Local Signaling Feature
•Configuration Examples for the OSPF Per-Interface Link-Local Signaling Feature
•Additional References
•Feature Information for OSPF Per-Interface Link-Local Signaling
Information About OSPF Per-Interface Link-Local Signaling
LLS allows for the extension of existing OSPF packets in order to provide additional bit space. The additional bit space enables greater information per packet exchange between OSPF neighbors. This functionality is used, for example, by the OSPF Nonstop Forwarding (NSF) Awareness feature that allows customer premises equipment (CPE) routers that are NSF-aware to help NSF-capable routers perform nonstop forwarding of packets.
When LLS is enabled at the router level, it is automatically enabled for all interfaces. The OSPF Per-Interface Link-Local Signaling feature allows you to selectively enable or disable LLS for a specific interface. You may want to disable LLS on a per-interface basis depending on your network design. For example, disabling LLS on an interface that is connected to a non-Cisco device that may be noncompliant with RFC 2328 can prevent problems with the forming of OSPF neighbors in the network.
How to Configure the OSPF Per-Interface Link-Local Signaling Feature
Turning Off LLS on a Per-Interface Basis
SUMMARY STEPS
1. enable
2. configure terminal
3. interface type slot/subslot/port
4. ip address ip-address mask [secondary]
5. no ip directed-broadcast [access-list-number | extended access-list-number]
6. ip ospf message-digest-key key-id encryption-type md5 key
7. [no | default] ip ospf lls [disable]
DETAILED STEPS
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Step 1 |
enable
Router> enable |
Enables privileged EXEC mode. •Enter your password if prompted. |
Step 2 |
configure terminal
Router# configure terminal |
Enters global configuration mode. |
Step 3 |
interface type slot/port
Router(config)# interface gigabitethernet 1/1/0 |
Configures an interface type and enters interface configuration mode. |
Step 4 |
ip address ip-address mask [secondary]
Router(config-if)# ip address 10.2.145.20 255.255.255.0 |
Sets a primary or secondary IP address for an interface. |
Step 5 |
no ip directed-broadcast [access-list-number | extended access-list-number]
Router(config-if)# no ip directed-broadcast |
Drops directed broadcasts destined for the subnet to which that interface is attached, rather than broadcasting them. •The forwarding of IP directed broadcasts on Ethernet interface 1/0 is disabled. |
Step 6 |
ip ospf message-digest-key key-id encryption-type
md5 key
Router(config-if)# ip ospf message-digest-key 100 md5 testing |
Enables OSPF Message Digest 5 (MD5) algorithm authentication. |
Step 7 |
[no | default] ip ospf lls [disable]
Router(config-if)# ip ospf lls disable |
Disables LLS on an interface, regardless of the global (router level) setting. |
What to Do Next
To verify that LLS has been enabled or disabled for a specific interface, use the show ip ospf interface command. See the "Example: Configuring and Verifying the OSPF Per-Interface Link-Local Signaling Feature" section for an example of the information displayed.
Configuration Examples for the OSPF Per-Interface Link-Local Signaling Feature
Example: Configuring and Verifying the OSPF Per-Interface Link-Local Signaling Feature
In the following example, LLS has been enabled on GigabitEthernet interface 1/1/0 and disabled on GigabitEthernet interface 2/1/0:
interface gigabitethernet1/1/0
ip address 10.2.145.2 255.255.255.0
ip ospf message-digest-key 1 md5 testing
interface gigabitethernet2/1/0
ip address 10.1.145.2 255.255.0.0
ip ospf message-digest-key 1 md5 testing
ip address 10.3.145.2 255.255.255.0
log-adjacency-changes detail
area 0 authentication message-digest
redistribute connected subnets
network 10.0.0.0 0.255.255.255 area 1
network 10.2.3.0 0.0.0.255 area 1
In the following example, the show ip ospf interface command has been entered to verify that LLS has been enabled for GigabitEthernet interface 1/1/0 and disabled for GigabitEthernet interface 2/1/0:
Router# show ip ospf interface
GigabitEthernet1/1/0 is up, line protocol is up
Internet Address 10.2.145.2/24, Area 1
Process ID 1, Router ID 10.22.222.2, Network Type BROADCAST, Cost: 10
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 10.2.2.3, Interface address 10.2.145.1
Backup Designated router (ID) 10.22.222.2, Interface address 10.2.145.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
! Supports Link-local Signaling (LLS)
Index 1/1, flood queue length 0
Last flood scan length is 2, maximum is 8
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 10.2.2.3 (Designated Router)
Suppress hello for 0 neighbor(s)
GigabitEthernet2/1/0 is up, line protocol is up
Internet Address 10.1.145.2/16, Area 1
Process ID 1, Router ID 10.22.222.2, Network Type BROADCAST, Cost: 10
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 10.2.2.3, Interface address 10.1.145.1
Backup Designated router (ID) 10.22.222.2, Interface address 10.1.145.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
! Does not support Link-local Signaling (LLS)
Index 2/2, flood queue length 0
Last flood scan length is 2, maximum is 11
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 45.2.2.3 (Designated Router)
Suppress hello for 0 neighbor(s)
GigabitEthernet3/1/0 is up, line protocol is up
Internet Address 10.3.145.2/24, Area 1
Process ID 1, Router ID 10.22.222.2, Network Type BROADCAST, Cost: 10
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 10.2.2.3, Interface address 10.3.145.1
Backup Designated router (ID) 10.22.222.2, Interface address 10.3.145.2
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
! Supports Link-local Signaling (LLS)
Index 3/3, flood queue length 0
Last flood scan length is 2, maximum is 11
Last flood scan time is 0 msec, maximum is 0 msec
Neighbor Count is 1, Adjacent neighbor count is 1
Adjacent with neighbor 10.2.2.3 (Designated Router)
Suppress hello for 0 neighbor(s)
Additional References
The following sections provide references related to the OSPF Per-Interface Link-Local Signaling feature.
Related Documents
Standards
MIBs
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No new or modified MIBs are supported by this feature, and support for existing MIBs has not been modified by this feature. |
To locate and download MIBs for selected platforms, Cisco IOS XE releases, and feature sets, use Cisco MIB Locator found at the following URL: http://www.cisco.com/go/mibs |
RFCs
Technical Assistance
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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. |
http://www.cisco.com/cisco/web/support/index.html |
Feature Information for OSPF Per-Interface Link-Local Signaling
Table 1 lists the release history for this feature.
Use Cisco Feature Navigator to find information about platform support and software image support. Cisco Feature Navigator enables you to determine which Cisco IOS XE software images support a specific software release, feature set, or platform. To access Cisco Feature Navigator, go to http://www.cisco.com/go/cfn. An account on Cisco.com is not required.
Note Table 1 lists only the Cisco IOS XE software release that introduced support for a given feature in a given Cisco IOS XE software release train. Unless noted otherwise, subsequent releases of that Cisco IOS XE software release train also support that feature.
Table 1 Feature Information for OSPF Per-Interface Link-Local Signaling
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OSPF Per-Interface Link-Local Signaling |
Cisco IOS XE Release 2.1 |
The OSPF Per-Interface Link-Local Signaling feature allows you to selectively enable or disable Link-Local Signaling (LLS) for a specific interface regardless of the global (router level) setting that you have previously configured. The following commands are introduced or modified in the feature documented in this module: •ip ospf lls |
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Any Internet Protocol (IP) addresses and phone numbers used in this document are not intended to be actual addresses and phone numbers. Any examples, command display output, network topology diagrams, and other figures included in the document are shown for illustrative purposes only. Any use of actual IP addresses or phone numbers in illustrative content is unintentional and coincidental.
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