Remote end failure detection

Answered Question
Dec 19th, 2008

Hi,

I'm expecting a simple service which is router1 - 1GE - ONS1 --- ONS2 - 1GE router2.

If the link router1 to ONS1 fails will router2 get a link down immediately and not have to wait for OSPF hello dead time for failure detection?

Thanks for any help.

Regards, MH

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Correct Answer by Tom Randstrom about 7 years 11 months ago

If you are using the CE-Series card, this is covered by the following feature:

*** Ethernet Link Integrity Support ***

The CE-1000-4 card supports end-to-end Ethernet link integrity (Figure 1-6). This capability is integral to providing an Ethernet private line service and correct operation of Layer 2 and Layer 3 protocols on the attached Ethernet devices. Link Integrity is implemented so that the Ethernet over SONET/SDH connection behaves more like an Ethernet cable from the viewpoint of the attached Ethernet devices.

End-to-end Ethernet link integrity means that if any part of the end-to-end path fails, the entire path fails. It disables the Ethernet port transmitter on the CE-1000-4 card when the remote Ethernet port does not have a receive signal or when the SONET/SDH near end of a far-end failure is detected. The failure of the entire path is ensured by turning off the transmit pair at each end of the path. The attached Ethernet devices recognize the disabled transmit pair as a loss of carrier and consequently an inactive link or link fail. The transport fail alarm is also raised when the port transmitter is disabled. Link integrity will support a double fault, which is when both Ethernet ports do not receive a signal.

Some network devices can be configured to ignore a loss of carrier condition. If a device configured to ignore a loss of carrier condition attaches to a CE-1000-4 card at one end, alternative techniques (such as use of Layer 2 or Layer 3 keep-alive messages) are required to route traffic around failures. The response time of such alternate techniques is typically much longer than techniques that use link state as indications of an error condition.

http://www.cisco.com/en/US/docs/optical/15000r9_0/ethernet/454/guide/45490a_ceop.html#wp369973

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Correct Answer
Tom Randstrom Fri, 12/19/2008 - 08:21

If you are using the CE-Series card, this is covered by the following feature:

*** Ethernet Link Integrity Support ***

The CE-1000-4 card supports end-to-end Ethernet link integrity (Figure 1-6). This capability is integral to providing an Ethernet private line service and correct operation of Layer 2 and Layer 3 protocols on the attached Ethernet devices. Link Integrity is implemented so that the Ethernet over SONET/SDH connection behaves more like an Ethernet cable from the viewpoint of the attached Ethernet devices.

End-to-end Ethernet link integrity means that if any part of the end-to-end path fails, the entire path fails. It disables the Ethernet port transmitter on the CE-1000-4 card when the remote Ethernet port does not have a receive signal or when the SONET/SDH near end of a far-end failure is detected. The failure of the entire path is ensured by turning off the transmit pair at each end of the path. The attached Ethernet devices recognize the disabled transmit pair as a loss of carrier and consequently an inactive link or link fail. The transport fail alarm is also raised when the port transmitter is disabled. Link integrity will support a double fault, which is when both Ethernet ports do not receive a signal.

Some network devices can be configured to ignore a loss of carrier condition. If a device configured to ignore a loss of carrier condition attaches to a CE-1000-4 card at one end, alternative techniques (such as use of Layer 2 or Layer 3 keep-alive messages) are required to route traffic around failures. The response time of such alternate techniques is typically much longer than techniques that use link state as indications of an error condition.

http://www.cisco.com/en/US/docs/optical/15000r9_0/ethernet/454/guide/45490a_ceop.html#wp369973

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