Types Of Fiber Splicing

What does happens when fiber cut occur? Someone need to fine the location of cut and restore. The restroration technique of fiber or merging the two fiber ends in one to increase its length is known as splicing. It is done in two ways

1. Mechanical Splicing
2. Fusion Splicing

Every splicing add some looses in the end to end calculation. For fusion splicing a loss of 0.02 dB is measured and for mechanical loss of 0.75 dB is measured. If it is not done in good manner it could increase the losses consequence drop in the data rate. The best way to check the total number of splices in end to end circuit is to see the OTDR (Optical Time Domain Reflector) report which helps to find the problems in the fiber.

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Single Mode and Multimode Fiber

I am always bit confused about single mode and multimode fiber cables. The differentiation between them is not so tough to understand. The only difference is the core part.
The core is the highly refractive region of the optical fiber from which the light is trasmitted. According to the ITU the diameter of the single mode fiber should fall between 8 to 10 micron meter and 50 to 62.5 micro meter of multi mode fiber cable.
Now how to remember which cable is used small or large distance. It's also very easy. Think single mode fiber cable is having a very small core where in only a light can transmit, it means a monopoloy of light is there and it could travel upto to a large distance. The multimode fiber cable is having a big core which means more lights could travel in the big core, a quarrel always happen where more than one comes, so no one can survive for a long period of time. Hence MMF cables are used for short distance.

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Opaque LSA Brought Router Down

Weird issue of OSPF has been seen with Cisco and another vendor integration. Cisco router one of the interface is sending the opaque lsa with odd bytes to the another router which forces the another vendor router to reboot.

According to RFC 2370
Opaque LSAs are Type 9, 10 and 11 link-state advertisements. These advertisements may be used directly by OSPF or indirectly by some application wishing to distribute information throughout the OSPF domain. The function of the Opaque LSA option is to provide for future extensibility of OSPF.
Opaque LSAs contain some number of octets (of application-specific
data) padded to 32-bit alignment.

But the question is that its a simple config but why Cisco is forwarding opaque LSA.

For temporary workaround we use "ip ospf database-filter all out" on specific interface which was forwarding opaque LSA.

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