ISIS.....WOW!

.....Today I tackled ISIS which at first sight of the NSAP address I was a little intimidated and thought this will take some time to understand but it was the complete opposite. ISIS was originally intended to work with the OSI protocol suite. The Connectionless Network Service *CLNS* is used by the OSI protocols and the Layer 3 routing protocol used is Connectionless Network Protocol *CLNP*. I found out after reading and viewing my CB trainsignal videos that the hardest part is learning the terminology and this is true but after writing my notes I felt pretty good with this....so here it is ISIS..

As I mentioned earlier the NSAP address through me for loop but reviewing how to read the address, it was quite simple...

The breakdown is very elementary after you viewed the address from right to left, example:
49.0001.4444.4444.4444.00

00 = NSEL or Network Selector ID is used to route within the ES and the router is always set to 00
4444.4444.4444.4444 = the next 12 digits or should i say 8 bytes is the system ID now this can be either the MAC address on a lan or the highest DLCI on a frame relay
49.0001 = is the area id which this router belongs too...
*any area that begins with 49 is only used fora Private areas and is similar to IPV4 RFC1981 Private IP Addresses*

I was quite pleased on how fairly well I grasped this and since working with OSPF it'll come easy to all as well.

It's a little late to be doing any labs tonight but I will tackle some tomorrow I have a few more EIGRP labs to complete and finish off the afternoon with ISIS and then on Thursday THE BIG DAY "BGP" I am so looking forward to really understanding BGP... I've read a few pages on it just to get a feel of it and like the other subjects, I'll do a little and understand it before going on.

Hope all is doing well and this journey has finally taken off, I'm more focus than I've ever been for the past few months.

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