Posts Tagged ‘pass’
The BSCI exam and CCNP certification requires that you be well versed in the basics of IP Version 6, or IPv6. If you’re new to IPv6, you’ll quickly learn that it’s not exactly just two more octets slapped onto an IPv4 address! IPv6 addresses are quite long, but there are two ways to acceptably shorten IPv6 address expression. To pass the BSCI exam, become a CCNP, and get that all-important understanding of IPv6, you’ve got to understand these different methods of expressing an IPv6 address. My last IPv6 tutorial discussed zero compression; today we’ll take a look at leading zero compression.
Leading zero compression allows us to drop the leading zeroes from every field in the address. Where we could only use zero compression once in an IPv6 address expression, leading zero compression can be used as often as is appropriate. The key with leading zero compression is that there must be at least one number left in each field, even if that remaining number is a zero.
You sometimes see books or websites refer to leading zero compression as “dropping zeroes and replacing them with a colon”, but that explanation can be a little confusing, since the blocks are separated with a colon to begin with. You’re not really replacing the leading zeroes, you’re dropping them.
Let’s look at an example of leading zero compression. Taking the address 1234:0000:1234:0000:1234:0000:1234:0123, we have four different fields that have leading zeroes. The address could be written out as it is, or drop the leading zeroes.
To pass the BSCI exam and earn your CCNP, you’ve got to know ISIS inside and out. There are many similarities between ISIS and OSPF, but one major difference is that ISIS has three different types of routers – Level 1 (L1), Level 2 (L2), and L1/L2.
L1 routers are contained in a single area, and are connected to other areas by an L1/L2 router. The L1 uses the L1/L2 router as a default gateway to reach destinations contained in other areas, much like an OSPF stub router uses the ABR as a default gateway.
L1 routers have no specific routing table entries regarding any destination outside their own area; they will use an L1/L2 router as a default gateway to reach any external networks. ISIS L1 routers in the same area must synchronize their databases with each other.
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BSCI exam success is all part of becoming a CCNP, and part of that success is now learning the basics of IP Version 6, or IPv6. One of the most difficult parts of learning IPv6 concepts is the radically different addressing scheme that IPv6 uses as compared to IPv4. Just look at these sample addresses:
Typical IPv4 address: 129.14.12.200
Typical IPv6 address: 1029:9183:81AE:0000:0000:0AC1:2143:019B
As you can see, IPv6 isn’t exactly just tacking two more octets onto an IPv4 address!
I haven’t met too many networkers who really like typing, particularly numbers. You’ll be happy to know there are some rules that will shorten those addresses a bit, and it’s a very good idea to be fluent with these rules for your exam.
You remember from your CCNA studies that there’s no difference between an upper-case letter and lower-case letter in hexadecimal. That’s one of three basic rules you need to know when working with IPv6 addressing. The other factors deal with all the zeroes you’ll run into in IPv6 addresses! One of these rules is the rule of zero compression.
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A major part of your BSCI and CCNP exam success is mastering BGP, and that includes filtering BGP routing updates. In this tutorial, we’ll take a look at how to filter BGP updates with prefix lists.
R4 is advertising three networks via BGP. The downstream router R3 sees these routes and places them into its BGP table as shown below. R3 has two downstream BGP peers, R1 and R2, and is advertising itself as the next-hop IP address for all BGP routes sent to those two routers.
R4(config)#router bgp 4
R4(config-router)#network 21.0.0.0 mask 255.0.0.0
R4(config-router)#network 22.0.0.0 mask 255.0.0.0
R4(config-router)#network 23.0.0.0 mask 255.0.0.0
R3#show ip bgp
BGP table version is 4, local router ID is 3.3.3.3
Status codes: s suppressed, d damped, h history, * valid, > best, i –
Internal
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