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Home > Archive > CCNP > March 2001 > 4 question about BSCN
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4 question about BSCN
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| what is port number of igrp and eigrp? which routed protocol is them depend on?
what is the size of TCP and UTP header?
who can tell me what "discontiguous subnets" is, I have no any idea about it.
what is summarization anyway?
it is very hard to find out the answer, please help me. | |
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| quote:
Originally posted by ct
what is port number of igrp and eigrp?
None. Remember, port numbers are attributes of UDP and TCP. EIGRP and IGRP are not encapsulated in either of these but directly inside IP. They use protocol number 88 in IP. Hint: Look at RFC1700 or STD2 for numbers like these.
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which routed protocol is them depend on?
IP.
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what is the size of TCP and UTP header?
UTP is probably a typo. The size of the UDP header is 8 bytes. TCP headers are much larger and variable in length. Look at the
apropriate RFC's if you are really interressted.
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who can tell me what "discontiguous subnets" is, I have no any idea about it.
what is summarization anyway?
Advertising multiple subnets as one larger net. This keeps routing traffic as well as routing table size down. A big topic really so study your books.
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it is very hard to find out the answer, please help me.
Most study guides for the CCNA exam and the router exam should help you with these questions.
Terje | |
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| quote:
Originally posted by ct
what is the size of TCP ... header?
The minimum size of the TCP header is 20 bytes (this is when there are no options). The maximum is 60 bytes (20 bytes the regular header, 40 bytes in options).
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who can tell me what "discontiguous subnets" is
Subnets that are not next to each other. If you subnet 10.0.0.0 with 255.255.0.0, 10.1.0.0 and 10.3.0.0 are discontiguous (there's 10.2.0.0 between them).
HTH | |
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| quote:
Originally posted by dmaftei
Subnets that are not next to each other. If you subnet 10.0.0.0 with 255.255.0.0, 10.1.0.0 and 10.3.0.0 are discontiguous (there's 10.2.0.0 between them).
I think I would only feel that this was discontiguous if 10.2.0.0 existed somewhere else in the network. It's not really discontingous because 10.2.0.0 is missing, but that a subnet right in the middle (10.2.0.0) was ripped out and stuck somewhere else. That may have been what you meant, though....
MadChef | |
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| quote:
Originally posted by MadChef
That may have been what you meant, though....
Well, no, I didn't mean that. Unless my English betrays me, discontiguous (non-contiguous) means an ordered set of objects, some of which are missing. If the initial set contains the subnets [10.0.0.0/16, 10.1.0.0/16, 10.2.0.0/16 and 10.3.0.0/16], then the subset [10.1.0.0/16, 10.3.0.0/16] is "discontiguous", no matter what happened to 10.0.0.0/16 and 10.2.0.0/16.
OTOH, if you look at this with route summarization in mind, I agree that you could consider 10.1.0.0/16 and 10.3.0.0/16 contiguous if 10.0.0.0/16 and 10.2.0.0/16 are not used somewhere else, and it would be OK summarize them in 10.0.0.0/14.
Cheers! | |
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| what is "outside local address and outside global address" in nat term?
thanks in advance | |
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| understood with you great help, thank you very very much | |
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| quote:
Originally posted by ct
what is "outside local address and outside global address" in nat term?
This is from Cisco:
quote:
- Inside Local (IL)---The IP address assigned to a host within an enterprise. This address may be globally unique, allocated out of the private address space defined in rfc 1918, or may be officially allocated to some other enterprise.
- Inside Global (IG)---The IP address of a host within an enterprise, as it appears in the Internet. These addresses are allocated from a globally-unique address space, typically provided by the ISP.
- Outside Local (OL)---The IP address of a host outside an enterprise as it appears within the enterprise. These addresses can be allocated from the rfc 1918 space if desired.
- Outside Global (OG)---The IP address of a host outside the enterprise, as it appears in the Internet. These addresses are allocated from a globally-unique address space.
Helps? | |
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| quote:
Originally posted by dmaftei
OTOH, if you look at this with route summarization in mind...
I don't think I've thought of it any other way. I think about a way I might design an addressing scheme for a network:
Area 1 - 10.0.0.0 /20
Site A - 10.0.0.0 /22
Site B - 10.0.4.0 /24
Site C - 10.0.8.0 /24
.....
Area 2 - 10.0.16.0 /20
Site A - 10.0.16.0 /23
Site B - 10.0.20.0 /24
......
I don't really think about the fact that I've created a discontiguous network because I might have left 10.0.5.0 /24 and 10.0.6.0 /24 unused so all my networks don't line up in a row. I'm more interested in the fact that Area 1 can neatly advertise 10.0.0.0 /22 because I didn't stick 10.0.5.0 /24 off in another part of the topological world. It's not so much that I didn't use each network in sequence, but that I didn't pull a network FROM the sequence and fling it off somewhere else so that it's no longer next to its siblings.
That's my take on it anyway. My impression is that this is what people are typically speaking of when they refer to discontigous subnets.
MadChef | |
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| I believe we are in agreement. 
Cheers! |
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