Re: Help about BGP regular expression
Sorry, I overlooked the ? in the expression. That would allow AS1.
MLC
Jaeheon Yoo [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
Hi,
I quite agree with vtam,
From p.376 of "Internet Routing Architectures" Sec. Edition,
ip as-path access-list 4 permit ^1 ?[0-9]*$
This has some side effects, which allow as-paths such as 109, 110, 120
like vtam has pointed out, in addition to "all the AS paths that start
with 1 and that are of length 2-that is, AS1 and its direct customers"
I think the right answer would be as follows:
ip as-path access-list 4 permit ^1 [0-9]*$
ip as-path access-list 4 permit ^1$
The first line is for its direct cumstomers, and the second line for
its local networks. I'm afraid there's no one line version of this.
Am I right?
On 1 Dec 2000 11:41:56 -0500, [EMAIL PROTECTED] ("michael champion")
wrote:
Although I am by no means a regular expression expert, I do not believe
that
^1 [0-9]*$ will match an AS-path of 1; the space forces a requirement of
a
maximum of two path elements, with the first element a 1. A single
AS-path
of 1 would not match. Multiple AS-path elements are separated by a space
.
Thus, the expression would match 1 100, 1 200, 1 1, 1 {any AS number},
but
would not match just 1. What is confusing about regular expressions is
that
every element in the expression is an operator, and sometimes you have
operators acting on other operators. Thus .* matches all paths because .
is
an operator representing any single character and * is an operator
representing . repeated as many times as necessary (not just the
particular
character that . matched). This is thus equivalent to .., ..., , etc.
as
many times as necessary.
Powerful, but cryptic, and not well-documented at all by Cisco (who knows
which type of regular expression engine they are using?) This all comes
from
the Unix world, which is why you see it in Perl, Tcl, egrep, etc.
Regards,
MLC
"vtam" [EMAIL PROTECTED] wrote in message
907i83$9l6$[EMAIL PROTECTED]">news:907i83$9l6$[EMAIL PROTECTED]...
The space is the books. Because it said it match all the AS_paths that
start
with 1 and of length 2, such as AS_path=1, =1 10, =1 200, etc. As you
said,
? # 0 or 1 of the preceding characters (in this case a space). So if
?=0,
it
is ^1[0-9]*$; if ?=1, it is ^1 [0-9]*$.
Do i misread your meaning?
"Drew Simonis" [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
^1 ?[0-9]*$
^
^
Is that space yours or the books? Broken apart, that regex matches
(assuming standard egrep'ish metachars)
^ # beginning of line
1 # followed by the digit 1
(space) # followed by a space
? # 0 or 1 of the preceding characters (in this case a space)
[0-9] # a single digit within the range of 0-9
* # 0 or more of the preceding characters, up to the end of
# the pattern
$ # end of line char
So, is this equivalent to ^1[0-9]*$? I don't think so. Assuming
that the pattern with a space was a typo, we are allowed an
optional 1. Assuming it wasn't a typo, we are allowed the space
character. Neither of these options would be matched by your more
restrictive pattern. As for the specific pattern to match, you
can't really say without knowing what you are matching with.
Different regex engines support different metachars.
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Re: Help about BGP regular expression
Although I am by no means a regular expression expert, I do not believe that
^1 [0-9]*$ will match an AS-path of 1; the space forces a requirement of a
maximum of two path elements, with the first element a 1. A single AS-path
of 1 would not match. Multiple AS-path elements are separated by a space .
Thus, the expression would match 1 100, 1 200, 1 1, 1 {any AS number}, but
would not match just 1. What is confusing about regular expressions is that
every element in the expression is an operator, and sometimes you have
operators acting on other operators. Thus .* matches all paths because . is
an operator representing any single character and * is an operator
representing . repeated as many times as necessary (not just the particular
character that . matched). This is thus equivalent to .., ..., , etc. as
many times as necessary.
Powerful, but cryptic, and not well-documented at all by Cisco (who knows
which type of regular expression engine they are using?) This all comes from
the Unix world, which is why you see it in Perl, Tcl, egrep, etc.
Regards,
MLC
"vtam" [EMAIL PROTECTED] wrote in message 907i83$9l6$[EMAIL PROTECTED]">news:907i83$9l6$[EMAIL PROTECTED]...
The space is the books. Because it said it match all the AS_paths that
start
with 1 and of length 2, such as AS_path=1, =1 10, =1 200, etc. As you
said,
? # 0 or 1 of the preceding characters (in this case a space). So if ?=0,
it
is ^1[0-9]*$; if ?=1, it is ^1 [0-9]*$.
Do i misread your meaning?
"Drew Simonis" [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
^1 ?[0-9]*$
^
^
Is that space yours or the books? Broken apart, that regex matches
(assuming standard egrep'ish metachars)
^ # beginning of line
1 # followed by the digit 1
(space) # followed by a space
? # 0 or 1 of the preceding characters (in this case a space)
[0-9] # a single digit within the range of 0-9
* # 0 or more of the preceding characters, up to the end of
# the pattern
$ # end of line char
So, is this equivalent to ^1[0-9]*$? I don't think so. Assuming
that the pattern with a space was a typo, we are allowed an
optional 1. Assuming it wasn't a typo, we are allowed the space
character. Neither of these options would be matched by your more
restrictive pattern. As for the specific pattern to match, you
can't really say without knowing what you are matching with.
Different regex engines support different metachars.
_
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Re: BGP as-path access-lists
The link that they have been giving you describes regular expression notation, but it is hard to see how it applies to routing. Use the command "show ip bgp regexp [regular-expression] to see what routes match. This will help you probably more than any tutorial on regular expressions, because regular expressions are not router-specific, and it is sometimes hard to figure out how this apples. However, every AS-PATH is in reality a regular expression, even though it shows up as a sequence of AS numbers in the bgp routing table. Regards, MLC Andre Fecteau [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hello, I have been recently placed in the awkward position of making some changes to our BGP configuration. The problem is that I understand how bgp works for the main part, but I don't have any information on the meaning of the symbols used in the following as-path access-lists (^, $, _, ., +, (), *). Could someone tell me what each of them mean? Could someone also point me to a Cisco page that explains them in detail? I have been searching and cannot find anything except examples that include these symbols. Unfortuneately these examples have not helped my understanding. I have a good idea as to what they probably mean, but I need to know their exact meaning. It is difficult to manage something you don't have a clear understanding of! ip as-path access-list 1 permit ^$ ip as-path access-list 4 permit ^(_6774) +$ ip as-path access-list 10 permit .*5413$ ip as-path access-list 6 permit ^ (_3414) + (_2423) +$ HELP!!! Andre
Re: Closest to the real one...
Ben, I think that you misunderstood what Juan was saying. He said that he failed the COLT practice test, not the real Cisco exam. Anyone can fail the COLT tests because most of them are just plain terrible, as has been attested to many others who have had no problems with the actual Cisco exams but could not do well on the COLT tests. Don't use your results on the COLT tests to determine whether you are ready for the real exam. JMHO MLC Ben Lovegrove [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... --- Juan Blanco [EMAIL PROTECTED] wrote: Folks, I have being taken the BOSON test for the last two week and getting 100% score for my BSCN test. Yesterday I made the decision of taken the CISCO online test and what a disappoint I FAILED the test. My question is which test is the closest one to the real test..What I am doing wrong here I though that when you getting 100% in all 4 test from BOSON I was ready to take the real one.. Juan Which test? What subjects were you weak on? The results sheet from the real test should tell you which subject you were weak on. Forgive my presumption, but do you believe you understand the material or have you just memorised the answers on the Boson tests? I have failed exams too, but passed them later after more study. Use the results of the real test to show you where you need more study and practice. HTH Ben = Ben Lovegrove, CCNP (+ Security) Redspan Solutions Ltd http://www.redspan.com http://www.bensbookmarks.com Cisco: Products, Training, Jobs, Study Guides, Resources. Do You Yahoo!? Get your free @yahoo.co.uk address at http://mail.yahoo.co.uk or your free @yahoo.ie address at http://mail.yahoo.ie _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Closest to the real one...
As has been stated many times in this discussion group, the Cisco On-Line tests are, for the most part, terrible. Even Priscilla found them confusing, inaccurate, and in some cases just plain wrong! To prove this point, I took one of them OPEN BOOK and still just barely passed it! They are a pool of questions that were not accepted for the real exam, and they have incorrect answers, no correct answers, improper wording, things taken directly from a valid source and subsequentlyreworded to change the meaning, etc. One test that I took had the following: (1). 10 incorrect answers, as verified by looking up the answer. (2). 8 wrongly worded questions - taken from a Cisco Press Book and then promptly incorrectly re-worded. (3). 5 ambiguous questions - written in such a way that no answer given was correct. This aloneis enough to make you fail the test. Just don't waste your time with them. If you score highly on them then the following is probably true: (1). You are a lucky quesser - your quess was in fact incorrect but matched the wrong answer from the test. (2). You don't really know the material. Most of these tests are an embarrassment to Cisco, and if they are going to offer them they should correct them. But since they are meaningless anyway why bother? JMHO MLC Juan Blanco [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Folks, I have being taken the BOSON test for the last two week and getting 100% score for my BSCN test. Yesterday I made the decision of taken the CISCO online test and what a disappoint I FAILED the test. My question is which test is the closest one to the real test..What I am doing wrong here I though that when you getting 100% in all 4 test from BOSON I was ready to take the real one.. Juan
Re: Certificationzone CCIE November test Q# 22
I agree with you. The NSSA does not send Type-7 LSA's to area 0.0.0.0., but converts them to Type-5. Their explanation contradicts their answer, but even the explanation is not correct; it should say "...which are advertised into the backbone as Type-5 LSA's" JMHO MLC "Ken Yeo" [EMAIL PROTECTED] wrote in message 8v1hk3$sbe$[EMAIL PROTECTED]">news:8v1hk3$sbe$[EMAIL PROTECTED]... According to Dolye's book p. 537, I think the answer is A and B instead of B, C. Any comments? Thanks, Ken. -- You chose the following answer(s), A, B The correct answer(s), B, C How does a not-so-stubby area interact with area 0.0.0.0? Choose 2 A. The NSSA sends type 5 LSAs to area 0.0.0.0 B. The NSSA blocks non-default type 5 LSAs from entering the NSSA from area 0.0.0.0 C. The NSSA sends type 7 LSAs to area 0.0.0.0 D. The NSSA accepts type 7 LSAs from area 0.0.0.0 Explanation External routes received by ASBRs in the NSSA are propagated throughout the NSSA as type 7 LSAs, which are advertised into the backbone. This is a directional transfer from the NSSA to area 0.0.0.0. Other than the default generated on the ABR, externals in area 0.0.0.0 are blocked from entering the NSSA. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Some OSPF Questions
If you look at page 432, Table 9.1 in Doyle's "Routing TCP/IP" for the OSPF interface state machine, you will see clearly that one of the events (6). is "the expiration of the RouterDeadInterval without having received a Hello from the DR or the BDR or both", which changes directly to the DR/BDR election state. This implies that the DR/BDR election process is associated with the Hello interval, not an LSA. It makes sense, because every Hello packet states the DR and the BDR. If the DR goes down, how does it send an LSA to notify anybody about it? I am not sure exactly what a "missed LSA" means in this regard. The state diagram is probably the source from which that actual software algorithms were derived. JMHO MLC "David Armstrong" [EMAIL PROTECTED] wrote in message 8up5n1$src$[EMAIL PROTECTED]">news:8up5n1$src$[EMAIL PROTECTED]... This has been an awesome thread to me. Thanks everyone for the input. Evidently I'm not alone in being confused over BDR to DR promotion. The books and literature I've found have clearly stated that the event to promote BDR's to DR's is a missed LSA; however, the tests here show otherwise. Winston, I'm with you: I hope they never ask this on the test. I'll have to decide between what I believe to be right and what the book states as right. I still think there's a piece missing. 40 seconds to take over the functions of DR seems like it could create routing delays or time outs on a large network. I'm going to continue to look for a definitive answer. Thanks Again, David ""David Armstrong"" [EMAIL PROTECTED] wrote in message 8uh8vj$c47$[EMAIL PROTECTED]">news:8uh8vj$c47$[EMAIL PROTECTED]... Last night at our BSCN study group meeting in Dallas we had some questions about OSPF that we weren't able to resolve. If someone or ones could answer these it would clarify some areas we're a little fuzzy on. Also, if you're iin the Dallas Ft. Worth area and would like to attend, we'd love to have you join us.. Thanks for any help, David Armstrong 1) What is the default time period that the BDR waits when listening to LSA's from the DR before it decides that the DR is down and promotes itself to DR. All the literature we could find simply said that the BDR waits for the specified time period but never said what that period is. 2) In a Point-to-Point network in which the router in Area 0 is connected to FR, ISDN, X.25 or ATM branch offices (networks), how does convergence and updates take place? From what we've found a DR and BDR is not elected in a strictly Point-to-Point network. I think an example would explain this question better: We have one 3620 router in our Ft. Worth office connected to an office in Houston (via FR), and office in Kansas City (via FR), an office in the DFW area (via ISDN) and the owner's home (via ISDN). The 3620 is behind a firewall (Pix 520) and the firewall is connected to a 1720 going to the Internet. I'd like to implement OSPF on our network simply for the experience. However, I don't have 2 routers internally on our Ethernet LAN that can be configured for Area 0 and elected to DR and BDR. All other routers connected to that router are via NBMA Point-to-Point connections. Since I only have one router on the Broadcast Multiaccess network (the 3620) and routers connected via PtoP don't participate in DR and BDR elections, how would updates occur? Can their only be one DR (in this case the 3620)? 3) The books and tutorials all state that "router ospf 6" defines ospf on the router with a process ID of 6. They then all say that you shouldn't define more than one process. Does that mean that you can have a router with the following: router ospf 6 network 10.100.0.0 0.0.255.255 router ospf 7 network 10.200.0.0 0.0.255.255 If this is an allowed configuration, what kind of instances would it be used for? Also, exactly what is the process ID used for? _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Colt test
If you pass the Colt test with a high score you may fail the real thing! The Colt tests are composed of all of the questions that didn't make it out of beta, and have not been re-worded correctly, or have had their answers corrected. They are terrible, and you will find that many of the contributors to this NG who have tried them, including CCNP's and CCIE's, will tell you to avoid them. In this case, you get what you pay for. Regards, MLC [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... If you pass the Colt test you should pass the real thing no problem, the boson tests are not as difficult but cover more of the area that the exams are actually based on. rgs peter. _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: COLT tests
Title: COLT tests My opinion of themis that they only confuse the issue. I counted over 15 questions on the CIT-Pre exam that either had no correct answers listed or had wrong answers; I even took the test OPEN-BOOK to try to get through it. There is a very good reason that these questions are not on the real exam (badly-worded questions, no correct choices, nebulous questions, badly-worded answers, questions so detailed and obscure that they require a Cisco white paper or field notice to answer, etc.),and no one has made any attempt to improve them. What is amazing about some of them is that they are direct mis-quotes from some of the Cisco-Press books, and some were paraphrasedincorrectly and unintentionally changed the meaning. It is my belief that these questions were not written by Cisco but rather some hired third-party who didn't understand the material they were asking about (let's hope that this is the case, or else they are a real embarrassment to Cisco!). I had to inform Cisco that the CIT-8/28 exam wasn't even showing the gifs (they have since fixed that at least). Don't use this resourse to make a decision on whether you are ready for the real exam, just use it as a reference to make sure that you have covered the material. The real exam has a few nebulous questions, but not to the extent that the assessment exams do. Regards, MLC "Lonnie Paschall" [EMAIL PROTECTED] wrote in message 8shead$gfk$[EMAIL PROTECTED]">news:8shead$gfk$[EMAIL PROTECTED]... They are practice beta exams that are avaialable to cco login users. No charge, excellent rescource! "Ricardo Ciganda" [EMAIL PROTECTED] wrote in message C3CBB71D56E4D3119C9C00902727B15C1A21B9@bmnt01">news:C3CBB71D56E4D3119C9C00902727B15C1A21B9@bmnt01... Hi all! I would like to know what is the finality of the COLT tests. May I have to paid for this or is only a simulation of a test? Thanks in advance. Ricardo Ciganda Dpto. de Sistemas Bytemaster Servicios Informaticos S.A.
Re: diff b/w BSCN and BCMSN?
deltan [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Could anyone tell me the differences between BSCN and BCMSN in terms of coverage for switching and routing etc? Uh, they are totally unrelated. The BCSN is about advanced routing protocols (EIGRP, OSPF, BGP4) and has little to do with switching. The BCMSN is primarily concerned with the Catalyst 5000 series of switches, and focuses on VLANs, Multicast, Spanning-tree, ISL, VTP, etc. You do not need to have completed your study of BCSN reference materials for the BCMSN, and vice-versa. A word of warning, however. Be very careful as to what command is used on which type of device. Although most routers and some switches use IOS software, the same command might mean different things depending on whether it is executed on a switch or a router. Regards, MLC Any more details would be highly appreciated. Thanks! -D __ Do You Yahoo!? Yahoo! Messenger - Talk while you surf! It's FREE. http://im.yahoo.com/ _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: IP Subnetting Question
Youmust have been using that god-awful CiscoPress ACRC book. You are absolutely correct, and the book is absolutely wrong. The sad part is that these kind of mistakes are rampant in CiscoPress books, and they make you begin to doubt whether you understand the concept. It is simple. /n is the number of contiguous 1 bits in the subnet mask, period. Regards, MLC "Robert Cabeca" [EMAIL PROTECTED] wrote in message 008001c0385b$a973eca0$[EMAIL PROTECTED]">news:008001c0385b$a973eca0$[EMAIL PROTECTED]... I am not understanding the concept of using an IP address followed by /n. Example 10.20.193.20 /28. The way I am looking at it I get a Subnet mask of 255.255.255.240. But I am being told that it is really a mask of 255.255.240.0, however I am not being given an explanation. I thought that 255.255.240.0 has a /20. but it is a /12 instead? Any enlightenment would be appreciated. peace Rob
Re: Vlans over Links
First things first. Just because an interface is Fast Ethernet does not mean that the switch or router will support ISL. (In fact, the 4000 series of switches do not support ISL). ISL is a Cisco-proprietary method of frame tagging for VLAN's; the industry standard is IEEE 802.1Q. Cisco 802.10 is used by Cisco for VLAN frame tagging over FDDI. If you are using only one VLAN and not connecting to anything else that is not in the VLAN's broadcast domain then you don't need a router. However, since you are using a firewall it is doubtful this is what you are trying to do. The router may or may not support ISL, depending on the interfaces and the IOS software version. "Donald B Johnson Jr" [EMAIL PROTECTED] wrote in message 023e01c03874$8862c4f0$[EMAIL PROTECTED]">news:023e01c03874$8862c4f0$[EMAIL PROTECTED]... If you just have one vlan I don't think you need a router Duck - Original Message - From: Andrew Twigger [EMAIL PROTECTED] To: [EMAIL PROTECTED] Sent: Tuesday, October 17, 2000 7:03 AM Subject: Vlans over Links Hi Group I wonder if any body can answer this or point me in the right direction for me. I am looking at VLANs and what can be done with them. I know I can use ISL to link two switches together with even a router in the middle and have a vlan running from switch to switch. I am also sure that I can use 802.10 to do the same. Also if my understanding is correct you can only use ISL when all interfaces are fast Ethernet? Question then, can you set up a Vlan between two switches but in between the switches is not just a router but a PIX as well, so you have :- Switch1(VLAN10) - - - - Router - - - - PIX - - - - - Router - - - - - Switch (VLAN10) Is this possible? if so do you use ISL or 802.10? Thank in advance. Andrew Andrew S. Twigger MCP, Network+, CCNA Snr Systems Engineer Technical Service's DIALnet PLC e : [EMAIL PROTECTED] t : 0121 624 5050 m : 07967 470 964 _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] _ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: major BCMSN(504) question who passed it?
Well, mine had a lot of product-specific questions, so I suppose it is from whatever pool you draw from. The 3500XL is still a viable solution, as is the 3900. Many of my questions were not conceptual at all, but quite product-specific. MLC "Favio T" [EMAIL PROTECTED] wrote in message news:[EMAIL PROTECTED]... I went to brainbuzz.com and printed out there cramsession sheet (640-504) when I looked at it, it said that I have to know Catalyst 3000 switches BUT I have the BCMSN Cisco press book by Karen WEbb and Catalyst start at 4000 not one word on 3000 switches should I tell brainbuzz to buzz off or what ? thanks for your help can't wait to pass this test any tips on study material thanks a million [EMAIL PROTECTED] _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Length of Ethernet frame
You left out the type/length field: 2 You don't count the preamble (it is used to sync the frame). Thus, DA: 6 SA: 6 Length/Type: 2 Data: 1500 FCS: 4 = 1518. Regards, MLC "M. A." [EMAIL PROTECTED] wrote in message 000a01c02c2d$b1f640b0$[EMAIL PROTECTED]">news:000a01c02c2d$b1f640b0$[EMAIL PROTECTED]... Dear group, I have one question which has bugged me for ages, that is, what exactly is the maximum length for an Ethernet frame (assuming no other encapsulation like ISL)? The number 1518 keeps on getting mentioned, but I just can't seem to work that number out: The way I see is: Preamble: 8 DA: 6 SA: 6 Data: 1500 FCS: 4 All those add up to 1524 How do people get the number of 1518??? Much appreciate any help! Martin
Re: PRI vs T1
A T1 frame is 193 bits. 192 bits (24X8) corresponds to data, and 1 bit is used for synchronization. There are 8000 frames per second. T1 was originally defined for PCM-encoded voice (8 bits per channel, but 1 bit for signaling when needed - "robbed-bit signaling"), with 24 voice channels per frame. It is actually unfortunate that "T-1" became a generic term for anything that has a 1.544 Mbs bit-rate, because T1, DS1, and ISDN PRI should be defined completely differently. T1 should have been reserved for 24-channel voice, DS1 for 24-channel data, and PRI for 23-channel +1D-channel (ISDN). Regardless T1 frame= 24(8-bit voice + signaling) channels + 1sync bit DS1 frame = 24(8-bit digital data) + 1 sync bit ISDN frame = 23(8-bit digital data) + 1(8-bit signaling) + 1 sync-bit(as logically represented on a T1 carrier) Therefore, 193X8000 = 1544000 clock-rate for T1 (DS1). 192X8000 = 1536000 data-bits/sec for T1 (DS1). 1X8000 = 8000 sync-bits/sec for T1 (DS1). Notice that there is no defined signaling channel. If multiple sites are sharing a T1(DS1) link then without some form of common signaling there would have to be in-band signaling, which would reduce the 8-bits per channel to 7-bits per channel (ever heard of "switched-56K"?). Fractional T1 would allow common signaling for a higher user data-rate. Therefore, assuming that some form of out-of-band signaling exists, T1(DS1) provides 1.536 Mbs of bandwidth, with 8Kbs lost due to sync bits. The question for PRI becomes even more confused. 23 B-channels + 1 D-channel + 1 sync-bit, but the D-channel is primarily used for common signaling. The question is if there are 23 B-channels at 64Kbs each, how much of the D-channel's bandwidth can be used for user data, if any (for example, by running X25 on top of the signaling channel)? This would imply that PRI would have only 23X64Kbs for user data plus 64Kbs for signaling. Although ISDN is considered to be all digital, in reality PCM-encoded voice on a T1 line is a digital representation of an analog sample. ISDN still uses T1, T3, etc. lines to bundle multiple facilities on a common line, but the channels are interpreted differently. What is really fascinating is to see how ISDN achieves these rates via the data format from the U-interface. So the question is "which provides 1.544 Mbs of bandwidth, T1 or PRI?" is nebulous at best. Neither can provide 1.544 Mbs for exclusive use for user data. But both have a 1.544 Mbs clock-rate. MLC "NetEng" [EMAIL PROTECTED] wrote in message 8qvlk4$vtv$[EMAIL PROTECTED]">news:8qvlk4$vtv$[EMAIL PROTECTED]... Is there a difference between a PRI and a T-1? What has 23B + 1D? What one has 24B? The reason I ask is I have a practice question that asks, "what provides 1.544Mbs bandwidth." PRI and T-1 are answers, but only PRI is the correct answer (according to the test). What's the final answer **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: ACRC v. BSCN
"Montgomery, Robert WARCOM Contractor" [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... For those who had the occasion to either take (or compare) the ACRC and BSCN exams, did you feel they were very, somewhat or not similar? I've been reviewing the ACRC guide to keep that info fresh, awaiting the BSCN guide, and wonder if this is a good idea or bad. I also wonder that, if one knows ACRC, will one have a good foundation for the BCSN (say a good 60% to 70% of the knowledge) or are they too dissimilar of a guide/course to carry each other? Any thoughts would be appreciated...even off line! If you use just the old ACRC material for the exam you will probably fail it. The new exam covers BGP in depth, OSPF in NBMA environments, and hardly deals at all with IPX or Appletalk. If you use the ACRC materials you are well-advised to read everything you can on BGP at Cisco's web-site. Also know what a "regular expression" is in terms of Cisco lists. MLC Rob Montgomery CCNA MCP Information Security Engineer IA Systems Analyst Sytex, Inc./ Naval Special Warfare Command **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BSCN Test (Routing)
Cisco is apparently using a logical "building-block" approach to their certification objectives. Assume that if you are taking a CCNP-level exam that you are already expected to know any information required for the CCNA (review the CCNA objectives to be sure you are confident in that material). It would be a violation of the NDA (Confidentiality Agreement) to discuss what subjects are on the exam other than rehashing the stated objectives or perhaps a relevant course outline. Regards, MLC "Stewart, Harley, M, Ii" [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... I've looked at all the objectives for this exam. They say that other things that are not listed could possibly be on the exam. I was wondering if anyone has taken it. If so, are there any other subjects I ought to prepare for before testing. Thanks, Harley Stewart Network Engineering ATT Solutions Technology One Alliance **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associates.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Passed BCRAN
Congratulations on passing BCRAN. However, if you used the Paquet CiscoPress book, I wouldn't exactly call it reviewing a few chapters. Rewriting a few chapters would be more accurate! This book has glaring errors on just about every page, and I am astonished that CiscoPress doesn't have a link to an errata for it. The errors are not merely typos, but whole sections of commands repeated with the same error (example "dialer-map" instead of "dialer map"), completely misleading and erroneous information about "dialer enable-timeout" and "dialer hold-cue", etc. And who can forget the assertion that you use Reverse Telnet through Windows 95 HyperTerminal to configure a modem attached directly to the local PC! After reviewing the material on the Cisco web-site I realized that Cisco could have presented questions that could have failed nearly everyone if they wanted to. Even Cisco's own documentation occasionally has errors. Regards, MLC "Jeffrey Eiber" [EMAIL PROTECTED] wrote in message 8pbc1n$ois$[EMAIL PROTECTED]">news:8pbc1n$ois$[EMAIL PROTECTED]... I passed BCRAN today with an 846 (706 to pass). It wasn't nearly as difficult as I was expecting. I used the Cisco Press BCRAN book by Catherin Paquet. I read the book once, skimmed it a second time, then reviewed a few chapters. I wrote out lots and lots of config fragments for practice. That's it. Jeff **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associate-Announcement.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associate-Announcement.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: what is dark fiber?
I thought that dark fiber was only used with DED's (dark-emitting diodes). MLC Ty Hill [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Depends on who you are talking to. To me dark fiber means 1. fiber strands that are currently not in use, or 2. private fiber that you or your company has installed, that is not part of the local telephone company's infrastructure. This is how I have been using the term for over 15 years. "Yee, Jason" wrote: I think dark fibre means a OC3 or OC12 link Jason -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]]On Behalf Of bahadir korkmaz Sent: Wednesday, September 06, 2000 12:04 AM To: [EMAIL PROTECTED] Subject: what is dark fiber? hi. what is dark fiber? i found some sites that says dark fiber means unused fiber. is it so? i think dark fiber must be different then unused fiber. i mean for example. 10gigabit ethernet runs on dark fiber. dark must be something related to bandwidth or wavelength. if someone knows dark fiber definition i ll be happy. _ Get Your Private, Free E-mail from MSN Hotmail at http://www.hotmail.com. Share information about yourself, create your own public profile at http://profiles.msn.com. ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associate-Announcement.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] **NOTE: New CCNA/CCDA List has been formed. For more information go to http://www.groupstudy.com/list/Associate-Announcement.html _ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: HDLC, SDLC...
They are all based on the original work done by IBM for SDLC. SDLC uses a complicated master-slave scheme that is not used in the other protocols. However, the fields in all of the frames of the protocols mentioned were basically derived from a special case of the SDLC protocol. Regards, MLC perez claude-vincent [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Dear all, I am a little bit confused about the difference of framing between hdlc, sdlc, lapb, lapd, llc2. Can someone help me? Thank you, cvp. __ Do You Yahoo!? Yahoo! Mail - Free email you can access from anywhere! http://mail.yahoo.com/ ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Dialer Interface * VERY URGENT *
As far as I know, Native ISDN does not support callback. Therefore, you can't use callback with the normal LAP-D signaling over the D-channel (out-of-band signaling). You must use PPP (or ARAP if an Appletalk network) which uses in-band signaling. The "dialer in-band" is required. Look at both at the physical interface and the dialer interface and you will probably see "encap ppp", "ppp callback", callback-secure", etc. JMHO Regards, MLC NRS Hariharan [EMAIL PROTECTED] wrote in message [EMAIL PROTECTED]">news:[EMAIL PROTECTED]... Hi all, I have installed a 2503 router for ISDN dial back for a leased line.The vendor who configured it has included the following commands in the dilaer interface . (1) #dialer in-band and (2) #dialer wait-for-carrier-time 60 Since the above commands should not be used for ISDN i removed them . But when I saved the new config and saw the file,the following commands were also missing fom the dialer interface which was there previously : #dialer idle-timeout #dialer string x Class xx #dilaer hold-queue xx #dialer load-threshold xxx either #dialer-group x and the only commands which were present from the previous config were : #ip address negotiate #no ip directed-broadcast #encapsulation ppp #ppp authentication pap callin #ppp pap sent-user password Can anyone provide a solution for the above Thanks in advance hari Get free email and a permanent address at http://www.netaddress.com/?N=1 ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] ___ UPDATED Posting Guidelines: http://www.groupstudy.com/list/guide.html FAQ, list archives, and subscription info: http://www.groupstudy.com Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: BCSN - OSPF
Title: BCSN - OSPF If it is mentioned in the objectives you better know it very well. Consult CCO and be familiar with all of the OSPF-related commands and case studies. Don't shortchange your acquisition of knowledge just for the sake of passing an exam. MLC "Henson, Luke" [EMAIL PROTECTED] wrote in message 017267FFF211D311B6850008C74C31909C6E66@lacex1">news:017267FFF211D311B6850008C74C31909C6E66@lacex1... Hi, Can anyone tell me how deep the exam goes into OSPF?? Any help much appreciated. Luke
