Wrong definition type 4 summary LSA for ASBRs [7:61615]
Hi, For those that are reading Cisco Press' CCNP Routing Exam Certification Guide: there is a very confusing definition of type 4 summary LSAs on page 292, chapter 6: The AS external ASBR summary link- This LSA is sent to a router that connects to the outside world (ASBR). It is sent from the Area Border Router to the Autonomous System Boundary Router. The LSA contains the metric cost from the ABR to the ASBR. This is identified as a Type 4 LSA. In my opinion this is wrong, isn't it? Or maybe I'm missing something? My understanding is that a type 4 summary LSA is originated by ABRs.It is sent into an area by the ABR to advertise the AS boundary routers. Could someone confirm my understanding? Eric Brouwers Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61615&t=61615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
RE: Wrong definition type 4 summary LSA for ASBRs [7:61615]
ericbrouwers wrote: > > Hi, > > For those that are reading Cisco Press' CCNP Routing Exam > Certification Guide: > there is a very confusing definition of type 4 summary LSAs on > page 292, > chapter 6: > > The AS external ASBR summary link- This LSA is sent to a router > that connects > to the outside world (ASBR). It is sent from the Area Border > Router to the > Autonomous System Boundary Router. The LSA contains the metric > cost from the > ABR to the ASBR. This is identified as a Type 4 LSA. > > In my opinion this is wrong, isn't it? Or maybe I'm missing > something? > > My understanding is that a type 4 summary LSA is originated by > ABRs.It is sent > into an area by the ABR to advertise the AS boundary routers. > > Could someone confirm my understanding? Yup, I have the same comment penciled into my copy of the book. Bottom line: don't even bother trying to learn OSPF from that book. It's a disaster. (It's a pretty good book otherwise, I think?) Read "Routing TCP/IP" by Doyle. You'll want to get that book anyway if you haven't already It's terrific for real-world and certs. ___ Priscilla Oppenheimer www.troubleshootingnetworks.com www.priscilla.com > > Eric Brouwers > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61622&t=61615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wrong definition type 4 summary LSA for ASBRs [7:61615]
here is the relative info from rfc 1247 3,4Summary link Originated by area border routers, and advs. flooded throughout their associated area. Each summary link advertisement describes a route to a destination outside the area, yet still inside the AS (i.e., an inter-area route). Type 3 advertisements describe routes to networks. Type 4 advertisements describe routes to AS boundary routers. ""Priscilla Oppenheimer"" a icrit dans le message de news: [EMAIL PROTECTED] > ericbrouwers wrote: > > > > Hi, > > > > For those that are reading Cisco Press' CCNP Routing Exam > > Certification Guide: > > there is a very confusing definition of type 4 summary LSAs on > > page 292, > > chapter 6: > > > > The AS external ASBR summary link- This LSA is sent to a router > > that connects > > to the outside world (ASBR). It is sent from the Area Border > > Router to the > > Autonomous System Boundary Router. The LSA contains the metric > > cost from the > > ABR to the ASBR. This is identified as a Type 4 LSA. > > > > In my opinion this is wrong, isn't it? Or maybe I'm missing > > something? > > > > My understanding is that a type 4 summary LSA is originated by > > ABRs.It is sent > > into an area by the ABR to advertise the AS boundary routers. > > > > Could someone confirm my understanding? > > Yup, I have the same comment penciled into my copy of the book. > > Bottom line: don't even bother trying to learn OSPF from that book. It's a > disaster. (It's a pretty good book otherwise, I think?) > > Read "Routing TCP/IP" by Doyle. You'll want to get that book anyway if you > haven't already It's terrific for real-world and certs. > > ___ > > Priscilla Oppenheimer > www.troubleshootingnetworks.com > www.priscilla.com > > > > Eric Brouwers Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61660&t=61615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wrong definition type 4 summary LSA for ASBRs [7:61615]
All of you, thanks for the answers. This routing exam cert. guide is a pretty good book, although I haven't read the BGP and IS-IS sections yet. But the OSPF section needs some corrections indeed . Anyway, I think I will follow Priscilla's advise to buy Doyle's routing book, because now I have around six books (a/o ICND, DCN and CID related books) that all cover fractions of routing, but not the full story. Moreover, sometimes they are in contradiction. Eric - Original Message - From: "Priscilla Oppenheimer" To: Sent: Wednesday, January 22, 2003 11:21 PM Subject: RE: Wrong definition type 4 summary LSA for ASBRs [7:61615] > ericbrouwers wrote: > > > > Hi, > > > > For those that are reading Cisco Press' CCNP Routing Exam > > Certification Guide: > > there is a very confusing definition of type 4 summary LSAs on > > page 292, > > chapter 6: > > > > The AS external ASBR summary link- This LSA is sent to a router > > that connects > > to the outside world (ASBR). It is sent from the Area Border > > Router to the > > Autonomous System Boundary Router. The LSA contains the metric > > cost from the > > ABR to the ASBR. This is identified as a Type 4 LSA. > > > > In my opinion this is wrong, isn't it? Or maybe I'm missing > > something? > > > > My understanding is that a type 4 summary LSA is originated by > > ABRs.It is sent > > into an area by the ABR to advertise the AS boundary routers. > > > > Could someone confirm my understanding? > > Yup, I have the same comment penciled into my copy of the book. > > Bottom line: don't even bother trying to learn OSPF from that book. It's a > disaster. (It's a pretty good book otherwise, I think?) > > Read "Routing TCP/IP" by Doyle. You'll want to get that book anyway if you > haven't already It's terrific for real-world and certs. > > ___ > > Priscilla Oppenheimer > www.troubleshootingnetworks.com > www.priscilla.com > > > > Eric Brouwers Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61710&t=61615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wrong definition type 4 summary LSA for ASBRs [7:61615]
ASB Link summary is the distance from ABR to ASBR. http://www.cisco.com/en/US/tech/tk648/tk365/technologies_white_paper09186a00800943a1.shtml Wei - Original Message - From: "ericbrouwers" To: Sent: Wednesday, January 22, 2003 4:48 PM Subject: Wrong definition type 4 summary LSA for ASBRs [7:61615] > Hi, > > For those that are reading Cisco Press' CCNP Routing Exam Certification > Guide: > there is a very confusing definition of type 4 summary LSAs on page 292, > chapter 6: > > The AS external ASBR summary link- This LSA is sent to a router that connects > to the outside world (ASBR). It is sent from the Area Border Router to the > Autonomous System Boundary Router. The LSA contains the metric cost from the > ABR to the ASBR. This is identified as a Type 4 LSA. > > In my opinion this is wrong, isn't it? Or maybe I'm missing something? > > My understanding is that a type 4 summary LSA is originated by ABRs.It is > sent > into an area by the ABR to advertise the AS boundary routers. > > Could someone confirm my understanding? > > Eric Brouwers Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61735&t=61615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wrong definition type 4 summary LSA for ASBRs [7:61615]
thing right now. I'm reading the Sybex BSCI book. Eric - Original Message - From: Pistone, Mike To: 'ericbrouwers' Sent: Thursday, January 23, 2003 10:50 PM Subject: RE: Wrong definition type 4 summary LSA for ASBRs [7:61615] I'm reading the CP CCNP Routing Cert Guide too, and have found many of the same faults you did. I found reading the Sybex CCNP books at the same time (the chapters almost exactly match up) works very well. Sybex gives you the introduction in a understandable way, and then the Cisco book elaborates on the topics... Mike ___ Mike Pistone NASA - Russian Services Group Marshall Space Flight Center Huntsville, AL 35806 Ph: (256) 544-2915 Em: [EMAIL PROTECTED] -Original Message- From: ericbrouwers [mailto:[EMAIL PROTECTED]] Sent: Thursday, January 23, 2003 2:52 PM To: [EMAIL PROTECTED] Subject: Re: Wrong definition type 4 summary LSA for ASBRs [7:61615] All of you, thanks for the answers. This routing exam cert. guide is a pretty good book, although I haven't read the BGP and IS-IS sections yet. But the OSPF section needs some corrections indeed . Anyway, I think I will follow Priscilla's advise to buy Doyle's routing book, because now I have around six books (a/o ICND, DCN and CID related books) that all cover fractions of routing, but not the full story. Moreover, sometimes they are in contradiction. Eric - Original Message - From: "Priscilla Oppenheimer" To: Sent: Wednesday, January 22, 2003 11:21 PM Subject: RE: Wrong definition type 4 summary LSA for ASBRs [7:61615] > ericbrouwers wrote: > > > > Hi, > > > > For those that are reading Cisco Press' CCNP Routing Exam > > Certification Guide: there is a very confusing definition of type 4 > > summary LSAs on page 292, > > chapter 6: > > > > The AS external ASBR summary link- This LSA is sent to a router that > > connects to the outside world (ASBR). It is sent from the Area > > Border Router to the > > Autonomous System Boundary Router. The LSA contains the metric > > cost from the > > ABR to the ASBR. This is identified as a Type 4 LSA. > > > > In my opinion this is wrong, isn't it? Or maybe I'm missing > > something? > > > > My understanding is that a type 4 summary LSA is originated by > > ABRs.It is sent into an area by the ABR to advertise the AS boundary > > routers. > > > > Could someone confirm my understanding? > > Yup, I have the same comment penciled into my copy of the book. > > Bottom line: don't even bother trying to learn OSPF from that book. > It's a disaster. (It's a pretty good book otherwise, I think?) > > Read "Routing TCP/IP" by Doyle. You'll want to get that book anyway if > you haven't already It's terrific for real-world and certs. > > ___ > > Priscilla Oppenheimer > www.troubleshootingnetworks.com > www.priscilla.com > > > > Eric Brouwers Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61845&t=61615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
Re: Wrong definition type 4 summary LSA for ASBRs [7:61615]
>The AS external ASBR summary link- This LSA is sent to a router that connects >to the outside world (ASBR). It is sent from the Area Border Router to the >Autonomous System Boundary Router. The LSA contains the metric cost from the >ABR to the ASBR. This is identified as a Type 4 LSA. > >In my opinion this is wrong, isn't it? Or maybe I'm missing something? The problem is, it is quite easy to get a contract for book writing these days. Furthermore, many publishers (not picking on any one in particular) are bring books to market before a proper editing (technical/copy/etc) process has been completed. Hence, I highly recommend you buy books that are either highly recommended, or written by authors who are either authoritative on the subject (ie participated in the spec development) or those that have a reputation for writing quality materials. There is unfortunately a fair amount of not very top notch books out there. Pete >My understanding is that a type 4 summary LSA is originated by ABRs.It is >sent >into an area by the ABR to advertise the AS boundary routers. > >Could someone confirm my understanding? > >Eric Brouwers Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=61847&t=61615 -- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
