13 Replies Latest reply: May 19, 2015 2:39 AM by Ady Wilson RSS

    Optimal Routing Design Book

    Terry Slattery

      I've been reading Optimal Routing Design and have found a number of things that need correction, could be clarified, or that warrant further discussion. I'm going to start a thread here to point out these things.

       

      The CiscoPress web page for this book includes a link to Updates, which contains a few errata. I've found that the errata tends to be overly brief, so I'm going to include what I find here. I'll position some items as a puzzle for readers as a challenge. Let me know what you think and also if you think I've made a mistake. The objective is to learn something from it.

        -Terry

        • 1. Re: Optimal Routing Design Book
          Terry Slattery

          pp 38, last paragraph on the page

          It has the definitions of interlayer and intralayer backwards. The errata sheet includes this one, but only corrects the first sentence. Make sure you know the difference between 'intra' and 'inter'.

          It should read:

           

          Intralayer traffic is traffic that is forwarded within the network layer, whereas interlayer traffic is traffic that is forwarded between network layers. In the same way, intrazone traffic is traffic that is forwarded within a network area, whereas interzone traffic is traffic that is forwarded between network areas.

          • 2. Re: Optimal Routing Design Book
            Terry Slattery

            pp 66 & 67

             

            There is a problem with the multiple redistribution diagram in Figure 2-23 on pp 66 and the steps outlined on pp 67. The errata sheet includes part of this one, but has its own mistakes.

            Determine what the right steps are that causes a loop to be formed.

             

            Exercise: Determine what happens if D advertises 10.1.1.0/24 into OSPF with a cost of 50. What happens when A's link to 10.1.1.0/24 dies.

            • 3. Re: Optimal Routing Design Book
              Terry Slattery

              pp 68, Figure 2-24 and pp 69-70, Figure 2-25 have similar problems to the one above on pp 66-67. Both of the descriptions refer to the wrong routers at some point in the description.

               

              Understand the difference between the use of route maps and tags when preventing multi-redistribution loops.

              • 4. Re: Optimal Routing Design Book
                Terry Slattery

                pp 79, Figure 3-3

                 

                Examine the figure and create a summarization plan. Which of the CIDR blocks in Fig 3-3 looks incorrect and what do you think it should be? How does your summarization plan change if the CIDR blocks remain unchanged vs when they are changed?

                • 5. Re: Optimal Routing Design Book
                  Terry Slattery

                  A network designer often has to help troubleshoot interesting network problems. In that light, examine the configuration shown on pp 105, Figure 3-16.

                  Why is the route redistribution filter not working?

                  This also makes a good CCIE question.

                  • 6. Re: Optimal Routing Design Book
                    Terry Slattery

                    Minor errata

                    pp 123, Example 3-17

                    The first ping command should be 'ping 192.168.10.2'


                    pp 124, last paragraph

                    Router A loses network 10.1.100.0/24 when its interface on that network is shut down.


                    pp 126, Example 3-19

                    The formatting of the text isn't what the router displays. Add a newline after 'r - Reply status'


                    pp 127, Example 3-20 and 3-21

                    The router addresses for replies should be the .2 address, as shown in Figure 3-22.

                     


                    • 7. Re: Optimal Routing Design Book
                      Terry Slattery

                      pp 70 (in the Errata sheet, but the corrected text is in error)

                      Router H receives the redistributed route from Router F, tagged 250. Router G has a filter to block routes that are tagged 250, so it does not forward this update, preventing a second possible routing loop.

                       

                      pp 105, Fig 3-16

                      The config should have the route-map matchtag as follows:

                      route-map matchtag deny 10

                        match tag 100

                      route-map matchtag permit 20

                       

                      router eigrp 2

                        redistribute eigrp 1 route-map matchtag

                       

                      The text on pp 106 correctly mentions the 'match tag' statement for filtering the routes to be redistributed.

                       

                      I would also make the tag '2', to match the EIGRP AS number, to reduce confusion, as recommended earlier in the book. Note that the text on pp 106 describes using a tag of '2'.

                      • 8. Re: Optimal Routing Design Book
                        Terry Slattery

                        Here are the last corrections I found in Optimal Routing Design. It is a very good book and I hope these corrections help others who are reading it.

                         

                        ====

                        pp 123, Ex 3-17

                        ping 182.168.x.y should be ping 192.168.x.y

                        ====

                        pp 124, at the bottom of the page,

                        change 'interface on that interface

                        to 'interface on that network'

                        ====

                        pp 127, the router addresses don't match Fig 3-22

                        For example change

                        'Router B is still waiting on a reply from 10.1.1.1, which is Router C.'

                        to 'Router B is still waiting on a reply from 10.1.1.2, which is Router C.'

                         

                        There are problems in the examples and in the text.

                        ====

                        pp 177, paragraph 2

                        The router-level and interface-level commands are swapped. It should read:

                        '… using either the router-level command neighbor database-filter or the interface-level command ip ospf database-filter.'

                        ====

                        pp 180 simply moving the link between routers A and so it's …

                        ====

                        pp 183 should forward via router E 10.1.1.4, not router C. Or change the dest to 172.16.0.0/16

                        ====

                        pp 192, Fig 5-2

                        Doesn't make sense with the text.

                        ====

                        pp 198 at routers G and F (not E and F)

                        ====

                        pp 211, First paragraph, change

                        Figure 5-14 illustrates.

                        to

                        Figure 5-15 illustrates.

                        ====

                        pp 212, Figure 5-15 is not the right figure for the description in the text. Fig 5-14 isn't either. A CCDE candidate should be able to create the right diagram from the text.

                        ====

                        pp 232, Fig 6-2

                        The core mesh is missing three links to form a full mesh.

                        ====

                        pp 237, Fig 6-3

                        The core mesh is missing three links to form a full mesh.

                        ====

                        pp 243, Fig 6-5

                        Router I is not labeled. It is the router shown between Router H and Router G.

                        ====

                        pp 252, Ex 6-19

                        Typo: Router C config should be 'set metric-type internal'

                        ====

                        pp 253, Ex 6-20

                        Router D config should reference Router B.

                        ====

                        pp 270, last paragraph

                        Change

                        Router B transmits when its control returns begin operating again

                        to

                        Router B transmits when its control plane begins operating again

                        ====

                        pp 279, paragraph 3

                        Change

                        Router A silently closes the old connection and marks all the routing information that it receives from this peer.

                        to

                        Router A silently closes the old connection and marks all the routing information that it received from this peer.

                        ====

                        pp 284, paragraph after Fig 7-14

                        Change

                        whereas an error between routers A and B,

                        to

                        whereas an error between routers A and C,

                        ====

                        pp 289, Fig 7-18

                        The Notification step should be Step 4 and removing the EIGRP neighbor should be Step 5. The numbers on the steps should be swapped so that they are sequential.

                        ====

                        pp 291

                        Step 4 should refer to Router B

                        ====

                        p 329, Fig 8-10

                        10.1.3.4.31 should be 10.1.3.4/31

                        ====

                        pp 337, first line, continued from pp 336, should match the text in Fig 8-12

                        Change

                        TTL greater than 254.

                        to

                        TTL of 254 or greater.

                        ====

                        pp 355

                        The description of label forwarding at the bottom of the page contains several errors and should be rewritten.

                        ====

                        pp 360, Fig 9-5

                        The figure should use a different address than 10.1.1.0/24 since that address was used in the prior figure as originating in Site 1.

                        ====

                        pp 366, step 3

                        Should say "exported from BGP into EIGRP"

                        ====

                        pp 375, Ex 9-4

                        Typo: netowrk

                        ====

                        pp 461, third bullet at the top of the page

                        Change

                        The Router B to C link has a bandwidth of 10 Mbps.

                        to

                        The Router C to D link has a bandwidth of 10 Mbps.

                        ====

                        pp 461, end of the paragraph after the first set of bullets

                        Change

                        What happens if the Router B to C link fails?

                        to

                        What happens if the Router C to D link fails?

                        ====

                        pp 461, middle of the page, after the second set of bullets

                        Change

                        What happens if the Router B to C link fails?

                        to

                        What happens if the Router C to D link fails?

                        ====

                        pp 461, Step 1

                        Change

                        Router B and C detect the link failure…

                        to

                        Router C and D detect the link failure…

                        ====

                        END

                        • 9. Re: Optimal Routing Design Book
                          Joe Harris

                          Terry great job! Considering this is one of the 'required reading' books for the CCDE practical exam, it's a definate benefit to ensure the material is as correct as possible....thanks again for doing this!

                           

                          Joe Harris

                          CCIE #6200 (R/S, Sec, SP)

                          • 10. Re: Optimal Routing Design Book
                            Terry Slattery

                            You're welcome!

                              -Terry

                            • 11. Re: Optimal Routing Design Book
                              Freddy Bello

                              Terry this is a Terrific Job!!!!!!

                               

                              I have found myself also some misleading info on pp 68 and the traffic flow explanation for routing loop prevention on point 4 and 5

                              • 12. Re: Optimal Routing Design Book
                                Terry Slattery

                                Freddy,

                                If you found some additional things, then please post them in this thread so everyone has them.

                                 

                                  -Terry

                                • 13. Re: Optimal Routing Design Book
                                  Ady Wilson

                                  Terry Slattery wrote:

                                   

                                  pp 68, Figure 2-24 and pp 69-70, Figure 2-25 have similar problems to the one above on pp 66-67. Both of the descriptions refer to the wrong routers at some point in the description.

                                   

                                  Understand the difference between the use of route maps and tags when preventing multi-redistribution loops.

                                  Thanks for the post Terry - an interesting and stimulating read!!

                                   

                                  I passed my CCDE written whilst at Cisco Live! in Melbourne (March 2015) and now having a read through some of the book-list. I'm going through this book and the listed errata's....and don't really agree with one error shown on the errata list. I wondered if you (or anyone else) thought the same:

                                   

                                  Route tags - pages 69-70          The Cisco press errata sheet states that the 5th bullet should be changed - from router G to router H.

                                   

                                  From the limited description provided, it doesn't really state whether routers B, E and H are doing any tag adds or blocks....so we must assume that they are learning and redistributing all learned routes.

                                   

                                  What the simplified scenario is trying to say is that Router D will only learn the route directly from B, and will ignore the redistributed route from C to D (via E) as it is tagged. (and not confusing the issue that the route from C (using EIGRP) has a lower AD than the OSPF learned route!).

                                   

                                  In the same way, router G will should only learn the route from router E, as the route which it learns from F (via H) will be tagged 250.

                                   

                                  So when the errata sheet says that the 5th bullet should be about router H, I believe that this is incorrect and should remain as router G (in the same way the 3rd bullet point is correct about router D learning the tagged route).

                                   

                                  Overall, what this section is missing, is the summary description that the loop is prevented by ignoring one of them (the tagged one) because Router D (and G) will attempt to learn the route twice via two other routers.