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H2+ Question

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#1 bencellini

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Posted 03 February 2019 - 09:40 PM

Hi All.  Please could someone explain to me:

In H2+, Jamesons core network, AS65001, why is iBGP needed between nodes?

obviously vpnv4 is required and bgp within vrf for PE routers but what purpose does peering using BGP ipv4 serve?

The peers within ipv4 do not carry any routes, as all BGP routes are reflected within vpnv4, also as the solution does not use “no bgp default ipv4” the PE routers attempt to peer with the CE routers, they obviously fail, as the edge router interfaces are within the vrf and peer using ipv4 vrf XXX address family instead.

Thank you if you could clear this up for me.

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#2 umar11891

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Posted 04 February 2019 - 09:49 PM

Hi there
In Jamesons core network, if u read the questions carefully they asked u to config ibgp peering,in which ur R1 is acting as route-reflector.
The command 'no bgp default ipv4 unicast' gives u more control in bgp, like if u not activate the nei in ipv4 address family the peering will not establish.

#3 ta1yu2ri3to4

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Posted 20 February 2019 - 02:13 PM

Hi,

Regarding sec2.11, my recognition is as follow as:
- DMVPN is nhrp phase3
- ospf network-type is point-to-multipoint
- HUB is R17
- Spokes are R19/R20/R21
- Multicast source is R19
- Multicast receivers are R20/R21
- RP is R17
-“ip pim nbma-mode” command is used for the interface which receives the pim join message:
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti/command/imc-cr-book/imc_i3.html#wp3854394110
Excerpt:When this command is configured, each Protocol Independent Multicast (PIM) join message is tracked in the outgoing interface list of a multicast routing table entry.

Question:
Based on requirement, I think "ip pim nbma-mode" command is not necessary for R20/R21. Is it correct? Since I checked the validation was successful after removing "ip pim nbma-mode" from R20/R21. I’m worry about it is equal to minus score or not, when non-necessary command is configured. Or, all we have to do is to make the show command result which exam is asking? (In spite of including unnecessary command)

I would appreciate it if you could give the feedback.

Thank you in advance


#4 johnspain

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Posted 22 February 2019 - 08:31 AM

View Postumar11891, on 04 February 2019 - 09:49 PM, said:

Hi there
In Jamesons core network, if u read the questions carefully they asked u to config ibgp peering,in which ur R1 is acting as route-reflector.
The command 'no bgp default ipv4 unicast' gives u more control in bgp, like if u not activate the nei in ipv4 address family the peering will not establish.
i agree. ipv4 does not carry any prefix but it is a requirement. also, in the exam there is a L3 diagram

#5 werby

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Posted 23 February 2019 - 04:07 AM

It is not about what is the correct or real life best practices but on what the lab asks you to do.

#6 knewrca

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Posted 24 February 2019 - 09:21 AM

Hi Bencellini, this puzzles me as well.

Question 2.4 seems to ask you to configure BGP for IPv4, when later it will become the VPNv4 core.
And once you switch the interfaces into a VRF the BGP IPv4 tables will clear.

I think there's two things going on here:
1) SPOTO material is not consistent. Sometimes answers include config for a later question in the exam. I think that's partly laziness or carelessness on Spoto's part. But this causes confusion for us. Question 2.4 does not mention VRF / VPNv4 stuff, but the asnwer does. I think that's because Spoto copied the answers into the 2.4 question after they finished the complete lab: so it includes stuff from later questions (3.2).
2) The CCIE lab is specifically designed to confuse you. They do this by putting the questsions in such an order that you'll waste a ton of time if you don't read the entire exam before start. This might be one of those questions where they intentionally want to have you make IPv4 and then overwrite it with VPNv4, undoing the IPv4 part and wasting your precious time.

I'd advise to just "skip over" the confusion here and be aware of it during your exam. It might be slightly different on the real exam, perhaps Spoto might not show that here, so read it carefully.

Best of luck!

#7 jordankn

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Posted 25 February 2019 - 09:13 AM

View Postta1yu2ri3to4, on 20 February 2019 - 02:13 PM, said:

Hi,

Regarding sec2.11, my recognition is as follow as:
- DMVPN is nhrp phase3
- ospf network-type is point-to-multipoint
- HUB is R17
- Spokes are R19/R20/R21
- Multicast source is R19
- Multicast receivers are R20/R21
- RP is R17
-“ip pim nbma-mode” command is used for the interface which receives the pim join message:
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti/command/imc-cr-book/imc_i3.html#wp3854394110
Excerpt:When this command is configured, each Protocol Independent Multicast (PIM) join message is tracked in the outgoing interface list of a multicast routing table entry.

Question:
Based on requirement, I think "ip pim nbma-mode" command is not necessary for R20/R21. Is it correct? Since I checked the validation was successful after removing "ip pim nbma-mode" from R20/R21. I’m worry about it is equal to minus score or not, when non-necessary command is configured. Or, all we have to do is to make the show command result which exam is asking? (In spite of including unnecessary command)

I would appreciate it if you could give the feedback.

Thank you in advance

Good point. I'm not sure if cisco will give you minus score it you configure something not necessery. Does anybody configure it on the real exam?

#8 m35a2

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Posted 26 February 2019 - 01:31 AM

View Postta1yu2ri3to4, on 20 February 2019 - 02:13 PM, said:

Hi,

Regarding sec2.11, my recognition is as follow as:
- DMVPN is nhrp phase3
- ospf network-type is point-to-multipoint
- HUB is R17
- Spokes are R19/R20/R21
- Multicast source is R19
- Multicast receivers are R20/R21
- RP is R17
-“ip pim nbma-mode” command is used for the interface which receives the pim join message:
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipmulti/command/imc-cr-book/imc_i3.html#wp3854394110
Excerpt:When this command is configured, each Protocol Independent Multicast (PIM) join message is tracked in the outgoing interface list of a multicast routing table entry.

Question:
Based on requirement, I think "ip pim nbma-mode" command is not necessary for R20/R21. Is it correct? Since I checked the validation was successful after removing "ip pim nbma-mode" from R20/R21. I’m worry about it is equal to minus score or not, when non-necessary command is configured. Or, all we have to do is to make the show command result which exam is asking? (In spite of including unnecessary command)

I would appreciate it if you could give the feedback.

Thank you in advance
I think 'ip pim nbma-mode' is the "use cisco proprietary protocol" part of 2.11

#9 ta1yu2ri3to4

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Posted 09 March 2019 - 09:46 AM

View Postm35a2, on 26 February 2019 - 01:31 AM, said:


I think 'ip pim nbma-mode' is the "use cisco proprietary protocol" part of 2.11

Thank you for giving the coment. My question is whether R20/R21 should use "ip pim nbma-mode" or not. I think that "use cisco proprietary protocol" is equal to use not BSR but Auto-RP.




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