Jump to content


1

Question on H2+ 2.6 & 2.8


4 replies to this topic

#1 ccieorbust32

ccieorbust32

    Junior Member

  • Members
  • PipPip
  • 6 posts
  • 4 thanks

Posted 13 January 2019 - 10:59 PM

Section 2.6 has the requirement that R18/R57 advertise only the /8 summaries given.
Section 2.8 requires specific subnets contained in those prefixes to prefer routing over the backdoor link with MPLS as a backup. All other routes should prefer MPLS. No route-maps or access-lists may be configured.

My question is that the 2.6 section has a route-map used as an unsuppress-map to allow the specific subnets mentioned in 2.8 through the BGP backdoor.
It seems that unsuppress-map is unrelated to 2.6 and really there to make 2.8 work. However, to me that this violates the "no route-map" requirement in 2.8.

Alternatives:

My first thought was to use a prefix-list to filter the specifics out of R55/56 advertisements across MPLS and just prefer the backdoor internally for the /8 route and more specifics for everything else.
That could work for the JACOB side but in 2.4 R15/R16 are aggregating to the same /8 toward MPLS so there are no more specifics for JACOB to prefer if the back door is made best for the /8.

What am I missing?
Either creating a route-map and applying as an unsuppress-map doesn't count against the 2.8 "no route-map" requirement or there is another solution I'm not seeing that isn't in the materials I have.

Thoughts?

#2 cciestudent1

cciestudent1

    Junior Member

  • Members
  • PipPip
  • 1 posts
  • 212 thanks

Posted 17 January 2019 - 07:32 AM

I have the same concern, what is the best solution for this section?

#3 johnspain

johnspain

    Advanced Member

  • Members
  • PipPipPip
  • 53 posts
  • 10 thanks

Posted 18 January 2019 - 08:28 AM

hi, just apply this solution:
- in H2,   use aggregate 10.x.x.x.x /8 + network 10.2.100.0 /24 (don't use summary-only. perform the same in R57)
- in H2+, use aggregate 10.x.x.x.x /8 summary-only + network 10.2.100.0 /24 + unsuppress-map (perform the same in R57)

#4 konuremrah35

konuremrah35

    Member

  • Members
  • PipPip
  • 13 posts
  • 1 thanks

Posted 19 January 2019 - 08:10 PM

View Postjohnspain, on 18 January 2019 - 08:28 AM, said:

hi, just apply this solution:
- in H2,   use aggregate 10.x.x.x.x /8 + network 10.2.100.0 /24 (don't use summary-only. perform the same in R57)
- in H2+, use aggregate 10.x.x.x.x /8 summary-only + network 10.2.100.0 /24 + unsuppress-map (perform the same in R57)

Hi johnspain ,

If you are use unsuppress-map ,you must use route-map configuration . But there is a restriction on the lab : "do not configure any route-map nor access-list".

#5 soepstun

soepstun

    Junior Member

  • Members
  • PipPip
  • 3 posts
  • 0 thanks

Posted 10 February 2019 - 08:51 AM

I have same concern about those questions.
I tried to use prefix-list because it's same output and also not in constraint.

R18:{Changed subnets in R57}
router bgp 65001
aggregate-address 10.0.0.0 255.0.0.0 <<< Am not using summary-only. In routing table there were 10.0.0.0/8 because R15/R16 summarized
network 10.2.100.0 mask 255.255.255.0  <<< For more specific
!
neighbor 10.2.0.46 prefix-list FILTER out
!
ip prefix-list FILTER permit 10.2.100.0/24
ip prefix-list FILTER permit 10.0.0.0/8




0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Organization

Community

Downloads

Test Providers

Site Info


Go to top