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300-415 · Question #184

Refer to the exhibit. A customer wants to implement primary and secondary Cisco SD-WAN overlay routing for prefixes that are advertised for both data centers. The east data center (TLOC…

The correct answer is A. tloc-list dc-preference-west tloc 100.100.100.100 color mpls encap ipsec preference 400 tloc 101.101.101.101 color mpls encap ipsec preference 200 ! control-policy adv-dc-preference-west sequence 10 match route site-list dc-sites ! action accept set tloc-list dc-preference-west ! default-action accept. To implement primary and secondary data center routing based on site location, a TLOC list with appropriate preferences must be defined and then applied using a control policy.

Policies

Question

Refer to the exhibit. A customer wants to implement primary and secondary Cisco SD-WAN overlay routing for prefixes that are advertised for both data centers. The east data center (TLOC 101.101.101.101) is primary for east sites, and the west data center (TLOC 100.100.100.100) is primary for west sites. Which configuration change achieves this objective?

Exhibit

300-415 question #184 exhibit

Options

  • Atloc-list dc-preference-west tloc 100.100.100.100 color mpls encap ipsec preference 400 tloc 101.101.101.101 color mpls encap ipsec preference 200 ! control-policy adv-dc-preference-west sequence 10 match route site-list dc-sites ! action accept set tloc-list dc-preference-west ! default-action accept
  • Btloc-list dc-preference-west tloc 100.100.100.100 color mpls encap ipsec preference 200 tloc 101.101.101.101 color mpls encap ipsec preference 400 ! control-policy adv-dc-preference-west sequence 10 match route site-list dc-sites ! action accept set tloc-list dc-preference-west ! default-action accept
  • Ctloc-list dc-preference-east tloc 100.100.100.100 color mpls encap ipsec preference 400 tloc 101.101.101.101 color mpls encap ipsec preference 200
  • Dtloc-list dc-preference-west tloc 100.100.100.100 color mpls encap ipsec preference 400 tloc 101.101.101.101 color mpls encap ipsec preference 200 ! control-policy adv-dc-preference-west sequence 10 match route site-list dc-sites ! action accept set tloc-list dc-preference-west ! default-action accept

How the community answered

(64 responses)
  • A
    84% (54)
  • B
    8% (5)
  • C
    6% (4)
  • D
    2% (1)

Why each option

To implement primary and secondary data center routing based on site location, a TLOC list with appropriate preferences must be defined and then applied using a control policy.

Atloc-list dc-preference-west tloc 100.100.100.100 color mpls encap ipsec preference 400 tloc 101.101.101.101 color mpls encap ipsec preference 200 ! control-policy adv-dc-preference-west sequence 10 match route site-list dc-sites ! action accept set tloc-list dc-preference-west ! default-action acceptCorrect

This configuration correctly defines a 'tloc-list dc-preference-west' where TLOC 100.100.100.100 (west) has a higher preference (400) than TLOC 101.101.101.101 (east) with a preference of 200. When applied via the 'adv-dc-preference-west' control-policy for west sites, this ensures they prioritize their local data center as primary while having the east data center as secondary.

Btloc-list dc-preference-west tloc 100.100.100.100 color mpls encap ipsec preference 200 tloc 101.101.101.101 color mpls encap ipsec preference 400 ! control-policy adv-dc-preference-west sequence 10 match route site-list dc-sites ! action accept set tloc-list dc-preference-west ! default-action accept

This configuration incorrectly assigns a higher preference to the east data center (400) within a TLOC list intended for west sites, contradicting the requirement for the west data center to be primary for west sites.

Ctloc-list dc-preference-east tloc 100.100.100.100 color mpls encap ipsec preference 400 tloc 101.101.101.101 color mpls encap ipsec preference 200

This option is incomplete, as it only shows a TLOC list for 'dc-preference-east' and lacks the crucial control-policy application necessary to enforce the routing preferences.

Dtloc-list dc-preference-west tloc 100.100.100.100 color mpls encap ipsec preference 400 tloc 101.101.101.101 color mpls encap ipsec preference 200 ! control-policy adv-dc-preference-west sequence 10 match route site-list dc-sites ! action accept set tloc-list dc-preference-west ! default-action accept

This option is identical to option A, which is the correct choice, implying a potential duplication in the question's provided answers.

Concept tested: Cisco SD-WAN TLOC preference and control policy

Source: https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/sdwan-xe-gs-book/m-policy-config.html#C_ID_AE489370_00

Topics

#SD-WAN Policies#Control Policy#TLOC Preference#Route Manipulation

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