A network engineer is configuring two dedicated Internet connections within the Internet module. One connection is the primary connection to all wired business communications, while the other is the primary connection for all customer wireless traffic. If one of the links goes down, the affected traffic needs to be redirected to the redundant link.
Which current technology should be deployed to monitor the scenario?
A. PBR
B. IP QoS
C. MMC
D. IP SLA
E. IP SAA
d
ip sla can decide to take the secundary path
read the question
One connection is the primary connection to all wired business communications, while the other is the primary connection for all customer wireless traffic. If one of the links goes down, the affected traffic needs to be redirected to the redundant link.
I’m going with D. IP SLA, because PBR doesn’t properly monitor end to end. It can only test that the next hop is reachable.
If there’s an downstream issue with one link where the gateway is still reachable (not uncommon,) then PBR will continue to send traffic that way.
IP SLA can monitor actual Internet connectivity (say by pinging 8.8.8.8) that will catch any type of outage.
If we look at the last part of the question “deployed to monitor the scenario”.
Although, the technology that can be deploy is Policy based routing, the question is asking to monitor after PBR is in place.
I believe the answer is IP SLA
Answer: A. PBR
“Policy-Based Routing Using the set ip default next-hop and set ip next-hop Commands Configuration Example” says,
The set ip next-hop command verifies the existence of the next hop specified, and…
– if the next hop exists in the routing table, then the command policy routes the packet to the next hop.
– if the next hop does not exist in the routing table, the command uses the normal routing table to forward the packet.
https://www.cisco.com/c/en/us/support/docs/ip/ip-routed-protocols/47121-pbr-cmds-ce.html
I think it is ‘IP SLA’ as ISP’s are not using CDP for clients
https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/iproute_pi/command/iri-cr-book/iri-cr-s1.html#wp8093935770
The set ip next-hop verify-availability command can be used in the following two ways:
– With policy-based routing (PBR) to verify next hop reachability using Cisco Discovery Protocol (CDP).
– With optional arguments to support object tracking using Internet Control Message Protocol (ICMP) ping or an HTTP GET request to verify if a remote device is reachable
set ip next-hop verify-availability
To configure policy routing to verify the reachability of the next hop of a route map before the router performs policy routing to that next hop, use the set ip next-hop verify-availability command in route-map configuration mode. To disable this function, use the no form of this command.
I would also say A, since somehow we have to check the source (wired or wireless), and we can do that with PBR.
A.
” One connection is the primary connection to all wired business communications, while the other is the primary connection for all customer wireless traffic” – it’s only release with PBR with next-hop.
PBR nativly chek reachability of next hop – so we don’t need sla-track for this scenario.
2 pbr state + with 2 static route 0.0.0.0 to ISP.
D
https://www.cisco.com/c/en/us/support/docs/ip/ip-routing/200785-ISP-Failover-with-default-routes-using-I.html
Introduction
This document describes how to configure WAN (or ISP) redundancies, wherein multiple WAN links terminate on the same end router.