300-410 Exam Dumps - Cisco CCNP Enterprise Questions and Answers

+ allows an LSR to remove the label before forwarding the packet: penultimate hop popping

+ accepts unlabeled packets and imposes labels: label edge router

+ group of packets that are forwarded in the same manner: forwarding equivalence class

+ receives labeled packets and swaps labels: label switch router

Explanation

A label edge router (LER, also known as edge LSR) is a router that operates at the edge of an MPLS network and acts as the entry and exit points for the network. LERspush an MPLS label onto an incoming packet and pop it off an outgoing packet.

A forwarding equivalence class (FEC) is a term

router eigrp 1

!

address-family ipv4 vrf CLIENT1

network 172.16.0.0 0.0.0.255

no auto-summary

autonomous-system 1

exit-address-family

After redistribution, R3 learns about network 10.1.1.0/24 via two paths:+ Internal BGP (IBGP): advertised from R4 with AD of 200 (and metric of 0)+ OSPF: advertised from R1 with AD of 110 (O E2) (and metric of 20)Therefore R3 will choose the path with the lower AD via OSPF

But this is a looped path which is received from R3 -> R2 -> R1 -> R3. So when the advertised route from R4 is expired, the looped path is also expired soon and R3 willreinstall the main path from R4. This is the cause of intermittent connectivity.In order to solve this issue, we can lower the AD of iBGP to a value which is lower than 110 so that it is preferred over OSPF-advertised route.

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipv6_fhsec/configuration/xe-3s/ip6f-xe-3s-book/ip6-snooping.pdf

A route received from one iBGP peer will NOT be advertised to another iBGP peer. Therefore R4 could not receive advertisement for network 192.168.100.0/24. We can overcome this BGP limitation by configuring R1 as a route reflector server and R4 as a route reflector client so that R1 sends advertisements for R4.

https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/23675-27.html

When R2 & R5 are route reflectors (RRs), routes from R4 & R8 are advertised to R5 and R5

advertises to R2. But R2 would drop them as R2 is also a RR. Therefore some routes are

missing on R1 to advertise to eBGP peers.

Good reference:

https://www.ciscolive.com/c/dam/r/ciscolive/emea/docs/2015/pdf/TECRST-2310.pdf

Route reflectors (RR) must be fully iBGP meshed so we cannot configure RR on both R1 and

R5.

We should choose routers at the center of the topology RRs, in this case R4 & R5.

According to this question, uRPF is running in strict mode because packets are dropped even

when that route exists in the routing table. Maybe packets are dropped because the receiving

interface is different from the interface the local router uses to send packets to that destination.

The ip verify unicast source reachable-via rx command enables Unicast RPF in strict mode.

To enable loose mode, administrators can use the any option (ip verify unicast source

reachable-via any). In loose mode, it doesn’t matter if we use this interface to reach the source

or not.

The allow-default option allows the use of the default

route in the source verification process.

https://www.cisco.com/c/en/us/td/docs/switches/datacenter/sw/5_x/nx-os/mpls/configuration/guide/mpls_cg/mp_mpls_overview.pdf

To turn off terminal monitor, use “terminal no monitor” in the enable mode

VPNv4 address consists of 64-bit Route Distinguisher (RD) prepended to IPv4 prefix. This is to

make routes unique that are in different VRFs.