Juniper JN0-664 Dumps Questions Answers

BGP GTSM is a technique that protects a BGP session by comparing the TTL value in the IP header of incoming BGP packets against a valid TTL range. If the TTL value is within the valid TTL range, the packet is accepted. If not, the packet is discarded. The valid TTL range is from 255 – the configured hop count + 1 to 255. When GTSM is configured, the BGP packets sent by the device have a TTL of 255. GTSM provides best protection for directly connected EBGP sessions, but not for multihop EBGP or IBGP sessions because the TTL of packets might be modified by intermediate devices.

In the exhibit, we can see that R2, R3, and R4 are in the same AS (AS 20) and R1 is in a different AS (AS 10). Based on this information, we can infer the following statements:

• You can implement BGP GTSM between R2, R3, and R4. This is not correct because R2, R3, and R4 are IBGP peers and GTSM does not provide effective protection for IBGP sessions. The TTL of packets between IBGP peers might be changed by intermediate devices or routing protocols.
• BGP GTSM requires a firewall filter to discard packets with incorrect TTL. This is not correct because BGP GTSM does not require a firewall filter to discard packets with incorrect TTL. BGP GTSM uses TCP option 19 to negotiate GTSM capability between peers and uses TCP option 20 to carry the expected TTL value in each packet. The receiver checks the expected TTL value against the actual TTL value and discards packets with incorrect TTL values.
• You can implement BGP GTSM between R2 and R1. This is correct because R2 and R1 are EBGP peers and GTSM provides effective protection for directly connected EBGP sessions. The TTL of packets between directly connected EBGP peers is not changed by intermediate devices or routing protocols.
• BGP GTSM requires a TTL of 1 to be configured between neighbors. This is not correct because BGP GTSM requires a TTL of 255 to be configured between neighbors. The sender sets the TTL of packets to 255 and the receiver expects the TTL of packets to be 255 minus the configured hop count.
• BGP GTSM requires a TTL of 255 to be configured between neighbors. This is correct because BGP GTSM requires a TTL of 255 to be configured between neighbors. The sender sets the TTL of packets to 255 and the receiver expects the TTL of packets to be 255 minus the configured hop count.

To provide Internet access for VPN-A using CE-1 as the hub CE, you need to do the following:

• You must use RIB groups to leak routes between the inet.0 and vpn-a.inet.0 tables on PE-1 and CE-1. RIB groups are routing options that allow you to import routes from one routing table into another routing table based on certain criteria. In this scenario, you need to configure RIB groups on PE-1 and CE-1 to import Internet routes from inet.0 into vpn-a.inet.0 and vice versa.
• Internet traffic from Site 2 takes the path of PE-2 -> PE-1 -> CE-1 -> PE-1 -> GW-1. This is because Site 2 does not have direct Internet access and needs to use CE-1 as its default gateway for Internet traffic. Site 2 sends its Internet traffic to PE-2, which forwards it to PE-1 based on VPN-A routes. PE-1 then sends it to CE-1 based on RIB group import policy. CE-1 then sends it back to PE-1 based on its default route pointing to GW-1. PE-1 then forwards it to GW-1 based on RIB group import policy again.

The correct order of packet flow through configurable components in the Junos OS CoS features is as follows:

• Behavior Aggregate Classifier: This component uses a single field in a packet header to classify traffic into different forwarding classes and loss priorities based on predefined or user-defined values.
• Input Policer: This component applies rate-limiting and marking actions to incoming traffic based on the forwarding class and loss priority assigned by the classifier.
• Multifield Classifier: This component uses multiple fields in a packet header to classify traffic into different forwarding classes and loss priorities based on user-defined values and filters.
• Forwarding Policy Options: This component applies actions such as load balancing, filtering, or routing to traffic based on the forwarding class and loss priority assigned by the classifier.
• Fabric Scheduler: This component schedules traffic across the switch fabric based on the forwarding class and loss priority assigned by the classifier.
• Output Policer: This component applies rate-limiting and marking actions to outgoing traffic based on the forwarding class and loss priority assigned by the classifier.
• Scheduler/Shaper/RED: This component schedules, shapes, and drops traffic at the egress interface based on the forwarding class and loss priority assigned by the classifier.
• Rewrite Marker: This component rewrites the code-point bits of packets leaving an interface based on the forwarding class and loss priority assigned by the classifier.