Which three attributes are considered in the default configuration of per-flow load balancing for routed IPv4 traffic? (Choose three.)

A.
incoming interface

B.
source MAC address

C.
protocol

D.
source IP address

E.
destination port

Explanation:
Configuring Per-Flow Load Balancing Based on Hash Values

By default, the JUNOS software uses a hashing method based only on the destination address to elect a forwarding next hop when multiple equal-cost paths are available. All Packet Forwarding Engine slots are assigned the same hash value by default.

Beginning with JUNOS Release 9.3, you can enable router-specific load balancing by configuring a unique, load balance hash value for each Packet Forwarding Engine slot.

To configure per-prefix load balancing. include the load-balance statement at the [edit forwarding-options] hierarchy level:

[edit forwarding-options]
load-balance {
indexed-next-hop;
per-flow {
hash-seed number;
}
}

To enable per-flow load balancing, you must include the hash-seed number statement. The range that you can configure is 0 through 65,535. 0 is the default value; if no hash seed is configured, the elected forwarding next hop would be the same as in previous releases.

Per-Flow and Per-Prefix Load Balancing Overview

By default, when there are multiple equal-cost paths to the same destination, the Junos OS chooses one of the next-hop addresses at random.

On all M Series Multiservice Edge Routers, MX Series Ethernet Services Routers, and T Series Core Routers, you have additional options:

* You can specify what information the routing platform uses for per-flow load balancing based on port data (instead of on source and destination IP addresses only). For aggregated Ethernet and aggregated SONET/SDH interfaces, you can load-balance based on the MPLS label information.
* You can also configure per-prefix load balancing, which allows you to configure a hash value that enables the router to elect a next hop independently of the route chosen by other routers.

In addition, on the M120, M320, and MX Series routers only, you can configure per-flow load balancing, which allows you to configure the router to assign a unique, load-balance hash value for each Packet Forwarding Engine slot.