HPE FlexNetwork 5510 HI Series

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Figure 134 uRPF work flow
1. uRPF checks source address validity:
 uRPF discards packets with a broadcast source address.
 uRPF discards packets with an all-zero source address but a non-broadcast destination
address. (A packet with source address 0.0.0.0 and destination address 255.255.255.255
might be a DHCP or BOOTP packet and cannot be discarded.)
 uRPF proceeds to step 2 for other packets.
2. uRPF checks whether the source address matches a FIB entry:
Checks the received packet
Broadcast source
address
?
All-zero source address?
Matching FIB entry
found
?
Broadcast destination
address?
Default route found
?
Loose uRPF?
Allows the packet to pass
Discards the packet
Yes
Yes
Yes
Yes
No
Yes
Yes
No
No
Receiving
interface matches
the output
interface of the default
route
？
No
No
NoNo
Loose uRPF?
Yes
No
No
Yes
Yes
Receiving
interface matches the
output interface of the
matching FIB entry？
Matching route is a direct
route?
No
Source IP address
matches an ARP entry?
Yes
No
Yes