3com S7906E Installation Instruction

 

1-2 

z 

Discards packets with all-zero source addresses but non-broadcast destination addresses. (A 

packet with source address 0.0.0.0 and destination address 255.255.255.255 might be a DHCP 

packet, and thus is not discarded.) 

2)  If the source address of an incoming packet is found in the FIB table: 

URPF does a reverse route lookup for routes to the source address of the packet. If at least one 

outgoing interface of such a route matches the receiving interface, the packet passes the check. 

Otherwise, the packet is rejected. 

3)  If the source address is not found in the FIB table: 

z 

If a default route is configured, URPF lets the packet pass if the outgoing interface of the default 

route is the receiving interface, and otherwise rejects it. 

z 

If a default route is not configured, the packet is discarded. 

Follow these steps to configure URPF globally: 

Enter system view 

–– 

Enable URPF check globally 

ip urpf strict 

Required 

Disabled by default. 

 

After you enable the URPF function on an S7900E series Ethernet switch, a half reduction of route 

entries may occur. For relevant information, refer to 

.  

Table 1-1 SRPUs/LPUs on which route entries half reduction may occur 

LSQ1SRP1CB, LSQ1MPUA 

SC LPU 

LSQ1SRP2XB, LSQ1SRPB, 
LSQ1CGP24TSC, LSQ1SRPD, 
LSQ1SRP12GB, 

LSQ1CGV24PSC

 

z 

SC LPU (with 
the last two 
letters of the 
LPU model 
being SC, such 
as 
LSQ1GP48SC)

z 

SD LPU (with 
the last two 
letters of the 
LPU model 
being SD, such 
as 
LSQ1GP48SD)

z 

EB LPU (with 
the last two 
letters of the 
LPU model 
being EB, such 
as 
LSQ1GP48EB)

SC LPU and 
SRPU 

SD LPU and EB 
LPU (not 
working in the 
route extension 
mode)