Dell PowerConnect 7048P User Manual - Page 164
NSF and DHCP Snooping, trusted
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NSF and DHCP Snooping Figure 8-14 illustrates an L2 access switch running DHCP snooping. DHCP snooping only accepts DHCP server messages on ports configured as trusted ports. DHCP snooping listens to DHCP messages to build a bindings database that lists the IP address the DHCP server has assigned to each host. IP Source Guard (IPSG) uses the bindings database to filter data traffic in hardware based on source IP address and source MAC address. Dynamic ARP Inspection (DAI) uses the bindings database to verify that ARP messages contain a valid sender IP address and sender MAC address. DHCP snooping checkpoints its bindings database. Figure 8-14. NSF and DHCP Snooping Hosts ` ` ` LAG ` ` ` Hosts DHCP Server If the Management Unit fails, all hosts connected to that unit lose network access until that unit reboots. The hardware on surviving units continues to enforce source filters IPSG installed prior to the failover. Valid hosts continue to communicate normally. During the failover, the hardware continues to drop data packets from unauthorized hosts so that security is not compromised. 164 Managing a Switch Stack
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1,220
-
1,221
-
1,222
-
1,223
-
1,224
-
1,225
-
1,226
-
1,227
-
1,228
-
1,229
-
1,230
-
1,231
-
1,232
-
1,233
-
1,234