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1002
BigIron RX Series Configuration Guide
53-1002253-01
Dynamic ARP inspection
35
How DAI works
DAI allows only valid ARP requests and responses to be forwarded.
A Brocade device on which DAI is configured does the following:
•
Intercepts ARP packets received by the system CPU.
•
Inspects all ARP requests and responses received on untrusted ports.
•
Verifies that each of the intercepted packets has a valid IP-to-MAC address binding before
updating the local ARP table, or before forwarding the packet to the appropriate destination.
•
Drops invalid ARP packets
When you enable DAI on a VLAN, by default, all member ports are untrusted. You must manually
configure trusted ports. In a typical network configuration, ports connected to host ports are
untrusted. You configure ports connected to other switches or routers as trusted.
DAI inspects ARP packets received on untrusted ports, as shown in
Figure 133
. DAI carries out the
inspection based on IP-to-MAC address bindings stored in a trusted binding database. For the
BigIron RX, the binding database is the ARP table, which supports DAI, DHCP snooping, and IP
Source Guard. To inspect an ARP request packet, DAI checks the source IP and source MAC
address against the ARP table. For an ARP reply packet, DAI checks the source IP, source MAC,
destination IP, and destination MAC addresses. DAI forwards the valid packets and discards those
with invalid IP-to-MAC address bindings.
When ARP packets reach a trusted port, DAI lets them through, as shown in
Figure 133
.
FIGURE 133
Dynamic ARP Inspection at work
ARP entries
DAI uses the IP/MAC mappings in the ARP table to validate ARP packets received on untrusted
ports.
ARP entries in the ARP table derive from the following:
•
Dynamic ARP – normal ARP learned from trusted ports.
•
Static ARP – statically configured IP/MAC/port mapping.
ARP
packet
ARP
packet
Brocade Device
Trusted
Untrusted
DAI
Содержание BigIron RX Series
Страница 100: ...24 BigIron RX Series Configuration Guide 53 1002253 01 Logging on through the Web Management Interface 2 ...
Страница 192: ...116 BigIron RX Series Configuration Guide 53 1002253 01 Configuring authentication method lists 4 ...
Страница 228: ...152 BigIron RX Series Configuration Guide 53 1002253 01 Enabling WAN PHY mode support 6 ...
Страница 312: ...236 BigIron RX Series Configuration Guide 53 1002253 01 Displaying IP information 7 ...
Страница 356: ...280 BigIron RX Series Configuration Guide 53 1002253 01 Resetting LLDP statistics 9 ...
Страница 402: ...326 BigIron RX Series Configuration Guide 53 1002253 01 Transparent firewall mode 11 ...
Страница 432: ...356 BigIron RX Series Configuration Guide 53 1002253 01 SuperSpan 12 ...
Страница 500: ...424 BigIron RX Series Configuration Guide 53 1002253 01 MRP CLI example 14 ...
Страница 580: ...504 BigIron RX Series Configuration Guide 53 1002253 01 Configuring multicast traffic engineering 18 ...
Страница 591: ...BigIron RX Series Configuration Guide 515 53 1002253 01 Displaying traffic reduction 19 ...
Страница 592: ...516 BigIron RX Series Configuration Guide 53 1002253 01 Displaying traffic reduction 19 ...
Страница 598: ...522 BigIron RX Series Configuration Guide 53 1002253 01 Viewing Layer 2 ACLs 20 ...
Страница 656: ...580 BigIron RX Series Configuration Guide 53 1002253 01 Trunk formation 22 ...
Страница 754: ...678 BigIron RX Series Configuration Guide 53 1002253 01 Displaying RIP filters 24 ...
Страница 814: ...738 BigIron RX Series Configuration Guide 53 1002253 01 Displaying OSPF information 25 ...
Страница 932: ...856 BigIron RX Series Configuration Guide 53 1002253 01 Generalized TTL security mechanism support 26 ...
Страница 980: ...904 BigIron RX Series Configuration Guide 53 1002253 01 Clearing IS IS information 28 ...
Страница 1000: ...924 BigIron RX Series Configuration Guide 53 1002253 01 Using secure copy 30 ...
Страница 1088: ...1012 BigIron RX Series Configuration Guide 53 1002253 01 IP source guard 35 ...
Страница 1108: ...1032 BigIron RX Series Configuration Guide 53 1002253 01 Reading CDP packets 37 ...
Страница 1126: ...1050 BigIron RX Series Configuration Guide 53 1002253 01 Clearing sFlow statistics 39 ...
Страница 1140: ...1064 BigIron RX Series Configuration Guide 53 1002253 01 802 1s Multiple Spanning Tree Protocol 40 ...
Страница 1324: ...1248 BigIron RX Series Configuration Guide 53 1002253 01 Displaying OSPFv3 information 48 ...
Страница 1363: ...BigIron RX Series Configuration Guide 1287 53 1002253 01 Continuous System Monitor 51 ...
Страница 1364: ...1288 BigIron RX Series Configuration Guide 53 1002253 01 Continuous System Monitor 51 ...
Страница 1404: ...1328 BigIron RX Series Configuration Guide 53 1002253 01 Commands That Require a Reload D ...
Страница 1458: ...1382 BigIron RX Series Configuration Guide 53 1002253 01 VSRP E ...