Dell S6000-ON, Руководство по настройке

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NOTE: If you configure the continue clause without specifying a module, the next sequential
module is processed.
Example of Using the
continue
Clause in a Route Map
!
route-map test permit 10
match commu comm-list1
set community 1:1 1:2 1:3
set as-path prepend 1 2 3 4 5
continue 30!
IP Fragment Handling
Dell Networking OS supports a configurable option to explicitly deny IP fragmented packets, particularly
second and subsequent packets.
It extends the existing ACL command syntax with the
fragments
keyword for all Layer 3 rules applicable
to all Layer protocols (permit/deny ip/tcp/udp/icmp).
• Both standard and extended ACLs support IP fragments.
• Second and subsequent fragments are allowed because a Layer 4 rule cannot be applied to these
fragments. If the packet is to be denied eventually, the first fragment would be denied and hence the
packet as a whole cannot be reassembled.
• Implementing the required rules uses a significant number of CAM entries per TCP/UDP entry.
• For IP ACL, Dell Networking OS always applies implicit deny. You do not have to configure it.
• For IP ACL, Dell Networking OS applies implicit permit for second and subsequent fragment just prior
to the implicit deny.
• If you configure an explicit deny, the second and subsequent fragments do not hit the implicit permit
rule for fragments.
• Loopback interfaces do not support ACLs using the
IP fragment
option. If you configure an ACL
with the
fragments
option and apply it to a Loopback interface, the command is accepted but the
ACL entries are not actually installed the offending rule in CAM.
IP Fragments ACL Examples
The following examples show how you can use ACL commands with the
fragment
keyword to filter
fragmented packets.
Example of Permitting All Packets on an Interface
The following configuration permits all packets (both fragmented and non-fragmented) with destination
IP 10.1.1.1. The second rule does not get hit at all.
Dell(conf)#ip access-list extended ABC
Dell(conf-ext-nacl)#permit ip any 10.1.1.1/32
Dell(conf-ext-nacl)# deny ip any 10.1.1.1/32 fragments
Dell(conf-ext-nacl)
Example of Denying Second and Subsequent Fragments
To deny the second/subsequent fragments, use the same rules in a different order. These ACLs deny all
second and subsequent fragments with destination IP 10.1.1.1 but permit the first fragment and non-
fragmented packets with destination IP 10.1.1.1.
Dell(conf)#ip access-list extended ABC
Dell(conf-ext-nacl)# deny ip any 10.1.1.1/32 fragments
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Access Control Lists (ACLs)