Users Guide

Example of the redistribute Command Using a Route Tag
!
router rip
redistribute ospf 34 metric 1 route-map torip
!
route-map torip permit 10
match route-type internal
set tag 34
!
Continue Clause
Normally, when a match is found, set clauses are executed, and the packet is then forwarded; no more route-map modules are processed.
If you configure the continue command at the end of a module, the next module (or a specified module) is processed even after a
match is found. The following example shows a continue clause at the end of a route-map module. In this example, if a match is found in
the route-map “test” module 10, module 30 is processed.
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.
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.
Example of Permitting All Packets on an Interface
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)
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.
Access Control Lists (ACLs)
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