Users Guide

Congure a Route Map for Route Tagging
One method for identifying routes from dierent routing protocols is to assign a tag to routes from that protocol.
As the route enters a dierent routing domain, it is tagged. The tag is passed along with the route as it passes through dierent routing
protocols. You can use this tag when the route leaves a routing domain to redistribute those routes again. In the following example, the
redistribute ospf command with a route map is used in ROUTER RIP mode to apply a tag of 34 to all internal OSPF routes that are
redistributed into RIP.
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 congure the continue command at the end of a module, the next module (or a specied 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 congure 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 congurable 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 rst fragment would be denied and hence the packet as a whole cannot be reassembled.
• Implementing the required rules uses a signicant number of CAM entries per TCP/UDP entry.
• For IP ACL, Dell Networking OS always applies implicit deny. You do not have to congure it.
• For IP ACL, Dell Networking OS applies implicit permit for second and subsequent fragment just prior to the implicit deny.
• If you congure 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 congure 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 oending rule in CAM.
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Access Control Lists (ACLs)