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fe-0/0/1.0 up up inet 10.0.15.2/24<br />

se-0/0/2 up down<br />

se-0/0/3 up up<br />

se-0/0/3.0 up up inet 10.0.21.1/24<br />

dsc up up<br />

gre up up<br />

ipip up up<br />

lo0 up up<br />

lo0.0 up up inet 192.168.42.1 --> 0/0<br />

lo0.16385 up up inet 10.0.0.1 --> 0/0<br />

10.0.0.16 --> 0/0<br />

lsi up up<br />

mtun up up<br />

pimd up up<br />

pime up up<br />

pp0 up up<br />

tap up up<br />

dsc is a virtual interface that is used to discard packets, which you might want to do<br />

if the router is experiencing a denial-of-service (DoS) attack. You can configure one<br />

discard interface. If you associate an output filter with the interface, you can log or<br />

count DoS traffic before discarding it to determine the source of the attack.<br />

The remaining interfaces are created by the kernel and are used internally by the<br />

JUNOS software. Some have corresponding configurable interfaces for setting up<br />

tunnels on Tunnel Services PICs. You set up unicast tunnels with the gr- or ipphysical<br />

interfaces, in place of the nonconfigurable gre and ipip interfaces, to use<br />

generic route encapsulation or IP-IP encapsulation, respectively. PIM tunnels, used<br />

by PIM sparse mode, have two interfaces, pe- and pd-, for encapsulating and deencapsulating<br />

PIM Register messages. When the router has a Tunnel Services PIC<br />

installed, the software automatically configures one multicast tunnel interface, mt-<br />

(corresponding to mtun), for each virtual private network (VPN) you configure.<br />

The lo0.16385 interface is created by the Internet Routing process (irsd) and is used<br />

for internal routing. The tap interface is used to copy discarded packets. lsi is a<br />

label-switched interface that is used by MPLS label-switched paths (LSPs).<br />

7.24 Configuring Interfaces Before the PICs Are<br />

Installed<br />

Problem<br />

You are expecting new PICs and want to prepare the configuration file in advance.<br />

242 | Chapter 7: Router Interfaces<br />

This is the Title of the Book, eMatter Edition<br />

Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.

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