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filter. For operations that are less time-critical, including processing Telnet connections, place the term toward the end of the filter. Then apply the filter to the desired interfaces. Here, we apply the filter to the lo0 interface because we want it to apply to all traffic destined to the router’s management addresses, even traffic that is coming to the address of one of the network (PIC) interfaces. The term in this recipe is just one of several terms in a single firewall filter. As a general point, you rarely just reject a firewall term without also either logging, syslogging, or running a counter on the rejections (which gives you data that you can graph). Tracking the rejections is useful for showing abuse of your router, attacks on the router, or even misconfigurations. For example, if you forget about an automated process that uses Telnet to read configuration information on your router that comes from 192.168.0.0/16 and you only permit 10.0.0.0/8, then the then syslog action (and appropriate syslog configuration statements) can be very handy for resolving issues. See Also Recipes 9.8, 9.11, 9.12, and 9.13 2.15 Setting the Source Address for Telnet Connections Problem You want to force Telnet to use a specific IP address when connecting from the router to another system. Solution Include the source address in the Telnet command: aviva@RouterA> telnet source 172.19.121.15 server1 Trying 172.19.121.246... Connected to server1.mycompany.com. Escape character is '^]'. server1 (ttyp0) login: <strong>Discussion</strong> By default, the source address included in locally generated Telnet and other TCP/IP packets is the address of the interface on which the Telnet request is sent. This means the source address may change from connection to connection. If multiple equal-cost next hops are present for a destination, the lo0 loopback interface address is used as the source address. If you configure the system default-address-selection 100 | Chapter 2: Basic Router Security and Access Control This is the Title of the Book, eMatter Edition Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved.
statement in the configuration, which uses the lo0 interface address as the router’s system address, this address is used as the source for most Telnet connections (see Recipe 7.4). The result of this behavior is that the default Telnet source address is not always the same and not always deterministic. If the source address matters when using Telnet to access another system, include it in the telnet command. One instance when you should do so is when filtering the source address on incoming connections, which may block packets coming to the default source address. Another instance is when you use Telnet as a generic way to check and troubleshoot other TCP ports (such as connecting to a server on port 25 to see if it is listening for SNMP mail connections). The source address that you specify must be an address that’s configured on the router. See Also Recipes 7.4 and 7.12 2.16 Creating a Login Banner Problem You want to display a banner during login that indicates that the router is for authorized users only. Solution You define a login banner: [edit system login] aviva@router1# set message "\n\ n==========================================================\n\nAccess to this device is limited to authorized users only.\n\n WARNING: All unauthorized access is prohibited.\n\n================================================= =========\n\n" <strong>Discussion</strong> A login banner is displayed each time anyone logs in to the router, before the login prompt: aviva-server% telnet router1 ========================================================== Access to this device is limited to authorized users only. WARNING: All unauthorized access is prohibited. ========================================================== router1 (ttyp0) login: This is the Title of the Book, eMatter Edition Copyright © 2008 O’Reilly & Associates, Inc. All rights reserved. Creating a Login Banner | 101
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JUNOS Cookbook
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JUNOS Cookbook Aviva Garrett Beijin
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Table of Contents Foreword . . . .
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3. IPSec . . . . . . . . . . . . .
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8.5 Creating Static Routes 263 8.6
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13.5 Adjusting Local Preference Val
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Foreword The early days at Juniper
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Throughout 1997 and early 1998, all
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Preface1 Over the past decade, netw
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Organization As the name suggests,
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Constant width Used for code sectio
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Chapter 1 CHAPTER 1 Router Configur
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You can use a number of operational
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The show command displays the items
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Each listed completion is the confi
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command on the left side of the pip
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The > tells you that you are in ope
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} } } root@# commit root@router1# e
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For the initial router configuratio
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At this point in configuring the ro
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1.4 Displaying the Commands to Recr
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Discussion It is generally good pra
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is often the first thing to check w
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In this example, the error is in th
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To track down what changed in the c
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Solution Use the following command
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login { class superuser-local { per
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If PIM is not yet configured, merge
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You can also save it to a file in y
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These files are also compressed. av
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You see that the running configurat
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Solution The rollback configuration
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See Also Recipe 1.17 1.19 Backing U
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ad1 11513 MB IBM-DARA-212000 AH0AHG
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J-series filesystems on a device co
Page 73 and 74: 1.22 Installing a Different Softwar
Page 75 and 76: Use the request system software add
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Page 79 and 80: JUNOS 7.0 was released in the fourt
Page 81 and 82: Some of the main processes are MGD,
Page 83 and 84: switching board (the SSB), and two
Page 85 and 86: 1.28 Gathering Information Before C
Page 87 and 88: The apply-groups statement causes t
Page 89 and 90: } } } address 10.0.16.1/24; Finally
Page 91 and 92: The commit synchronize command comm
Page 93 and 94: modules/ packages/ proc/ root/ sbin
Page 95 and 96: At this point, you can also upgrade
Page 97 and 98: lets them gain access to the router
Page 99 and 100: client/server systems—the RADIUS
Page 101 and 102: You need to enable FTP only if you
Page 103 and 104: use of the root account. Logging in
Page 105 and 106: A slight twist to this recipe is to
Page 107 and 108: Also, you will not be able to commi
Page 109 and 110: Solution Set all plain-text passwor
Page 111 and 112: Discussion When you want users to b
Page 113 and 114: individual user accounts with passw
Page 115 and 116: ead-only Can perform all actions in
Page 117 and 118: If you try to enter a command that
Page 119 and 120: aviva@router1# set class operator-p
Page 121 and 122: If you use a centralized server, it
Page 123: aviva@RouterF# set term ssh-telnet
Page 127 and 128: een idle, and what they are doing.
Page 129 and 130: Mike would be logged out: mike@rout
Page 131 and 132: Encryption, which is the encoding o
Page 133 and 134: networks, it does not scale well. A
Page 135 and 136: } } [edit interfaces] es-3/0/0 { #
Page 137 and 138: have to set up an IKE SA and a fire
Page 139 and 140: Here’s what the relevant portions
Page 141 and 142: Finally, configure the domain’s I
Page 143 and 144: Configure the security gateway rout
Page 145 and 146: [edit protocols ospf area 0.0.0.0]
Page 147 and 148: Then, configure the IPSec tunnel to
Page 149 and 150: Issuer: Organization: mycompany, Co
Page 151 and 152: Alternate subject: RouterB.mycompan
Page 153 and 154: Chapter 4 CHAPTER 4 SNMP4 4.0 Intro
Page 155 and 156: juniperMIB, which is the top node o
Page 157 and 158: Juniper Networks provides several d
Page 159 and 160: 4.2 Setting Router Information for
Page 161 and 162: Table 4-1. SNMP trap categories Key
Page 163 and 164: Solution You can add a term to the
Page 165 and 166: You might want to give access to al
Page 167 and 168: aviva@router1> show snmp mib get "j
Page 169 and 170: 4.9 Collecting Router Operational I
Page 171 and 172: CPU utilization: User 0 percent Bac
Page 173 and 174: Table 4-2. System logging severity
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Discussion RMON is an SNMP specific
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See Also RFC 2819, Remote Network M
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nms1 sha/3des nonvolatile active Gr
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Again, this recipe is somewhat invo
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Finally, configure which traps the
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} notify chassis-notification-list
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Some are the same as those used by
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Solution Use the following commands
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5.2 Limiting the Messages Collected
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Discussion The default maximum size
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no longer need. Here, we logged RIP
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Discussion This configuration redir
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This command causes all messages se
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Apr 29 22:55:16 router xntpd[4977]:
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The traceoption flags indicate the
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Chapter 6 CHAPTER 6 NTP6 6.0 Introd
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6.2 Setting the Time Zone Problem Y
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Engine boots, the ntpdate utility r
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You can also have all the routers s
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6.6 Checking NTP Status Problem You
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Chapter 7 CHAPTER 7 Router Interfac
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under the name of the interface and
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Solution Use the show interfaces co
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the physical interface. It allows y
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Solution The show interfaces extens
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Broadcast packets 0 [0] Multicast p
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Input packets : 5 Output packets: 5
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1.0.12.2/30 so-1/0/0 Mars 1.0.0.1/3
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To remove an extra IP address, use
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Discussion For MPLS traffic to tran
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Flags: None Addresses, Flags: Is-Pr
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Solution Configure the router’s m
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On an M-series or a T-series router
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You can confirm the presence of the
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Protocol inet6, MTU: 1500 Flags: Is
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Solution Use the Virtual Router Red
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Solution There are three steps to s
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7.16 Configuring T1 Interfaces Prob
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Run the loopback test, which sends
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7.18 Setting Up a BERT Test on a T1
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You can configure an error rate to
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Discussion Synchronous Optical Netw
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SEF 22 182 OK LOS 22 1 OK LOF 22 1
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Use the show aps command to check t
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type of ATM PIC, the configuration
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gre up ipip up lo0 up up lo0.0 up u
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Solution Add the new interface to t
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While this does what you want, it m
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When a single routing protocol prov
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IPv6 uses 128-bit addresses that co
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8.1 Viewing the Routes in the Routi
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oute is learned from a dynamic rout
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} } family iso { address 49.0020.19
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8.2 Viewing Routes to a Particular
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8.3 Viewing Routes Learned from a S
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ff00::/8 perm 0 mdsc 53 1 ff02::1/1
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The actual forwarding tables that t
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and the traffic to these networks i
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Attacker A B Target Real source add
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Check the firewall filter counts wi
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Solution Create a routing policy th
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Discussion Martian addresses are pr
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Solution After configuring both OSP
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To verify the preference change, lo
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Peer supports Refresh capability (2
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This recipe shows how to enable gra
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Because the policy and filter condi
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then accept; } } } protocols { ospf
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The first command in the recipe def
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[edit] aviva@router1# set protocols
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Table 9-4. Actions that change rout
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(called longest-match lookup), so t
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aviva@router1# set term 2 then reje
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See Also IANA, http://www.iana.org/
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the community string from the route
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used to verify that the router is m
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} } Discussion } } Placing firewall
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Table 9-5. Header match conditions
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counterintuitive. However, understa
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protocol-except tcp; } then { count
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protocol tcp; destination-port [ te
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Firewall filter terms are evaluated
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9.12 Using a Firewall Filter to Cou
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04:58:41 pfe A t1-0/0/3.0 TCP 10.0.
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which traffic is more important and
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The next term allows TCP traffic: [
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Routing Engine, you want to make su
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from { source-address { 10.0.8.0/24
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9.16 Rate-Limiting Traffic Flow to
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list of IP addresses in one place i
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lished TCP connections and you sudd
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By default, the JUNOS software impl
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} } } neighbor fe-0/0/0.0; neighbor
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10.0.0.0/24 *[Direct/0] 2w4d 23:05:
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The routing policy you set up is a
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so the inbound metrics are 1. The m
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can use it in the authentication-ke
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10.6 Sending Version 1 Update Messa
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Mar 31 10:11:13 Group beta-rip-grou
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Chapter 11 CHAPTER 11 IS-IS11 11.0
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oundary. This means that the IS-IS
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might be useful when migrating two
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Interface System L State Hold (secs
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RouterA.02-00 0x59 0xeda9 632 L1 L2
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The next four lines show the IP pre
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configuring the preference statemen
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11.5 Configuring a Level 1-Only Rou
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11.6 Controlling DIS Election Probl
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key, or password, for each interfac
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} } from protocol static; then acce
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Again, we expect the metric to chan
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RouterA Level 2 RouterB Level 2 Rou
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Increasing the IS-IS cost of Router
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11.12 Moving IS-IS Traffic off a Ro
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11.14 Tracing IS-IS Protocol Traffi
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Using some of the other flags, you
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OSPF views routers as nodes, which
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Area 0.0.0.0 RouterG lo0:192.168.19
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Another common problem in establish
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The route entries starting with [OS
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entries that originated from the lo
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OSPF network. Route 192.168.18.1:0.
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Checking on RouterA at the other en
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192.168.19.1/32 *[Direct/0] 3d 01:5
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The routers in the stub area no lon
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Router 192.168.16.1 192.168.16.1 0x
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Solution You configure MD5 authenti
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Use the show ospf interface detail
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With the default metric, traffic fr
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12.12 Improving OSPF Convergence Ti
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This output shows two BFD sessions
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aviva@RouterG# commit aviva@RouterG
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Jun 14 22:00:26 CHANGE 192.168.17.1
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Jun 13 16:55:20 IP Route added with
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list of ASs to see whether a route
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E Route was originally learned from
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Then configure an EBGP session to t
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NLRI for this session: inet-unicast
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Next is information about routes le
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Looking at the remote peer router,
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* 10.0.31.0/24 Self I * 172.19.121.
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aviva@RouterE> show bgp summary Gro
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to 10.0.31.1 via t1-0/0/3.0 10.0.29
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lem with BGP itself. When the TCP s
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13.4 Adjusting the Next-Hop Attribu
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The first configuration in this rec
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13.7 Prepending AS Numbers to the A
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13.8 Filtering BGP Routes Based on
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Translated, this match looks for fo
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Type: External State: Established F
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This recipe configures MD5 authenti
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oute reflector system has a set of
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10.0.24.0/24 *[BGP/170] 00:18:38, l
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AS 65500 Sub-AS 65501 RouterF 192.1
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figure-of-merit value correlates to
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Once the routing policy is set up,
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change, the router will unsuppress
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See Also RFC 2439, BGP Route Flap D
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You see that the route to 192.168.1
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When setting up policies, also crea
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} See Also next-hop 192.0.2.1; acce
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Another restriction for multipath B
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This forwarding table is then copie
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BGP establishes the connection, fro
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Chapter 14a CHAPTER 14 MPLS14 14.0
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Layer 2 header MPLS header Layer 3
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RouterG 192.168.19.1 Ingress router
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The main difference between LDP and
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family to the t1-4/0/0 interface; o
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Also verify the MPLS-enabled interf
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The first line of the output shows
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aviva@RouterG> show configuration p
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via t1-4/0/0.0, Push 100000 192.168
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aviva@RouterG> show route forwardin
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This recipe shows how to configure
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Oct 5 19:25:52 Msg Hello (0x100), l
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aviva@R3# set rsvp interface fxp0.0
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fxp0 up up fxp0.0 up up inet 192.16
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aviva@R1> show rsvp interface RSVP
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y 13:31:06 the LSP was up and runni
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10.0.0.6 10.0.0.1 Up 0 1 FF 3 - R1-
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Solution On the ingress router, loo
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for LSP signaling. On the egress an
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Discussion There are several ways t
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14.9 Verifying that the RSVP-Signal
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14.11 Protecting an LSP’s Path Pr
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RSVP RRO in the path calculation lo
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The configuration allocates 50 Mbps
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However, RSVP cannot establish the
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Solution Fast reroute reduces packe
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PATH sentto: 10.1.13.2 (so-0/0/2.0)
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The RSVP interface status shows tha
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14.13 Automatically Allocating Band
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Then examine the history of the LSP
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To understand how preemption works,
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10.0.0.5 From: 10.0.0.1, State: Up,
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9 Oct 14 10:51:20 Deselected as act
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The router knows how to reach its i
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10.1.13.1/32 *[Local/0] 2d 20:39:51
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aviva@R1> clear log rsvp-trace-log
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PATH rcvfrom: 10.1.13.2 (so-0/0/2.0
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The discussion of Layer 3 VPNs invo
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VPN, and routes announced by a remo
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The third and final step is to conf
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One last protocol that you need to
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All routes that are part of the VPN
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--- 192.168.13.1 ping statistics --
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1 *[MPLS/0] 1d 18:03:41, metric 1 R
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65500:3:10.0.31.0/24 *[BGP/170] 00:
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emains private. When configuring th
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} } peer-as 65500; neighbor 10.0.1.
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The VPN2 routing table also knows n
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Just to make sure that prefixes are
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Multicast senders and receivers are
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You administratively configure the
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10.0.21.2/24 RouterB 192.168.12.1 R
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IGMP Last Member Query Interval: 1.
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Again, verify the configured group
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willing to be an RP send RP Announc
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JUNOS routers perform the encapsula
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Now check the RP status on the rout
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Also, make sure that the router’s
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Check to see which RPs the various
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The anycast PIM configuration is qu
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Solution Specify the group address
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The interfaces toward the multicast
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Discussion Flags: sparse Upstream i
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IGMP Query Response Interval: 10.0
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If you are not sure that the domain
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Discussion With PIM-SM, the RP in e
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The full RIB group configuration lo
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} address 192.168.19.1; # ping 224
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Upstream interface: local Upstream
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The first entry is for the source i
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IGMP Last Member Query Interval: 1.
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The command in this recipe is a sim
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adjacencies (continued) IGPs and, 1
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BGP (Border Gateway Protocol) (cont
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configure command (continued) exclu
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dotted quad notation, 248 down arro
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firewall filters (continued) loggin
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IBGP (internal BGP) (continued) LOC
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IP multicast (continued) limiting g
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Level 1 systems (IS-IS) authenticat
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martian addresses/prefixes (continu
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O Object Identifier (see OID) OID (
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plain-text passwords (continued) JU
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RFC (Request for Comment) on BGP, 4
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outing tables (continued) checking
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set route-filter command, 296 set r
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show ospf interface command, 386, 3
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ssh command, 3, 89 SSM (Source-Spec
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tracing (trace logging) (continued)
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About the Author Aviva Garrett has
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