H3C S10500 Switch Series

Transcription

1 H3C S10500 Switch Series Layer 3 - IP Routing Configuration Guide Hangzhou H3C Technologies Co., Ltd. Software version: Release 1126 and Later Document version: C-1.01

2 Copyright 2011, Hangzhou H3C Technologies Co., Ltd. and its licensors All rights reserved Trademarks No part of this manual may be reproduced or transmitted in any form or by any means without prior written consent of Hangzhou H3C Technologies Co., Ltd. H3C,, Aolynk,, H 3 Care,, TOP G,, IRF, NetPilot, Neocean, NeoVTL, SecPro, SecPoint, SecEngine, SecPath, Comware, Secware, Storware, NQA, VVG, V 2 G, V n G, PSPT, XGbus, N-Bus, TiGem, InnoVision and HUASAN are trademarks of Hangzhou H3C Technologies Co., Ltd. Notice All other trademarks that may be mentioned in this manual are the property of their respective owners The information in this document is subject to change without notice. Every effort has been made in the preparation of this document to ensure accuracy of the contents, but all statements, information, and recommendations in this document do not constitute the warranty of any kind, express or implied.

3 Preface The H3C S10500 documentation set includes 12 configuration guides, which describe the software features for the H3C S10500 Switch Series and guide you through the software configuration procedures. These configuration guides also provide configuration examples to help you apply software features to different network scenarios. The Layer 3 IP Routing Configuration Guide describes routing fundamentals and configuration. It covers the mainstream routing protocols for IPv4 and IPv6 networks, and describes how to use policies to filter routes and affect routing decisions. This preface includes: Audience Conventions Obtaining documentation Technical support Documentation feedback Audience This documentation is intended for: Network planners Field technical support and servicing engineers Network administrators working with the S10500 series Conventions This section describes the conventions used in this documentation set. Command conventions Convention Boldface Italic Description Bold text represents commands and keywords that you enter literally as shown. Italic text represents arguments that you replace with actual values. [ ] Square brackets enclose syntax choices (keywords or arguments) that are optional. { x y... } [ x y... ] { x y... } * [ x y... ] * Braces enclose a set of required syntax choices separated by vertical bars, from which you select one. Square brackets enclose a set of optional syntax choices separated by vertical bars, from which you select one or none. Asterisk marked braces enclose a set of required syntax choices separated by vertical bars, from which you select at least one. Asterisk marked square brackets enclose optional syntax choices separated by vertical bars, from which you select one choice, multiple choices, or none.

4 Convention &<1-n> Description The argument or keyword and argument combination before the ampersand (&) sign can be entered 1 to n times. # A line that starts with a pound (#) sign is comments. GUI conventions Convention Boldface Description Window names, button names, field names, and menu items are in Boldface. For example, the New User window appears; click OK. > Multi-level menus are separated by angle brackets. For example, File > Create > Folder. Convention Description < > Button names are inside angle brackets. For example, click <OK>. [ ] Window names, menu items, data table and field names are inside square brackets. For example, pop up the [New User] window. / Multi-level menus are separated by forward slashes. For example, [File/Create/Folder]. Symbols Convention WARNING CAUTION IMPORTANT NOTE TIP Description An alert that calls attention to important information that if not understood or followed can result in personal injury. An alert that calls attention to important information that if not understood or followed can result in data loss, data corruption, or damage to hardware or software. An alert that calls attention to essential information. An alert that contains additional or supplementary information. An alert that provides helpful information. Network topology icons Represents a generic network device, such as a router, switch, or firewall. Represents a routing-capable device, such as a router or Layer 3 switch. Represents a generic switch, such as a Layer 2 or Layer 3 switch, or a router that supports Layer 2 forwarding and other Layer 2 features. Port numbering in examples The port numbers in this document are for illustration only and might be unavailable on your device.

5 Obtaining documentation You can access the most up-to-date H3C product documentation on the World Wide Web at Click the links on the top navigation bar to obtain different categories of product documentation: [Technical Support & Documents > Technical Documents] Provides hardware installation, software upgrading, and software feature configuration and maintenance documentation. [Products & Solutions] Provides information about products and technologies, as well as solutions. [Technical Support & Documents > Software Download] Provides the documentation released with the software version. Technical support Documentation feedback You can your comments about product documentation to We appreciate your comments.

6 Contents IP routing basics configuration 1 IP routing overview 1 Routing table 1 Dynamic routing protocols 2 Routing preference 3 Load sharing 4 Route backup 4 Route recursion 4 Route redistribution 4 Displaying and maintaining a routing table 4 Static routing configuration 7 Introduction 7 Static route 7 Default route 7 Static route configuration items 7 Configuring a static route 8 Configuration prerequisites 8 Configuration procedure 8 Configuring BFD for static routes 9 BFD control packet mode 9 BFD echo packet mode 10 Configuring static route FRR 10 Displaying and maintaining static routes 11 Static route configuration examples 12 Basic static route configuration example 12 Static route FRR configuration example 14 BFD for static routes configuration example (direct session) 16 BFD for static routes configuration example (indirect session) 18 RIP configuration 21 RIP overview 21 RIP working mechanism 21 Operation of RIP 22 RIP version 22 RIP message format 23 Supported RIP features 24 Protocols and standards 25 RIP configuration task list 25 Configuring RIP basic functions 26 Configuration prerequisites 26 Configuration procedure 26 Configuring RIP route control 28 Configuring an additional routing metric 28 Configuring RIPv2 route summarization 28 Disabling host route reception 29 Advertising a default route 30 Configuring inbound or outbound route filtering 30 Configuring a priority for RIP 31 Configuring RIP route redistribution 31 i

7 Tuning and optimizing RIP networks 32 Configuring RIP timers 32 Configuring split horizon and poison reverse 32 Configuring the maximum number of load balanced routes 33 Enabling zero field check on incoming RIPv1 messages 33 Enabling source IP address check on incoming RIP updates 34 Configuring RIPv2 message authentication 34 Specifying a RIP neighbor 35 Configuring RIP-to-MIB binding 35 Configuring the RIP packet sending rate 35 Configuring RIP FRR 36 Configuring BFD for RIP 37 Single-hop detection in BFD echo packet mode 37 Bidirectional detection in BFD control packet mode 37 Displaying and maintaining RIP 38 RIP configuration examples 38 Configuring RIP version 38 Configuring RIP route redistribution 40 Configuring an additional metric for a RIP interface 42 Configuring RIP to advertise a summary route 44 RIP FRR configuration example 46 Configuring BFD for RIP (single-hop detection in BFD echo packet mode) 48 Configuring BFD for RIP (bidirectional detection in BFD control packet mode) 51 Troubleshooting RIP 54 No RIP updates received 54 Route oscillation occurred 55 OSPF configuration 56 Introduction to OSPF 56 Basic concepts 56 Area based OSPF network partition 58 Router types 61 Classification of OSPF networks 62 DR and BDR 63 OSPF packet formats 64 Supported features 72 Protocols and standards 74 OSPF configuration task list 75 Enabling OSPF 76 Configuration prerequisites 76 Configuration procedure 76 Configuring OSPF areas 77 Configuration prerequisites 77 Configuring a stub area 78 Configuring an NSSA area 78 Configuring a virtual link 79 Configuring OSPF network types 79 Configuration prerequisites 80 Configuring the OSPF network type for an interface as broadcast 80 Configuring the OSPF network type for an interface as NBMA 80 Configuring the OSPF network type for an interface as P2MP 81 Configuring the OSPF network type for an interface as P2P 82 Configuring OSPF route control 82 Configuration prerequisites 82 Configuring OSPF route summarization 82 ii

8 Configuring OSPF inbound route filtering 83 Configuring ABR Type-3 LSA filtering 84 Configuring an OSPF cost for an interface 84 Configuring the maximum number of OSPF routes 85 Configuring the maximum number of load-balanced routes 85 Configuring OSPF preference 86 Configuring OSPF route redistribution 86 Advertising a host route 87 Tuning and optimizing OSPF networks 88 Configuration prerequisites 88 Configuring OSPF packet timers 88 Specifying LSA transmission delay 89 Specifying SPF calculation interval 89 Specifying the LSA arrival interval 90 Specifying the LSA generation interval 90 Disabling interfaces from receiving and sending OSPF packets 91 Configuring stub routers 91 Configuring OSPF authentication 91 Adding the interface MTU into DD packets 92 Configuring the maximum number of external LSAs in LSDB 92 Enabling compatibility with RFC Logging neighbor state changes 93 Configuring OSPF network management 93 Enabling message logging 94 Enabling the advertisement and reception of opaque LSAs 94 Configuring OSPF to give priority to receiving and processing hello packets 95 Configuring the LSU transmit rate 95 Enabling OSPF ISPF 95 Configuring OSPF FRR 96 Configuring OSPF Graceful Restart 97 Configuring the OSPF GR Restarter 97 Configuring the OSPF GR Helper 98 Triggering OSPF Graceful Restart 99 Configuring OSPF NSR 99 Configuring BFD for OSPF 100 Configuring control packet bidirectional detection 100 Configuring echo packet single-hop detection 100 Displaying and maintaining OSPF 101 OSPF configuration examples 102 Configuring OSPF basic functions 102 Configuring OSPF route redistribution 105 Configuring OSPF to advertise a summary route 107 Configuring an OSPF stub area 109 Configuring an OSPF NSSA area 112 Configuring OSPF DR election 114 Configuring OSPF virtual links 118 Configuring OSPF Graceful Restart 120 Configuring OSPF NSR 122 Configuring route filtering 124 Configuring OSPF FRR 126 Configuring BFD for OSPF 129 Troubleshooting OSPF configuration 133 No OSPF neighbor relationship established 133 Incorrect routing information 133 iii

9 IS-IS configuration 134 IS-IS overview 134 Basic concepts 134 IS-IS area 136 IS-IS network type 138 IS-IS PDU format 139 Supported IS-IS features 145 Protocols and standards 147 IS-IS configuration task list 147 Configuring IS-IS basic functions 148 Configuration prerequisites 148 Enabling IS-IS 149 Configuring the IS level and circuit level 149 Configuring the network type of an interface as P2P 150 Configuring IS-IS routing information control 150 Configuration prerequisites 150 Configuring IS-IS link cost 150 Specifying a priority for IS-IS 152 Configuring the maximum number of equal cost routes 152 Configuring IS-IS route summarization 152 Advertising a default route 153 Configuring IS-IS route redistribution 153 Configuring IS-IS route filtering 154 Configuring IS-IS route leaking 155 Tuning and optimizing IS-IS networks 155 Configuration prerequisites 155 Specifying intervals for sending IS-IS hello and CSNP packets 155 Specifying the IS-IS hello multiplier 156 Configuring a DIS priority for an interface 156 Disabling an interface from sending or receiving IS-IS packets 157 Enabling an interface to send small hello packets 157 Configuring LSP parameters 157 Configuring SPF parameters 160 Assigning a high priority to IS-IS routes 160 Setting the LSDB overload bit 160 Configuring system ID to host name mappings 161 Enabling the logging of neighbor state changes 162 Enhancing IS-IS network security 162 Configuration prerequisites 162 Configuring neighbor relationship authentication 162 Configuring area authentication 163 Configuring routing domain authentication 163 Configuring IS-IS GR 164 Configuring IS-IS FRR 164 Enabling IS-IS SNMP trap 166 Binding an IS-IS process with MIBs 166 Configuring BFD for IS-IS 166 Displaying and maintaining IS-IS 167 IS-IS configuration examples 168 IS-IS basic configuration 168 DIS election configuration 172 Configuring IS-IS route redistribution 176 IS-IS Graceful Restart configuration example 180 IS-IS FRR configuration example 181 iv

10 IS-IS authentication configuration example 183 Configuring BFD for IS-IS 186 BGP configuration 190 BGP overview 190 Formats of BGP messages 190 BGP path attributes 193 BGP route selection 197 ibgp and IGP synchronization 199 Settlements for problems in large scale BGP networks 199 BGP GR 202 MP-BGP 203 Protocols and standards 203 BGP configuration task list 204 Configuring BGP basic functions 205 Configuration prerequisites 205 Creating a BGP connection 205 Specifying the source interface for TCP connections 206 Allowing establishment of ebgp connection to an indirectly connected peer or peer group 207 Controlling route generation 207 Configuration prerequisites 207 Injecting a local network 208 Configuring BGP route redistribution 208 Enabling default route redistribution into BGP 208 Controlling route distribution and reception 209 Configuration prerequisites 209 Configuring BGP route summarization 209 Advertising a default route to a peer or peer group 210 Configuring BGP route distribution/reception filtering policies 210 Enabling BGP and IGP route synchronization 211 Limiting prefixes received from a peer or peer group 212 Configuring BGP route dampening 212 Configuring a shortcut route 213 Configuring BGP route attributes 213 Configuration prerequisites 213 Specifying a preferred value for routes received 213 Configuring preferences for BGP routes 214 Configure the default local preference 214 Configuring the MED attribute 214 Configuring the next hop attribute 216 Configuring the AS-PATH attribute 217 Tuning and optimizing BGP networks 220 Configuration prerequisites 220 Configuring the BGP keepalive interval and holdtime 220 Configuring the interval for sending the same update 221 Configuring BGP soft-reset 221 Enabling the BGP ORF capability 222 Enabling 4-byte AS number suppression 223 Enabling quick ebgp session reestablishment 224 Enabling MD5 authentication for TCP connections 224 Configuring BGP load balancing 224 Forbiding session establishment with a peer or peer group 225 Configuring a large scale BGP network 225 Configuration prerequisites 225 Configuring BGP peer groups 225 v

11 Configuring BGP community 227 Configuring a BGP route reflector 228 Configuring a BGP confederation 229 Configuring BGP GR 230 Enabling trap 230 Enabling logging of peer state changes 231 Configuring BFD for BGP 231 Displaying and maintaining BGP 231 Displaying BGP 231 Resetting BGP connections 233 Clearing BGP information 233 BGP configuration examples 233 BGP basic configuration 233 BGP and IGP synchronization configuration 238 BGP load balancing configuration 240 BGP community configuration 243 BGP route reflector configuration 245 BGP confederation configuration 247 BGP path selection configuration 250 BGP GR configuration 254 Configuring BFD for BGP 255 Troubleshooting BGP 259 BGP peer relationship not established 259 IPv6 static routing configuration 261 Introduction to IPv6 static routing 261 Features of IPv6 static routes 261 Default IPv6 route 261 Configuring an IPv6 static route 261 Configuration prerequisites 261 Configuration procedure 261 Displaying and maintaining IPv6 static routes 262 IPv6 static routing configuration example 262 RIPng configuration 265 Introduction to RIPng 265 RIPng working mechanism 265 RIPng packet format 266 RIPng packet processing procedure 267 Protocols and standards 267 RIPng configuration task list 267 Configuring RIPng basic functions 268 Configuration prerequisites 268 Configuration procedure 268 Configuring RIPng route control 268 Configuring an additional routing metric 269 Configuring RIPng route summarization 269 Advertising a default route 269 Configuring a RIPng route filtering policy 270 Configuring a priority for RIPng 270 Configuring RIPng route redistribution 270 Tuning and optimizing the RIPng network 271 Configuring RIPng timers 271 Configuring split horizon and poison reverse 271 Configuring zero field check on RIPng packets 272 vi

12 Configuring the maximum number of equal cost routes for load balancing 272 Displaying and maintaining RIPng 273 RIPng configuration examples 273 Configure RIPng basic functions 273 Configuring RIPng route redistribution 276 OSPFv3 configuration 279 Introduction to OSPFv3 279 OSPFv3 overview 279 OSPFv3 packets 279 OSPFv3 LSA types 280 Timers of OSPFv3 280 OSPFv3 features supported 281 Protocols and standards 281 OSPFv3 configuration task list 281 Enabling OSPFv3 282 Configuration prerequisites 282 Enabling OSPFv3 282 Configuring OSPFv3 area parameters 283 Configuration prerequisites 283 Configuring an OSPFv3 stub area 283 Configuring an OSPFv3 virtual link 284 Configuring OSPFv3 network types 284 Configuration prerequisites 285 Configuring the OSPFv3 network type for an interface 285 Configuring an NBMA or P2MP neighbor 285 Configuring OSPFv3 routing information control 285 Configuration prerequisites 285 Configuring OSPFv3 route summarization 286 Configuring OSPFv3 inbound route filtering 286 Configuring an OSPFv3 cost for an interface 286 Configuring the maximum number of OSPFv3 load-balanced routes 287 Configuring a priority for OSPFv3 287 Configuring OSPFv3 route redistribution 288 Tuning and optimizing OSPFv3 networks 288 Configuration prerequisites 289 Configuring OSPFv3 timers 289 Configuring a DR priority for an interface 290 Ignoring MTU check for DD packets 290 Disable interfaces from receiving and sending OSPFv3 packets 290 Enable the logging of neighbor state changes 291 Configuring OSPFv3 GR 291 Configuring GR Restarter 291 Configuring GR Helper 292 Configuring BFD for OSPFv3 292 Displaying and maintaining OSPFv3 293 OSPFv3 configuration examples 294 Configuring OSPFv3 areas 294 Configuring OSPFv3 DR election 297 Configuring OSPFv3 route redistribution 300 Configuring OSPFv3 GR 303 Configuring BFD for OSPFv3 305 Troubleshooting OSPFv3 configuration 308 No OSPFv3 neighbor relationship established 308 Incorrect routing information 308 vii

13 IPv6 IS-IS configuration 310 Introduction to IPv6 IS-IS 310 Configuring IPv6 IS-IS basic functions 310 Configuration prerequisites 310 Configuration procedure 310 Configuring IPv6 IS-IS routing information control 311 Configuration prerequisites 311 Configuration procedure 311 Configuring BFD for IPv6 IS-IS 312 Displaying and maintaining IPv6 IS-IS 313 IPv6 IS-IS configuration examples 314 IPv6 IS-IS basic configuration example 314 Configuring BFD for IPv6 IS-IS 318 IPv6 BGP configuration 322 IPv6 BGP overview 322 IPv6 BGP configuration task list 323 Configuring IPv6 BGP basic functions 324 Configuration prerequisites 324 Specifying an IPv6 BGP peer 324 Injecting a local IPv6 route 324 Configuring a preferred value for routes from a peer or peer group 325 Specifying the source interface for establishing TCP connections 325 Allowing the establishment of an indirect ebgp connection 326 Configuring a description for an IPv6 peer or peer group 326 Disabling session establishment to an IPv6 peer or peer group 326 Logging IPv6 peer or peer group state changes 327 Controlling route distribution and reception 327 Configuration prerequisites 327 Configuring IPv6 BGP route redistribution 327 Configuring IPv6 BGP route summarization 328 Advertising a default route to an IPv6 peer or peer group 328 Configuring outbound route filtering 328 Configuring inbound route filtering 329 Configuring IPv6 BGP and IGP route synchronization 330 Configuring route dampening 330 Configuring IPv6 BGP route attributes 331 Configuration prerequisites 331 Configuring IPv6 BGP preference and default LOCAL_PREF and NEXT_HOP attributes 331 Configuring the MED attribute 332 Configuring the AS_PATH attribute 332 Tuning and optimizing IPv6 BGP networks 333 Configuration prerequisites 333 Configuring IPv6 BGP timers 333 Configuring IPv6 BGP soft reset 334 Enabling the IPv6 BGP ORF capability 335 Enabling 4-byte AS number suppression 336 Configuring the maximum number of load-balanced routes 336 Enabling MD5 authentication for TCP connections 337 Configuring a large-scale IPv6 BGP network 337 Configuration prerequisites 337 Configuring IPv6 BGP peer group 338 Configuring IPv6 BGP community 339 Configuring an IPv6 BGP route reflector 339 Configuring BFD for IPv6 BGP 340 viii

14 Displaying and maintaining IPv6 BGP 341 Displaying BGP 341 Resetting IPv6 BGP connections 342 Clearing IPv6 BGP information 342 IPv6 BGP configuration examples 342 IPv6 BGP basic configuration 342 IPv6 BGP route reflector configuration 344 Configuring BFD for IPv6 BGP 346 Troubleshooting IPv6 BGP configuration 350 IPv6 BGP peer relationship not established 350 Routing policy configuration 351 Introduction to routing policy 351 Routing policy application 351 Routing policy implementation 351 Filters 351 Routing policy configuration task list 353 Defining filters 353 Prerequisites 353 Defining an IP-prefix list 353 Defining an AS path list 354 Defining a community list 354 Defining an extended community list 355 Configuring a routing policy 355 Prerequisites 355 Creating a routing policy 355 Defining if-match clauses 356 Defining apply clauses 357 Defining a continue clause 359 Displaying and maintaining the routing policy 360 Routing policy configuration examples 360 Applying a routing policy to IPv4 route redistribution 360 Applying a routing policy to IPv6 route redistribution 363 Applying a routing policy to filter received BGP routes 364 Troubleshooting routing policy configuration 367 IPv4 routing information filtering failure 367 IPv6 routing information filtering failure 367 Policy-based routing configuration 368 Introduction to PBR 368 PBR modes 368 Concepts 369 QoS mode 369 Configuring PBR (using a PBR policy) 370 Defining a policy 370 Configuring local PBR 371 Configuring interface PBR 371 PBR and track 372 Configuring PBR (using a QoS policy) 372 Configuring a QoS policy 372 Applying the QoS policy 373 Displaying and maintaining PBR configuration 374 PBR configuration (using a PBR policy) 374 PBR configuration (using a QoS policy) 374 PBR configuration examples 375 ix

15 Configuring local PBR based on packet type 375 Configuring interface PBR based on packet type 377 IPv4 PBR configuration example (using a QoS policy) 378 IPv6 PBR configuration example (using a QoS policy) 379 Index 381 x

16 IP routing basics configuration NOTE: The term router in this document refers to both routers and Layer 3 switches. The types of interfaces that appear in any figures other than the network diagrams for configuration examples are for illustration only. Some of them might be unavailable on your switch. The term interface in the routing features refers to Layer 3 interfaces, including VLAN interfaces and route-mode (or Layer 3) Ethernet ports. You can set an Ethernet port to operate in route mode by using the port link-mode route command (see Layer 2 LAN Switching Configuration Guide). IP routing overview Upon receiving a packet, a router determines the optimal route based on the destination address and forwards the packet to the next router in the path. When the packet reaches the last router, it then forwards the packet to the destination host. Routing provides the path information that guides the forwarding of packets. Routes can be divided into the following categories by destination: Network route The destination is a network. The subnet mask is less than 32 bits. Host route The destination is a host. The subnet mask is 32 bits. Routes can be divided into the following types based on whether the destination is directly connected to the router: Direct routes The destination is directly connected to the router. Indirect routes The destination is not directly connected to the router. Routing table Introduction to routing table A router selects optimal routes from the routing table, and sends them to the forwarding information base (FIB) table to guide packet forwarding. Each router maintains a routing table and a FIB table. Routes in a routing table can be divided into the following categories by origin: Direct routes Routes discovered by data link protocols, also known as interface routes Static routes Routes manually configured. Static routes are easy to configure and require less system resources. They work well in small and stable networks. Static routes cannot adjust to network changes. You must manually configure the routes again whenever the network topology changes. Dynamic routes Routes discovered dynamically by routing protocols Each entry in the FIB table specifies a physical interface that packets destined for a certain address should go out to reach the next hop the next router or the directly connected destination. 1

17 NOTE: For more information about the FIB table, see Layer 3 IP Services Configuration Guide. Routing table information Display the brief information of a routing table by using the display ip routing-table command. For example: <Sysname> display ip routing-table Routing Tables: Public Destinations : 7 Routes : 7 Destination/Mask Proto Pre Cost NextHop Interface /24 Direct Vlan /24 Static Vlan /24 OSPF Vlan13 (Part of the output information is omitted) A route entry includes the following key items: Destination Destination IP address or destination network Mask The network mask specifies, in company with the destination address, the address of the destination network. A logical AND operation between the destination address and the network mask yields the address of the destination network. For example, if the destination address is and the mask , the address of the destination network is A network mask is made up of a certain number of consecutive 1s. It can be expressed in dotted decimal format or by the number of the 1s. Pre Preference of the route. Among routes to the same destination, the one with the highest preference is optimal. Cost When multiple routes to a destination have the same preference, the one with the smallest cost becomes the optimal route. NextHop Specifies the IP address of the next hop Interface Specifies the interface through which a matching IP packet is to be forwarded Dynamic routing protocols Based on dynamic routing protocols, dynamic routing can detect network topology changes and recalculate the routes, so it is suitable for large networks. However, dynamic routing is difficult to configure, imposes higher requirements on the system, and consumes a certain amount of network resources. Dynamic routing protocols can be classified based on different criteria, as shown in Table 1: 2

18 Table 1 Dynamic routing protocols Criterion scope Routing algorithm Destination address type IP version Categories Interior gateway protocols (IGPs) Work within an autonomous system (AS). Examples include RIP, OSPF, and IS-IS. Exterior gateway protocols (EGPs) Work between ASs. The most popular one is BGP. Distance-vector protocols RIP and BGP. BGP is also considered a path-vector protocol. Link-state protocols OSPF and IS-IS Unicast routing protocols RIP, OSPF, BGP, and IS-IS Multicast routing protocols PIM-SM and PIM-DM IPv4 routing protocols RIP, OSPF, BGP, and IS-IS IPv6 routing protocols RIPng, OSPFv3, IPv6 BGP, and IPv6 IS-IS NOTE: An AS refers to a group of routers sharing the same routing policy and working under the same administration. This chapter focuses on unicast routing protocols. For more information about multicast routing protocols, see IP Multicast Configuration Guide. Routing preference Different routing protocols can find different routes to the same destination. However, not all of those routes are optimal. For route selection, routing protocols, direct routes, and static routes are assigned different preferences. The route with the highest preference is preferred. The preference of a direct route is always 0 and cannot be changed. You can manually configure preferences for any other route type. Each static route can be configured with a different preference. The following table lists the types of routes and the default preferences. The smaller the preference value, the higher the preference. Routing approach Preference Direct route 0 OSPF 10 IS-IS 15 Static route 60 RIP 100 OSPF ASE 150 OSPF NSSA 150 ibgp 255 ebgp 255 Unknown (route from an untrusted source) 256 3

19 Load sharing A routing protocol can be configured with multiple equal-cost routes to the same destination. These routes have the same preference and will all be used to accomplish load sharing if there is no route with a higher preference available. NOTE: At present, routing protocols supporting load sharing include static routing/ipv6 static routing, RIP/RIPng, OSPF/OSPFv3, BGP/IPv6 BGP, and IS-IS/IPv6 IS-IS. Route backup Route backup can help improve network reliability. With route backup, you can configure multiple routes to the same destination, expecting the one with the highest preference to be the main route and all the rest backup routes. Under normal circumstances, packets are forwarded through the main route. When the link fails, the route with the highest preference among the backup routes is selected to forward packets. When the link recovers, the route selection process is performed again and the main route is selected again to forward packets. Route recursion The next hops of some BGP routes (except ebgp routes) and static routes may not be directly connected. The outgoing interface to reach the next hop must be available. Route recursion is used to find the outgoing interface based on the next hop information of the route. Link-state routing protocols, such as OSPF and IS-IS, do not need route recursion because they obtain next hop information through route calculation. Route redistribution Different routing protocols running on a network learn route information from each other through route redistribution. Each routing protocol can redistribute routes from other protocols, direct routes, and static routes. For more information, see relevant protocols in this configuration guide. Displaying and maintaining a routing table Display information about the routing table display ip routing-table [ vpn-instance vpn-instance-name ] [ verbose ] [ { begin exclude include } regular-expression ] Available in any view 4

20 Display information about routes permitted by an IPv4 basic ACL Display information about routes to the specified destination Display information about routes with destination addresses in the specified range Display routing information permitted by an IPv4 prefix list Display routes of a routing protocol Display statistics about the routing table Clear statistics for the routing table Display IPv6 routing table information Display routing information permitted by an IPv6 ACL Display routing information for a specified destination IPv6 address Display IPv6 routing information for an IPv6 address range display ip routing-table [ vpn-instance vpn-instance-name ] acl acl-number [ verbose ] [ { begin exclude include } regular-expression ] display ip routing-table [ vpn-instance vpn-instance-name ] ip-address [ mask mask-length ] [ longer-match ] [ verbose ] [ { begin exclude include } regular-expression ] display ip routing-table [ vpn-instance vpn-instance-name ] ip-address1 { mask mask-length } ip-address2 { mask mask-length } [ verbose ] [ { begin exclude include } regular-expression ] display ip routing-table [ vpn-instance vpn-instance-name ] ip-prefix ip-prefix-name [ verbose ] [ { begin exclude include } regular-expression ] display ip routing-table [ vpn-instance vpn-instance-name ] protocol protocol [ inactive verbose ] [ { begin exclude include } regular-expression ] [ { begin exclude include } regular-expression ] [ { begin exclude include } regular-expression ] display ip routing-table [ vpn-instance vpn-instance-name ] statistics [ { begin exclude include } regular-expression ] reset ip routing-table statistics protocol [ vpn-instance vpn-instance-name ] { protocol all } display ipv6 routing-table [ vpn-instance vpn-instance-name ] [ verbose ] [ { begin exclude include } regular-expression ] display ipv6 routing-table [ vpn-instance vpn-instance-name ] acl acl6-number [ verbose ] [ { begin exclude include } regular-expression ] display ipv6 routing-table [ vpn-instance vpn-instance-name ] ipv6-address prefix-length [ longer-match ] [ verbose ] [ { begin exclude include } regular-expression ] display ipv6 routing-table [ vpn-instance vpn-instance-name ] ipv6-address1 prefix-length1 ipv6-address2 prefix-length2 [ verbose ] [ { begin exclude include } regular-expression ] Available in any view Available in any view Available in any view Available in any view Available in any view Available in any view Available in user view Available in any view Available in any view Available in any view Available in any view 5

21 Display routing information permitted by an IPv6 prefix list Display IPv6 routing information of a routing protocol Display IPv6 routing statistics Clear specified IPv6 routing statistics display ipv6 routing-table [ vpn-instance vpn-instance-name ] ipv6-prefix ipv6-prefix-name [ verbose ] [ { begin exclude include } regular-expression ] display ipv6 routing-table [ vpn-instance vpn-instance-name ] protocol protocol [ inactive verbose ] [ { begin exclude include } regular-expression ] display ipv6 routing-table [ vpn-instance vpn-instance-name ] statistics [ { begin exclude include } regular-expression ] reset ipv6 routing-table statistics protocol [ vpn-instance vpn-instance-name ] { protocol all } Available in any view Available in any view Available in any view Available in user view 6

22 Static routing configuration NOTE: The term router in this document refers to both routers and Layer 3 switches. Introduction Static route Static routes are manually configured. If a network s topology is simple, you only need to configure static routes for the network to work properly. The proper configuration and usage of static routes can improve network performance and ensure bandwidth for important network applications. The disadvantage of using static routes is that they cannot adapt to network topology changes. If a fault or a topological change occurs in the network, the relevant routes will be unreachable and the network breaks. When this happens, the network administrator must modify the static routes manually. Default route Without a default route, a packet that does not match any routing entries is discarded. A default route is used to forward packets that do not match any routing entry. It can be configured in either of the following ways: The network administrator can configure a default route with both the destination and mask being The router forwards any packet whose destination address fails to match any entry in the routing table to the next hop of the default static route. Some dynamic routing protocols, such as OSPF, RIP, and IS-IS, can also generate a default route. For example, an upstream router running OSPF can generate a default route and advertise it to other routers, which install the default route with the next hop being the upstream router. Static route configuration items Before configuring a static route, you must know the following concepts: 1. Destination address and mask In the ip route-static command, an IPv4 address is in dotted decimal format. A mask can be either in dotted decimal format or in the form of mask length the number of consecutive 1s in the mask. 2. Output interface and next hop address When configuring a static route, specify either the output interface, next hop address, or both depending on the specific occasion. The next hop address cannot be a local interface IP address; otherwise, the route configuration will not take effect. Each route lookup operation has to find the next hop to resolve the destination link layer address. When specifying the output interface, observe the following rules: 7

23 If the output interface is a Null 0 interface, no next hop address is required. If you specify a broadcast interface (such as an Ethernet interface or VLAN interface) as the output interface, you must specify the corresponding next hop for the output interface. 3. Other attributes You can configure different priorities for different static routes so that route management policies can be more flexible. For example, specifying the same priority for different routes to the same destination enables load sharing, but specifying different priorities for these routes enables route backup. Configuring a static route Configuration prerequisites Before configuring a static route, complete the following tasks: Configure the physical parameters for related interfaces Configure the link-layer attributes for related interfaces Configure the IP addresses for related interfaces Configuration procedure Follow these steps to configure a static route: Configure a static route Configure the default preference for static routes ip route-static dest-address { mask mask-length } { next-hop-address [ track track-entry-number ] interface-type interface-number [ next-hop-address ] vpn-instance d-vpn-instance-name next-hop-address [ track track-entry-number ] } [ preference preference-value ] [ tag tag-value ] [ permanent ] [ description description-text ] ip route-static vpn-instance s-vpn-instance-name&<1-6> dest-address { mask mask-length } { next-hop-address [ public ] [ track track-entry-number ] interface-type interface-number [ next-hop-address ] vpn-instance d-vpn-instance-name next-hop-address [ track track-entry-number ] } [ preference preference-value ] [ tag tag-value ] [ permanent ] [ description description-text ] ip route-static default-preference default-preference-value Use one of the approaches. By default, preference for static routes is 60, tag is 0, and no description information is configured. Do not specify the permanent and track keywords simultaneously. If the outgoing interface is down, the permanent static route is still active. 60 by default 8

24 NOTE: When configuring a static route, the static route does not take effect if you specify the next hop address first and then configure it as the IP address of a local interface, such as Ethernet interface and VLAN interface. If you do not specify the preference when configuring a static route, the default preference will be used. Reconfiguring the default preference applies only to newly created static routes. You can flexibly control static routes by configuring tag values and using the tag values in the routing policy. If the destination IP address and mask are both configured as with the ip route-static command, then the route is the default route. For detailed information about track, see High Availability Configuration Guide. Configuring BFD for static routes Bidirectional forwarding detection (BFD) provides a general-purpose, standard, medium-, and protocol-independent fast failure detection mechanism. It can uniformly and quickly detect the failures of the bidirectional forwarding paths between two routers for protocols, such as routing protocols and Multiprotocol Label Switching (MPLS). For more information about BFD, see High Availability Configuration Guide. A dynamic routing protocol notifies BFD of its neighbor information. BFD uses such information to establish sessions with neighbors by sending BFD control packets. Static routing has no neighbor discovery mechanism. This section describes how static routing implements BFD. BFD control packet mode To use BFD control packets for bidirectional detection between two devices, you need to enable BFD control packet mode for each device s static route destined to the peer. To configure a static route and enable BFD control packet mode for it, specify an outbound interface and a direct next hop BFD establishes a direct session, or specify an indirect next hop and a specific BFD packet source address BFD establishes an indirect session for the static route. Follow these steps to configure a static route with BFD control packet mode enabled (direct session): Configure a static route and enable BFD control packet mode for it ip route-static dest-address { mask mask-length } interface-type interface-number next-hop-address bfd control-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ] ip route-static vpn-instance s-vpn-instance-name&<1-6> dest-address { mask mask-length } interface-type interface-number next-hop-address bfd control-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ] Use either command 9

25 Follow these steps to configure a static route with BFD control packet mode enabled (indirect session): Configure a static route and enable BFD control packet mode for it ip route-static dest-address { mask mask-length } next-hop-address bfd control-packet bfd-source ip-address [ preference preference-value ] [ tag tag-value ] [ description description-text ] ip route-static vpn-instance s-vpn-instance-name&<1-6> dest-address { mask mask-length } next-hop-address bfd control-packet bfd-source ip-address [ preference preference-value ] [ tag tag-value ] [ description description-text ] Use either command BFD echo packet mode With BFD echo packet mode enabled for a static route, the local device sends BFD echo packets to the peer, which loops it back to test the link. Follow these steps to configure BFD echo packet mode for static routes: Configure the source address of echo packets Enable BFD echo packet mode for static routes bfd echo-source-ip ip-address ip route-static dest-address { mask mask-length } interface-type interface-number next-hop-address bfd echo-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ] ip route-static vpn-instance s-vpn-instance-name&<1-6> dest-address { mask mask-length } interface-type interface-number next-hop-address bfd echo-packet [ preference preference-value ] [ tag tag-value ] [ description description-text ] Not configured by default Use either command NOTE: If route flaps occur, enabling BFD could worsen them. For the echo mode, only one end needs to establish the BFD session, and the source address of echo packets must be configured. BFD cannot be used for a static route with the outbound interface having the spoofing attribute. Configuring static route FRR When a link or a router fails, the packets on the path may be discarded, or a routing loop occurs. To avoid such problems, you can enable static route fast reroute (FRR). 10

26 Figure 1 Network diagram for static route FRR As shown in Figure 1, upon a link failure, FRR designates a backup next hop by using a routing policy for routes matching the specified criteria. Packets are directed to the backup next hop to avoid traffic interruption. Configuration prerequisites Configuring static route FRR needs to reference a routing policy. You can specify a backup next hop in a routing policy by using the apply fast-reroute backup-interface command. For more information about the command and routing policy configurations, see the chapter Routing policy configuration. Configuration procedure Follow these steps to configure static route FRR: Configure the source address of echo packets Configure static route FRR bfd echo-source-ip ip-address ip route-static [ vpn-instance vpn-instance-name ] fast-reroute route-policy route-policy-name Not configured by default. Not configured by default. NOTE: Static route FRR takes effect only for static routes that have both the outbound interface and next hop specified. Do not use FRR and BFD at the same time. Displaying and maintaining static routes Display information of static routes display ip routing-table protocol static [ inactive verbose ] [ { begin exclude include } regular-expression ] Available in any view Delete all the static routes delete [ vpn-instance vpn-instance-name ] static-routes all Available in system view NOTE: For more information about the display ip routing-table protocol static [ inactive verbose ] [ { begin exclude include } regular-expression ] command, see Layer 3 IP Routing Command Reference. 11

27 Static route configuration examples Basic static route configuration example Network requirements The IP addresses and masks of the switches and hosts are shown in Figure 2. Static routes are required for interconnection between any two hosts. Figure 2 Network diagram for static route configuration Configuration procedure 1. Configure IP addresses for interfaces. (Details not shown) 2. Configure static routes. # Configure a default route on Switch A. <SwitchA> system-view [SwitchA] ip route-static # Configure two static routes on Switch B. <SwitchB> system-view [SwitchB] ip route-static [SwitchB] ip route-static # Configure a default route on Switch C <SwitchC> system-view [SwitchC] ip route-static Configure the hosts. The default gateways for hosts A, B, and C are , and , respectively. The configuration procedure is not shown. 4. Display the configuration. # Display the IP routing table of Switch A. [SwitchA] display ip routing-table Routing Tables: Public Destinations : 7 Routes : 7 12

28 Destination/Mask Proto Pre Cost NextHop Interface /0 Static Vlan /24 Direct Vlan /32 Direct InLoop /30 Direct Vlan /32 Direct InLoop /8 Direct InLoop /32 Direct InLoop0 # Display the IP routing table of Switch B. [SwitchB] display ip routing-table Routing Tables: Public Destinations : 10 Routes : 10 Destination/Mask Proto Pre Cost NextHop Interface /24 Static Vlan /24 Static Vlan /30 Direct Vlan /32 Direct InLoop /30 Direct Vlan /32 Direct InLoop /8 Direct InLoop /32 Direct InLoop /24 Direct Vlan /32 Direct InLoop0 # Use the ping command on Host B to check the reachability of Host A, assuming Windows XP runs on the two hosts. C:\Documents and Settings\Administrator>ping Pinging with 32 bytes of data: Reply from : bytes=32 time=1ms TTL=255 Reply from : bytes=32 time=1ms TTL=255 Reply from : bytes=32 time=1ms TTL=255 Reply from : bytes=32 time=1ms TTL=255 Ping statistics for : Packets: Sent = 4, Received = 4, Lost = 0 (0% loss), Approximate round trip times in milli-seconds: Minimum = 1ms, Maximum = 1ms, Average = 1ms # Use the tracert command on Host B to check the reachability of Host A. C:\Documents and Settings\Administrator>tracert Tracing route to over a maximum of 30 hops 1 <1 ms <1 ms <1 ms

29 2 <1 ms <1 ms <1 ms ms <1 ms <1 ms Trace complete. Static route FRR configuration example Network requirements Switch S, Switch A, and Switch D are interconnected through static routes, as illustrated in Figure 3. Configure static route FRR so that when the link between Switch S and Switch D fails, traffic can be switched to Link B immediately. Figure 3 Network diagram for static route FRR configuration Switch A Loop /32 Switch S Vlan-int /24 Vlan-int /24 Vlan-int /24 Link B Link A Vlan-int /24 Vlan-int /24 Vlan-int /24 Switch D Loop /32 Configuration procedure 1. Configure IP addresses for the interfaces on each switch and configure static routes. Follow Figure 3 to configure the IP address and subnet mask of each interface on the switches. (Details not shown) Configure static routes on Switch S, Switch A, and Switch D so that Switch S can reach Loopback 0 on Switch D and Switch D can reach Loopback 0 on Switch S. # Configure a static route on Switch S. <SwitchS> system-view [SwitchS] ip route-static vlan-interface [SwitchS] ip route-static vlan-interface preference 65 # Configure a static route on Switch D. <SwitchD> system-view [SwitchD] ip route-static vlan-interface [SwitchD] ip route-static vlan-interface preference 65 # Configure a static route on Switch A. <SwitchA> system-view [SwitchA] ip route-static vlan-interface [SwitchA] ip route-static vlan-interface Configure static route FRR. # Configure Switch S. [SwitchS] bfd echo-source-ip [SwitchS] ip ip-prefix abc index 10 permit [SwitchS] route-policy frr permit node 10 [SwitchS-route-policy] if-match ip-prefix abc 14

30 [SwitchS-route-policy] apply fast-reroute backup-interface vlan-interface 100 backup-nexthop [SwitchS-route-policy] quit [SwitchS] ip route-static fast-reroute route-policy frr # Configure Switch D. [SwitchD] bfd echo-source-ip [SwitchD] ip ip-prefix abc index 10 permit [SwitchD] route-policy frr permit node 10 [SwitchD-route-policy] if-match ip-prefix abc [SwitchD-route-policy] apply fast-reroute backup-interface vlan-interface 101 backup-nexthop [SwitchD-route-policy] quit [SwitchD] ip route-static fast-reroute route-policy frr 3. Verify the configuration. # Display route /32 on Switch S to view the backup next hop information. [SwitchS] display ip routing-table verbose Routing Table : Public Summary Count : 1 Destination: /32 Protocol: Static Process ID: 0 Preference: 60 Cost: 0 IpPrecedence: QosLcId: NextHop: Interface: vlan 200 BkNextHop: BkInterface: vlan 100 RelyNextHop: Neighbor : Tunnel ID: 0x0 Label: NULL BKTunnel ID: 0x0 BKLabel: NULL State: Active Adv Age: 00h01m27s Tag: 0 # Display route /32 on Switch D to view the backup next hop information. [SwitchD] display ip routing-table verbose Routing Table : Public Summary Count : 1 Destination: /32 Protocol: Static Process ID: 0 Preference: 60 Cost: 0 IpPrecedence: QosLcId: NextHop: Interface: vlan 200 BkNextHop: BkInterface: vlan 101 RelyNextHop: Neighbor : Tunnel ID: 0x0 Label: NULL BKTunnel ID: 0x0 BKLabel: NULL State: Active Adv Age: 00h01m27s Tag: 0 15