H3C S5120-SI Switch Series
Layer 3 - IP Routing Configuration Guide
Hangzhou H3C Technologies Co., Ltd.
http://www.h3c.com
Software version: Release 1513
Document version: 6W100-20130425
Copyright © 2013, Hangzhou H3C Technologies Co., Ltd. and its licensors
All rights reserved
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.
Trademarks
H3C, , H3CS, H3CIE, H3CNE, Aolynk, , H
3
Care, , IRF, NetPilot, Netflow,
SecEngine, SecPath, SecCenter, SecBlade, Comware, ITCMM and HUASAN are trademarks of
Hangzhou H3C Technologies Co., Ltd.
All other trademarks that may be mentioned in this manual are the property of their respective owners
Notice
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.
Preface
The H3C S5120-SI documentation set includes 10 configuration guides, which describe the software
features for the H3C S5120-SI Switch Series Release 1513, 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.
This preface includes:
• Audience
• Added and modified features
• Conventions
• About the H3C S5120-SI documentation set
• 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 S5120-SI series
Added and modified features
None
Conventions
This section describes the conventions used in this documentation set.
Command conventions
Convention Descri
p
tion
Boldface Bold text represents commands and keywords that you enter literally as shown.
Italic Italic text represents arguments that you replace with actual values.
[ ] Square brackets enclose syntax choices (keywords or arguments) that are optional.
{ x | y | ... }
Braces enclose a set of required syntax choices separated by vertical bars, from which
you select one.
[ x | y | ... ]
Square brackets enclose a set of optional syntax choices separated by vertical bars, from
which you select one or none.
{ x | y | ... } *
Asterisk marked braces enclose a set of required syntax choices separated by vertical
bars, from which you select at least one.
[ x | y | ... ] *
Asterisk marked square brackets enclose optional syntax choices separated by vertical
bars, from which you select one choice, multiple choices, or none.
&<1-n>
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 Descri
p
tion
Boldface
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 Descri
p
tion
< > 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 Descri
p
tion
WARNING
An alert that calls attention to important information that if not understood or followed can
result in personal injury.
CAUTION
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.
IMPORTANT
An alert that calls attention to essential information.
NOTE
An alert that contains additional or supplementary information.
TIP
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.
About the H3C S5120-SI documentation set
The H3C S5120-SI documentation set includes:
Cate
g
or
y
Documents Pur
p
oses
Product
description and
specifications
Marketing brochures Describe product specifications and benefits.
RPS Ordering Information for H3C
Low-End Ethernet Switches
Provides the RPS and switch compatibility matrix and
RPS cable specifications.
H3C Low End Series Ethernet
Switches Pluggable Modules
Manual
Describes the models, appearances, and
specifications of the pluggable modules available for
the products.
Hardware
installation
Quick Start Guide Provides a quick guide to hardware installation.
Installation Manual
Provides a complete guide to hardware installation
and hardware specifications.
Provides regulatory information and the safety
instructions that must be followed during installation.
Pluggable SFP[SFP+][XFP]
Transceiver Modules Installation
Guide
Guides you through installing SFP/SFP+/XFP
transceiver modules.
Software
configuration
Configuration guides
Describe software features and configuration
procedures.
Command references Provide a quick reference to all available commands.
Operations
and
maintenance
Release notes
Provide information about the product release,
including the version history, hardware and software
compatibility matrix, version upgrade information,
technical support information, and software
upgrading.
Obtaining documentation
You can access the most up-to-date H3C product documentation on the World Wide Web
at http://www.h3c.com
.
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
servi[email protected]
http://www.h3c.com
Documentation feedback
You can e-mail your comments about product documentation to info@h3c.com.
We appreciate your comments.
i
Contents
IP routing basics ··························································································································································· 1
IP routing overview ··························································································································································· 1
Routing ······································································································································································· 1
Routing table and FIB table ····································································································································· 1
Routing protocol overview ················································································································································ 3
Static routing and dynamic routing ························································································································ 3
Routing protocols and routing preference ············································································································· 3
Displaying and maintaining a routing table ·················································································································· 4
Static routing configuration ········································································································································· 6
Introduction ········································································································································································ 6
Static route ································································································································································ 6
Default route ······························································································································································ 6
Static route configuration items ······························································································································· 6
Configuring a static route ················································································································································· 7
Configuration prerequisites ····································································································································· 7
Configuration procedure ········································································································································· 7
Displaying and maintaining static routes ······················································································································· 8
Static route configuration examples ································································································································ 8
Basic static route configuration example ··············································································································· 8
IPv6 static routing configuration ································································································································ 11
Introduction to IPv6 static routing ································································································································· 11
IPv6 static route features ······································································································································· 11
Default IPv6 route ·················································································································································· 11
Configuring an IPv6 static route ··································································································································· 11
Configuration prerequisites ·································································································································· 11
Configuration procedure ······································································································································ 12
Displaying and maintaining IPv6 static routes ············································································································ 12
IPv6 static routing configuration example ··················································································································· 12
Index ··········································································································································································· 15
1
IP routing basics
NOTE:
The term
router
in this document refers to a routing-capable device.
IP routing overview
Routing
Routing in the Internet is achieved through routers. Upon receiving a packet, a router determines the
optimal path 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 intended destination host.
Routing provides the path information that guides the forwarding of packets.
Routing table and FIB table
The routing table plays a key role in route selection and the forwarding information base (FIB) table plays
a key role in 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 that are manually configured
• Dynamic routes—Routes that are 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.
Introduction to routing table
Each router maintains a local routing table, and each routing protocol maintains a protocol routing table.
• Routing table of a protocol
A protocol routing table stores routes discovered by the routing protocol.
• Local routing table
A local routing table stores the routes found by all protocols and delivers the optimal routes to the FIB
table to guide packet forwarding. The optimal route selection is based on the routing protocol
preferences and route metrics.
2
Contents of a routing table
A route entry includes the following key items:
• Destination address—Destination IP address or destination network
• 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 129.102.8.10 and
the mask 255.255.0.0, the address of the destination network is 129.102.0.0. 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.
• Outbound interface—Specifies the interface through which a matching IP packet is to be
forwarded.
• Next hop—Specifies the IP address of the next-hop router on the path. If only the outbound interface
is specified, its IP address will be the IP address of the next hop.
• Preference for the route—Routes to the same destination but having different next hops may have
different priorities and be found by various routing protocols or manually configured. The optimal
route is the one with the highest preference (with the smallest metric).
Routes can be divided into the following categories by destination:
• Subnet route—The destination is a subnet.
• Host route—The destination is a host.
Based on whether the destination is directly connected to the router, routes can be divided into:
• Direct routes—The destination is directly connected to the router.
• Indirect routes—The destination is not directly connected to the router.
To prevent the routing table from getting too large, configure a default route. Packets not matching any
specific entries in the routing table will be forwarded through the default route.
In Figure 1, R
outer A is connected to three networks. Its routing table is shown under the network
topology.
3
Figure 1 A sample routing table
Destination Network Nexthop
Interface
11.1.1.0 1.1.1.2 Vlan1
12.1.1.0 2.2.2.1
Vlan2
13.1.1.0 3.3.3.1
Vlan3
Routing protocol overview
Static routing and dynamic routing
Static routing is easy to configure and requires less system resources. It works well in small, stable
networks with simple topologies. Its major drawback is that you must perform routing configuration
again whenever the network topology changes; it cannot adjust to network changes by itself.
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. It not only imposes higher requirements on the system, but also consumes a certain amount of
network resources.
Routing protocols and routing preference
Different routing protocols may find different routes to the same destination. However, not all of those
routes are optimal. In fact, at a particular moment, only one protocol can uniquely determine the current
optimal route to the destination. For route selection, each routing protocol—including static routes—is
assigned a preference. The route found by the routing protocol with the highest preference is preferred.
11.1.1.0/24
13.1.1.0/2412.1.1.0/24
Router A
Router B
Router C Router D
Vlan1
1.1.1.1/24
Vlan2
2.2.2.2/24
Vlan3
3.3.3.3/24
1.1.1.2/24
2.2.2.1/24 3.3.3.1/24
4
Table 1 Some routing protocols and the default priorities for routes found by them
Routing approach Preference
DIRECT
0
STATIC 60
UNKNOWN 256
NOTE:
• The smaller the preference value, the higher the preference.
• The preference for a direct route is always 0, which cannot be changed. Any other type of routes can
have their priorities manually configured.
• Each static route can be configured with a different preference.
• IPv4 and IPv6 routes have their own respective routing tables.
Displaying and maintaining a routing table
To do… Use the command… Remarks
Display brief information about the
active routes in the routing table
display ip routing-table [ verbose ] [ |
{ begin | exclude | include }
regular-expression ]
Available in any view
Display information about routes to
the specified destination
display ip routing-table ip-address
[ mask-length | mask ] [ longer-match ]
[ verbose ] [ | { begin | exclude |
include } regular-expression ]
Available in any view
Display information about routes
with destination addresses in the
specified range
display ip routing-table ip-address1
{ mask-length | mask } ip-address2
{ mask-length | mask } [ verbose ] [ |
{ begin | exclude | include }
regular-expression ]
Available in any view
Display information about routes
permitted by an IPv4 basic ACL
display ip routing-table acl acl-number
[ verbose ] [ | { begin | exclude |
include } regular-expression ]
Available in any view
Display routes of a routing protocol
display ip routing-table protocol protocol
[ inactive | verbose ] [ | { begin | exclude
| include } regular-expression ] [ | { begin
| exclude | include } regular-expression ]
[ | { begin | exclude | include }
regular-expression ]
Available in any view
Display statistics about the network
routing table
display ip routing-table statistics [ |
{ begin | exclude | include }
regular-expression ]
Available in any view
Clear statistics for the routing table
reset ip routing-table statistics protocol
{ protocol | all }
Available in user view
Display brief IPv6 routing table
information
display ipv6 routing-table [ | { begin |
exclude | include } regular-expression ]
Available in any view
5
To do… Use the command… Remarks
Display verbose IPv6 routing table
information
display ipv6 routing-table verbose [ |
{ begin | exclude | include }
regular-expression ]
Available in any view
Display routing information for a
specified destination IPv6 address
display ipv6 routing-table ipv6-address
prefix-length [ longer-match ] [ verbose ]
[ | { begin | exclude | include }
regular-expression ]
Available in any view
Display routing information
permitted by an IPv6 ACL
display ipv6 routing-table acl
acl6-number [ verbose ] [ | { begin |
exclude | include } regular-expression ]
Available in any view
Display IPv6 routing information of
a routing protocol
display ipv6 routing-table protocol
protocol [ inactive | verbose ] [ | { begin
| exclude | include } regular-expression ]
Available in any view
Display IPv6 routing statistics
display ipv6 routing-table statistics [ |
{ begin | exclude | include }
regular-expression ]
Available in any view
Display IPv6 routing information
for an IPv6 address range
display ipv6 routing-table ipv6-address1
prefix-length1 ipv6-address2
prefix-length2 [ verbose ] [ | { begin |
exclude | include } regular-expression ]
Available in any view
Clear specified IPv6 routing table
statistics
reset ipv6 routing-table statistics protocol
{ protocol | all }
Available in user view
6
Static routing configuration
NOTE:
The term
router
in this document refers to a routing-capable device.
Introduction
Static route
A static route is 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 routes will be unreachable and the network breaks.
The network administrator has to modify the static routes manually.
Default route
Without a default route, a packet that does not match any routing entries is discarded and an ICMP
destination-unreachable packet is sent to the source.
A default route is used to forward packets that match no entry in the routing table. The network
administrator can configure a default route with both destination and mask being 0.0.0.0. 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.
Static route configuration items
Before configuring a static route, you need to know the following concepts:
1. Destination address and mask
In the ip route-static command, an IPv4 address is in dotted decimal format and 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 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.
7
In fact, 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:
• If the output interface is a Null 0 interface, no next hop address is required.
• If you specify a broadcast interface—such as VLAN interface—as the output interface, you must
specify the next hop for the output interface.
Configuring a static route
Configuration prerequisites
Before you configure 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:
To do… Use the command…
Remarks
Enter system view
system-view —
Configure a static route
ip route-static dest-address { mask | mask-length }
{ next-hop-address [ track track-entry-number ]|
interface-type interface-number [ next-hop-address ] }
[ preference preference-value ] [ description
description-text ]
Required
By default, preference
for static routes is 60,
and no description
information is
configured.
Configure the default
preference for static
routes
ip route-static default-preference default-preference-value
Optional
60 by default
NOTE:
• When confi
g
urin
g
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 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.
• If the destination IP address and mask are both configured as 0.0.0.0 with the ip route-static command,
the route is the default route.
8
Displaying and maintaining static routes
To do… Use the command…
Remarks
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 static-routes all Available in system view
NOTE:
For more information about the display ip routing-table protocol static
[ inactive | verbose ] [ | { be
g
in
| exclude | include }
regular-expression
] command, see the chapter "IP routing basics configuration
commands."
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. Configuring IP addresses for interfaces. (Details not shown)
2. Configuring static routes.
# Configure a default route on Switch A.
<SwitchA> system-view
[SwitchA] ip route-static 0.0.0.0 0.0.0.0 1.1.4.2
# Configure two static routes on Switch B.
9
<SwitchB> system-view
[SwitchB] ip route-static 1.1.2.0 255.255.255.0 1.1.4.1
[SwitchB] ip route-static 1.1.3.0 255.255.255.0 1.1.5.6
# Configure a default route on Switch C
<SwitchC> system-view
[SwitchC] ip route-static 0.0.0.0 0.0.0.0 1.1.5.5
3. Configure the hosts.
Configure the default gateways of hosts A, B and C as 1.1.2.3, 1.1.6.1 and 1.1.3.1. (Details 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
Destination/Mask Proto Pre Cost NextHop Interface
0.0.0.0/0 Static 60 0 1.1.4.2 Vlan500
1.1.2.0/24 Direct 0 0 1.1.2.3 Vlan300
1.1.2.3/32 Direct 0 0 127.0.0.1 InLoop0
1.1.4.0/30 Direct 0 0 1.1.4.1 Vlan500
1.1.4.1/32 Direct 0 0 127.0.0.1 InLoop0
127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0
127.0.0.1/32 Direct 0 0 127.0.0.1 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
1.1.2.0/24 Static 60 0 1.1.4.1 Vlan500
1.1.3.0/24 Static 60 0 1.1.5.6 Vlan600
1.1.4.0/30 Direct 0 0 1.1.4.2 Vlan500
1.1.4.2/32 Direct 0 0 127.0.0.1 InLoop0
1.1.5.4/30 Direct 0 0 1.1.5.5 Vlan600
1.1.5.5/32 Direct 0 0 127.0.0.1 InLoop0
127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0
127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0
1.1.6.0/24 Direct 0 0 1.1.6.1 Vlan100
1.1.6.1/32 Direct 0 0 127.0.0.1 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 1.1.2.2
Pinging 1.1.2.2 with 32 bytes of data:
10
Reply from 1.1.2.2: bytes=32 time=1ms TTL=255
Reply from 1.1.2.2: bytes=32 time=1ms TTL=255
Reply from 1.1.2.2: bytes=32 time=1ms TTL=255
Reply from 1.1.2.2: bytes=32 time=1ms TTL=255
Ping statistics for 1.1.2.2:
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.
[HostB] tracert 1.1.2.2
Tracing route to 1.1.2.2 over a maximum of 30 hops
1 <1 ms <1 ms <1 ms 1.1.6.1
2 <1 ms <1 ms <1 ms 1.1.4.1
3 1 ms <1 ms <1 ms 1.1.2.2
Trace complete.
11
IPv6 static routing configuration
NOTE:
The term
router
in this document refers to a routing-capable device.
Introduction to IPv6 static routing
Static routes are manually configured by network administrators and work well in simple networks.
Configuring and using them properly can improve network performance and ensure enough bandwidth
for important applications. However, static routes also have limitations. Any topology changes require
the network administrator to manually configure and modify the relevant static routes.
IPv6 static route features
Similar to IPv4 static routes, IPv6 static routes work well in simple IPv6 network environments.
Their major difference lies in the destination and next hop addresses. IPv6 static routes use IPv6
addresses, whereas IPv4 static routes use IPv4 addresses.
Default IPv6 route
An IPv6 static route with a destination prefix of ::/0 is a default IPv6 route. The default route is used to
forward packets that match no specific routes in the routing table.
Configuring an IPv6 static route
In small IPv6 networks, IPv6 static routes can be used to forward packets. In comparison to dynamic
routes, it helps to save network bandwidth.
Configuration prerequisites
• Configure parameters for the related interfaces
• Configure link layer attributes for the related interfaces
• Enable IPv6 packet forwarding
• Ensure that the neighboring nodes can reach each other
12
Configuration procedure
Follow these steps to configure an IPv6 static route:
To do… Use the commands…
Remarks
Enter system view system-view
—
Configure an IPv6 static route with
the output interface being a
broadcast or NBMA interface
ipv6 route-static ipv6-address prefix-length
[ interface-type interface-number ]
nexthop-address [ preference preference-value ]
Required
The default
preference of IPv6
static routes is 60.
Displaying and maintaining IPv6 static routes
To do… Use the command…
Remarks
Display IPv6 static route
information
display ipv6 routing-table protocol
static [ inactive | verbose ] [ |
{ begin | exclude | include }
regular-expression ]
Available in any view
Remove all IPv6 static routes delete ipv6 static-routes all Available in system view
NOTE:
• Using the undo ipv6 route-static command can delete a single IPv6 static route. Using the delete ipv6
static-routes all command deletes all IPv6 static routes including the default route.
• For more information about the display ipv6 routing-table protocol static
[ inactive | verbose ] [ |
{ begin | exclude | include }
regular-expression
] command, see the chapter "IP routing basics
configuration commands."
IPv6 static routing configuration example
Network requirements
As shown in Figure 3, configure IPv6 static routes so that hosts can reach one another.
13
Figure 3 Network diagram for IPv6 static route configuration
Configuration procedure
1. Configure the IPv6 addresses for all VLAN interfaces. (Details not shown)
2. Configure IPv6 static routes.
# Configure a default IPv6 static route on Switch A.
<SwitchA> system-view
[SwitchA] ipv6
[SwitchA] ipv6 route-static :: 0 4::2
# Configure two IPv6 static routes on Switch B.
<SwitchB> system-view
[SwitchB] ipv6
[SwitchB] ipv6 route-static 1:: 64 4::1
[SwitchB] ipv6 route-static 3:: 64 5::1
# Configure a default IPv6 static route on Switch C.
<SwitchC> system-view
[SwitchC] ipv6
[SwitchC] ipv6 route-static :: 0 5::2
3. Configure the IPv6 addresses and gateways for hosts.
Configure the IPv6 addresses for all the hosts based on the network diagram, configure the default
gateway of Host A as 1::1, that of Host B as 2::1, and that of Host C as 3::1.
4. Display configuration information.
# Display the IPv6 routing table of Switch A.
[SwitchA] display ipv6 routing-table
Routing Table :
Destinations : 5 Routes : 5
Destination : :: Protocol : Static
NextHop : 4::2 Preference : 60
Interface : Vlan-interface200 Cost : 0
Page is loading ...
Page is loading ...
/