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Operation Manual – Static Routing
H3C S9500 Series Routing Switches Table of Contents
i
Table of Contents
Chapter 1 Static Routing Configuration......................................................................................1-1
1.1 Introduction........................................................................................................................1-1
1.1.1 Static Route.............................................................................................................1-1
1.1.2 Default Route ..........................................................................................................1-1
1.1.3 Application Environment of Static Routing..............................................................1-2
1.2 Configuring a Static Route.................................................................................................1-2
1.2.1 Configuration Prerequisites.....................................................................................1-2
1.2.2 Configuration Procedure.........................................................................................1-3
1.3 Displaying and Maintaining Static Routes.........................................................................1-4
1.4 Configuration Example ......................................................................................................1-4
Operation Manual – Static Routing
H3C S9500 Series Routing Switches Chapter 1 Static Routing Configuration
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Chapter 1 Static Routing Configuration
When configuring a static route, go to the following sections for information you are
interested in:
z Introduction
z Configuring a Static Route
z Displaying and Maintaining Static Routes
z Configuration Example
Note:
The term “router” in this document refers to a router in a generic sense or an Ethernet
switch running routing protocols.
1.1 Introduction
1.1.1 Static Route
A static route is a special route that is manually configured by the network administrator.
If a network’s topology is simple, you only need configure static routes for the network
to work normally. The proper configuration and usage of static routes can improve a
network’s performance and ensure bandwidth for important network applications.
The disadvantage of using a static route is that, if a fault or a topological change occurs
to the network, the routes will be unavailable and the network breaks. In this case, the
network administrator has to modify the static routes manually.
1.1.2 Default Route
A router selects the default route only when it cannot find any matching entry in the
routing table.
If the destination address of a packet fails to match any entry in the routing table, the
router selects the default route to forward the packet.
If there is no default route and the destination address of the packet fails to match any
entry in the routing table, the packet will be discarded and an ICMP packet will be sent
to the source to report that the destination or the network is unreachable.
You can create the default route with both destination and mask being 0.0.0.0, and
some dynamic routing protocols, such as OSPF, RIP and IS-IS, can also generate the
default route.
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1.1.3 Application Environment of Static Routing
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 digits of
consecutive 1s in the mask).
2) Output interface and next hop address
While configuring a static route, you can specify either the output interface or the next
hop address depending on the specific occasion. The next hop address can not be a
local interface IP address; otherwise, the route configuration will not take effect.
In fact, all the route entries must have a next hop address. When forwarding a packet, a
router first searches the routing table for the route to the destination address of the
packet. The system can find the corresponding link layer address and forward the
packet only after the next hop address is specified.
When specifying the output interface, note that:
z If the output interface is a NULL0 interface, there is no need to configure the next
hop address.
z If the output interface is a point-to-point interface, there is no need to configure the
next hop address. You need not change the configuration even if the peer’s
address changes. For example, a PPP interface obtains the peer’s IP address
through PPP negotiation, so you need only specify the output interface.
z If the output interface is an NBMA or P2MP interface, which support
point-to-multipoint network, the IP address to link layer address mapping must be
established. Therefore, it is recommended to configure both the next hop IP
address and the output interface.
z You are not recommended to specify a broadcast interface (such as an Ethernet
interface, virtual template, or VLAN interface) as the output interface, because a
broadcast interface may have multiple next hops. If you have to do so, you must
specify the corresponding next hop for the output interface.
3) Other attributes
You can configure different preferences for different static routes so that route
management policies can be applied more flexibly. For example, specifying the same
preference for different routes to the same destination enables load sharing, while
specifying different preferences for these routes enables route backup.
1.2 Configuring a Static Route
1.2.1 Configuration Prerequisites
Before configuring a static route, you need to finish the following tasks:
Operation Manual – Static Routing
H3C S9500 Series Routing Switches Chapter 1 Static Routing Configuration
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z Configure the physical parameters for related interfaces
z Configure the link-layer attributes for related interfaces
z Configure the IP addresses for related interfaces
1.2.2 Configuration Procedure
Follow these steps to configure a static route:
To do… Use the command… Remarks
Enter system
view
system-view
—
ip route-static dest-address { mask |
mask-length } { gateway-address |
interface-type interface-number
[ gateway-address ] | vpn-instance
d-vpn-instance-name gateway-address }
[ preference preference-value ] [ tag
tag-value ] [ description description-text ]
Configure a
static route
ip route-static vpn-instance
s-vpn-instance-name&<1-6> dest-address
{ mask | mask-length } { gateway-address
[ public ] | interface-type interface-number
[ gateway-address ] | vpn-instance
d-vpn-instance-name gateway-address }
[ preference preference-value ] [ tag
tag-value ] [ description description-text ]
Required
By default, the
preference of
static routes is
60, tag is 0, 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:
z If you specify the next hop of a static route and then configure the next hop as the IP
address of a local interface such as a VLAN interface, the static route cannot take
effect.
z 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.
z A description can describe the usage, function of some specific static routes for
easy and flexible management, classification and configuration of static routes.
z You can flexibly control static routes by configuring tag values and using the tag
values in the routing policy.
z 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.
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1.3 Displaying and Maintaining Static Routes
To do… Use the command… Remarks
View the current
configuration information
display current-configuration
View the brief information
of the IP routing table
display ip routing-table
View the detailed
information of the IP
routing table
display ip routing-table verbose
View information of static
routes
display ip routing-table protocol
static [ inactive | verbose ]
Available in
any view
Delete all the static routes
delete [ vpn-instance
vpn-instance-name ] static-routes all
Available In
system view
1.4 Configuration Example
I. Network requirements
The IP addresses and masks of the switches and hosts are shown in the following
figure. Static routes are required for interconnection between any two hosts.
II. Network diagram
Figure 1-1 Network diagram for static route configuration
III. Configuration procedure
1) Configure IP addresses for interfaces (omitted).
2) Configure static routes.
# Configure a default route on Switch A
<SwitchA> system-view
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[SwitchA] ip route-static 0.0.0.0 0.0.0.0 1.1.4.2
# Configure two static routes on Switch B
<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.
The default gateways for the three hosts A, B and C are 1.1.2.3, 1.1.6.1 and 1.1.3.1
respectively.
4) View the configuration result.
# 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
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127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0
1.1.6.0/24 Direct 0 0 192.168.1.47 Vlan100
1.1.6.1/32 Direct 0 0 127.0.0.1 InLoop0
# Use the ping command on Host B to check reachability to Host A (assuming that the
hosts run Windows XP).
C:\Documents and Settings\Administrator>ping 1.1.2.2
Pinging 1.1.2.2 with 32 bytes of data:
Reply from 1.1.2.2: bytes=32 time=1ms TTL=253
Reply from 1.1.2.2: bytes=32 time=1ms TTL=253
Reply from 1.1.2.2: bytes=32 time=1ms TTL=253
Reply from 1.1.2.2: bytes=32 time=1ms TTL=253
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 reachability to 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.
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