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

 

Chapter 1  Static Routing Configuration

When configuring a static route, go to the following sections for information you are interested in:

l           Introduction

l           Configuring a Static Route

l           Displaying and Maintaining Static Routes

l           Configuration Example

 

 

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.

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:

l           If the output interface is a NULL0 interface, there is no need to configure the next hop address.

l           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.

l           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.

l           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:

l           Configure the physical parameters for related interfaces

l           Configure the link-layer attributes for related interfaces

l           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	—
Configure a static route	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 ]	Required By default, the preference of static routes is 60, tag is 0, and no description information is configured.
	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 ]
Configure the default preference for static routes	ip route-static default-preference default-preference-value	Optional 60 by default

 

 

1.3  Displaying and Maintaining Static Routes

To do…	Use the command…	Remarks
View the current configuration information	display current-configuration	Available in any view
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 ]
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

[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

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.