Table of Contents Chapter 1 IP Addressing Configuration

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1 Table of Contents Table of Contents IP Addressing Overview IP Address Classes Special Case IP Addresses Subnetting and Masking IP Unnumbered Configuring IP Addresses Assigning an IP Address to an Interface IP Addressing Configuration Example Configuring IP Unnumbered Configuration Prerequisites Configuration Procedure IP Unnumbered Configuration Example Displaying IP Addressing Configuration i

2 When assigning IP addresses to interfaces on your device, go to these sections for information you are interested in: IP Addressing Overview Configuring IP Addresses Configuring IP Unnumbered Displaying IP Addressing Configuration 1.1 IP Addressing Overview This section covers these topics: IP Address Classes Special Case IP Addresses Subnetting and Masking IP Unnumbered IP Address Classes IP addressing uses a 32-bit address to identify each host on a network. An example is in binary. To make IP addresses in 32-bit form easier to read, they are written in dotted decimal notation, each being four octets in length, for example, for the address just mentioned. Each IP address breaks down into two parts: Net-id: First several bits of the IP address defining a network, also known as class bits. Host-id: Identifies a host on a network. For administration sake, IP addresses are divided into five classes. Which class an IP address belongs to depends on the first one to four bits of the net-id, as shown in the following figure (in which the blue parts represent the address class). 1-1

3 Figure 1-1 IP address classes Table 1-1 describes the address ranges of these five classes. Currently, the first three classes of IP addresses are used in quantity. Table 1-1 IP address classes and ranges Class Address range Description A to The IP address is used by a host at startup for temporary communication. This address is never a valid destination address. Addresses starting with 127 are reserved for loopback test. Packets destined to these addresses are processed locally as input packets rather than sent out. B to C to D to Multicast address E to Reserved address Special Case IP Addresses The following IP addresses are for special use, and they cannot be used as host IP addresses: IP address with an all-zero net ID: Identifies a host on the local network. For example, IP address indicates the host with a host ID of 16 on the local network. IP address with an all-zero host ID: Identifies a network. IP address with an all-one host ID: Identifies a directed broadcast address. For example, a packet with the destination address of will be broadcasted to all the hosts on the network

4 1.1.3 Subnetting and Masking Subnetting was developed to address the risk of IP address exhaustion resulting from fast expansion of the Internet. The idea is to break a network down into smaller networks called subnets by using some bits of the host-id to create a subnet-id. To identify the boundary between the host-id and the combination of net-id and subnet-id, masking is used. (When subnetting is not adopted, a mask identifies the boundary between the host-id and the host-id.) Each subnet mask comprises 32 bits related to the corresponding bits in an IP address. In a subnet mask, the part containing consecutive ones identifies the combination of net-id and subnet-id whereas the part containing consecutive zeros identifies the host-id. Subnetting is valid with a single network. All these subnetworks appear as one. As subnetting adds an additional level, subnet-id, to the two-level hierarchy with IP addressing, IP routing now involves three steps: delivery to the site, delivery to the subnet, and delivery to the host. Figure 1-2 shows how a Class B network is subnetted. Figure 1-2 Subnet a Class B network In the absence of subnetting, some special addresses such as the addresses with the net-id of all zeros and the addresses with the host-id of all ones, are not assignable to hosts. The same is true of subnetting. When designing your network, you should note that subnetting is somewhat a tradeoff between subnets and accommodated hosts. For example, a Class B network can accommodate 65,534 ( Of the two deducted Class B addresses, one with an all-one host-id is the broadcast address and the other with an all-zero host-id is the network address) hosts before being subnetted. After you break it down into 512 (2 9 ) subnets by using the first 9 bits of the host-id for the subnet, you have only 7 bits for the host-id and thus have only 126 (2 7 2) hosts in each subnet. The maximum number of hosts is thus 64,512 ( ), 1022 less after the network is subnetted. Class A, B, and C networks, before being subnetted, use these default masks (also called natural masks): , , and respectively. 1-3

5 1.1.4 IP Unnumbered Logically, to enable IP on an interface, you must assign this interface a unique IP address. Yet, you can borrow an IP address already configured on one of other interfaces on your device instead. This is called IP unnumbered and the interface borrowing the IP address is called IP unnumbered interface. You may need to use IP unnumbered to save IP addresses either when available IP addresses are inadequate or when an interface is brought up but for occasional use. 1.2 Configuring IP Addresses Currently, the S9500 series switches support only manual IP address configuration Assigning an IP Address to an Interface You may assign an interface multiple IP addresses, one primary and multiple secondaries, to connect multiple logical subnets on the same physical subnet. Follow these steps to assign an IP address to an interface: To do Use the command Remarks Enter system view system-view Enter interface view Assign an IP address to the interface interface interface-type interface-number ip address ip-address { mask mask-length } [ sub ] The IP address can be configured on a VLAN interface, POS interface, and tunnel interface, but cannot be configured in Ethernet interface view. Required No IP address is assigned by default. Caution: The primary IP address you assigned to the interface can overwrite the previous one if there is any. You cannot assign a secondary IP address when the interface is configured to borrow one through IP unnumbered. 1-4

6 1.2.2 IP Addressing Configuration Example I. Network requirements As shown in Figure 1-3, the VLAN-interface 1 on Switch is connected to a LAN comprising two segments: /24 and /24. To enable the hosts on the two network segments to access external networks through Switch and to communicate with each other, do the following Assign two IP addresses to VLAN-interface 1 on the switch. Set the switch as the gateway on all PCs. II. Network diagram Figure 1-3 Network diagram for IP addressing configuration III. Configuration procedure # Assign a primary IP address and a secondary IP address to VLAN-interface 1. <Sysname> system-view [Sysname] interface vlan-interface 1 [Sysname-Vlan-interface1] ip address [Sysname-Vlan-interface1] ip address sub # Set the gateway address to on the PCs attached to the subnet /24, and to on the PCs attached to the subnet /24. The configuration method may vary with operating systems, so you need to refer to the operating system configuration manual of the PC. # Use the ping command to verify the connectivity between Switch and the hosts on the subnet /24. <Sysname> ping

7 PING : 56 data bytes, press CTRL_C to break Reply from : bytes=56 Sequence=1 ttl=255 time=25 ms Reply from : bytes=56 Sequence=2 ttl=255 time=27 ms Reply from : bytes=56 Sequence=3 ttl=255 time=26 ms Reply from : bytes=56 Sequence=4 ttl=255 time=26 ms Reply from : bytes=56 Sequence=5 ttl=255 time=26 ms ping statistics packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 25/26/27 ms The above information shows that Switch can communicate with the hosts on the subnet /24. # Use the ping command to verify the connectivity between Switch and the hosts on the subnet /24. <Sysname> ping PING : 56 data bytes, press CTRL_C to break Reply from : bytes=56 Sequence=1 ttl=255 time=25 ms Reply from : bytes=56 Sequence=2 ttl=255 time=26 ms Reply from : bytes=56 Sequence=3 ttl=255 time=26 ms Reply from : bytes=56 Sequence=4 ttl=255 time=26 ms Reply from : bytes=56 Sequence=5 ttl=255 time=26 ms ping statistics packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 25/25/26 ms The above information shows that Switch can communicate with the hosts on the subnet /24. # Use the ping command to verify the connectivity between hosts on the subnet /24 and hosts on subnet /24. Ping Host B from Host A to verify that the ping operation is successful. 1.3 Configuring IP Unnumbered This section includes: Configuration Prerequisites Configuration Procedure IP Unnumbered Configuration Example 1-6

8 1.3.1 Configuration Prerequisites Assign a primary IP address to the interface from which you want to borrow the IP address Configuration Procedure Follow these steps to configure IP unnumbered on an interface: To do Use the command Remarks Enter system view system-view Enter POS interface view Specify the current interface to borrow the IP address of the specified interface interface pos interface-number ip address unnumbered interface interface-type interface-number Required The interface does not borrow IP addresses from other interfaces by default. Caution: One interface cannot borrow an IP address from an unnumbered interface. Multiple interfaces can use the same unnumbered IP address. One interface borrows only the primary IP address among multiple IP addresses from another interface. The IP address of the borrowing interface always keeps consistent and varies with that of the borrowed interface. That is, if an IP address is configured for the borrowed interface, the IP address of the borrowing interface is the same as that of the borrowed interface; if no IP address is configured for the borrowed interface, no IP address is assigned for the borrowing interface. VLAN interfaces, tunnel interfaces, and loopback interfaces cannot borrow IP addresses of other interfaces, but other interfaces can borrow IP addresses of these interfaces. A VLAN interface should be created before its IP address can be borrowed IP Unnumbered Configuration Example I. Network requirements Two switches, Switch A and Switch B, on an intranet are connected to each other through POS interfaces across DDN. The interfaces connecting them to DDN are both POS 2/1/1. They each connect to a LAN through interface VLAN-interface

9 To save IP addresses, configure the POS interfaces to borrow IP addresses from the VLAN interfaces. The IP address of VLAN-interface 1 on Switch A is /24, and the IP address of VLAN-interface 1 on Switch B is /24. II. Network diagram Figure 1-4 Network diagram for IP unnumbered configuration III. Configuration procedure 1) Configure Switch A # Assign an IP address to VLAN-interface 1. <SysnameA> system-view [SysnameA] interface vlan-interface 1 [SysnameA-Vlan-interface1] ip address [SysnameA-Vlan-interface1] quit # Configure the POS interface to borrow an IP address from VLAN-interface 1. [SysnameA] interface pos 2/1/1 [SysnameA-Pos2/1/1] ip address unnumbered interface vlan-interface 1 [SysnameA-Pos2/1/1] link-protocol ppp [SysnameA-Pos2/1/1] quit # Create a route to the segment attached to Switch B, specifying interface POS2/1/1 as the outgoing interface. [SysnameA] ip route-static pos 2/1/1 2) Configure Switch B # Assign an IP address to VLAN-interface 1. <SysnameB> system-view [SysnameB] interface vlan-interface 1 [SysnameB-Vlan-interface1] ip address [SysnameB-Vlan-interface1] quit # Configure the POS interface to borrow an IP address from VLAN-interface

10 [SysnameB] interface pos 2/1/1 [SysnameB-Pos2/1/1] ip address unnumbered interface vlan-interface 1 [SysnameB-Pos2/1/1] link-protocol ppp [SysnameB-Pos2/1/1] quit # Create a route to the segment attached to Switch A, specifying interface POS2/1/1 as the outgoing interface. [SysnameB] ip route-static pos 2/1/1 3) Ping a host attached to Switch B from Switch A to verify the configuration. [Sysname] ping PING : 56 data bytes, press CTRL_C to break Reply from : bytes=56 Sequence=1 ttl=255 time=25 ms Reply from : bytes=56 Sequence=2 ttl=255 time=25 ms Reply from : bytes=56 Sequence=3 ttl=255 time=26 ms Reply from : bytes=56 Sequence=4 ttl=255 time=26 ms Reply from : bytes=56 Sequence=5 ttl=255 time=26 ms ping statistics packet(s) transmitted 5 packet(s) received 0.00% packet loss round-trip min/avg/max = 25/25/26 ms 1.4 Displaying IP Addressing Configuration To do Use the command Remarks Display information about a specified or all Layer 3 interfaces Display brief information about a specified or all Layer 3 interfaces display ip interface [ interface-type interface-number ] display ip interface brief [ interface-type interface-number ] Available in any view Available in any view 1-9