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Table of Contents

IP Services

IP Services

This chapter describes provisioning IP on the Cisco IAD1101 and includes the following sections:

Static IP Routing

EMS uses static IP routes to define paths through the Cisco IAD1101 and across the network. You can assign static IP routes to direct IP traffic on the Ethernet interface, and any T1 lines configured for IP (IP over Frame Relay or IP over PPP).

A static IP route consists of the following information:

Figure 11-1 shows a sample network, with a Cisco IAD1101 connected to a router over a PPP link.


Note   The IP addresses used in this chapter are only for illustration. You must use your own IP addresses, based on your licensing.

To assign a static route from the Cisco IAD1101 to Host A, over a T1 line, enter the following information:

Network Route:

Default Route:

Host Route:


Figure 11-1: Static IP Route Example - over T1


To assign a static route from the Cisco IAD1101 to Host A, over Ethernet, enter the following information:

Network Route:

Default Route:

Host Route:


Figure 11-2: Static IP Route Example - over Ethernet


Assigning Static IP Routes


Step 1   From Cisco 6700 NodeView, double-click the node nameplate. EMS launches the NE provision window. (See Figure 11-3.)


Figure 11-3: IAD1101 NE Provision Window


Step 2   From the function bar on the left, click the IP & Datalink Route Configuration button. EMS launches the data link route configuration window. (See Figure 11-4.)


Figure 11-4: IP & Datalink Route Configuration Window


Step 3   Set the following parameters in the data link route configuration window:

Step 4   Click Add when finished.

Step 5   Click the Exit button (on the function bar) to return to the NodeView.



Note   You can add as many routes as needed, but only one route can be the default route.

Access Lists

An access list is a sequential collection of permit and deny conditions that apply to IP addresses. EMS tests addresses against the conditions in an access list one by one. All entries in the list are checked. If at any point there is a mismatch, the software rejects the address. The following flow charts illustrate how the decisions are made. (See


Figure 11-5: Access List - Inbound Decision Tree



Figure 11-6: Access List - Outbound Decision Tree


Access lists allow the Cisco IAD1101 to filter incoming or outgoing IP packets based on the following criteria:


Note   UDP ports 161 and 162 are used for management and alarm traffic, respectively.

Provisioning Access Lists

To provision access lists on the NE, complete the following steps starting in the NE provisioning window:


Step 1   Click IP Access Lists in the function bar. EMS launches the access list provisioning window. (See
Figure 11-7.)


Figure 11-7: Provisioning IP Access Lists


Step 2   Set the following fields to configure the access list:

Step 3   Click Add when finished.

Step 4   Repeat Step 2 and Step 3 to configure additional access lists. You can configure as many as 32 access lists.

Step 5   Click Enable/Disable Access Lists.


Caution   EMS rejects traffic on every interface that does not have an access list definition. Before you proceed, you must create at least one entry per interface to accept traffic, or the NE will reject all traffic on the unprovisioned interface, including management traffic. Be sure to enable the SNMP protocol in the access list, and provision an accept statement to allow packets in and out of the interface on UDP port 161.

Step 6   Click Apply NE Enable to activate access lists.


Caution   Enabling access lists might prevent user traffic from entering or exiting the NE, including management traffic.


Blocking Telnet Sessions-Examples











Figure 11-8:


Sample Network



sun1 ------------------

r1 ------------------ 1101 ------------------ r2 ------------------ sun2

There are two ways to provision the access list to block a Telnet session from network 2 (200.200.200.0) to network 1 (10.0.0.0). Method 1 (see Figure 11-9) filters on the inbound interface, preventing the Cisco IAD1101 from routing the packet first, then having to possibly reject it later because of an access list condition. Method 2 (see Figure 11-10) sets up filtering on the outbound interface.


Figure 11-9: Method 1

reject either out 200.200.200.0/24/all 10.0.0.0/8/23 TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

out

0.0.0.0/0/all

0.0.0.0/0/all

all


Figure 11-10:
Method 2

reject 1 out 200.200.200.0/24/all 10.0.0.0/8/23 TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

out

0.0.0.0/0/all

0.0.0.0/0/all

all

There are two ways to provision the access list to block a Telnet session from network 1 (10.0.0.0) to network 2 (200.200.200.0). Method 1 (see Figure 11-11) filters on the inbound interface, preventing the Cisco IAD1101 from routing the packet first, then having to possibly reject it later because of an access list condition. Method 2 (see Figure 11-12) sets up filtering on the outbound interface.


Figure 11-11 : Method 1

r

reject either in 10.0.0.0/8/all 200.200.200.0/24/23 TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

out

0.0.0.0/0/all

0.0.0.0/0/all

all


Figure 11-12 :
Method 2

reject 1 out 10.0.0.0/8/all 200.200.200.0/24/23 TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

out

0.0.0.0/0/all

0.0.0.0/0/all

all

Blocking ftp Sessions-Examples

In the same sample network (see Figure 11-8), there are two ways to provision the access list to block an ftp session from network 2 (200.200.200.0) to network 1 (10.0.0.0). Method 1 (see Figure 11-13) filters on the inbound interface, preventing the Cisco IAD1101 from routing the packet first, then having to possibly reject it later because of an access list condition. Method 2 (see Figure 11-14) sets up filtering on the outbound interface.


Figure 11-13 : Method 1

r

reject 1 in 200.200.200.0/24/all 10.0.0.0/8/20 TCP

reject 1

in

200.200.200.0/24/all

10.0.0.0/8/21

TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

out

0.0.0.0/0/all

0.0.0.0/0/all

all


Figure 11-14 :
Method 2

reject ether out 200.200.200.0/24/all 10.0.0.0/8/20 TCP

reject ether

out

200.200.200.0/24/all

10.0.0.0/8/21

TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

out

0.0.0.0/0/all

0.0.0.0/0/all

all

There are two ways to provision the access list to block an ftp session from network 1 (10.0.0.0) to network 2 (200.200.200.0). Method 1 (see Figure 11-15) filters on the inbound interface, preventing the Cisco IAD1101 from routing the packet first, then having to possibly reject it later because of an access list condition. Method 2 (see Figure 11-16) sets up filtering on the outbound interface.


Figure 11-15 : Method 1

reject either in 10.0.0.0/8/all 200.200.200.0/24/20 TCP

reject either

in

10.0.0.0/8/all

200.200.200.0/24/21

TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept either

out

0.0.0.0/0/all

0.0.0.0/0/all

all


Figure 11-16 :
Method 2

reject 1 out 10.0.0.0/8/all 200.200.200.0/24/20 TCP

reject 1

out

10.0.0.0/8/all

200.200.200.0/24/21

TCP

accept 1

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept 1

out

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

in

0.0.0.0/0/all

0.0.0.0/0/all

all

accept ether

out

0.0.0.0/0/all

0.0.0.0/0/all

all

To accept only SNMP traffic to the Cisco IAD1101 from subnet 10.0.0./8, provision the access list as follows:

accept either in 10.0.0.0/8/161 130.130.130.2/32/161 UDP

accept either

out

130.130.130.2/32/161

10.0.0.0/8/161

UDP

Modifying or Deleting Access Lists

Use the following buttons to modify or delete an access list.


Caution   Changes made to an access list entry take place immediately. Cisco Systems recommends that you disable access lists for the NE before making changes.

About Network Address Translation

Network Address Translation (NAT) is a feature that allows an organization's IP network to appear from the outside to use different IP address space than what it is actually using. Thus, NAT allows an organization with nonglobally routable addresses to connect to the Internet by translating those addresses into globally routable address space. NAT is described in RFC 1631.

NAT enables private IP internetworks that use nonregistered IP addresses to connect to the Internet. NAT is configured on the router at the border of a stub domain (referred to as the inside network) and a public network such as the Internet (referred to as the outside network). NAT translates the internal local addresses to globally unique IP addresses before sending packets to the outside network.

Figure 11-17 shows an example of NAT configured on a Cisco IAD1101.


Figure 11-17: NAT Example


Using Static and Dynamic NAT

NAT offers two types of address translation, static and dynamic.

    10.0.0.1 --> 11.0.0.5 10.0.0.2 --> 11.0.0.6 10.0.0.3 --> 11.0.0.7
    10.0.0.1 --> 12.0.0.9 10.0.0.2 --> 12.0.0.9 10.0.0.3 --> 12.0.0.9

Note   The IP addresses used in this chapter are only for illustration. You must use your own IP addresses, based on your licensing.

Observing NAT Restrictions

The following conditions apply to NAT provisioned on the Cisco IAD1101:


Caution   Enabling NAT might prevent user traffic from entering or exiting the Cisco IAD1101, including management traffic.

Provisioning NAT


Step 1   From the NE provision window, select IP Network Access Translation (NAT) in the function bar. EMS launches the NAT provisioning window. (See Figure 11-18.)


Figure 11-18: Provisioning NAT


Step 2   Set the following fields to configure the network address translation:

Step 3   Click Add when finished.

Step 4   Repeat Step 2 and Step 3 to configure additional NAT entries. You can configure as many as 8 NAT entries.

Step 5   Click Enable/Disable NAT to activate NAT.


Caution   Enabling NAT might prevent user traffic from entering or exiting the Cisco IAD1101, including management traffic.


Modifying or Deleting NAT

Click a NAT entry in the list window, and use the following buttons to modify or delete a NAT entry:

Securing the Network with NAT

On a Cisco IAD1101 with a static or dynamic NAT translation, an outside host can still gain access to an inside (untranslated) host address. To block outside access to the inside network, create a static NAT that translates inbound addresses into a "dummy" address, then create an access list that filters out the dummy address. See "Access Lists" for access list information and procedures.

The following security procedure uses a "dummy" address, as previously described.


Note   The IP addresses used in this chapter are only for illustration. You must use your own IP addresses, based on your licensing.


Step 1   Provision the Cisco IAD1101 with a static NAT entry:

Step 2   Create a dynamic NAT entry to prevent direct outside access to 10.0.0.0/8. Use 99.0.0.1 as the dummy address.

Step 3   Create an access list entry that rejects all inbound traffic with IP address 99.0.0.1:


Routing Information Protocol

The Routing Information Protocol (RIP) is a distance-vector protocol that uses hop count as its metric (where hop is defined as the next IP addressed equipment downstream). RIP sends routing-update messages at regular intervals, and whenever the network topology changes. When a router receives a routing update that includes changes to an entry, it updates its routing table to reflect the new route.


Note   On a Cisco IAD1101 with a Frame Relay link, but without a PPP link, RIP does not advertise the node IP address over the Frame Relay link. To gain access to the Cisco IAD1101 over the Frame Relay link, use the Frame Relay address (not the node address) as the address for the Cisco IAD1101. This is not needed when both Frame Relay and PPP links exist on the Cisco IAD1101.

Provisioning RIP

To provision RIP on the NE, complete the following steps starting in the NE provision window:


Step 1   Click IP RIP Configuration. EMS launches the RIP provisioning window. (See Figure 11-19.)


Figure 11-19: Provisioning RIP


Step 2   Click Enable RIP for NE.

Step 3   In the IP Interfaces list, select the interfaces to be provisioned for RIP.

Step 4   Click Enable RIP.

Step 5   Select the Rx RIP Version1, 2, or 1 or 2.

Step 6   Select the Tx RIP VersionNone, 1, RIP1Compatible, or 2.

Step 7   Select the AuthenticationNone or Password.

Step 8   If password authentication is selected (RIPv2 only), enter the password in the Authentication Key field.

Step 9   Click Apply to provision RIP for the selected interfaces.



Note   When you activate RIP on a Cisco IAD1101 interface, RIP advertises all directly-connected nodes over the interface.


Note   RIP1Compatible is a version of RIPv2 that can be processed by a node using RIPv1.

IP Statistics

EMS maintains statistics for all IP activity on the Cisco IAD1101, including routing tables, interface activity, and Layer 4 protocol statistics.

Monitoring IP Statistics


Step 1   From Cisco 6700 NodeView, select Objects > IP Statistics from the NodeView menu bar. EMS launches the IP statistics window (See Figure 11-20.)


Figure 11-20: IP Statistics Window


Step 2   Under Available IP Statistics, click the icon for the desired display. Statistic information appears in the a new frame on the right side of the window. Statistic information and descriptions can be found in RFC1213 (Management Information Base for Network Management of TCP/IP-based internets: MIB-II).

Step 3   Use the following buttons to alter the display:

Step 4   Click Close to close the display.



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Posted: Mon Feb 5 13:06:57 PST 2001
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