RIPng uses a hop count to measure the distance to a destination. The hop count is referred to as metric or cost. The hop count from a router to a directly connected network is 0. The hop count between two directly connected routers is 1. When the hop count is greater than or equal to 16, the destination network or host is unreachable.

By default, the routing update is sent every 30 seconds. If the router receives no routing updates from a neighbor after 180 seconds, the routes learned from the neighbor are considered as unreachable. After another 240 seconds, if no routing update is received, the router will remove these routes from the routing table.

RIPng supports Split Horizon and Poison Reverse to prevent routing loops, and route redistribution.

Each RIPng router maintains a routing database, including route entries of all reachable destinations. A route entry contains the following information:

l Destination address: IPv6 address of a host or a network.

l Next hop address: IPv6 address of a neighbor along the path to the destination.

l Egress interface: Outbound interface that forwards IPv6 packets.

l Metric: Cost from the local router to the destination.

l Route time: Time that elapsed since a route entry is last changed. Each time a route entry is modified, the routing time is set to 0.

l Route tag: Identifies the route, used in routing policy to control routing information.

1.1.2 RIPng Packet Format

I. Basic format

A RIPng packet consists of a header and multiple Route Table Entries (RTEs). The maximum number of RTEs in a packet depends on the MTU of the sending interface.

Figure 1-1 shows the packet format of RIPng.

Figure 1-1 RIPng basic packet format

l Command: Type of message. 0x01 indicates Request, 0x02 indicates Response.

l Version: Version of RIPng. It can only be 0x01 currently.

l RTE: Route table entry, 20 bytes for each entry.

II. RTE format

There are two types of RTE in RIPng.

l Next hop RTE: Defines the IPv6 address of a next hop

l IPv6 prefix RTE: Describes the destination IPv6 address, route tag, prefix length and metric in the RIPng routing table.

Figure 1-2 shows the format of the next hop RTE:

Figure 1-2 Next hop RTE format

IPv6 next hop address is the IPv6 address of the next hop.

Figure 1-3 shows the format of the IPv6 prefix RTE.

Figure 1-3 IPv6 prefix RTE format

l IPv6 prefix: Destination IPv6 address prefix.

l Route tag: Route tag.

l Prefix len: Length of the IPv6 address prefix.

l Metric: Cost of a route.

1.1.3 RIPng Packet Processing Procedure

I. Request packet

When a RIPng router first starts or needs to update some entries in its routing table, generally a multicast request packet is sent to ask for needed routes from neighbors.

The receiving RIPng router processes RTEs in the request. If there is only one RTE with the IPv6 prefix and prefix length both being 0, and with a metric value of 16, the RIPng router will respond with the entire routing table information in response messages. If there are multiple RTEs in the request message, the RIPng router will examine each RTE, update its metric, and send the requested routing information to the requesting router in the response packet.

II. Response packet

The response packet containing the local routing table information is generated as:

l A response to a request

l An update periodically

l A trigged update caused by route change

After receiving a response, a router checks the validity of the response before adding the route to its routing table, such as whether the source IPv6 address is the link-local address, whether the port number is correct. The response packet failed the check will be discarded.

1.1.4 Protocols and Standards

l RFC2080: RIPng for IPv6

l RFC2081: RIPng Protocol Applicability Statement

l RFC2453: RIP Version 2

1.2 Configuring RIPng Basic Functions

In this section, you are presented with the information to configure the basic RIPng features.

You need to enable RIPng first before configuring other tasks, but it is not necessary for RIPng related interface configurations, such as assigning an IPv6 address.

1.2.1 Configuration Prerequisites

Before the configuration, accomplish the following tasks first:

l Enable IPv6 packet forwarding.

l Configure an IP address for each interface, and make sure all nodes are reachable.

1.2.2 Configuration Procedure

Follow these steps to configure the basic RIPng functions:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enable a RIPng process and enter RIPng view	ripng [ process-id ]	Required Not created by default
Return to system view	quit	—
Enter interface view	interface interface-type interface-number	––
Enable RIPng on the interface	ripng process-id enable	Required

& Note:

If RIPng is not enabled on an interface, the interface will not send and receive any RIPng route.

1.3 Configuring RIPng Route Control

This section describes how to configure the attributes of RIPng routes, such as configuration of RIPng route preference and cost, and how to control incoming and outgoing routes and how to redistribute routes from other protocols.

This section covers the following topics:

l Configuring an Additional Route Metric

l Configuring RIPng Route Summarization

l Advertising a Default Route

l Configuring a RIPng Route Filtering Policy

l Configuring the RIPng Priority

l Configuring RIPng Route Redistribution

1.3.1 Prerequisites

Before the configuration, accomplish the following tasks first:

l Configure an IPv6 address for each interface.

l Configure RIPng basic functions

l Define an IPv6 ACL before using it for route filtering. Refer to ACL configuration for related information.

l Define an IPv6 address prefix list before using it for route filtering. Refer to Routing Policy Configuration for related information.

1.3.2 Configuring an Additional Route Metric

An additional route metric can be added to the metric of an inbound or outbound RIP route, namely, the inbound and outbound additional metric.

The outbound additional metric is added to the metric of a sent route, the route’s metric in the routing table is not changed.

The inbound additional metric is added to the metric of a received route before the route is added into the routing table, so the route’s metric is changed.

Follow these steps to configure an inbound/outbound additional routing metric:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter interface view	interface interface-type interface-number	––
Specify an inbound route additional metric	ripng metricin value	Optional 0 by default
Specify an outbound route additional metric	ripng metricout value	Optional 1 by default

1.3.3 Configuring RIPng Route Summarization

Follow these steps to configure RIPng route summarization:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter interface view	interface interface-type interface-number	––
Advertise a summary IPv6 prefix	ripng summary-address ipv6-address prefix-length	Required

& Note:

After configuration, the device advertises a summary IPv6 prefix rather than a specific route through the interface.

1.3.4 Advertising a Default Route

Follow these steps to advertise a default route:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter interface view	interface interface-type interface-number	––
Advertise a default route	ripng default-route { only \| originate } [ cost cost ]	Required Not advertised by default

& Note:

With this feature enabled, a default route is advertised via the specified interface regardless of whether the default route is available in the local IPv6 routing table.

1.3.5 Configuring a RIPng Route Filtering Policy

You can reference a configured IPv6 ACL or prefix list to filter received/advertised routing information as needed. For filtering outbound routes, you can also specify a routing protocol from which to filter routing information redistributed.

Follow these steps to configure a RIPng route filtering policy:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter RIPng view	ripng [ process-id ]	––
Configure a filter policy to filter incoming routes	filter-policy { acl6-number \| ipv6-prefix ipv6-prefix-name } import	Required By default, RIPng does not filter incoming routing information.
Configure a filter policy to filter outgoing routes	filter-policy { acl6-number \| ipv6-prefix ipv6-prefix-name } export [ protocol [ process-id ] ]	Required By default, RIPng does not filter outgoing routing information.

1.3.6 Configuring the RIPng Priority

Any routing protocol has its own protocol priority used for optimal route selection. You can set a priority for RIPng manually. The smaller the value is, the higher the priority is.

Follow these steps to configure a RIPng priority:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Enter RIPng view	ripng [ process-id ]	—
Configure a RIPng priority	preference [ route-policy route-policy-name ] preference	Optional By default, the RIPng priority is 100.

1.3.7 Configuring RIPng Route Redistribution

Follow these steps to configure RIPng route redistribution:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter RIPng view	ripng [ process-id ]	––
Configure a default routing metric for redistributed routes	default cost cost	Optional By default, the default metric of redistributed routes is 0.
Redistribute routes from another routing protocol	import-route protocol [ process-id ] [ allow-ibgp ] [ cost cost ] [ route-policy route-policy-name ]	Required If no cost is specified, the default metric applies.

1.4 Tuning and Optimizing the RIPng Network

This section describes how to tune and optimize the performance of the RIPng network as well as applications under special network environments. This section covers the following topics:

l Configuring RIPng Timers

l Configuring Split Horizon

l Configuring Poison Reverse

l Enabling Zero Field Check on RIPng Packets

l Configuring the Maximum Number of Equal Cost Routes for Load Balancing

1.4.1 Prerequisites

Before tuning and optimizing the RIPng network, complete the following tasks:

l Configure a network layer address for each interface

l Configure the basic RIPng functions

1.4.2 Configuring RIPng Timers

You can adjust RIPng timers to optimize the performance of the RIPng network.

Follow these steps to configure RIPng timers:

To do…	Use the command…	Remarks
Enter system view	system-view	—
Enter RIPng view	ripng [ process-id ]	—
Configure RIPng timers	timers { garbage-collect garbage-collect-value \| suppress suppress-value \| timeout timeout-value \| update update-value } *	Optional. The RIPng timers have the following defaults: l 30 seconds for the update timer l 180 seconds for the timeout timer l 120 seconds for the suppress timer l 120 seconds for the garbage-collect timer

& Note:

When adjusting RIPng timers, you should consider the network performance and perform unified configurations on routers running RIPng to avoid unnecessary network traffic.

1.4.3 Configuring Split Horizon

The split horizon function disables a route learned from an interface from being advertised via the interface to prevent routing loops between neighbors.

Follow these steps to configure the split horizon:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter interface view	interface interface-type interface-number	––
Enable the split horizon function	ripng split-horizon	Optional Enabled by default

& Note:

Generally, you are recommended to enable the split horizon to prevent routing loops.

1.4.4 Configuring Poison Reverse

Follow these steps to configure poison reverse:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter interface view	interface interface-type interface-number	––
Enable the poison reverse function	ripng poison-reverse	Required Disabled by default

& Note:

l The poison reverse function enables a route learned from an interface to be advertised via the interface. However, the metric of the route is set to 16. That is to say, the route is unreachable.

l If both the split horizon and poison reverse are configured, only the poison reverse function takes effect.

1.4.5 Enabling Zero Field Check on RIPng Packets

Follow these steps to configure RIPng zero field check:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter RIPng view	ripng [ process-id ]	––
Enable zero field check on RIPng packets	checkzero	Optional Enabled by default

& Note:

Some fields in the RIPng packet must be zero. These fields are called zero fields. With the zero field check on RIPng packets enabled, if such a field contains a non-zero value, the entire RIPng packet will be discarded.

1.4.6 Configuring the Maximum Number of Equal Cost Routes for Load Balancing

Follow these steps to configure the maximum number of equal cost RIPng routes for load balancing:

To do…	Use the command…	Remarks
Enter system view	system-view	––
Enter RIPng view	ripng [ process-id ]	––
Configure the maximum number of equal cost RIPng routes for load balancing	maximum load-balancing number	Optional

1.5 Displaying and Maintaining RIPng Configuration

To do…	Use the command…	Remarks
Display configuration information of a RIPng process	display ripng [ process-id ]	Available in any view
Display routes in the RIPng database	display ripng process-id database	Available in any view
Display the routing information of a specified RIPng process	display ripng process-id route	Available in any view
Display RIPng interface information	display ripng process-id interface [ interface-type interface-number ]	Available in any view

1.6 RIPng Configuration Example

I. Network requirements

As shown in Figure 1-4, all switches run RIPng. The prefix length of all IP addresses in the figure is 64, and neighboring switches use link-local IPv6 addresses for interconnection.

Configure Switch B to filter the route (3::/64) learnt from Switch C, which means the route will not be added to the routing table of Switch B, and Switch B will not forward it to Switch A.

II. Network diagram

Figure 1-4 Network diagram for RIPng configuration

III. Configuration procedure

1) Enable IPv6 globally and configure the IPv6 address for each interface (omitted)

2) Configure basic RIPng functions

# Configure Switch A.

<SwitchA> system-view

[SwitchA] ripng 1

[SwitchA-ripng-1] quit

[SwitchA] interface vlan-interface 100

[SwitchA-Vlan-interface100] ripng 1 enable

[SwitchA-Vlan-interface100] quit

[SwitchA] interface vlan-interface 400

[SwitchA-Vlan-interface400] ripng 1 enable

[SwitchA-Vlan-interface400] quit

# Configure Switch B.

<SwitchB> system-view

[SwitchB] ripng 1

[SwitchB-ripng-1] quit

[SwitchB] interface vlan-interface 200

[SwitchB-Vlan-interface200] ripng 1 enable

[SwitchB-Vlan-interface200] quit

[SwitchB] interface vlan-interface 100

[SwitchB-Vlan-interface100] ripng 1 enable

[SwitchB-Vlan-interface100] quit

# Configure Switch C.

<SwitchC> system-view

[SwitchC] ripng 1

[SwitchC-ripng-1] quit

[SwitchC] interface vlan-interface 200

[SwitchC-Vlan-interface200] ripng 1 enable

[SwitchC-Vlan-interface200] quit

[SwitchC] interface vlan-interface 500

[SwitchC-Vlan-interface500] ripng 1 enable

[SwitchC-Vlan-interface500] quit

[SwitchC] interface vlan-interface 600

[SwitchC-Vlan-interface600] ripng 1 enable

[SwitchC-Vlan-interface600] quit

# Display the routing table of Switch B.

[SwitchB] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::20F:E2FF:FE23:82F5 on Vlan-interface100

Dest 1::/64,

via FE80::20F:E2FF:FE23:82F5, cost 1, tag 0, A, 6 Sec

Dest 2::/64,

via FE80::20F:E2FF:FE23:82F5, cost 1, tag 0, A, 6 Sec

Peer FE80::20F:E2FF:FE00:100 on Vlan-interface200

Dest 3::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 11 Sec

Dest 4::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 11 Sec

Dest 5::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 11 Sec

# Display the routing table of Switch A.

[SwitchA] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::200:2FF:FE64:8904 on Vlan-interface100

Dest 1::/64,

via FE80::200:2FF:FE64:8904, cost 1, tag 0, A, 31 Sec

Dest 4::/64,

via FE80::200:2FF:FE64:8904, cost 2, tag 0, A, 31 Sec

Dest 5::/64,

via FE80::200:2FF:FE64:8904, cost 2, tag 0, A, 31 Sec

Dest 3::/64,

via FE80::200:2FF:FE64:8904, cost 1, tag 0, A, 31 Sec

3) Configure Switch B to filter incoming and outgoing routes.

[SwitchB] acl ipv6 number 2000

[SwitchB-acl6-basic-2000] rule deny source 3::/64

[SwitchB-acl6-basic-2000] rule permit

[SwitchB-acl6-basic-2000] quit

[SwitchB] ripng 1

[SwitchB-ripng-1] filter-policy 2000 import

[SwitchB-ripng-1] filter-policy 2000 export

# Display routing tables of Switch B and Switch A.

[SwitchB] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::20F:E2FF:FE23:82F5 on Vlan-interface100

Dest 1::/64,

via FE80::20F:E2FF:FE23:82F5, cost 1, tag 0, A, 2 Sec

Dest 2::/64,

via FE80::20F:E2FF:FE23:82F5, cost 1, tag 0, A, 2 Sec

Peer FE80::20F:E2FF:FE00:100 on Vlan-interface200

Dest 4::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 5 Sec

Dest 5::/64,

via FE80::20F:E2FF:FE00:100, cost 1, tag 0, A, 5 Sec

[SwitchA] display ripng 1 route

Route Flags: A - Aging, S - Suppressed, G - Garbage-collect

----------------------------------------------------------------

Peer FE80::20F:E2FF:FE00:1235 on Vlan-interface100

Dest 1::/64,

via FE80::20F:E2FF:FE00:1235, cost 1, tag 0, A, 2 Sec

Dest 4::/64,

via FE80::20F:E2FF:FE00:1235, cost 2, tag 0, A, 2 Sec

Dest 5::/64,

via FE80::20F:E2FF:FE00:1235, cost 2, tag 0, A, 2 Sec

H3C S9500 Operation Manual-Release2132[V2.03]-03 IP Routing Volume

1.1 Introduction to RIPng

1.1.1 RIPng Working Mechanism

1.1.2 RIPng Packet Format

I. Basic format

II. RTE format

I. Request packet

II. Response packet

1.2 Configuring RIPng Basic Functions

1.3 Configuring RIPng Route Control

1.3.2 Configuring an Additional Route Metric

1.3.3 Configuring RIPng Route Summarization

1.3.4 Advertising a Default Route

1.3.5 Configuring a RIPng Route Filtering Policy

1.3.6 Configuring the RIPng Priority

1.3.7 Configuring RIPng Route Redistribution

1.4 Tuning and Optimizing the RIPng Network

1.4.3 Configuring Split Horizon

1.4.5 Enabling Zero Field Check on RIPng Packets

1.4.6 Configuring the Maximum Number of Equal Cost Routes for Load Balancing

1.5 Displaying and Maintaining RIPng Configuration

1.6 RIPng Configuration Example

I. Network requirements

II. Network diagram

III. Configuration procedure

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