Configuring static IPv6 routes

This feature enables you to create static routes (including null routes with or without ICMP notification to the sender) by adding such routes directly to the route table in the routing switch.

This section describes how to add static and null routes to the IPv6 route table.

Syntax:

[no] ipv6 route <dest–ipv6–addr>|<prefix–length> <next-hop–gateway–addr | vlan <vid> | blackhole | reject > [distance <1–255>]

<dest–ipv6–addr>|<prefix–length> : Network prefix for the destination on IPv6 address.

<next-hop–gateway–addr|vlan <vid>> : The gateway for reaching the destination.

The next-hop address option (link-local or global unicast) is not required to be directly reachable on a local subnet. (If it is not directly reachable, the route is added to the routing table when a path to this address is learned.)

If the next-hop address is link-local, it must include both the address and the applicable VLAN VID.

For example: FE80::127%vlan10,where VLAN 10 is the interface where FE80::127 exists.

blackhole : Specifies a null route where IP traffic for the specified destination is discarded and no ICMP error notification is returned to the sender.

reject : Specifies a null route where IP traffic for the specified destination is discarded and an ICMP error notification is returned to the sender.

distance : Specifies the administrative distance to associate with a static route. Default: 1; Range: 1–255

The no form of the command deletes the specified static or null route from the routing table.

The no form of the command deletes the specified route from the routing table for the specified destination next-hop pair.

Configuring static routes configures two static routes for traffic delivery and identifies two other null routes for which traffic should be discarded instead of forwarded.

Configuring static routes

HP Switch(config)# ipv6 route 2001:db8:0:1::/64 fe80::10.1

Configures static route to a specific destination network. Notice that the next-hop gateway can be either a link-local or a global unicast address.

HP Switch(config)# ipv6 route 2001:db8:0:2::/64 reject

Configures a null route to drop traffic for the 2001:db8:0:2::/64 network and return an ICMP notice to the sender.

HP Switch(config)# ipv6 route 2001:db8:0:5::/64 blackhole

Configures a null route to drop traffic for the 2001:db8:0:2::/64 network without ICMP notice to the sender.

HP Switch(config)# ipv6 route 2001:db8::/48 vlan 66 distance 120

Configures a static route for traffic to destinations in the 2001:db8:0::/48 network. Sets the administrative distance higher than the default distance for any dynamic routes discovered for the same destination, which gives precedence in the routing table to dynamic routes.

Viewing static route information

Syntax:

show ipv6 route [ipv6–addr|connected|static]

Lists all entries in the IPv6 routing table.

[ipv6–addr] : Lists entries for a specific IPv6 address. Can be followed by any of the other options for this command.

[connected] : Lists entries for connected routes. Can be followed by the ipv6-addr option to list only the connected routes having a specific link-local or global IPv6 address.

[static] : Lists entries for static routes in the routing table. Can be followed by the ipv6–addr option to list only the static routes matching a specific destination.

The following examples shows the static routes in the routing table for Router "B" in Example of a routing domain.

Displaying static routes in the IPv6 routing table for the Switch 2620-series

HP Switch(config)# show ipv6 route static

                               IPv6 Route Entries

 T (Type):
  S: Static   C: Connected   O: OSPFv3

 ST (Sub–type):
  O : OSPF Intra  E1: External1  N1: NSSA Ext1
  OI: OSPF Inter  E2: External2  N2: NSSA Ext2

 Destination/
  Gateway                              T   ST  Distance   Metric
 ––––––––––––––––––––––––––––––––––––– ––– ––– –––––––––– –––––––
 2620:a::/64 / 2620:b::22:1            S   NA  1          1
 2620:a::/64 / 2620:e::55:2            S   NA  1          1

Displaying static routes in the IPv6 routing table for the Switch 2920-series

HP Switch(config)# show ipv6 route static

                             IPv6 Route Entries

Destination : 2620:a::/64
Gateway : 2620:b::22:1
Type : static      Sub-Type : NA        Distance : 1      Metric : 1

Destination : 2620:c::/64
Gateway : 2620:e::55:2
Type : static      Sub-Type : NA        Distance : 1      Metric : 1

Equal-cost multi-path routing (ECMP) for the Switch 2620-series


	IMPORTANT: Equal-cost multi-path routing (ECMP) applies to the Switch 2620-series only.

The ECMP feature allows OSPFv3 to add routes with multiple next-hop addresses and with equal costs to a given destination in the forwarding information base (FIB) on the routing switch. For example, if multiple, equal-cost, next-hop routes exist on a routing switch for a destination in a network with the prefix 2620:e::/64, these routes would appear similar to the following in the IPv6 Route Entries Table:

The show ipv6 route command with multiple next-hop routes

Multiple next-hop gateway addresses are displayed for the destination network 2620:a::/64

HP Switch(config)# show ipv6 route

               IPv6 Route Entries

Destination : ::1/128
Gateway : lo0
Type: connected  Sub–Type: NA         Distance: 0    Metric: 1

Destination : 2620:c::/64
Gateway : 2620:e::55:2
Type: static     Sub–Type: NA         Distance: 200  Metric: 1

Destination : 2620:a::/64
Gateway : fe80::22:3%vlan22
Type: ospf3      Sub–Type: InterArea  Distance: 110  Metric: 2

Destination : 2620:a::/64
Gateway : fe80::22:5%vlan22
Type: ospf3      Sub–Type: InterArea  Distance: 110  Metric: 2

Destination : 2620:a::/64
Gateway : fe80::22:11%vlan22
Type: ospf3      Sub–Type: InterArea  Distance: 110  Metric: 2

Multiple ECMP next-hop routes cannot be a mixture of intra-area, inter-area, and external routes. For example, in The show ipv6 route command with multiple next-hop routes, the multiple next-hop routes to network 2620:a::/64 are all inter-area.

Also, according to the distributed algorithm used in the selection of ECMP next-hop routes:

Intra-area routes are preferred to inter-area routes.
Inter-area routes are preferred to external routes through a neighboring autonomous system (AS).

In addition, ECMP ensures that all traffic forwarded to a given host address follows the same path, which is selected from the possible next-hop routes.

ECMP load-sharing does not affect routed traffic to different hosts on the same subnet. That is, all traffic for different hosts on the same subnet will go through the same next-hop router. For example, if subnet 2001:db8:0:1f::/64 includes two servers at 2001:db8:0:1f::1ab.101 and 2001:db8:0:1f::1ab.93, all traffic from router "A" to these servers will go through the same next-hop router.

Syntax:

[no] ip load-sharing <2–4>

The no form of the command disables this load-sharing so that only one route in a group of multiple, equal-cost, next-hop routes is used for traffic that could otherwise be load-shared across multiple routes.

NOTE: Disabling load-sharing means that router "1" selects only one next-hop router for traffic that is actually eligible for load-sharing through different next-hop routers.

In the default configuration, load-sharing is enabled by default for both IPv4 and IPv6.

<2–4> : Specifies the maximum number of equal-cost next-hop paths the router allows. (Default: 4; Range: 2–4)

In OSPFv3 ECMP multiple next-hop routing (inter-area), the ECMP inter-area routes to destination network 2001:db8:0:e::/64 consist of the following next-hop gateway addresses:

2001:db8:0:b::b:101
2001:db8:0:c::c:101
2001:db8:0:d::d:101

OSPFv3 ECMP multiple next-hop routing (inter-area)

However, the forwarding software distributes traffic across the three possible next-hop routes in such a way that all traffic for a specific host is sent to the same next-hop router.

As shown in OSPFv3 ECMP multiple next-hop routing (inter-area), one possible distribution of traffic to host devices is:

Traffic to host "A" passes through next-hop router "3"
Traffic to host "B" passes through next-hop router "2"
Traffic to host "C" passes through next-hop router "3"
Traffic to host "D" passes through next-hop router "4"

IP packet destination	Next hop used
`2001:db8:0:e::100`	`2001:db8:0:b::b:10`
`2001:db8:0:e::110`	`2001:db8:0:c::c:20`
`2001:db8:0:e::120`	`2001:db8:0:b::b:10`
`2001:db8:0:e::130`	`2001:db8:0:d::d:30`

Viewing the current IP load-sharing configuration for the Switch 2620-series


	IMPORTANT: The content in this section applies to the Switch 2620-series only.

Use show running to view the currently active load-sharing configuration and show config to view the load-sharing configuration in the startup-config file. (While in its default configuration [ip load-sharing 4] load-sharing does not appear in the command output.) If load sharing is configured with non-default settings (disabled or configured for either two or three equal-cost next-hop paths), the current settings are displayed in the command output.

Displaying a non-default IP load-sharing configuration

HP Switch(config)# show running
 Running configuration:
 ; J8697A Configuration Editor; Created on release #xx.15.xx

 hostname "HP Switch"
 snmp–server community "public" Unrestricted
 vlan 1
    name "DEFAULT_VLAN"
    untagged 1–24
    ip address dhcp–bootp
    exit
 ip load-sharing 3

Indicates a non-default load-sharing configuration allowing three equal-cost next-hop paths for routed traffic with different subnet destinations. If the routing switch is configured with the default load-sharing configuration, load-sharing does not appear in the show config or show running command output.

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