C H A P T E R 4

IPv6

IPv6 is a new version of IP which is designed to be an evolutionary step from IPv4. It can be installed as a normal software upgrade in Internet devices and is interoperable with the current IPv4. It has expanded routing and addressing capabilities because of the 128-bit addressing as compared to the 32-bit addressing in IPv4. Its deployment strategy is designed to not have any flag days or other dependencies. IPv6 is designed to run well on high performance networks (for example, extreme-Ethernet, OC-12, ATM, and so on.) and at the same time still be efficient for low-bandwidth networks (such as wireless). In addition, it provides a platform for new Internet functionality that will be required in the near future.

IPv6 includes a transition mechanism, which is designed to allow users to adopt and deploy IPv6 in a highly diffuse fashion and to provide direct interoperability between IPv4 and IPv6 hosts. The IPv6 transition allows the users to upgrade their hosts to IPv6, and the network operators to deploy IPv6 in routers, with very little coordination between the two.

The changes from IPv4 to IPv6 fall primarily into the following categories.

- Expanded routing and addressing capabilities

- Usage of anycast address

- Header format simplification

- Improved support for options

- Quality-of-service capabilities

- Authentication and privacy capabilities

##

4.1 IPv6 Commands

The list of CLI commands for the configuration of IPv6 is as follows:

- ipv6 enable

- ipv6 unicast-routing

- ipv6 address - prefix prefix-len

- ipv6 address - ipv6-prefix | prefix-length

- ipv6 - link-local address

- ipv6 - static routes

- ipv6 - neighbor

- ipv6 default - hop limit

- ipv6 nd suppress-ra

- ipv6 nd managed-config flag

- ipv6 nd other-config flag

- ipv6 hop-limit

- ipv6 nd ra-lifetime

- ipv6 nd dad attempts

- ipv6 nd reachable-time

- ipv6 nd ns - interval

- ipv6 nd ra-mtu

- ipv6 nd ra-interval

- ipv6 nd prefix

- ping ipv6

- debug ipv6

- traceroute

- clear ipv6 neighbors

- clear ipv6 traffic

- clear ipv6 route

- show ipv6 interface

- show ipv6 route

- show ipv6 route summary

- show ipv6 neighbors

- show ipv6 traffic

### 4.1.1 `ipv6 enable`

Enables IPv6 processing on an interface that has not been configured with an explicit IPv6 address. The `no` form of the command disables IPv6 processing on the interface that has not been configured with an explicit IPv6 address.

    ipv6 enable

    no ipv6 enable

Mode | Interface Configuration
Defaults | Disabled.
Example | SEFOS(config-if)# ipv6 enable
Notes | IPv6 is enabled on the default VLAN interface.

#### Related Commands

- ipv6 address - prefix prefix-len - Configures IPv6 address on the interface

- show ipv6 interface - Displays the IPv6 interfaces

- ipv6 router rip / ipv6 router rip - name - Enables RIP6 and enters into the router configuration mode

### 4.1.2 `ipv6 unicast-routing`

Enables unicast routing. The `no` form of the command disables unicast routing.

    ipv6 unicast-routing

    no ipv6 unicast-routing

Mode | Global Configuration
Defaults | Enabled.
Example | SEFOS(config)# ipv6 unicast-routing

#### Related Commands

- ipv6 router rip / ipv6 router rip - name - Enables RIP6 and enters into the router configuration mode

### 4.1.3 `ipv6 address -` prefix prefix-len

Configures IPv6 address on the interface. The `no` form of the command deletes the configured IPv6 address.

    ipv6 address prefix prefix-len [{unicast | anycast | eui64}]

    no ipv6 address prefix prefix-len [{unicast | anycast | eui64}]

Syntax Description | prefix - IPv6 prefix for the interface. prefix-len - IPv6 prefix length. unicast - Unicast type of prefix. anycast - Anycast type of prefix. eui64 - Type of prefix where the latter 64 bits are formed from the link layer address.
Mode | Interface Configuration
Defaults | `unicast`
Example | SEFOS(config-if)# ipv6 address 3333::1111 64 unicast
Notes | The prefix length for eui64 type must be 64.

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

### 4.1.4 `ipv6 address -` ipv6-prefix`|` prefix-length

Configures IPv6 address on the interface.

    ipv6 address {ipv6-prefix | prefix_length} [{unicast | anycast | eui-64 | link-local}]

Syntax Description | ipv6-prefix - IPv6 prefix for the interface. prefix-length - IPv6 prefix length. unicast - Unicast type of prefix. anycast - Anycast type of prefix. eui64 - Type of Prefix where the latter 64 bits are formed from the link layer address. link-local - Link local type prefix.
Mode | Interface Configuration
Defaults | `unicast`
Example | SEFOS(config-if)# ipv6 address 3333::1111/64 unicast
Notes | The prefix length for `eui64` type must be 64.

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

### 4.1.5 `ipv6 - link-local address`

Configures the IPv6 link-local address on the interface. The `no` form of the command deletes the configured IPv6 link-local address.

    ipv6 address prefix link-local

    no ipv6 address prefix link-local

Syntax Description | prefix - IPv6 Prefix for the interface. link-local - Type of address.
Mode | Interface Configuration
Example | SEFOS(config-if)# ipv6 address fe80::2222 link-local
Notes | The prefix specified must be a valid `link-local` prefix.

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

### 4.1.6 `ipv6 - static routes`

Configures static routes. The `no` form of the command deletes the configured static routes.

    ipv6 route prefix prefix-len ([next-hop] {[vlan vlan-id]}) [administrative-distance] [unicast]

    no ipv6 route prefix prefix-len ([nex-hop] {[vlan vlan-id]}) [administrative-distance] [unicast]

Syntax Description | prefix - IPv6 prefix of the destination. prefix-len - Destination prefix length. next-hop - IPv6 prefix of the next hop that is used to reach the destination network. vlan - VLAN identifier. administrative-distance - Metric to reach the destination. unicast - Unicast type of prefix.
Mode | Global Configuration
Defaults | administrative-distance - 1 unicast
Example | SEFOS(config)# ipv6 route 2111::1111 64 3111::1111
Notes | A route will be configured only when a proper route exists for the next-hop prefix in the route table.

#### Related Commands

- ipv6 - link-local address - Configures the IPv6 link-local address on the interface

- show ipv6 route - Displays the IPv6 routes

### 4.1.7 `ipv6 - neighbor`

Configures a static entry in the IPv6 neighbor cache table. The `no` form of the command removes the static entry from the IPv6 neighbor cache table.

    ipv6 neighbor prefix {vlan vlan-id} mac-address

    no ipv6 neighbor prefix {vlan vlan-id} mac-address

Syntax Description | prefix - IPv6 prefix of the neighbor vlan - VLAN identifier mac-address - Link layer address of the interface
Mode | Global Configuration
Example | SEFOS(config)# ipv6 neighbor 3333::1111 vlan 1 00:11:22:33:44:55

#### Related Commands

- show ipv6 neighbors - Displays the IPv6 neighbor cache entries

### 4.1.8 `ipv6 default - hop limit`

Defaults hop limit for IPv6 datagrams. The `no` form of command resets default hop limit for IPv6 datagrams.

    ipv6 default-hop limit hop-limit_1-255

    no ipv6 default-hop limit

Mode | Global Configuration
Example | SEFOS(config)# ipv6 default-hop limit 100

`ipv6 nd suppress-ra`

Suppresses IPv6 router advertisement. The `no` form of the command enables IPv6 router advertisement.

    ipv6 nd suppress-ra

    no ipv6 nd suppress-ra

Mode | Interface Configuration
Defaults | Router advertisements are suppressed.
Example | SEFOS(config-if)# ipv6 nd suppress-ra

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

- show ipv6 traffic - Displays the IPv6 ICMP and UDP statistics

### 4.1.9 `ipv6 nd suppress-ra`

Suppresses IPv6 router advertisement. The `no` form of the command enables IPv6 router advertisement.

    ipv6 nd suppress-ra

    no ipv6 nd suppress-ra

Mode | Interface Configuration
Defaults | Router advertisements are suppressed.
Example | SEFOS(config-if)# ipv6 nd suppress-ra

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

- show ipv6 traffic - Displays the IPv6 ICMP and UDP statistics

### 4.1.10 `ipv6 nd managed-config flag`

Sets the `managed-config flag` which allows the host to use DHCP for address configuration. The `no` form of the command resets the `managed-config flag` which in turn does not allow the host to use DHCP for address configuration.

    ipv6 nd managed-config flag

    no ipv6 nd managed-config flag

Mode | Interface Configuration
Example | SEFOS(config-if)# ipv6 nd managed-config flag

#### Related Commands

- `no` ipv6 nd suppress-ra - Enables IPv6 router advertisement

### 4.1.11 `ipv6 nd other-config flag`

Sets the `other-config flag`, which allows the host to use DHCP for other stateful configuration. The `no` form of the command resets the `other-config flag`, which in turn does not allow the host to use DHCP for other stateful configuration.

    ipv6 nd other-config flag

    no ipv6 nd other-config flag

Mode | Interface Configuration
Example | SEFOS(config-if)# ipv6 nd other-config flag

#### Related Commands

- `no` ipv6 nd suppress-ra - Enables IPv6 router advertisement

### 4.1.12 `ipv6 hop-limit`

Configures the maximum hoplimit for all IPv6 packets originating from the interface and the configured hop limit is also used in router advertisement packet current hop limit field. The `no` form of the command resets the hop limit to the default value for all IPv6 packets originating from the interface and also the value in the router advertisement packet current hop limit field is reset to the default value.

    ipv6 hop-limito-limit_0-255

    no ipv6 hop-limit

Mode | Interface Configuration
Defaults | 64
Example | SEFOS(config-if)# ipv6 hop-limit 100

### 4.1.13 `ipv6 nd ra-lifetime`

Sets the IPv6 router advertisement lifetime.

    ipv6 nd ra-lifetime seconds_0-9000

Mode | Interface Configuration
Defaults | 1800 seconds.
Example | SEFOS(config-if)# ipv6 nd ra-lifetime 1000
Notes | The ND RA lifetime value must be greater than or equal to the RA interval.

#### Related Commands

- `no` ipv6 nd suppress-ra - Enables IPv6 router advertisement

- show ipv6 interface - Displays the IPv6 interfaces

### 4.1.14 `ipv6 nd dad attempts`

Sets the number of duplicate address detection attempts. The `no` form of the command resets the duplicate address detection attempts to its default value.

    ipv6 nd dad attempts number-of-attempts_1-10

    no ipv6 nd dad attempts

Mode | Interface Configuration
Defaults | 1
Example | SEFOS(config-if)# ipv6 nd dad attempts 5

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

- `no` ipv6 nd suppress-ra - Enables IPv6 router advertisement

### 4.1.15 `ipv6 nd reachable-time`

Sets the advertised reachability time. The `no` form of the command resets the advertised reachability time to default value.

    ipv6 nd reachable-time seconds_0-3600 | msec miliseconds_0-3600000

    no ipv6 nd reachable-time

Mode | Interface Configuration
Defaults | 30
Example | SEFOS(config-if)# ipv6 nd reachable-time 500

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

- no ipv6 nd suppress-ra - Enables IPv6 router advertisement

### 4.1.16 `ipv6 nd ns - interval`

Sets the advertised retransmission time. The `no` form of the command resets the advertised retransmission time to default value.

    ipv6 nd ns-interval retranmission-time-miliseconds_1000-3600000

    no ipv6 nd ns-interval

Mode | Interface Configuration
Example | SEFOS(config-if)# ipv6 nd ns-interval 1000

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

### 4.1.17 `ipv6 nd ra-mtu`

Sets router advertisement MTU optional value. The value ranges between 1280 and 1500. The `no` form of command resets the router advertisement MTU option value to the default value.

    ipv6 nd ra-mtu router-advertisement-MTU

    no ipv6 nd ra-mtu

Mode | Interface Configuration
Example | SEFOS(config-if)# ipv6 nd ra-mtu 1400

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

### 4.1.18 `ipv6 nd ra-interval`

Sets the IPv6 router advertisement interval. The `no` form of the command resets the IPv6 Router Advertisement interval to its default value.

    ipv6 nd ra-interval maximum-interval-seconds_4-1800 [minimum-interval-seconds_3-1350]

    no ipv6 nd ra-interval

Syntax Description | minimum-interval-seconds_3-1350 - Minimum router advertisement interval time in seconds. maximum-interval-seconds_4-1800 - Maximum router advertisement interval time in seconds.
Mode | Interface Configuration
Defaults | 600 seconds.
Example | SEFOS(config-if)# ipv6 nd ra-interval 200

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

- `no` ipv6 nd suppress-ra - Enables IPv6 router advertisement

### 4.1.19 `ipv6 nd prefix`

Configures the prefix to be advertised in IPv6 router advertisement. The `no` form of the command removes the prefix from the IPv6 router advertisement.

    ipv6 nd prefix {prefix-addr prefix-len | default} [{{valid-lifetime> | infinite | at var-valid-lifetime} {preferred-lifetime | infinite | at var-preferred-lifetime} | no-advertise}] [off-link] [no-autoconfig]

    no ipv6 nd prefix {prefix-addr prefix-len | default}

Syntax Description | prefix-addr - IPv6 prefix to be advertised. prefix-len - Length of the configured prefix. default - Changes the default value of the rest of the parameters. valid-lifetime - Sets the valid lifetime value for the prefix. infinite - Sets the infinite valid lifetime value for the prefix. at - Sets the variable valid lifetime value for the prefix. preferred-lifetime - Sets the preferred lifetime value for the prefix. infinite - Sets the infinite Preferred lifetime value for the prefix. at - Sets the variable valid lifetime value for the prefix. no-advertise - Sets the No-Advertise flag. off-link - Sets the off-link flag. no-autoconfig - Sets the no-autoconfig flag.
Mode | Interface Configuration
Defaults | RA valid-lifetime - 25,9200 seconds. RA preferred-lifetime - 60,4800 seconds.
Example | SEFOS(config-if)# ipv6 nd prefix 3333::1111 64 500 400
Notes | valid-lifetime must be greater than or equal to preferred-lifetime.

#### Related Commands

- show ipv6 interface - Displays the IPv6 interfaces

### 4.1.20 `ping ipv6`

Sends IPv6 echo messages.

    ping ipv6 prefix [data hex-str] [repeat count] [size value] [anycast] [source {vlan vlan-id | source-prefix}] [timeout seconds_1-100]

Syntax Description | prefix - IPv6 Destination prefix. data - Data to be sent in ping message. repeat - Number of ping messages. size - Size of the ping message. anycast - Type of prefix. source - Source interface of the `ping` message can be as follows: vlan source-prefix timeout - Duration to wait for the reply.
Mode | Privileged EXEC
Defaults | data - a5a5 repeat count - 5 size - 100 bytes. timeout - 5 seconds.
Example | SEFOS# ping ipv6 3333::1111 data a6b6

### 4.1.21 `debug ipv6`

Enables IPv6 trace. The `no` form of the command disables IPv6 trace.

    debug ipv6 {IP6 | ICMP | UDP6 | ND | PING6}

    no debug ipv6

Syntax Description | IP6 - IP6 trace. ICMP - ICMP trace. UDP6 - UDP6 trace. ND - Neighbor discovery trace. PING6 - PING6 trace.
Mode | Privileged EXEC
Defaults | Disabled.
Example | SEFOS# debug ipv6 IP6

### 4.1.22 `traceroute`

Traces route to the destination.

    traceroute [ipv6 prefix]

Syntax Description | ipv6 - IPv6 destination prefix.
Mode | Privileged EXEC
Example | SEFOS# traceroute ipv6 4444::1111

### 4.1.23 `clear ipv6 neighbors`

Removes all the entries in the IPv6 neighbor table.

    clear ipv6 neighbors

Mode | Privileged EXEC
Example | SEFOS# clear ipv6 neighbors

#### Related Commands

- show ipv6 neighbors - Displays the IPv6 Neighbor Cache Entries

### 4.1.24 `clear ipv6 traffic`

Removes all the entries in the IPv6 traffic table.

    clear ipv6 traffic

Mode | Privileged EXEC
Example | SEFOS# clear ipv6 traffic

#### Related Commands

- show ipv6 traffic - Displays the IPv6 ICMP and UDP statistics

### 4.1.25 `clear ipv6 route`

Removes all the entries in IPv6 route table.

    clear ipv6 route

Mode | Privileged EXEC
Example | SEFOS# clear ipv6 route

#### Related Commands

- show ipv6 route - Displays the IPv6 routes

### 4.1.26 `show ipv6 interface`

Displays the IPv6 interfaces.

    show ipv6 interface [{vlan vlan-id}[prefix]]

Syntax Description | vlan - VLAN identifier. prefix - Prefix information.
Mode | Privileged EXEC
Example | SEFOS# show ipv6 interface vlan 1 prefix Codes: A - Address , P - Prefix-Advertisement D - Default , N - Not Advertised
| AD 2222:: 64 [LA] Valid lifetime 2592000 , Preferred lifetime 604800
| AD 2223:1:2:3:: 64 [LA] Valid lifetime 2592000 , Preferred lifetime 604800
| P 3333:: 64 [LA] Valid lifetime 700 , Preferred lifetime 600
| PD 3334:: 64 [LA] Valid lifetime 2592000 , Preferred lifetime 604800
| PN 3335:: 64 [] Valid lifetime 2592000 , Preferred lifetime 604800
| SEFOS# show ipv6 interface vlan1 is up, line protocol is up IPv6 is Enabled
| Link local address: fe80::201:2ff:fe03:405 Global unicast address(es):
| Not Configured. Joined group address(es): ff02::1
| ff02::2 ff02::1:ff03:405
| MTU is 1500 ICMP redirects are enabled
| ND DAD is enabled, Number of DAD attempts: 1 ND router advertisement is enabled

#### Related Commands

- ipv6 enable - Enables IPv6 processing on an interface that has not been configured with an explicit IPv6 address

- ipv6 address - prefix prefix-len / ipv6 address - ipv6-prefix | prefix-length - Configures IPv6 address on the interface

- ipv6 - link-local address - Configures the IPv6 link-local address on the interface

- `no` ipv6 nd suppress-ra - Enables IPv6 router advertisement

- ipv6 nd ra-lifetime - Sets the IPv6 router advertisement lifetime

- ipv6 nd dad attempts - Sets duplicate address detection attempts

- ipv6 nd reachable-time - Sets the advertised reachability time

- ipv6 nd ra-interval - Sets the IPv6 router advertisement interval

- ipv6 nd prefix - Configures the prefix to be advertised in IPv6 router advertisement

### 4.1.27 `show ipv6 route`

Displays the IPv6 routes.

    show ipv6 route

Mode | Privileged EXEC
Example | SEFOS# show ipv6 route IPv6 Routing Table - 4 entries Codes : C - Connected, S - Static O - OSPF, R - RIP, B - BGP C 2222::/64 [1/1] via ::, vlan1 C 2223:1:2:3::/64 [1/1] via ::, vlan1 S 4444::/64 [1/20] via 2222::2222, vlan1 S 4445::/64 [1/20] via 2222::2222, vlan1

#### Related Commands

- ipv6 - static routes - Configures static routes

### 4.1.28 `show ipv6 route summary`

Displays the summary of IPv6 routes.

    show ipv6 route summary

Mode | Privileged EXEC
Example | SEFOS# show ipv6 route summary IPv6 Routing Table Summary - 4 entries 2 Connected, 2 Static, 0 RIP, 0 BGP, 0 OSPF Number of prefixes: /64: 4

#### Related Commands

- show ipv6 route - Displays the IPv6 routes

### 4.1.29 `show ipv6 neighbors`

Displays the IPv6 neighbour cache entries.

    show ipv6 neighbors

Mode | Privileged EXEC
Example | SEFOS# show ipv6 neighbors IPv6 Address Age Link-layer Addr State Interface 5555::1111 58 00:11:22:33:44:55 Static vlan1 5556::1111 58 11:22:33:44:55:66 Static vlan1

#### Related Commands

- ipv6 - neighbor - Configures a static entry in the IPv6 neighbor cache table

### 4.1.30 `show ipv6 traffic`

Displays the IPv6 ICMP and UDP statistics.

    show ipv6 traffic [interface {vlan vlan-id | tunnel tunnel-id | interface-type if-num}] [hc]

Syntax Description | vlan-id - Vlan identifier. tunnel-id - Tunnel identifier. interface-type - Interface type. interface-id - Interface identifier. hc - High counters (64-bit).
Mode | Privileged EXEC
Example | SEFOS# show ipv6 traffic IPv6 Statistics *************** 0 Rcvd 0 HdrErrors 0 TooBigErrors 0 AddrErrors 0 FwdDgrams 0 UnknownProtos 0 Discards 0 Delivers 1 OutRequests 0 OutDiscards 0 OutNoRoutes 0 ReasmReqds 0 ReasmOKs 0 ReasmFails 0 FragOKs 0 FragFails 0 FragCreates 0 RcvdMCastPkt 1 SentMcastPkts 0 TruncatedPkts 0 RcvdRedirects 0 SentRedirects
| 0 InOctets 0 InNoRoutes 0 OutFwdDatgrms 0 OutFrgRqds 1 OutTrnsmit 64 OutOctets 0 InMcstOctets 24 OutMcastOctets 0 InBcstPkts 0 OutBcstPkts 0 DiscntTime 1000 RefrshRate ICMP Statistics ***************
| Received : 0 ICMPPkts 0 ICMPErrPkt 0 DestUnreach 0 TimeExcds 0 ParmProbs 0 PktTooBigMsg 0 ICMPEchoReq 0 ICMPEchoReps 0 RouterSols 0 RouterAdv 0 NeighSols 0 NeighAdv 0 Redirects 0 AdminProhib 0 ICMPBadCode Sent : 0 ICMPMsgs 0 ICMPErrMsgs 0 DstUnReach 0 TimeExcds 0 ParmProbs 0 PktTooBigs 0 EchoReq 0 EchoReply 0 RouterSols 0 RouterAdv 1 NeighSols 0 NeighborAdv 0 RedirectMsgs 0 AdminProhibMsgs
| UDP statistics ************** Received : 0 UDPDgrams 1 UDPNoPorts 0 UDPErrPkts Sent : 0 UDPDgrams
| SEFOS# show ipv6 traffic interface vlan 1 IPv6 Statistics for interface vlan1 ------------------------------------- 0 Rcvd 0 InOctets 0 HdrErrors 0 InNoRoutes 0 AddrErrors 0 UnknownProtos 0 TruncatedPkts 0 FwdDatagrms 0 ReasmReqds 0 ReasmOKs 0 ReasmFails 0 Discards 0 Delivers 0 OutRequests 0 OutFwdDgrms 0 OutDiscards 0 FragReqds 0 FragOKs 0 FragFails 0 FragCreates 0 OutTrnsmits 0 OutOctets 0 InMcstPkts 0 InMcstOctets 0 OutMcstPkts 0 OutMcstOctets 0 InBcstPkts 0 OutBcstPkts 0 DiscntTime 1000 RefrshRate
| SEFOS# show ipv6 traffic hc IPv6 Statistics *************** 0 InRcvs 0 InOctets 0 InFwdDgrms 0 InDelivers 2 OutRequests 0 OutFwdDgrms 2 OutTrnsmits 128 OutOctets 0 InMcstPkts 0 InMcstOctets 2 OutMcstPkts 48 OutMcstOctets 0 InBcast 0 OutBcast UDP statistics ************** 0 HC InDatagrams 0 HC OutDatagrams

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