11: ipv6 routing table and static routes rick graziani cabrillo college [email protected]

11: IPv6 Routing Table and Static Routes

Rick GrazianiCabrillo College

[email protected]

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For more information please check out my Cisco Press book and video series:

IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6• By Rick Graziani• ISBN-10: 1-58714-313-5

IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6• By Rick Graziani• ISBN-10: 1-58720-457-6

11.1: Enabling the IPv6 Router

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Routers versus IPv6 Routers

• A router (not enabled as an IPv6 router):• Configure IPv6 addresses• Member of All-IPv6 devices multicast group

• An IPv6 router:• Same as a non-IPv6 router• Member of All-IPv6 routers multicast group• Sends ICMPv6 Router Advertisement messages• Can enable IPv6 routing protocols• Forward IPv6 packets (transiting the router)

Router IPv6 Router

2001:DB8:CAFE:1::1/64FE80::1

2001:DB8:CAFE:1::1/64FE80::1

FF02::1 (All-IPv6 devices) FF02::1 (All-IPv6 devices)FF02::2 (All-IPv6 routers)

ICMPv6 Router Advertisement

Forward IPv6 Packets

RIPng OSPFv3 EIGRP for IPv6

Router(config)# ipv6 unicast-routing

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Non-IPv6 Enabled Router

• Unlike IPv4, a router must be configured to be an “IPv6 router”.• You can configure IPv6 addresses, but not IPv6 routing protocols.

R1(config)# interface gigabitEthernet 0/0R1(config-if)# ipv6 address 2001:db8:cafe:1::1/64R1(config-if)# ipv6 address fe80::1 link-localR1(config-if)# no shutdownR1(config-if)# exitR1(config)# ipv6 router eigrp 1% IPv6 routing not enabledR1(config)#

R1

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Non-IPv6 Enabled RouterR1# show ipv6 interface gig 0/0GigabitEthernet0/0 is up, line protocol is up IPv6 is enabled, link-local address is FE80::1 No Virtual link-local address(es): Global unicast address(es): 2001:DB8:CAFE:1::1, subnet is 2001:DB8:CAFE:1::/64 Joined group address(es): FF02::1 FF02::1:FF00:1<output to be continued>

• IPv6 Routers are part of the All-IPv6 routers multicast group (FF02::2)

All-IPv6 devices on this linkMember of these Multicast Groups

Solicited-node multicast addresses (GUA and link-local)

No FF02::2 All-IPv6 routers

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Non-IPv6 Enabled RouterR1# show ipv6 interface gig 0/0<output continued> MTU is 1500 bytes ICMP error messages limited to one every 100 milliseconds ICMP redirects are enabled ICMP unreachables are sent ND DAD is enabled, number of DAD attempts: 1 ND reachable time is 30000 milliseconds (using 30000) ND NS retransmit interval is 1000 millisecondsR1#

• IPv6 Routers send ICMPv6 Router Advertisement messages out its interfaces

No “ND router advertisements”

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ip unicast-routing Command: IPv6 Router

• ICMPv6

R1(config)# ipv6 unicast-routingR1(config)# exitR1# show ipv6 interface gig 0/0GigabitEthernet0/0 is up, line protocol is up IPv6 is enabled, link-local address is FE80::1 No Virtual link-local address(es): Global unicast address(es): 2001:DB8:CAFE:1::1, subnet is 2001:DB8:CAFE:1::/64 Joined group address(es): FF02::1 FF02::2 FF02::1:FF00:1<output to be continued>

All-IPv6 routers

Member of these Multicast Groups

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IPv6 Enabled Router

• ICMPv6

R1# show ipv6 interface gig 0/0<output continued> ICMP error messages limited to one every 100 milliseconds ICMP redirects are enabled ICMP unreachables are sent ND DAD is enabled, number of DAD attempts: 1 ND reachable time is 30000 milliseconds (using 30000) ND advertised reachable time is 0 (unspecified) ND advertised retransmit interval is 0 (unspecified) ND router advertisements are sent every 200 seconds ND router advertisements live for 1800 seconds ND advertised default router preference is Medium Hosts use stateless autoconfig for addresses.R1#

Sending ICMPv6 Router Advertisement Messages

Default: SLAAC

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IPv6 Enabled Router

• IPv6 routing protocols can now be configured!• No error message

R1(config)# ipv6 router eigrp 1 R1(config-rtr)#

11.2: IPv6 Routing Table

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• ICMPv6

R1# show ipv6 routeIPv6 Routing Table - default - 6 entriesCodes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, R - RIP, I1 - ISIS L1, I2 - ISIS L2 IA - ISIS interarea, IS - ISIS summary, D - EIGRP, EX - EIGRP external ND - ND Default, NDp - ND Prefix, DCE - Destination, NDr - Redirect O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2, a – Application

C 2001:DB8:CAFE:1::/64 [0/0] via GigabitEthernet0/0, directly connectedL 2001:DB8:CAFE:1::1/128 [0/0] via GigabitEthernet0/0, receiveL FF00::/8 [0/0] via Null0, receiveR1#

R1

2001:DB8:CAFE:1::/64Gig 0/0:1

IPv6 Routing Table

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• ICMPv6



R1

2001:DB8:CAFE:1::/64Gig 0/0:1

Connected Routes

[Administrative Distance/Metric]

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• ICMPv6



R1

2001:DB8:CAFE:1::/64Gig 0/0:1

Local Routes• Local routes are /128 routes

(host routes) for the router’s IPv6 unicast addresses.

• Allows the router to more efficiently process packets directed to the router itself rather than for packet forwarding.

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• ICMPv6



R1

2001:DB8:CAFE:1::/64Gig 0/0:1

FF00::/8 to Null0• By default multicast packets

(FF00::/8) are not forwarded.• Any ‘more specific’ multicast

packets (such as FF05::1:3 All-DHCPv6 servers) would take precedence. • ipv6 multicast-routing

would need to be configured• Link-local multicast (FF02) are

never forwarded off the link.

R1

11.3: IPv6 Static Routes and CEF

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Router(config)# ipv6 route ipv6-prefix/prefix-length {exit-intf | ipv6-address}

Parameter Descriptionipv6-prefix

• Destination IPv6 network address of the remote network to be added to the routing table.

/prefix-length

• Prefix-length of the remote network or summarized group networks to be added to the routing table.

exit-intf • Use the outgoing interface to forward packets to the destination network.

ipv6-address • Commonly referred to as the next-hop router’s IPv6 address.

Simplified IPv6 Static Route Configuration

• Similar to configuring static routes in IPv4.

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Configuring IPv6 Static Route

R2(config)# ipv6 unicast-routingR2(config)# ipv6 route 2001:db8:cafe:1::/64 2001:db8:cafe:2::1

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2

2001:DB8:CAFE:1::/64 2001:DB8:CAFE:2::/64 2001:DB8:FEED:1::/642001:DB8:FEED:2::/642001:DB8:FEED:3::/642001:DB8:FEED:4::/642001:DB8:FEED:5::/64

Static Route

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Verifying IPv6 Static Route

R2# show ipv6 route staticIPv6 Routing Table - default - 14 entriesCodes: C - Connected, L - Local, S - Static, U - Per-user Static route<output omitted>S 2001:DB8:CAFE:1::/64 [1/0] via 2001:DB8:CAFE:2::1R2#

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


Static Route

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IPv6 Static Routes

R1(config)# ipv6 unicast-routingR1(config)# ipv6 route 2001:db8:feed:1::/64 2001:db8:cafe:2::2R1(config)# ipv6 route 2001:db8:feed:2::/64 2001:db8:cafe:2::2R1(config)# ipv6 route 2001:db8:feed:3::/64 2001:db8:cafe:2::2R1(config)# ipv6 route 2001:db8:feed:4::/64 2001:db8:cafe:2::2R1(config)# ipv6 route 2001:db8:feed:5::/64 2001:db8:cafe:2::2

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


Static Routes

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IPv6 Static Routes

R1# show ipv6 route static<output omitted>S 2001:DB8:FEED:1::/64 [1/0] via 2001:DB8:CAFE:2::2S 2001:DB8:FEED:2::/64 [1/0] via 2001:DB8:CAFE:2::2S 2001:DB8:FEED:3::/64 [1/0] via 2001:DB8:CAFE:2::2S 2001:DB8:FEED:4::/64 [1/0] via 2001:DB8:CAFE:2::2S 2001:DB8:FEED:5::/64 [1/0] via 2001:DB8:CAFE:2::2

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


• Options to reduce routing table:• Summarized static route• Default static route• (coming soon)

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IPv6 Static Route Using Exit Interfaces

• IPv6 CEF (Cisco Express Forwarding) is automatically enabled when ipv6 unicast-routing is enabled.

• Because CEF takes care of any recursive lookup issues, it is best to use next-hop address instead of exit-interface.

• Next-hop addresses and exit-interfaces should still be used on broadcast networks such as Ethernet.

R2(config)# ipv6 unicast-routingR2(config)# ipv6 route 2001:db8:cafe:1::/64 serial0/0/0

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


Static Route

2001:db8:cafe:2::1

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A Note About CEF for IPv6R1# show running-config<output omitted>ip cefno ipv6 cefR1# R1# show ip cefPrefix Next Hop Interface0.0.0.0/0 no route<output omitted> R1# show ipv6 cef%IPv6 CEF not runningR1#

R1

• CEF (Cisco Express Forwarding) is a forwarding mechanism to optimize the Layer 3 and Layer 2 lookup processes into a single process.

CEF for IPv4 is enabled by defaultCEF for IPv6 is disabled by default

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Enabling CEF for IPv6R1(config)# ipv6 unicast-routingR1(config)# exitR1# show running-config<output omitted>ip cefipv6 cefR1# R1# show ipv6 cef::/0 nexthop 2001:DB8:CAFE:2::2 Serial0/0/0<output omitted>R1# config tR1(config)# ipv6 cefR1(config)

R1

• You may need to enable CEF for IPv6.

CEF IPv6 is now enabled

Prior to IOS 15.x you may need to use this command in addition to ipv6 unicast-routing

11.4: IPv6 Summary Static Routes

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Summary Static IPv6 Routes

Summarize these routes

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


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2001:0db8:feed:0001::/642001:0db8:feed:0002::/642001:0db8:feed:0003::/642001:0db8:feed:0004::/642001:0db8:feed:0005::/64

Summarizing IPv6 Routes


Step 1: Starting with left-most bits, identify where the addresses begin to differ (in red)

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Step 3: Count the left most matching bits (in red)

16 + 16 + 16 + 13 = 61 bits or /61

Note: Summary will also cover the 2001:db8:feed::/64, 2001:db8:feed:6::/64 and 2001:db8:feed:7::/64 subnets.

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2001:0db8:feed:0000000000000000::

Step 4: Add zeros after matching bits and convert Binary back to Hex

2001:0DB8:FEED:0000::/61or

2001:0DB8:FEED:0::/61or

2001:DB8:FEED::/61

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Configuring IPv6 Summary Static Route

• Remove existing routes• Configure summary route

R1(config)# no ipv6 route 2001:db8:feed:1::/64 2001:db8:cafe:2::2R1(config)# no ipv6 route 2001:db8:feed:2::/64 2001:db8:cafe:2::2R1(config)# no ipv6 route 2001:db8:feed:3::/64 2001:db8:cafe:2::2R1(config)# no ipv6 route 2001:db8:feed:4::/64 2001:db8:cafe:2::2R1(config)# no ipv6 route 2001:db8:feed:5::/64 2001:db8:cafe:2::2R1(config)# ipv6 route 2001:db8:feed::/61 2001:db8:cafe:2::2

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


Summary Route

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Verifying IPv6 Summary Static Route

R1# show ipv6 route static<output omitted>S 2001:DB8:FEED::/61 [1/0] via 2001:DB8:CAFE:2::2R1# ping 2001:db8:feed:1::1Sending 5, 100-byte ICMP Echos to 2001:DB8:FEED:1::1, timeout is 2

seconds:!!!!!R1#

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


Summary Route

11.5: IPv6 Default Static Route

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Router(config)# ipv6 route ::/0 {exit-intf | ipv6-address}

IPv6 Static Default Route

• Similar to configuring default route in IPv4.

:: “all zeroes” prefix “zero” prefix-length

Router(config)# ip route 0.0.0.0 0.0.0.0 {exit-intf | ipv4-add}

IPv4 default static route

IPv6 default static route

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Configuring IPv6 Default Static Routes

• Remove existing summary route• Configure default route

R1(config)# no ipv6 route 2001:db8:feed::/61 2001:db8:cafe:2::2R1(config)# ipv6 route ::/0 2001:db8:cafe:2::2

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


Default Route

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Verifying IPv6 Default Static Routes

R1# show ipv6 route static<output omitted>S ::/0 [1/0] via 2001:DB8:CAFE:2::2R1# ping 2001:db8:feed:1::1Sending 5, 100-byte ICMP Echos to 2001:DB8:FEED:1::1, timeout is 2

seconds:!!!!!R1#

R1 R2G0/0

:1S0/0/0:1

S0/0/0:2


Default Route

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For more information please check out my Cisco Press book and video series:

IPv6 Fundamentals: A Straightforward Approach to Understanding IPv6• By Rick Graziani• ISBN-10: 1-58714-313-5

IPv6 Fundamentals LiveLessons: A Straightforward Approach to Understanding IPv6• By Rick Graziani• ISBN-10: 1-58720-457-6

11: IPv6 Routing Table and Static Routes

Rick GrazianiCabrillo College

[email protected]

11: ipv6 routing table and static routes rick graziani cabrillo college [email protected]

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