static routes.pptx

IPv6 Static Routes

John RullanCisco Certified Instructor TrainerThomas A. Edison CTE HS

Stephen LynchNetwork Architect, CCIE #36243ABS Technology Architects

© 2013 Cisco and/or its affiliates. All rights reserved. Cisco Public 2

Static Routes

• Static routes defines explicit path between two routers. They are not automatically updated which means you must manually reconfigure static routes when network changes occur.

• Static routes use less bandwidth than dynamic routes.

• No CPU cycles are used to calculate and analyze routing updates.

• Static routes should be used in an environments where network traffic is predictable and where the network design is simple.

• Static routes should not be used in a large network environment where it’s constantly changing because static routes cannot react to network changes.

• Even though static routes are obsolete due to the high use of dynamic routes in a network, some companies still implement static routes for special occasions.

• Static routes are also useful for specifying a gateway of last resort (a default route which all un-routeable packets are sent).


Types of Static Routes

There are four types of static routes. The following types of IPv4 and IPv6 static routes will be discussed:

• Standard static route

• Default static route

• Summary static route

• Floating static route


Directly Connected Static Route

• You must specify only the output interface (the interface on which all packets are sent to the destination network) in a directly connected static route.

• The router assumes the destination is directly attached to the output interface.

Directly Connected

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::1/64

2001:DB8:3::1/64

S0/0/0S0/0/1 InternetS0/0/0

Branch-1

LAN-1

LAN-2

Branch-1(config)# ipv6 route 2001:DB8:2::1/64 s0/0/1Branch-1(config)# ipv6 route 2001:DB8:3::1/64 s0/0/1

Directly Connected


Directly Connected Static Route

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::1/64

2001:DB8:3::1/64Branch-1(config)# ipv6 route 2001:DB8:2::1/64 s0/0/1Branch-1(config)# ipv6 route 2001:DB8:3::1/64 s0/0/1


Branch-1

Directly Connected

LAN-1

LAN-2

Branch-1#show ipv6 route (Output Omitted)S 2001:DB8:2::/62 [1/0] via ::, Serial0/0/1S 2001:DB8:3::/62 [1/0] via ::, Serial0/0/1C 2001:DB8:A::2/127 [0/0] via ::, Serial0/0/1L 2001:DB8:A::3/128 [0/0] via ::, Serial0/0/1C 2001:DB8:B::/127 [0/0] via ::, Serial0/0/0L 2001:DB8:B::/128 [0/0] via ::, Serial0/0/0L FF00::/8 [0/0] via ::, Null0Branch-2#

“L” in the routing table is a new identifier which indicates the specific address assigned to an interface, as opposed to “C” which only displaysthe subnet.


Next Hop/Recursive Static Route• In a next-hop static route, the IPv6 address of the neighboring

router is specified.

• The output interface is derived from the next hop.

• Before any packet is forwarded by router, the routing table process must determine the exit interface to use to in order to forward the packet. This causes the router to take a second look at the routing table to determine the exit interface for the destination network.

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::1/64

2001:DB8:3::1/64


Branch-1

LAN-1

LAN-2

Next Hop/Recursive Branch-1(config)# ipv6 route 2001:DB8:2::1/64 2001:DB8:A::2 Branch-1(config)# ipv6 route 2001:DB8:3::1/64 2001:DB8:A::2


Next Hop/Recursive Static Route

Branch-1(config)# ipv6 route 2001:DB8:2::1/64 2001:DB8:A::2 Branch-1(config)# ipv6 route 2001:DB8:3::1/64 2001:DB8:A::2

Next Hop/Recursive

Branch-1#show ipv6 route (Output Omitted)S 2001:DB8:2::/64 [1/0] via 2001:DB8:A::2S 2001:DB8:3::/64 [1/0] via 2001:DB8:A::2C 2001:DB8:A::2/127 [0/0] via ::, Serial0/0/1L 2001:DB8:A::3/128 [0/0] via ::, Serial0/0/1C 2001:DB8:B::/127 [0/0] via ::, Serial0/0/0L 2001:DB8:B::/128 [0/0] via ::, Serial0/0/0L FF00::/8 [0/0] via ::, Null0Branch-2#

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::1/64

2001:DB8:3::1/64


Branch-1

LAN-1

LAN-2


Fully Specified Static Route

Branch-2

2001:DB8:A::2/64 2001:DB8:A::1/642001:DB8:2::1/64

2001:DB8:3::1/64

G0/0 G0/0 Branch-1

LAN-1

LAN-2

Branch-1(config)# ipv6 route 2001:DB8:2::1/64 g0/0 2001:DB8:A::2 Branch-1(config)# ipv6 route 2001:DB8:3::1/64 g0/0 2001:DB8:A::2 Fully Specified

• The output interface and the next-hop address are both used in a fully specify static route.

• Used when the output interface is a multi-access interface and needs the next-hop address to be identified.

• The next-hop must be directly attached to the specified output interface.

G0/0

G0/0 Branch-4

Branch-3

2001:DB8:A::4/64

2001:DB8:A::3/64

DSW-1G0/1

G0/0


Fully Specified Static Route Output

Fully Specified

Branch-1#show ipv6 route (Output Omitted)S 2001:DB8:2::1/64 [1/0] via 2001:DB8:A::2, Gigabit0/0S 2001:DB8:3::1/64 [1/0] via 2001:DB8:A::2, Gigabit0/0C 2001:DB8:A::2/127 [0/0] via ::, Serial0/0/1L 2001:DB8:A::3/128 [0/0] via ::, Serial0/0/1C 2001:DB8:B::/127 [0/0] via ::, Serial0/0/0L 2001:DB8:B::/128 [0/0] via ::, Serial0/0/0L FF00::/8 [0/0] via ::, Null0Branch-2#

Branch-2

2001:DB8:A::2/64 2001:DB8:A::1/642001:DB8:2::1/64

2001:DB8:3::1/64

G0/0 G0/0 Branch-1

LAN-1

LAN-2G0/0

G0/0 Branch-4

Branch-3

2001:DB8:A::4/64

2001:DB8:A::3/64

DSW-1G0/1

G0/0


Default Static Route

• No other routes in the routing table match the packet destination IP address. In other words, when a more specific match does not exist.

• A common use is when connecting a company's edge router to the ISP’s network.

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::1/64


Branch-1

LAN-1

LAN-2

Branch-1(config)#ipv6 route ::/0 s0/0/0Branch-1(config)#ipv6 route ::/0 2001:DB8:A::2Branch-1(config)#ipv6 route ::/0 s0/0/0 2001:DB8:A::2

2001:DB8:3::1/64


Default Static Route

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::1/64

2001:DB8:3::1/64


Branch-1

LAN-1

LAN-2

Branch-1(config)#ipv6 route ::/0 s0/0/0

Branch-1#sh ipv6 route (Output Omitted)S ::/0 [1/0] via ::, Serial0/0/0S 2001:DB8:2::1/64 [1/0] via 2001:DB8:A::2, Serial0/0/1S 2001:DB8:3::1/64 [1/0] via 2001:DB8:A::2, Serial0/0/1C 2001:DB8:A::2/127 [0/0] via ::, Serial0/0/1L 2001:DB8:A::3/128 [0/0] via ::, Serial0/0/1C 2001:DB8:B::/127 [0/0] via ::, Serial0/0/0L 2001:DB8:B::/128 [0/0] via ::, Serial0/0/0L FF00::/8 [0/0] via ::, Null0Branch-1#

Default Route


Summary Route

• Summary routes are used to reduce the number of routing table entries.

• Multiple static routes can be summarized into a single static route if:

- The destination networks are contiguous and can be summarized into a single network address.

- The multiple static routes all use the same exit interface or next-hop IP address.

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::1/64


Branch-1

LAN-1

LAN-22001:DB8:3::1/64


Summary Route

Branch-1(config)#ipv6 route 2001:DB8:2::/46 s0/0/0

Branch-1#show ipv6 route(output omitted)S ::/0 [1/0] via ::, Serial0/0/0S 2001:DB8::/46 [1/0] via ::, Serial0/0/1

2001:DB8:00000000000000102001:DB8:0000000000000011

Summarize based on common bits:• 16-bits in the 1st and 2nd hextets for a total of 32-bits• 14-bits in the 3rd hextet• Total of 46-bits in common between the two addresses

Common Bits

Branch-1# ping 2001:db8:2::1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 2001:db8:2::, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 1/10/41 msBranch-1# ping 2001:db8:3::1Type escape sequence to abort.Sending 5, 100-byte ICMP Echos to 2001:db8:3::, timeout is 2 seconds:!!!!!Success rate is 100 percent (5/5), round-trip min/avg/max = 2/9/18 msBranch-1#

Branch-2

2001:DB8:A::2/127

2001:DB8:A::3/127

2001:DB8:2::/64


Branch-1

LAN-1

LAN-22001:DB8:3::/64


Floating Static Route• A floating static route is a static route that the router uses to back up

dynamic route.

• You must configure a floating static route with a higher administrative distance than the dynamic route that it backs up.

• In this instance, the router prefers a dynamic route to a floating static route. You can use a floating static route as a replacement if the dynamic route is lost.

InternetBranch-1

Branch-2

S0/0/0

S0/0/1

S0/0/0

S0/0/1Floating Static Route

Routing Protocol

2001:DB8:A::1/127

2001:DB8:B::1/127


Floating Static Route

InternetBranch-1

Branch-2

S0/0/0

S0/0/1

S0/0/0

S0/0/1

Floating Static Route 2001:DB8:A::1/127

2001:DB8:B::1/127Routing Protocol

Branch-1(config)# ipv6 route 2001:DB8:4::1/127 s0/0/1 91Branch-1(config)# ipv6 route 2001:DB8:5::1/127 s0/0/1 91Branch-1(config)# ipv6 route 2001:DB8:6::1/127 s0/0/1 91Branch-1(config)# ipv6 route 2001:DB8:C::1/127 s0/0/1 91Branch-1(config)# ipv6 route 2001:DB8:A::1/127 s0/0/1 91

Branch-1#sh ipv6 route (output omitted)D 2001:DB8:4::/128 [90/3321856] via FE80::2E0:8FFF:FE31:4201, Serial0/0/0D 2001:DB8:5::/128 [90/3321856] via FE80::2E0:8FFF:FE31:4201, Serial0/0/0D 2001:DB8:6::/128 [90/3321856] via FE80::2E0:8FFF:FE31:4201, Serial0/0/0D 2001:DB8:B::/127 [90/3193856] via FE80::2E0:8FFF:FE31:4201, Serial0/0/0D 2001:DB8:C::/127 [90/2681856] via FE80::2E0:8FFF:FE31:4201, Serial0/0/0Branch-1#

Branch-1#show ipv6 route(output omitted)S 2001:DB8:4::/128 [91/0] via ::, Serial0/0/1S 2001:DB8:5::/128 [91/0] via ::, Serial0/0/1S 2001:DB8:6::/128 [91/0] via ::, Serial0/0/1S 2001:DB8:A::/128 [91/0] via ::, Serial0/0/1S 2001:DB8:C::/128 [91/0]Branch-1#

Thank you.

static routes.pptx

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