sábado, 19 de julio de 2014
viernes, 13 de junio de 2014
CCNA v5.0 modul 2 Chapter: 6 - Static Routing
1. Introduction
Routers learn
about remote networks either dynamically, using routing protocols, or manually,
or using static routes. In many cases, routers use a combination of both
dynamic routing protocols and static routes.
Static routes do
not require the same amount of processing and overhead as dynamic routing
protocols.
CCNA: methods: Classless
Inter-Domain Routing (CIDR) and the variable-length subnet mask (VLSM).
1 1.1 Static Routing Implementation
A router can
learn about remote networks in one of two ways:
·
Manually - Remote networks are
manually entered into the route table using static routes.
·
Dynamically - Remote routes are
automatically learned using a dynamic routing protocol.
Static route =
Reach specific networks and manually configured
1 1.2 Why Use Static Routing?
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Administrative distance (AD) of a static
route is 1.
Static for small network and with only
one path to an outside network.
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1.3 When to Use Static Routes
Static routing
has three primary uses:
·
Providing ease of routing table
maintenance in smaller networks that are not expected to grow significantly.
·
Routing to and from stub
networks. A stub network is a network accessed by a single route, and the
router has only one neighbor.
·
Using a single default route to
represent a path to any network that does not have a more specific match with
another route in the routing table. Default routes are used to send traffic to
any destination beyond the next upstream router.
2 2.
Types of Static Routes
2 2.1 Static Route Applications
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Static route
are used to:
-
Connect stub networks.
-
Connect to a specific network
-
Summarize routing table entry
-
Create backup route
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CCNA: IPv4 and
IPv6 static routes:
- Standard
static
- route
Default
- static route
- Summary
static route
- Floating
static route
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2 2.2 Standard Static Route
A static route
can be used to connect to any network.
2 2.3 Default Static Route
Static route is
a route that matches all packets. A default route identifies the gateway IP
address to which the router sends all IP packets that it does not have a
learned or static route. A default static route is simply a static route with
0.0.0.0/0 as the destination IPv4 address. Configuring a default static route
creates a Gateway of Last Resort.
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Note: route for larger subnets takes preference over default static
route
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Default static
routes are used:
-
Only one other router to which
it is connected. This condition is known as a stub router.
-
Default exit: routerß--àISP (An edge router to a service provider network)
2 2.4 Summary Static Route
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To reduce the number of routing table entries,
multiple static routes can be summarized into a
single static route if:
-
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.
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2 2.5 Floating Static Route
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Floating
static routes are static routes that are used to provide a backup path to a
primary static or dynamic route, in the event of a link failure. The floating
static route is only used when the primary route is not available.
Example:
AD:95 Static route entry
AD: 90 EIGRP static route entry.
If learned route fails static route is
the backup.
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3 3. Configure Static and Default
Routes
3 3.1 ip route Command
R1(config)#ip
route network-address network-mask {ip-address | exit-interface}
3 3.2 Next-Hop Options
The next hop can
be identified by an IP address, exit interface, or both. How the destination is
specified creates one of the three following route types:
-
Next-hop route - Only the
next-hop IP address is specified.
-
Directly connected static route
- Only the router exit interface is specified.
-
Fully specified static route -
The next-hop IP address and exit interface are specified.
3 3.3 Configure a Next-Hop Static Route
Before any
packet is forwarded by a router, the routing table process must determine the
exit interface to use to forward the packet. This is known as route
resolvability. The route resolvability process will vary depending upon the
type of forwarding mechanism being used by the router. CEF (Cisco Express
Forwarding) is the default behavior on most platforms running IOS 12.0 or
later.
R1(config)#ip
route network-address network-mask ip-address
AD=1
3 3.4 Configure a Directly Connected Static Route
This method is
used to avoid the recursive lookup problem.
R1(config)#ip
route network-address network-mask exit-interface
AD=0
3 3.5 Configure a Fully Specified Static Route
In a fully
specified static route, both the output interface and the next-hop IP address
are specified. This is another type of static route that is used in older IOSs,
prior to CEF
R1(config)# ip
route 192.168.2.0 255.255.255.0 GigabitEthernet 0/1
3 3.6 Verify a Static Route
Along with ping
and traceroute, useful commands to verify static routes include:
-
show ip route
-
show ip route static
-
show ip route network
4 4. Configure IPv4 Default
Routes
4 4.1 Default Static Route (code “S”)
A default route
is a static route that matches all packets
R1(config)# ip
route 0.0.0.0 0.0.0.0 { ip-address | exit-intf }
Default static
routes are commonly used when connecting:
-
An edge router to a service
provider network
-
A stub router (a router with
only one upstream neighbor router)
5 5. Configure IPv6 Static Routes
5 5.1 The ipv6 route Command
Static routes
for IPv6 are configured using the ipv6 route global configuration command.
Router(config)#
ipv6 route ipv6-prefix/prefix-length
{ ipv6-address | exit-intf }
Most of
parameters are identical to the IPv4 version of the command. IPv6 static routes
can also be implemented as:
-
Standard IPv6 static route
Default
-
IPv6 static route Summary
-
IPv6 static route Floating
-
IPv6 static route
-
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R1(config)#ipv6 unicast-routing command
enable the router to forward IPv6 packets
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5.2 Verify IPv6 Static Routes
verify static
routes include:
show ipv6 route
show ipv6 route
static
show ipv6 route
network
5 5.3 Default Static IPv6 Route
R1(Config)# ipv6
route ::/0 { ipv6-address | exit-intf }
6 6. CIDR
Will be developed soon.
7 7. VLSM
Will be developed soon.
CCNA v5.0 modul 2 Chapter: 5 - Inter-VLAN Routing
1. Inter-VLAN Routing
1.1 Whats is Inter-VLAN Routing?
Process of forwarding network traffic from
one VLAN to another VLAN using routing is known as inter-VLAN routing. L3
operation that can to done in tree way form.
1.2 Inter-Vlan routing Type:
·
Legacy: A router with many interfaces each interface own a VLAN ID and the
router takes the task to forwarding frame to VLAN ID destination.
·
Router-on-stick: Switch connected to a
router with only one interface configured as trunk. The router performs
inter-VLAN routing by accepting VLAN-tagged traffic. The internal routing is
accomplished using subinterfaces. (Software-based virtual interfaces).
·
Multilayer-switch: Multilayer switches
can perform Layer 2 and Layer 3 functions, replacing the need for dedicated routers.
Multilayer switches support dynamic routing and inter-VLAN routing.
2. Configure Legacy Inter-VLAN Routing
2.1 switch configuration
Each of its physical interfaces connected:
-
Unique VLAN
-
And IP address for the subnet
associated with the particular VLAN to which it is connected.
Devices use the interface IP as a gateway
to access the devices connected to the other VLANs.
The routing process requires the source
device to determine if the destination device is local or remote to the local
subnet. Done by comparing the source and
destination IP addresses against the subnet.
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S1(config)#vlan 10
S1(config-vlan)#vlan 30
S1(config-vlan)#interface f0/11
S1(config-if)#switchport access vlan 10
S1(config-if)#interface f0/4
S1(config-if)#switchport access vlan 10
S1(config-if)#interface f0/6
S1(config-if)#switchport access vlan 30
S1(config-if)#interface f0/5
S1(config-if)#switchport access vlan 30
S1(config-if)#end
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2.2 router configuration
The process is repeated for all router
interfaces. Each router interface must be assigned to a unique subnet for
routing to occur.
After
the IP addresses are assigned to the physical interfaces and the interfaces
are enabled, the router is capable of performing inter-VLAN
Routing table using the show ip route.
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R1(config)#interface g0/0
R1(config-if)#ip address 172.17.10.1
255.255.255.0
R1(config-if)#no shutdown
R1(config)#interface g0/1
R1(config)#ip address 172.17.30.1
255.255.255.0
R1(config)#no shutdown
R1(config)#end
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3. Configure Router-on-a-Stick
Inter-VLAN Routing
3.1 Switch configuration
This technique is termed router-on-a-stick
and uses virtual subinterfaces on the router to overcome the hardware
limitations based on physical router interfaces.
Each subinterface is configured
independently with its own IP address and subnet mask.
The physical interface of the router must
be connected to a trunk link on the adjacent switch
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S1(config)#vlan 10
S1(config-vlan)#vlan 30
S1(config-vlan)#interface f0/5
S1(config-if)#switchport mode trunk
S1(config-if)#end
Note: The router does not
support the Dynamic Trunking Protocol (DTP), which is used by switches, so
the following commands cannot be used: S1(config-if)#switchport mode dynamic
auto
S1(config-if)#switchport mode dynamic
desirable.
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3.2 Configure Router-on-a-Stick: Router
Subinterface Configuration
Individual subinterfaces can be
administratively shut down with the shutdown command.
By default, Cisco routers are configured
to route traffic between local subinterfaces.
R1# show vlans
Verify:
Ping: End to end device ICMP pakets
Traceroute: Hops information path+ICMP
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R1(config)#interface g0/0.10
R1(config-subif)#encapsulation dot1q 10
R1(config-subif)#ip address 172.17.10.1
255.255.255.0
R1(config-subif)#interface g0/0.30
R1(config-subif)#encapsulation dot1q 30
R1(config-subif)#ip address 172.17.30.1
255.255.255.0
R1(config)#interface g0/0
R1(config-if)#no shutdown
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4. Troubleshoot Inter-VLAN Routing
4.1 Switch Port Issues
- Legacy:
verify the correct VLAN on all interfaces
- Router-on-a-Stick:
Verify connection between switch and router is correctly set on mode trunk.
Verify the entire path correctly setup VLAN
to reach the router final destination.
4.2 Verify Switch Configurations
S1#show interfaces interface-id switchport
S1#show running-config
Verify :
-Administrative mode:
-Access mode vlan:
4.3 Interface Issues
Verify: Physical router interface is not in
wrong switch port.
4.4 Verify Router Configurations
With router-on-a-stick configurations, a
common problem is assigning the wrong VLAN ID to the subinterface. Using the show interfaces and the show running-config commands can be
useful in troubleshooting this type of issue, as shown in the figure.
Verify correct setup: encapsulation dot1q
(correct vlan). Shows up with show
interfaces and show run
4.5 IP Addressing Issues - IP Address and
Subnet Mask
Each interface, or subinterface, must be
assigned an IP address corresponding to the subnet to which it is connected.
R1# show ip interface
5. Layer 3 switching
5.1 Introduction to Layer 3 Switching
Layer 3 switches usually have
packet-switching throughputs in the millions of packets per second (pps),
whereas traditional routers provide packet switching in the range of 100,000
pps to more than 1 million pps.
All Catalyst multilayer switches support
the following types of Layer 3 interfaces:
-
Routed port: Layer 3 port
-
Switch Virtual Interface (SVI): A
virtual VLAN interface for inter-VLAN routing
High-performance switches (Layer 3 + Cisco
Express Forwarding):
- Catalyst 6500
- Catalyst 4500
Catalyst 2960 : IOS < 12.2(55) support
Static routing.
All members of the Catalyst 3560 and 4500
families of switches use Layer 2 interfaces by default.
Members of the Catalyst 6500 family of
switches running Cisco IOS use Layer 3 interfaces by default
5.2 Inter-VLAN Routing with Switch Virtual
Interfaces
In the early days speed of switchs
prompted designer to extend layer 2 to access, distribution and core layer. This
topology created loop issues. To solve these issues, spanning-tree
technologies were used to prevent loops while still enabling flexibility and
redundancy in inter-switch connections.
Today, routing can be performed at
hardware speed. One consequence of this evolution is that routing can be
transferred to the core and the distribution layers without impacting network
performance.
Users on VLAN and on different subnets
are routed with distribution switches as Layer 3 gateways.
Every VLAN have this own IP address.
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By default, an SVI is created for the
default VLAN (VLAN 1) to permit remote switch administration
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Whenever the SVI is created, ensure that
particular VLAN is present in the VLAN database
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Reasons to configure SVI:
·
To provide a gateway for a VLAN
so that traffic can be routed into or out of that VLAN
·
To provide Layer 3 IP
connectivity to the switch
·
To support routing protocol and
bridging configurations
Advantages of SVIs (the only disadvantage
is that multilayer switches are more expensive):
·
It is much faster than
router-on-a-stick, because everything is hardware switched and routed.
·
No need for external links from
the switch to the router for routing.
·
Not limited to one link. Layer
2 EtherChannels can be used between the switches to get more bandwidth.
·
Latency is much lower, because
it does not need to leave the switch.
5.3 Inter-VLAN Routing with Routed Ports
Routed Ports and Access Ports on a Switch
Routed is a physical port that acts like
an interface in router.
Routed port is not associated with a
particular VLAN
Layer 2 functionality has been removed
(STP)
Routed ports on a Cisco IOS switch do not
support subinterfaces.
Routed ports are used for point-to-point
links.
configure routed ports:
S1(config-if)#no switchport
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Following are some of the advantages of
routed ports: A multilayer switch can
have both SVI and routed ports in a single switch. Multilayer switches forward
either Layer 2 or Layer 3 traffic in hardware, helping to perform routing
faster.
Note: Routed ports are not supported on
Catalyst 2960 Series switches.
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A Catalyst 2960 switch can function as a
Layer 3 device and route between VLANs and a limited number of static routes.
The Cisco Switch Database Manager (SDM)
provides multiple templates for the 2960 switch. The templates can be enabled
to support specific roles depending on how the switch is used in the network.
For example, the sdm lanbase-routing template can be enabled to allow the
switch to route between VLANs and to support static routing.
show sdm prefer
The SDM template can be changed in global
configuration mode with the sdm prefer
command.
Enabling routing IPv4 routing functionality
on a 2960
S1(config)#interface f0/6
S1(config-if)#switchport access vlan 2
S1(config-if)#interface vlan 1
S1(config-if)#ip address 192.168.1.1
255.255.255.0
S1(config-if)#interface vlan 2
S1(config-if)#ip address 192.168.2.1
255.255.255.0
S1(config-if)#no shutdown
IPv4:S1(config)#ip routing
IPv6:S1(config)# ipv6 unicast-routing
Verify:
Show ip route
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