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by Edgar C Francis
A Trunk link is apoint-to-pointlink between
two network devices. Trunk links carry more than one VLAN. With VLAN trunking,
we can extend our configured VLAN across the entire network. Remember,
sending information from an access link on one VLAN to another VLAN is not
possible without the additional device a router, or an external layer 2 bridge
connected between the VLAN.
A Trunk link can transport multiple VLAN traffic through a
single switch port. A trunk link is not assigned to a specific VLAN.
Types of links/ports.
Access links
Connecting to end devices (hosts or router)
Part of one VLAN
ACCESS LINK
Trunk links
Do not belong to any VLAN
It Carry multiple VLAN traffic
It’s a physical Link between two switches
TRUNK LINK
Frame tagging
In order to make sure that the same VLAN users on different
switches communicate with each other there is a method of tagging happens on
trunk links. A tag is added before a frame is sent and removed once it is
received on the trunk link. Frame tagging happens only on the trunk links.
VLAN Frame Identification
A Trunk link can transport multiple VLAN traffic; a switch
must identify frames with their respective VLANs as they are sent and received
over a trunk link.
VLAN identification can be performed usingtwo methods, each usinga different frame identification mechanism:
Inter-switch link (ISL) protocol
IEEE 802.1Q (Dot1Q) protocol
Inter-switch link (ISL) is a Cisco-proprietary method for
preserving the source VLAN identification of frame passing over the trunk link. ISL
works with Ethernet, Token ring, and FDDI. ISL adds a 26-byte header and a byte
trailer to the frame you can say its adds 30 bytes of tag. The ISL method of
VLAN identification or trunking encapsulation no longer is supported across all
Cisco catalyst switch platforms.
The IEEE 802.1Q protocol is also used to carry VLAN traffic,
dot1q is an open standard trunking protocol, it works only on Ethernet, dot1q
introduces us to the concept of Native VLAN on a trunk. The frame belongs to native
VLAN is not encapsulation and with no tag. Dot1q is only adding 4 bytes tag
will be added to the original frame just after the source address field.
Let's see the configuration:
Topology:-
GOAL:
configure VLAN 110, and VLAN 120 on both the switches
shift the ports in to their respective VLAN as per our topology
configure link between switch 1 and switch 2 as trunk link
make sure the users of same VLAN on the different switch must communicate with each other.
host 2 can communicate to host 3 both are in same VLAN 110.
host 3 can communicate with host 1 both are in same VLAN 110, but host 3 can not communicate with host 5 its also in the same VLAN 110, because there is no trunking is configure yet .
(The ISL method of VLAN identification or trunking encapsulation no longer is supported across all Cisco catalyst switch platform.)
some cisco switch do not have option of ISL. so there is no need to specify encapsulation dot.1q ,
sw1#show interfaces trunk
Port Mode Encapsulation Status Native vlan
Fa0/10 on 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/10 110-120
Port Vlans allowed and active in management domain
Fa0/10 110,120
Port Vlans in spanning tree forwarding state and not pruned
Fa0/10 110,120
sw2#show interfaces trunk
Port Mode Encapsulation Status Native vlan
Fa0/10 on 802.1q trunking 1
Port Vlans allowed on trunk
Fa0/10 110-120
Port Vlans allowed and active in management domain
Fa0/10 110,120
Port Vlans in spanning tree forwarding state and not pruned
Fa0/10 110,120
after configuring trunk between both the switch now host 3 can communicate with host 5.
Sometimes you notice a network design where you have more
than one serial link between two routers. A single serial link doesn’t
provide enough bandwidth or maybe in case you want some extra redundancy. All the
interfaces on a router need a different IP address, a design that looks like
this:
Multilink PPP allows us to make a combination of multiple
physical serial links into a single logical link or MLP bundle. MLP is used to aggregate multiple WAN links into one logical
channel for the transportation of traffic from one router to another, MLP enable the load—balancing of traffic from different links as we and allows some level of redundancy in case of line failure on a single link.MLP Supports a maximum of ten member links per bundle or single logical link.
Route reflectors (RR) are one method to eliminate the full mesh of IBGP peers in your network. The route reflector allows
all IBGP speakers within your autonomous system to learn about the available
routes without creating loops.
There are three types of peering in route reflectors:
EBGP neighbor
IBGP client neighbor
IBGP non-client neighbor
When configuring a route reflector (RR), we must tell
the router whether the other IBGP router is a client or non-client. AnIBGP client is an IBGP router that the route
reflector will “reflect” routes to, the non-client is just a regular IBGP
neighbor.
When a route reflector forwards a route update, there are a
few rules that must be followed:
A route learned from an EBGP neighbor can be forwarded to
another EBGP neighbor, a client, and a non-client.
A route learned from a client can be forwarded to another
EBGP neighbor, client or non-client.
A route learned from a non-client can be forwarded to
another EBGP neighbor and client, but not to a non-client.
In other words: Route Reflector-RR to advertise route
received from aniBGP peers
to other iBGP peers. All the valid clients update server Route Reflector-RR and
server update to all the valid clients.
Each client only establishes a neighbor relationship with
servers, clients are not allowed to establish neighbors with other clients. Route
Reflector (servers) establish neighbor relationships with other servers (if you
have more the one server) and clients.
I hope now you have an idea of what is route reflector, so let's see the configuration:
Before we start BGP configuration check out some important of BGP CCIE exam topics.
we have already learned what is route redistribution and why we need, if you don't then click here . In this section we see configuration.
R1#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 10.1.1.1 YES manual up up
Serial3/0 1.1.1.1 YES manual up up
Serial3/3 4.1.1.2 YES manual up up
Serial3/6 15.1.1.1 YES manual up up
Loopback0 11.0.0.1 YES manual up up
Loopback1 11.0.1.1 YES manual up up
Loopback2 11.0.2.1 YES manual up up
Loopback3 11.0.3.1 YES manual up up
R2#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 20.1.1.1 YES manual up up
Serial3/0 1.1.1.2 YES manual up up
Serial3/1 2.1.1.1 YES manual up up
Serial3/4 24.1.1.1 YES manual up up
Loopback0 12.0.0.1 YES manual up up
Loopback1 12.0.1.1 YES manual up up
Loopback2 12.0.2.1 YES manual up up
Loopback3 12.0.3.1 YES manual up up
v
R3#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 30.1.1.1 YES manual up up
Serial3/1 2.1.1.2 YES manual up up
Serial3/2 3.1.1.1 YES manual up up
Serial3/5 35.1.1.1 YES manual up up
Loopback0 13.0.0.1 YES manual up up
Loopback1 13.0.1.1 YES manual up up
Loopback2 13.0.2.1 YES manual up up
Loopback3 13.0.3.1 YES manual up up
R4#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 40.1.1.1 YES manual up up
Serial3/2 3.1.1.2 YES manual up up
Serial3/3 4.1.1.1 YES manual up up
Serial3/7 45.1.1.1 YES manual up up
Loopback0 14.0.0.1 YES manual up up
Loopback1 14.0.1.1 YES manual up up
Loopback2 14.0.2.1 YES manual up up
Loopback3 14.0.3.1 YES manual up up
R5#show ip interface brief
Interface IP-Address OK? Method Status Protocol
FastEthernet0/0 50.1.1.1 YES manual up up
Serial3/4 24.1.1.2 YES manual up up
Serial3/5 35.1.1.2 YES manual up up
Serial3/6 15.1.1.1 YES manual up up
Serial3/7 45.1.1.2 YES manual up up
Loopback0 150.0.0.1 YES manual up up
Loopback1 150.0.1.1 YES manual up up
Loopback2 150.0.2.1 YES manual up up
Loopback3 150.0.3.1 YES manual up up
R1(config)#router eigrp 210
R1(config-router)#network 1.0.0.0
R1(config-router)#network 10.0.0.0
R1(config-router)#no auto-summary
R1(config-router)#exit
R1(config)#router rip
R1(config-router)#version 2
R1(config-router)#network 15.0.0.0
R1(config-router)#network 11.0.0.0
R1(config-router)#no auto-summary
R1(config-router)#exit
R1(config)#router eigrp 140
R1(config-router)#network 4.0.0.0
R1(config-router)#no auto-summary
R1(config-router)#exit
R2(config)#router eigrp 210
R2(config-router)#network 1.0.0.0
R2(config-router)#network 20.0.0.0
R2(config-router)#no auto-summary
R2(config-router)#exit
R2(config)#router rip
R2(config-router)#version 2
R2(config-router)#network 12.0.0.0
R2(config-router)#network 2.0.0.0
R2(config-router)#exit
R2(config)#router ospf 11
R2(config-router)#network 25.0.0.0 0.255.255.255 area 0
R2(config-router)#exit
R3(config)#router rip
R3(config-router)#version 2
R3(config-router)#network 2.0.0.0
R3(config-router)#network 13.0.0.0
R3(config-router)#no auto-summary
R3(config-router)#exit
R3(config)#router eigrp 53
R3(config-router)#network 35.0.0.0
R3(config-router)#network 30.0.0.0
R3(config-router)#no auto-summary
R3(config-router)#exit
R3(config)#router ospf 10
R3(config-router)#network 3.0.0.0 0.255.255.255 area 0
R3(config-router)#exit
R4(config)#router ospf 10
R4(config-router)#network 3.0.0.0 0.255.255.255 a
R4(config-router)#network 3.0.0.0 0.255.255.255 area 0
R4(config-router)#exit
R4(config)#router rip
R4(config-router)#version 2
R4(config-router)#network 45.0.0.0
R4(config-router)#network 14.0.0.0
R4(config-router)#no auto-summary
R4(config-router)#exit
R4(config)#router eigrp 140
R4(config-router)#network 4.0.0.0
R4(config-router)#network 40.0.0.0
R4(config-router)#no auto-summary
R4(config-router)#exit
R5(config)#router rip
R5(config-router)#ver 2
R5(config-router)#network 45.0.0.0
R5(config-router)#no auto-summary
R5(config-router)#exit
R5(config)#router ospf 11
R5(config-router)#network 24.0.0.0 0.255.255.255 a
R5(config-router)#network 24.0.0.0 0.255.255.255 area 0
R5(config-router)#network 50.0.0.0 0.255.255.255 area 0
R5(config-router)#exit
R5(config)#router eigrp 53
R5(config-router)#network 35.0.0.0
R5(config-router)#network 150.0.0.0
R5(config-router)#no auto-summary
R5(config-router)#exit
R5(config)#router rip
R5(config-router)#version 2
R5(config-router)#network 15.0.0.0
R5(config-router)#no auto-summary
R5(config-router)#exit
R1#show ip protocols
*** IP Routing is NSF aware ***
Routing Protocol is "eigrp 210"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(210)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
NSF-aware route hold timer is 240
Router-ID: 11.0.3.1
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
1.0.0.0
10.0.0.0
Routing Information Sources:
Gateway Distance Last Update
1.1.1.2 90 00:38:42
Distance: internal 90 external 170
Routing Protocol is "rip"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Sending updates every 30 seconds, next due in 23 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Redistributing: rip
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
Serial3/6 2 2
Loopback0 2 2
Loopback1 2 2
Loopback2 2 2
Loopback3 2 2
Automatic network summarization is not in effect
Maximum path: 4
Routing for Networks:
11.0.0.0
15.0.0.0
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 120)
Routing Protocol is "eigrp 140"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(140)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
NSF-aware route hold timer is 240
Router-ID: 11.0.3.1
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
4.0.0.0
Routing Information Sources:
Gateway Distance Last Update
4.1.1.1 90 00:20:14
Distance: internal 90 external 170
R2#show ip protocols
*** IP Routing is NSF aware ***
Routing Protocol is "eigrp 210"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(210)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
NSF-aware route hold timer is 240
Router-ID: 12.0.3.1
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
1.0.0.0
20.0.0.0
Routing Information Sources:
Gateway Distance Last Update
1.1.1.1 90 00:39:50
Distance: internal 90 external 170
Routing Protocol is "rip"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Sending updates every 30 seconds, next due in 7 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Redistributing: rip
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
Serial3/1 2 2
Automatic network summarization is in effect
Maximum path: 4
Routing for Networks:
2.0.0.0
11.0.0.0
Routing Information Sources:
Gateway Distance Last Update
2.1.1.2 120 00:00:27
Distance: (default is 120)
Routing Protocol is "ospf 11"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 12.0.3.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
25.0.0.0 0.255.255.255 area 0
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 110)
R3#show ip protocols
*** IP Routing is NSF aware ***
Routing Protocol is "rip"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Sending updates every 30 seconds, next due in 11 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Redistributing: rip
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
Serial3/1 2 2
Loopback0 2 2
Loopback1 2 2
Loopback2 2 2
Loopback3 2 2
Automatic network summarization is not in effect
Maximum path: 4
Routing for Networks:
2.0.0.0
13.0.0.0
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 120)
Routing Protocol is "eigrp 53"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(53)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
NSF-aware route hold timer is 240
Router-ID: 13.0.3.1
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
30.0.0.0
35.0.0.0
Routing Information Sources:
Gateway Distance Last Update
35.1.1.2 90 00:29:09
Distance: internal 90 external 170
Routing Protocol is "ospf 10"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 13.0.3.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
3.0.0.0 0.255.255.255 area 0
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 110)
R4#show ip protocols
*** IP Routing is NSF aware ***
Routing Protocol is "ospf 10"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 14.0.3.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
3.0.0.0 0.255.255.255 area 0
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 110)
Routing Protocol is "rip"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Sending updates every 30 seconds, next due in 28 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Redistributing: rip
Default version control: send version 2, receive version 2
Interface Send Recv Triggered RIP Key-chain
Serial3/7 2 2
Loopback0 2 2
Loopback1 2 2
Loopback2 2 2
Loopback3 2 2
Automatic network summarization is not in effect
Maximum path: 4
Routing for Networks:
14.0.0.0
45.0.0.0
Routing Information Sources:
Gateway Distance Last Update
45.1.1.2 120 00:00:11
Distance: (default is 120)
Routing Protocol is "eigrp 140"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(140)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
NSF-aware route hold timer is 240
Router-ID: 14.0.3.1
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
4.0.0.0
40.0.0.0
Routing Information Sources:
Gateway Distance Last Update
Distance: internal 90 external 170
R5#show ip protocols
*** IP Routing is NSF aware ***
Routing Protocol is "ospf 11"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Router ID 150.0.3.1
Number of areas in this router is 1. 1 normal 0 stub 0 nssa
Maximum path: 4
Routing for Networks:
24.0.0.0 0.255.255.255 area 0
50.0.0.0 0.255.255.255 area 0
Routing Information Sources:
Gateway Distance Last Update
Distance: (default is 110)
Routing Protocol is "eigrp 53"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Default networks flagged in outgoing updates
Default networks accepted from incoming updates
EIGRP-IPv4 Protocol for AS(53)
Metric weight K1=1, K2=0, K3=1, K4=0, K5=0
NSF-aware route hold timer is 240
Router-ID: 150.0.3.1
Topology : 0 (base)
Active Timer: 3 min
Distance: internal 90 external 170
Maximum path: 4
Maximum hopcount 100
Maximum metric variance 1
Automatic Summarization: disabled
Maximum path: 4
Routing for Networks:
35.0.0.0
150.0.0.0
Routing Information Sources:
Gateway Distance Last Update
35.1.1.1 90 00:30:12
Distance: internal 90 external 170
Routing Protocol is "rip"
Outgoing update filter list for all interfaces is not set
Incoming update filter list for all interfaces is not set
Sending updates every 30 seconds, next due in 20 seconds
Invalid after 180 seconds, hold down 180, flushed after 240
Redistributing: rip
Default version control: send version 2, receive version 2
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