Networking

In this scenario we have two internet line and separate the user group for internet using. I want to setup  NET_G1 group use internet line 1 and NET_G2 group use internet line 2. At NET_G1 sale and MKT department are included and at NET_G2 HR and IT are included. First step create the vrf. R1/R4/R5 ip vrf NET_G1 ip vrf NET_G2 Second step -set the interfaces belong to vrf. R1 ip vrf NET_G1 ip vrf NET_G2 int f0/0 ip vrf forwarding NET_G1 ip add 10.10.10.2 255.255.255.252 description Internet 1 no sh int f1/0 no sh ip vrf forwading NET_G2 ip add 172.16.12.2 255.255.255.252 description Internet 2 no sh int f2/0 no sh int f2/0.10 encapsulation dot1q 10 ip vrf for NET_G1 ip add 192.168.14.1 255.255.255.252 int f2/0.20 encapsulation dot1q 20 ip vrf for NET_G2 ip add 192.168.14.1 255.255.255.252 int f3/0 no sh int f3/0.10 encapsulation dot1q 10 ip vrf for NET_G1 ip add 192.168.15.1 255.255.255.252 int f3/0.20 encapsulation dot1q 20 ip

VRF (Virtual Routing and Forwarding) is like a logical router, no need to require many router for different routing or different customers.VRF are most commonly associated MPLS service providers. Deployment without MPLS is know as VRF lite.In this topology we configure the VRF Lite. Let see, we have two customer Green and Yellow are using our network service.They have same network prefixes. As we know router don't accept same network prefixes but Vrf can solve that problem. First step we need to create vrf. R1 ip vrf GREEN ip vrf YELLOW R2 ip vrf GREEN ip vrf YELLOW R3 ip vrf GREEN ip vrf YELLOW Each routed interface (virtual or physical) belongs to exactly one VRF.  For vrf GREEN R2 int lo0 ip vrf forwarding GREEN ip add 192.168.1.1 255.255.255.0 int f0/0.1 encapsulation dot1q 10 ip vrf forwarding GREEN ip add 10.10.12.2 255.255.255.252 R1 int f0/0.1  encapsulation dot1Q 10  ip vrf forwarding GREEN  ip address 10.10.12.1 255.255.255.252 int

In this scenario I want to filter 192.168.3.x /25 , /26, /27 networks form R1 route update. I can use access list but I need to set the rules for every network. In prefix list it will easy to filter. R2(config-router)#do sh ip bgp BGP table version is 8, local router ID is 2.2.2.2 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,               r RIB-failure, S Stale Origin codes: i - IGP, e - EGP, ? - incomplete    Network          Next Hop            Metric LocPrf Weight Path *> 192.168.1.0      10.10.10.1               0             0 1 i *> 192.168.2.0      10.10.10.1               0             0 1 i *> 192.168.3.0/25   10.10.10.1               0             0 1 i *> 192.168.3.128/26 10.10.10.1               0             0 1 i *> 192.168.3.192/27 10.10.10.1               0             0 1 i *> 192.168.4.0/25   10.10.10.1               0             0 1 i *> 192.168.4.128/26 10.10.10.1               0   

In this scenario R1 connect R2 with different bandwidth line. If we can't change EIGRP 'k' values, bandwidth and delay on the existing interfaces and only involve EIGRP, offset list is the way to solve this cause. Now R1 know only one route to 3.3.3.0/24 network. R1#sh ip route eigrp      3.0.0.0/24 is subnetted, 1 subnets D       3.3.3.0 [90/3142400] via 10.10.12.2, 00:48:21, Serial0/0      10.0.0.0/24 is subnetted, 3 subnets D       10.10.23.0 [90/3014400] via 10.10.12.2, 00:53:18, Serial0/0 We see R1 have only one path to 3.3/14 network. Now I will set offset list on R2. First I need to check R1 metric value for 3.3.3.0/24 network. R1#sh ip eigrp top IP-EIGRP Topology Table for AS(123)/ID(1.1.1.1) Codes: P - Passive, A - Active, U - Update, Q - Query, R - Reply,        r - reply Status, s - sia Status P 1.1.1.0/24, 1 successors, FD is 128256         via Connected, Loopback0 P 3.3.3.0/24, 1 successors, FD is 3142400         via 10.10.12.2 ( 3142400/ 15616

At BGP best path selection algorithm the weight attribute is first. The default weight for learned routes is 0 and the default weight for a locally originated route is 32768. Weight attribute is preferred large number weight. Only effect on outgoing traffic.   Figure 1.1 In this scenario by default R1 will choose AS200 to reach AS500. We want to use AS300 path to reach to AS500. So let play with weight. We have  two options using to Weight Set the weight attribute on the neighbor (That will affect all routes learn from that neighbor) Using Route map can specific routes to have the weight set. Configuration Weight attribute on neighbor R1 router bgp 140  no synchronization  bgp log-neighbor-changes  network 1.1.1.0 mask 255.255.255.0  neighbor 10.1.12.2 remote-as 200  neighbor 10.1.14.4 remote-as 140  neighbor 10.1.14.4 next-hop-self  neighbor 10.1.14.4 weight 100  no auto-summary R2  router bgp 200  no synchronization  bgp log-neighbor-changes  neig

Never redistribute BGP to IGP on internet facing router. It look like you try to put space ship in your house.

The LOCAL_PREF attribute affects only traffic leaving the AS. To influence incoming traffic, the MULTI_EXIT_DISC attribute, known as the MED for short, is used.

Figure 1.1 In this scenario I use OSPF for TCP reachability. We can see the difference 'disable connected' check and 'EBGP multihop'. We can use both for EBGP neighbor connection with loopback address. Disable connected check This command used to disable the connection verification process for ebgp. Use for ebgp neighbor are directly connected and they using the loopback address for peering. It not increment TTL but neighbor must reachable at single hop. EBGP multihop This command can use for ebgp neighbor are not directly connected. It increment TTL. R1 router bgp 100  neighbor 2.2.2.2 remote-as 200  neighbor 2.2.2.2 disable-connected-check  neighbor 2.2.2.2 update-source Loopback0  neighbor 3.3.3.3 remote-as 300  neighbor 3.3.3.3 ebgp-multihop 2  neighbor 3.3.3.3 update-source Loopback0 R2 router bgp 200  neighbor 1.1.1.1 remote-as 100  neighbor 1.1.1.1 disable-connected-check  neighbor 1.1.1.1 update-source Loopback0 R3

Figure 1.1 R1 router bgp 65000  bgp cluster-id 10  neighbor 2.2.2.2 remote-as 65000  neighbor 2.2.2.2 update-source Loopback0  neighbor 2.2.2.2 route-reflector-client  neighbor 3.3.3.3 remote-as 65000  neighbor 3.3.3.3 update-source Loopback0  neighbor 3.3.3.3 route-reflector-client R2 router bgp 65000  bgp cluster-id 20  net 22.22.22.0 mask 255.255.255.0  neighbor 1.1.1.1 remote-as 65000  neighbor 1.1.1.1 update-source Loopback0  neighbor 4.4.4.4 remote-as 65000  neighbor 4.4.4.4 update-source Loopback0  neighbor 4.4.4.4 route-reflector-client R3 router bgp 65000  bgp cluster-id 30  net 33.33.33.0 mask 255.255.255.0  neighbor 1.1.1.1 remote-as 65000  neighbor 1.1.1.1 update-source Loopback0  neighbor 5.5.5.5 remote-as 65000  neighbor 5.5.5.5 update-source Loopback0  neighbor 5.5.5.5 route-reflector-client R4 router bgp 65000  network 44.44.44.0 mask 255.255.255.0  neighbor 2.2.2.2 remote-as 65000  neighbor 2.2.2.2 update-source

Figure 1.1 In this topology, I will use static route to connect the R1 and R2 networks. Static route can use the outgoing interface or next hop address, also can combine that two configure. R1 ip route 192.168.2.0 255.255.255.128 10.1.13.3 ip route 192.168.2.128 255.255.255.128 10.1.13.3 R2 ip route 192.168.1.0 255.255.255.0 10.1.23.3 R3 ip route 192.168.1.0 255.255.255.0 10.1.13.1 ip route 192.168.2.0 255.255.255.0 f1/0 At R3 we can use summary route for 192.168.2.0/25 and 192.168.2.128/25. R1#sh ip route      10.0.0.0/24 is subnetted, 2 subnets C       10.1.13.0 is directly connected, FastEthernet1/0 C       10.1.12.0 is directly connected, FastEthernet0/0 C    192.168.1.0/24 is directly connected, Loopback0      192.168.2.0/25 is subnetted, 2 subnets S       192.168.2.0 [1/0] via 10.1.13.3 S       192.168.2.128 [1/0] via 10.1.13.3 R1#ping 192.168.2.1 source lo0        Type escape sequence to abort. Sending 5, 100-byte ICMP Echos t