Network Operations ေလ့က်င့္ခန္းမ်ား (အပုိင္း ၂)

ေလ့က်င့္ခန္း (၂) Add a static route on a router (အလြယ္ ၁)
ကြန္ပ်ဴတာ ၂ လုံးနဲ.၊ Router ၂ ခု ပါတဲ့ Network တစ္ခုကုိ ဒီေလ့က်င္းခန္းမ်ားမွာ သုံးသြားပါမယ္။
pcA -- e0 (RouterA) e1 ----- e0 (RouterB) e1 --- pcB

pcA = 192.168.10.10/24 , pcB = 192.168.30.10/24
RouterA e0 = 192.168.10.1/24 , RouterA e1 = 192.168.20.1/24
RouterB e0 = 192.168.20.2/24 , RouterB e0 = 192.168.30.1/24

pcA နဲ. pcB တုိ. ဆက္သြယ္လုိ.ရေအာင္ RouterA နဲ. RouterB မွာ static route ကုိ ေအာက္ပါအတုိင္း configure လုပ္ရပါမယ္။

RouterB(config)#ip route 192.168.10.0 255.255.255.0 192.168.20.1

RouterA(config)#ip route 192.168.30.0 255.255.255.0 192.168.20.2
RouterA(config)#^z
RouterA#ping 192.168.30.10
Type escape sequence to abort. 
Sending 5, 100-byte ICMP Echos to 192.168.30.10, timeout is 2 seconds: 
!!!!! 
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/18/20 ms
RouterA#
RouterA#show ip arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  192.168.20.2          2   00a0.6900.85f3  ARPA   Ethernet0

ေလ့က်င့္ခန္း (၃) Add a static route on a router (အလြယ္ ၂)
static route ကုိ neihgbor router ရဲ. IP address ကုိ သုံးမဲ့အစား local interface ကုိ သုံးရင္လည္းရပါတယ္။
RouterA ရဲ. ARP entry မွာ တစ္ခုတုိးလာတာကုိ သတိျပဳေစခ်င္ပါတယ္။

RouterA ရဲ.အျမင္မွာ pcA နဲ. RouterB တုိ. MAC Address (hardware address) တူေနပါတယ္။
တနည္းေျပာရရင္ RouterB က သူ.ကုိယ္ပုိင္ MAC Address ကုိသုံးျပီး ARP request ေတြကုိ ျပန္ေျဖေနလုိ.ပါ။
အေပၚက ေလ့က်င့္ခန္း (၂) မွာ RouterA ဟာ pcB ကုိ ARP entry ထဲမွာ မျမင္ရပါဘူး။
ဒါဘာေၾကာင့္ျဖစ္ရတဲ့ အေၾကာင္းရင္း ၂ ခုရွိပါတယ္။
၁၊ RouterA က static route ကုိ Local Interface ကုိ ညြန္းထားတယ္၊
၂၊ RouterB ရဲ. e0 မွာ proxy-arp ကုိ enable လုပ္ထားတယ္၊ (this is by default)

RouterA(config)#no ip route 192.168.30.0 255.255.255.0 192.168.20.2
RouterA(config)#ip route 192.168.30.0 255.255.255.0 e1

RouterA#
RouterA#ping 192.168.30.10
Type escape sequence to abort. 
Sending 5, 100-byte ICMP Echos to 192.168.30.10, timeout is 2 seconds: 
!!!!! 
Success rate is 100 percent (5/5), round-trip min/avg/max = 16/18/20 ms
RouterA#
RouterA#show ip arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  192.168.20.2          2   00a0.6900.85f3  ARPA   Ethernet0
Internet  192.168.30.10         2   00a0.6900.85f3  ARPA   Ethernet0

ေလ့က်င့္ခန္း (၄) Disabling proxy-arp (အလြယ္ ၁)
RouterB မွာ Proxy-arp ကုိ disable လုပ္လုိက္ရင္ RouterA ကေန pcB ကုိ ping လုပ္လုိ. ရေတာ့မွာ မဟုတ္ပါဘူး။ RouterA ရဲ့ ARP table မွာ pcB ရဲ. entry ေပ်ာက္သြားတာကုိလဲ ေတြ.ရပါလိမ့္မယ္။

static route ကုိသုံးရင္ တတ္ႏုိင္သေလာက္ next hop IP address ကုိဘဲ သုံးပါ။ local interface ကုိမသုံးပါနဲ.။

RouterB(config)#int e0
RouterB(conf-if)#no ip proxy-arp

RouterA#
RouterA#ping 192.168.30.10
Type escape sequence to abort. 
Sending 5, 100-byte ICMP Echos to 192.168.30.10, timeout is 2 seconds: 
..... 
Success rate is 0 percent (0/5) 

RouterA#
RouterA#show ip arp
Protocol  Address          Age (min)  Hardware Addr   Type   Interface
Internet  192.168.20.2          2   00a0.6900.85f3  ARPA   Ethernet0
Internet  192.168.30.10         0   Incomplete      ARPA