#Encore

📡 ENCOR 350-401 | Chapter 6
IP Routing Essentials

🔥 CCNA da aytilmagan KEY POINTS
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1️⃣ TERMINOLOGIYA FARQI

Path — ikki tarmoq orasidagi mavjud havolalar
Route — routing protokoli tanlagan yo'l (RIB da)

⚡️ CCNA da path = route deyiladi
ENCOR da bular FARQ QILADI


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2️⃣ RIP TIMERLAR

🕐 Update → 30s (table yuborish)
🕐 Invalid → 180s (update kelmasa → invalid)
🕐 Holddown → 180s (yomon info bloklash)
🕐 Flush → 240s (table dan o'chirish)

⚡️ Holddown nima qiladi?
Route tushgandan keyin 180s davomida
"yaxshi" yangi ma'lumotni QABUL QILMAYDI
→ Routing loop oldini oladi

⚡️ RIP da Hello YO'Q
Qo'shni o'ligini 180s kutib bilib oladi
(OSPF = 40s, EIGRP = 15s)


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3️⃣ OSPF FLOODING QACHON TUGAYDI?

Down → Init → 2-Way → Exchange → FULL

⚡️ Router "tugadi" deb bilmaydi
U LSDB ni qo'shnisi bilan TAQQOSLAYDI
Full state = LSDB bir xil = sinxron


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4️⃣ PATH SELECTION — 3 QADAM

1. Prefix Length /28 > /26 > /24
2. AD past AD → ustun
3. Metric past metric → ustun

📋 DEFAULT AD JADVALI

Connected → 0
Static → 1
eBGP → 20
EIGRP internal → 90 ✅
OSPF → 110 ✅
IS-IS → 115
RIPv2 → 120
EIGRP external → 170
iBGP → 200 ✅

⚡️ iBGP AD = 200
CCNA da o'tilmaydi
BGP iBGP path tanlasa → RIB ga AD=200
OSPF (110) uni preempt QILMAYDI


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5️⃣ ECMP vs UNEQUAL LOAD BALANCING

ECMP → barcha IGP (RIP, EIGRP, OSPF, IS-IS)
• Metric bir xil → ikkala path RIB ga
• Traffic teng taqsimlanadi

Unequal-Cost → FAQAT EIGRP
• Default o'chiq — variance bilan yoqiladi
• Metric farqli → nisbatga qarab taqsimlaydi

⚡️ show ip route — ECMP ko'rinadi
⚡️ show ip route x.x.x.x — traffic share count


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6️⃣ STATIC ROUTE — 3 TUR

Directly Attached
ip route net mask INTERFACE
→ Faqat P2P (Serial) da ishlating!

Recursive
ip route net mask NEXT-HOP-IP
→ Ethernet da xavfli — link tushsa
noto'g'ri interfeysga o'tib ketadi

Fully Specified ✅
ip route net mask INTERFACE NEXT-HOP-IP
→ Ethernet + static = HAR DOIM shu!

⚡️ Ethernet + Directly Attached = XATO
Har paket uchun ARP ishlaydi
→ CPU va xotira sarflanadi → tizim beqaror

⚡️ Ethernet + Recursive = XAVFLI
Link tushsa → RIP 180s kutadi
Static darhol noto'g'ri yo'lga o'tadi


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7️⃣ FLOATING STATIC — BACKUP TEXNIKA

ip route 10.0.0.0 255.0.0.0 10.1.1.2 10
ip route 10.0.0.0 255.0.0.0 Serial1/0 210

AD=10 → asosiy (RIB da ko'rinadi)
AD=210 → backup (asosiy tushsa faollashadi)

⚡️ AD o'zgartirish routing loop ga
olib kelishi mumkin — ehtiyot bo'ling!


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8️⃣ NULL0 — LOOP OLDINI OLISH

ip route 172.16.0.0 255.255.240.0 Null0

Aniq route (longer match) → yo'naltiriladi ✅
Aniq route yo'q → Null0 DROP ✅ (loop yo'q)

⚡️ Summary route + Null0 = standart pattern
ISP lar va enterprise da keng ishlatiladi


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9️⃣ VRF — KOMANDALAR TARTIBI

vrf definition MGMT
address-family ipv4

interface GigabitEthernet0/3
vrf forwarding MGMT
ip address 10.0.3.1 255.255.255.0

⚡️ vrf forwarding kiritilganda
IP manzil AVTOMATIK o'chadi — normal holat!
Keyin qayta yozing

⚡️ show ip route — VRF interfeyslar KO'RINMAYDI
show ip route vrf MGMT — ko'rinadi


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🔟 RIB vs FIB — ENG MUHIM FARQ

RIB (Routing Table)
• Control Plane
• RAM da saqlanadi
• Best path hisoblash
• show ip route

FIB / CEF (Forwarding Table)
• Data Plane
• TCAM — hardware darajasida
• Real paket yo'naltirish
• show ip cef

⚡️ SDN va Controller-based arxitekturada
Control Plane va Data Plane ajratish
ENCOR ning asosiy mavzularidan biri

📚 ENCOR 350-401 Official Cert Guide
2nd Edition — Chapter 6

✍️ CCIE Enterprise Infrastructure seriyasidan @cisco_server

#Encore

📡 ENCOR 350-401 | Chapter 7

📡 EIGRP — CCNA da aytilmagan KEY POINTS
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🧠 DUAL Algoritmi
EIGRP oddiy distance vector emas. DUAL
(Diffusing Update Algorithm) loop-free
backup yo'llarni oldindan hisoblaydi va
convergence ni tezlashtiradi.

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📊 FD, RD va Feasibility Condition

- FD (Feasible Distance) — router o'zi
hisoblagan to'liq path metric

- RD (Reported Distance) — qo'shni
e'lon qilgan o'z masofasi

- Feasibility Condition:
✅ RD < FD → Feasible Successor
❌ RD ≥ FD → Backup sifatida qabul
qilinmaydi (loop xavfi)

💡 RD — bu qo'shni masofasi, to'liq
path metric emas! Path metric = RD +
o'zingning link cost.

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⚖️ Unequal-Cost Load Balancing

EIGRP variance multiplier orqali har xil
metrikdagi yo'llarni bir vaqtda ishlatadi.

Variance = Feasible Successor FD ÷
Successor FD (yuqoriga yaxlitlanadi)

Feasible Successor FD < Variance qiymati
bo'lsa → RIB ga o'rnatiladi.

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🔄 Convergence: Passive vs Active

- Passive (P) → topology barqaror ✅
- Active (A) → yo'l yo'qoldi, DUAL
hisoblash boshlandi ⚙️

Feasible Successor bor → darhol
Passive ga qaytadi (hech kim bilmaydi)

Feasible Successor yo'q → Query jarayoni
boshlanadi.

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📨 Query / Reply Mexanizmi

Query kelganda router MAJBURIY javob
berishi shart. 2 ta to'g'ri javob:
1️⃣ "Bu prefix menda yo'q"
2️⃣ "Menda boshqa yo'l bor" (+ attributes)

Jim qolish = o'lim 💀

Reply Status Flag — router yuborgan har
bir query uchun, har bir qo'shni bo'yicha
alohida kuzatiladi. Barcha flag = 0
bo'lganda DUAL yakunlanadi.

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🆘 SIA — Stuck In Active

Query ga 3 daqiqada reply kelmasa →
adjacency RESET (faqat o'sha prefix emas,
BARCHA prefix lar uchun!)

1.5 daqiqada SIA-Query yuboriladi:
"Sen tiriksan, lekin nima bo'ldi?"

Hello timer ≠ SIA-Query:
- Hello → "Qo'shni tirikmi?" (adjacency)
- SIA-Query → "DUAL hisoblash
tugatdingmi?" (computation)

Router tirik bo'la turib ham javob bera
olmasligi mumkin — chunki u ham chuqurroq
birovni kutmoqda!

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📦 Classic vs Wide Metrics

Classic → delay 10μs, bandwidth kbps
❌ 11 Gbps va 50 Gbps ni ajrata olmaydi

Wide → delay pikosekund (10⁻¹²),
65,536 ga ko'paytirilgan
✅ 655 Tbps gacha masshtab

K₆ → jitter, energy kabi extended
attribute lar uchun qo'shimcha qiymat

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🗺 Route Summarization — Null0 siri

R2 summary advertise qilganda o'z
routing table iga avtomatik:
172.16.0.0/16 → Null0 ⛔️
qo'shadi.

Mavjud bo'lmagan /24 ga paket kelsa:
→ Longest Match → Null0 → DROP
→ Loop emas, Black Hole nazorat ostida

⚠️ Summarization ishlashi uchun har bir
region ga UNIQUE address blok berilishi
shart. Bir xil summary → Black Hole!

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⏱️ Timers

Fast Slow (T1↓)
Hello │ 5 sec │ 60 sec
Hold │ 15 sec │ 180 sec

Hold = Hello × 3 (default)
Hold = 0 → neighbor unreachable →
DUAL ga topology change xabari

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#EIGRP #CCNP #ENCOR #Networking

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