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#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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