Полезные ссылки

Блоги:
http://prosto-seti.blogspot.com 
http://internetworklabs.blogspot.com/
http://blog.ioshints.info/
http://dbenda.blogspot.ru Блог по VOIP

Тематический сайт на русском:

http://faq-cisco.ru/

Недокументированные команды Cisco:

http://www.elemental.net/~lf/undoc/

TCP/IP:

TCP/IP крупным планом

Формат кадров Ethernet:
http://www.olifer.co.uk/new_rus/CN-4ed/aditions/Ethernet-frame-formats.html
http://habrahabr.ru/post/227729/ 

MST:
http://habrahabr.ru/post/128172/ 
Understanding MSTP 
Configuring Multiple Spanning Tree
MST Migration Guide  
http://blog.internetworkexpert.com/2008/07/27/mstp-tutorial-part-i-inside-a-region/ 
http://blog.ine.com/2008/09/24/mstp-tutorial-part-ii-outside-a-region/

Фрагментация пакетов:

Resolve IP Fragmentation, MTU, MSS, and PMTUD Issues with GRE and IPSEC 

Фрагментация пакетов и бит DF
Статья от Ivan Pepelnjak The Never-Ending Story of IP Fragmentation

IPSec:
Stateful Failover for IPSec
Configuring a Virtual Tunnel Interface with IP Security

VoIP + IPSec:

Voice and Video Enabled IPSec VPN Solution Overview

Voice and Video Enabled IPSec VPN (V3PN) Solution Reference Network Design

V3PN: Redundancy and Load Sharing Design Guide  

IKEv2 (RFC 5996)

VoIP:

Cisco Unified CallManager Express Solution Reference Network Design Guide

Enterprise QoS Solution Reference Network Design Guide
High-Density Packet Voice Digital Signal Processor Modules 
Связь между телефонными станциями через сеть передачи данных
 
VSS:

VSS-enbled campus best practice configuration example

VSS Failiure Scenarios. Dual-active recovery.
Migrate Standalone Cisco Catalyst 6500 Switch to Cisco Catalyst 6500 Virtual Switching System

Hardware:

Circuit Emulation over IP Network Modules

Registered jack
Cisco Gigabit Ethernet Transceiver Modules Compatibility Matrix
How To Cross Over Fiber Cables   

Stateful NAT + Firewall
NAT Stateful Failover for Asymmetric Outside-to-Inside and ALG Support--Stateful NAT Phase 2

Tools:

DSP Calculator

Cisco Type 7 Passwords Decryption

Правильный TFTP Server 

Работа с конфигами

Cisco Product Advisor

Cisco SNMP Object Navigator

Security 

http://habrahabr.ru/post/130921/ 

VRF& EVN

http://packetlife.net/blog/2009/apr/30/intro-vrf-lite/

http://packetlife.net/blog/2010/mar/29/inter-vrf-routing-vrf-lite/

http://www.cisco.com/en/US/docs/ios-xml/ios/evn/configuration/xe-3s/evn-xe-3s-book.pdf

ACL

http://www.cisco.com/en/US/tech/tk648/tk361/technologies_white_paper09186a00801afc76.shtml

RFC
Special-Use IPv4 Addresses

HP ProCurve Switches -- Defining Find, Fix, and Inform Events

HP ProCurve Switches -- Defining Find, Fix, and Inform Events

Справочник по IOS
Обозначения образа ОС Cisco IOS