Tunnel Interfaces

1. Tunnel Modes A tunnel makes two distant devices appear directly connected over a logical interface. When a packet is sent out on the tunnel interface, it is encapsulated in the “carrier” protocol and sent over a physical interface.The most used carrier protocols are GRE, IP-in-IP and IPv6, and this …

More BGP

1. Route Dampening It is used to stop unstable routes from being forwarded throughout the network. When a route flaps, a penalty is assigned to the route (Default: 1000 per flap). A timer called Half-Life is used to reduce the penalty value to half (Default: 15 min). If the penalty …

Interconnecting IPv6 and IPv4

1. Dual Stack Dual Stack means running both IPv4 and IPv6 on the same interface. This doesn’t mean they are actually interconnected, just that they can both run at the same time on an interface. 2. Tunnels 2.1 Manual Tunnels 2.1.1 IPv6 in IP Tunnels IPv6 can be encapsulated in …

IPv4 101

1. Setting an IP Address Any combination of IP-ADDR and NETMASK can be used as long as the host portion of the address is not all zeros. One exception is allowed, when using a /31 mask. By default, the router will accept combinations that result in a subnet portion of …

AutoInstall

1.AutoInstall Process The autoinstall process discribed in the following paragraphs is used in autoconfiguration of a clean router (no config) over an IP network. The following flowchart best describes this process: Here are some details about the AutoInstall steps: 1.1 Assign IP Address The first step in the AutoInstall process …

Cisco CLI Tips and Tricks

1. Key shortcuts Key Combination Result Recalling Commands Ctrl+P or UP Moves backwards through command history Ctrl+N or DOWN Moves forward through command history Moving Cursor Ctrl+B or LEFT Moves 1 character to the left (Backward) Ctrl+F or RIGHT Moves 1 character to the right (Forward) ESC,B Moves 1 word …

ARP 101

1. ARP ARP is a protocol used on broadcast networks such as Ethernet, Token Ring or FDDI that is used to map L3 Addresses (like IP) to layer 2 Addresses (like Ethernet MAC). When a host needs to send traffic to another host, it knows its Layer 3 address, but …

DNS 101

1. Defining hosts and domains locally To define a static host name to address mapping, use the following command: For hosts that are accessed without a domain name at the end, (hostname.domain-name), you can define a default domain name or a list of domain names to be used, using one …

WCCP 101

WCCP support on Cisco router is a feature used to intercept traffic (usually HTTP requests) and redirect it to a cluster of content engines. This feature is mainly used for webcaching or WAAS implementations. The WCCP protocol is a control protocol used by router and Content Engines to communicate with …

RSVP 101

1. RSVP Basics RSVP (Resource Reservation Protocol) is an industry standard protocol used to implement IntServ QoS architecture. RSVP is used by the sender to request a certain QoS level from the routers along the path to the receiver. Devices along the way should be RSVP aware and they will …