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 …

Header and Payload Compression

1. Header Compression (RTP,TCP) Header compression works by creating a context on both sides of a connection for each TCP/RTP data stream. The context contains header information for the stream so that data doesn’t need to be sent with every packet. For RTP, you can also send full headers periodically …

SPD – Selective Packet Discard

SPD is a feature that allows prioritisation of the Input Queue. Normally, the Input Queue only allows FIFO scheduling. With SPD enabled, 2 additional queues are created, the SPD Headroom and the SPD Extended Headroom. Layer 2 keepalives and IGP packets are allowed to be enqueued in any of the …

QoS 101

1. Congestion, Delay, Jitter Congestion occurs when there is more traffic to be sent than the interface can physically send. Depending on the configuration, packets that are waiting to be sent can be dropped or queued. Dropping is no good because the information is lost (UDP) or it may require …

CAR 101

1. Committed Access Rate CAR can be enabled per interface to limit the incoming and outgoing traffic. CAR can perform classification, marking and policing. 1.1 Configuring CAR 1.2. Filtering If no FILTER is used, the rate-limiting parameters are applied to all incoming or outgoing traffic. You can use FILTERS to …

Switching QoS

The following considerations are based on the Cisco 3560 platform. 1. Enabling QoS By default, QoS is disabled on a switch. You can enable it with: Once QoS is enabled, all incoming packets are assigned a QoS label for internal processing. This QoS label is used for Classification and is …

SNMP and RMON 101

1. SNMP Basics SNMP requires a SNMP Manager (usually a NMS – Network Management System) that sends SNMP requests (get or set) and a SNMP Agent (usually running on the managed device – router, switch) that responds to these requests. The SNMP Agent listens for requests on UDP port 161. …

Logging 101

1. Configuring Logging Logging messages generated by the router are sent to the logging process. It controls the distribution of the messages to various destinations. If the logging process is off, then only the console receives log messages. To enable logging, use: Without this command only the console will receive …