Cisco 10GBASE SFP+ Modules

Product Overview

The Cisco 10GBASE SFP+ modules (Figure 1) offer customers a wide variety of 10 Gigabit Ethernet connectivity options for data center, enterprise wiring closet, and service provider transport applications.

Figure 1. Cisco 10GBASE SFP+ Modules

Features and Benefits

Main features of Cisco 10GBASE SFP+ modules include:

• Smallest 10G form factor

• Supports 10GBASE Ethernet

• Hot-swappable input/output device that plugs into an Ethernet SFP+ port of a Cisco switch

• Provides flexibility of interface choice

• Supports "pay-as-you-populate" model

• Supports digital optical monitoring capability

• Supports the Cisco quality identification (ID) feature that enables a Cisco switch to identify whether the module is certified and tested by Cisco

• Optical interoperability with 10G BASE XENPAK, 10G ESR-HH-8FE-TX, and 10GBASE XFP interfaces on the same link

Stability Features of IGRP Protocol

IGRP provides a number of features that are designed to enhance its stability.These include hold downs,split horizons,and poison-reverse updates.Hold downs are used to prevent regular update messages from inappropriately reinstating a route that might have gone bad.When a router goes down, neighboring routers detect this via the lack of regularly scheduled update messages.These routers then calculate new routes and send routing update messages to inform their neighbors of the router change. This activity begins a wave of triggered updates that filter through the network.These triggered updates do not instantly arrive at every network device.Thus,it is possible for a device that has yet to be informed of a network failure to send a regular update message,which advertises a failed route as being valid to a device that has just been notified of the network failure.In this case, the latter device would contain (and  potentially advertise)incorrect routing information. Hold downs tell routers to hold down any changes that might affect routes for some period of time. The holddown period usually is calculated to be just greater than the period of time necessary to update the entire network with a routing change.

Split horizons derive from the premise that it is never useful to send information about a route back in the direction from which it came.illustrates the split-horizon rule.Router 1(R1)advertises that it has a route to Network A.There is no reason for Router 2 (R2) to include this route in its update back to R1 because R1 is closer to Network A.The split-horizon rule says that R2 should strike this route from any updates that it sends to R1.The split-horizon rule helps prevent routing loops.Consider,for example, the case in which R1’s interface to Network A goes down. Without split horizons, R2 continues to inform R1 that it can get to Network A (through R1).If R1 does not have sufficient intelligence,it actually might pick up R2’s route as an alternative to its failed direct connection,causing a routing loop.Although holddowns should prevent this,split horizons are implemented in IGRP because they provide extra algorithm stability.Split horizons should prevent routing loops between adjacent routers,but poison-reverse updates are necessary to defeat larger routing loops.Increases in routing metrics generally indicate routing loops.

Poison-reverse updates then are sent to remove the route and place it in holddown. In Cisco’s implementation of IGRP, poison-reverse updates are sent if a route metric has increased by a factor of 1.1 or greater

Timers

IGRP maintains a number of timers and variables containing time intervals.These include an update
timer,an invalid timer,a hold-time period,and a flush timer.The update timer specifies how frequently routing update messages should be sent.The IGRP default for this variable is 90 seconds.The invalid timer specifies how long a router should wait in the absence of routing-update messages about a specific route before declaring that route invalid.The IGRP default for this variable is three times the update period.The hold-time variable specifies the hold down period.The IGRP default for this variable is three times the update timer period plus 10 seconds.Finally,the flush timer indicates how much time should pass before a route should be flushed from the routing table.The IGRP default is seven times the routing update period

IGRP Protocol Characteristics

IGRP is a distance vector Interior Gateway Protocol (IGP). Distance vector routing protocols mathematically compare routes using some measurement of distance. This measurement is known as the distance vector. Routers using a distance vector protocol must send all or a portion of their routing table in a routing-update message at regular intervals to each of their neighboring routers. As routing information proliferates through the network, routers can identify new destinations as they are added to the network, learn of failures in the network, and, most importantly, calculate distances to all known destinations.

Distance vector routing protocols are often contrasted with link-state routing protocols, which send local connection information to all nodes in the inter network. For a discussion of Open Shortest Path First (OSPF) and Intermediate System-to-Intermediate System (IS-IS), two popular link-state routing algorithms, see (A7984A) “Open Shortest Path First,” , “Open System Interconnection Routing Protocol,” respectively.
IGRP uses a composite metric that is calculated by factoring weighted mathematical values for internetwork delay, bandwidth, reliability, and load. Network administrators can set the weighting factors for each of these metrics, although great care should be taken before any default values are manipulated. IGRP provides a wide range for its metrics. Reliability and load, for example, can take on any value between 1 and 255; bandwidth can take on values reflecting speeds from 1200 bps to 10 Gbps, while delay can take on any value from 1 to 224. These wide metric ranges are further complemented by a series of user-definable constants that enable a network administrator to influence route selection.

These constants are hashed against the metrics, and each other, in an algorithm that yields a single,composite metric. Thus, the network administrator can influence route selection by giving higher or lower weighting to specific metrics. This flexibility allows administrators to fine-tune IGRP’s automatic route selection.

To provide additional flexibility, IGRP permits multipath routing. Dual equal-bandwidth lines can run a single stream of traffic in round-robin fashion, with automatic switchover to the second line if one line goes down. Multiple paths can have unequal metrics yet still be valid multipath routes. For example, if one path is three times better than another path (its metric is three times lower), the better path will be used three times as often. Only routes with metrics that are within a certain range or variance of the best route are used as multiple paths. Variance is another value that can be established by the network
administrator.

Guidelines for Cisco Unified IP Conference Station 7936

Guidelines for Best Performance

Follow these guidelines to ensure optimum performance with the IP Conference Station 7936 and the external microphones. See the “Conference Room Setup Examples” section on page 16 for an illustration of proper equipment placement for different conference room configurations. 

• The recommended room conditions include closed offices and conference rooms up to 20 feet x 20 feet (without external microphones) and 20 feet x 30 feet (with external microphones) without major glass and/or ceramic surface. 

• Place the IP Conference Station 7936 base on a flat surface and make sure that it is clear from any reflective surfaces.

• Maintain a minimum distance of 4 feet between each external microphone and the IP Conference Station 7936(A7985A) base and other objects.
• Make sure that all microphones are acoustically unobstructed.
• Position the external microphones toward the areas that need to be covered, and so that the main pickup direction is pointed away from the IP Conference Station 7936 base.
• Seat all conference participants the same distance from the IP Conference Station 7936.
• Speak at normal conversation levels and direct your voice toward the IP Conference Station 7936.
• Do not move or handle the IP Conference Station 7936 base or the external microphones while on a call.
• Minimize background noise from air conditioning units, fans, or other equipment in the office or conference room.
• Do not shuffle papers near the IP Conference Station 7936.

SSL Services Module

This module offloads processor-intensive tasks related to securing traffic with Secure Sockets Layer (SSL), increases the number of secure connections supported by a web site,and reduces the operational complexity of high performance web server farms.

• Ensures high availability when installed in a redundant Cisco Catalyst 6500 (LDA2409) configuration, maintaining SSL sessions if hardware failures occur.

• Simplifies security management while encrypting user data to the web servers,  providing privacy, confidentiality, and  authentication using a wide range of certificates, including Netscape and VeriSign. 

• An integrated Content Switching Module or external load-balancing appliance can load balance secure HTTPS content requests to multiple Cisco SSL services modules, maximizing SSL termination performance and providing SSL scalability.

• Provides the best price/performance ratio of any SSL accelerator on the market. Cost of maintenance is included in the maintenance contract of the Cisco Catalyst chassis, providing cost savings on annual service contracts.And  by offloading the processing-intensive SSL termination burden from the web servers, the SSL Service Module eliminates the need to purchase additional servers

What is a VPN?

A VPN,or Virtual Private Network,is a connection between two endpoints—a VPN Router, for instance—in different networks that allows private data to be sent securely over a shared or public network, such as the Internet. This establishes a private network that can send data securely between these two locations ornetworks.
This is done by creating a “tunnel”.A VPN tunnel connects the two PCs or networks and allows data to be transmitted over the Internet as if it were still within those networks.Not a literal tunnel, it is a connection secured by encrypting the data sent between the two networks.VPN was created as a cost-effective alternative to using a private,dedicated,leased line for a private network.Using industry standard encryption and authentication techniques—IPSec,short for IP Security—the VPN creates a secure connection that, in effect, operates as if you were directly connected to your local network. Virtual Private Networking can be used to create secure networks linking a central office with branch offices,telecommuters, and/or professionals on the road (travelers can connect to a VPN Router using any computer with
the Linksys VPN client software.) There are two basic ways to create a VPN connection:
• VPN Router to VPN Router • Computer (using the Linksys VPN client software) to VPN Router
The VPN Router creates a “tunnel” or channel between two endpoints, so that data transmissions between them are secure. A computer with the Linksys VPN client software can be one of the two endpoints (refer to “Appendix C: Using the Linksys QuickVPN Software for Windows 2000 or XP”). If you choose not to run the VPN client software,any computer with the built-in IPSec Security Manager (Microsoft 2000 and XP) allows the VPN Router to create a VPN tunnel using IPSec (refer to “Appendix Configuring IPSec between a Windows 2000 or XP PC and the Router”).Other versions of Microsoft operating systems require additional,third-party VPN client software applications that support IPSec to be installed.

Network Topology

A wireless local area network (WLAN) is exactly like a regular local area network (LAN),except that each computer in the WLAN uses a wireless device to connect to the network.Computers in a WLAN share the same frequency channel and SSID,which is an identification name shared by the wireless devices belonging to the same wireless network.

Ad-Hoc versus Infrastructure Mode Unlike wired networks,wireless networks have two different modes in which they may be set up:infrastructure and ad-hoc. An infrastructure configuration is a WLAN and wired LAN communicating to each other through an access point.An ad-hoc(DT6409) configuration is wireless-equipped computers communicating directly with each other.Choosing between these two modes depends on whether or not the wireless network needs to share data or peripherals with a wired network or not.If the computers on the wireless network need to be accessible by a wired network or need to share a peripheral,such as a printer, with the wired network computers, the wireless network should be set up in Infrastructure mode.The basis of Infrastructure mode centers around an access point or wireless router,such as the Wireless-G VPN Broadband Router, which serves as the main point of communications in a wireless network.The Router transmits data to PCs equipped with wireless network adapters, which can roam within a certain radial range of the Router. You can arrange the Router and multiple access points to work in succession to extend the roaming range, and you can set up your wireless network to communicate with your Ethernet hardware as well.If the wireless network is relatively small and needs to share resources only with the other computers on the wireless network,then the Ad-Hoc mode can be used.Ad-Hoc mode allows computers equipped with wireless transmitters and receivers to communicate directly with each other,eliminating the need for a wireless router oraccess point.The drawback of this mode is that in Ad-Hoc mode,wireless-equipped computers are not able to communicate with computers on a wired network. And,of course, communication between the wireless equipped computers is limited by the distance and interference directly between them.