Low Latency Queue (LLQ) Cheatsheet

• LLQ = CBWFQ + “priority” keyword
• You can have more than 1 queue at a time
• PQ can consume 100% bandwidth and starve low priority queue
• LLQ discard traffic when exceed configured bandwidth – Policing!

Example Configuration

R11(config)#class-map voip-class

R11(config-cmap)#match ip dscp ef

R11(config-cmap)#policy-map voip-map

R11(config-pmap)#class voip-class

R11(config-pmap-c)#priority percent 33

R11(config-pmap-c)#int fa0/0

R11(config-if)#service-policy output voip-map

Double LLQ – 2 policing in 1 queue

Example:

1 Video Conference session = 320kbps

3 G.729a voice calls = 80kbps

If you configure “priority 400”, and if you have more than 3 G.729a voice calls, it will affect the video conferencing quality as it will exceed the policed rate 400kbps.

If you have 2 separate class-maps, i.e.

R11(config-pmap)#policy-map 2llq-map

R11(config-pmap)#class voice-class

R11(config-pmap-c)#priority 80

R11(config-pmap)#class video-class

R11(config-pmap-c)#priority 320

You can’t have more than 1 video conference call or more than 3 G.729a calls as it is policed in 2 difference classes. 

PIM SM - SPT Threshold

In PIM Sparse mode, SPT Thresholds can be configured to control when to switch to the Shortest Path Tree (SPT) or Source Tree.

The command in IOS is:

ip pim spt-threshold {kbps | infinity} [group-list access-list-number] 

Default is 0kbps, which means that all sources are switched over to SPT immediately.  By switching to SPT, usually you will get the most optimal path to deliver the multicast traffic.

If you use the “infinity” keyword, the source will not be switched to SPT and remain on the shared tree.  In networks with large numbers of senders, like video surveillance cameras, you will need extra resources on routers to keep track of the increased amount of states.  Using the “infinity” keyword can force certain groups to remain on shared tree when latency is not a big issue.

Did you know 3.0

 

This is the 2008 Latest Edition

Creating Virtual Blades with Cisco WAAS and Windows Server

There is a new feature on WAAS 4.1 called Virtual Blade, which allows you to run a Windows 2008 Server on a WAVE box.

What will your people do when network is down?

Cisco WebEx Connect Demo

A new all-in-one (voice, video, team space, IM, etc) collaboration apps by Cisco WebEx.

How to setup syslog server on Linux to receive log messages from Cisco Devices

1. Setup your Cisco devices to send Cisco log to your syslog server

logging 1.2.3.4 ! where 1.2.3.4 is your Cisco log server

logging trap debug

logging on 

2. Make sure rsyslog daemon is installed on your host.  I'm using rsyslog-2.0.2-3.fc8.

3. Tell the syslog daemon to listen for messages from remote devices

vi /etc/sysconfig/rsyslog

SYSLOGD_OPTIONS="-m0 -r" 

4. Tell the rsyslog daemon to write the messages to cisco.log

vi /etc/rsyslog.conf

local7.debug    /var/log/cisco.log

Mounting ISO images

The quick way to use your ISO images without burning a CD is to mount it directly to your filesystem.

mount -t iso9660 -o ro,loop /isopath/your-iso-image.iso /mnt/iso

Ripping data-cd from a CD-ROM

You can use dd to rip an ISO image from a CD-ROM:

dd if=/dev/cdrom of=your-cd-image.iso

A Car’s Life – The first ever interactive game in Youtube

Enjoy :P