Implementation – Low Latency Queueing
CBT Nuggets Lab Example
Under interface turn on NBAR (Internet facing Serial interface)
ip nbar protocol-discovery
load-interval 60 (Default 5 min average… lower average to 60 seconds instead)
1. Class Map to match protocol HTTP (NBAR)
2. Class Map to match protocol FTP (NBAR)
3. Single Policy Map to mark traffic. (MARK_TRAFFIC)
4. For HTTP Class Map: set dscp AF21 for HTTP
5. For FTP Class Map: set dcsp AF11 for FTP
6. show policy-map to review
7. service-policy input MARK_TRAFFIC (Marking is typically done on the INBOUND interface from the source.)
8. show policy-map interface eth0 (applied interface)
1. Class Map to match DSCP AF11 and AF21 for HTTP and FTP
2. Policy Map named ‘LLQ’ class match AF11 (FTP)
Guarantee FTP bandwidth
bandwidth bitrate/percent (10 percent for FTP) (CBWFQ)
bandwidth remaining percent 10 (Look at 75 percent of interface, assign 10 percent of remaining bandwidth) You will never breach the 75 percent best practice)
class class-default fair-queue (Enable WFQ, this is now a CBWFQ setup)
For HTTP – AF21
Not just bandwidth, but priority bandwidth!
priority percent 70
On the outbound/local eth0/0 direction interface on R2:
service-policy output LLQ (Policy Map name)
Only an output feature!
class mark and police only on an inbound interface
75 percent rule applies to Serial/WAN
Eth is 65 percent (Legacy?)
max-reserved-bandwidth – change default reserved bandwidth value! be careful!
Remember that this only applies when there is congestion! Eth interface of 100Mbps, may not actually be congested. Issue is across the cloud/internet…
On the WAN interface of the exit router on R3 we need to apply QoS….
R3 Serial 0/0
priority percent 100
int Serial 0/0
service-policy output LLQ
max-reserved-bandwidth 100 (Lab!!!)
FTP will eventually die due to this configuration!
This is true end to end QoS.