We need to redirect internet traffic to ISP1 when ISP2 is down or overloaded.
When all work fine, LAN1 will go to ISP1 and LAN2 to ISP2
We need to allocate bandwidth for LAN1 when both LAN1 and LAN2 go one ISP.
How can we do that, how to detect that bandwidth is overloaded and to allocate bandwidth.
To cover a condition when link to one ISP goes
down and you want to redirect traffic
destines to that very ISP to ISP2 you can
just run BGP to both ISPs. As soon one link
is lost your exit point will shift to the second ISP.
Now, to be capable of making your redirection
decision based on the link load you can try
to use object tracking with IP SLA where you
can set desirable response time from the
target and change the exit point if it is not
within your requirements.
and what about bandwidth limitation? should we configure Qos, and on which router , or there is other method for doing this ?
You can configure bandwidth allocation along these lines
LAN1 = 192.168.1.0/24
LAN2 = 192.168.2.0/24
LAN1 gets 30%
LAN2 gets 40%
class-map match-any lan1
match access-group 101
class-map match-any lan2
match access-group 102
bandwidth percent 30
bandwidth percent 40
service-policy output restrict
access-list 101 permit ip 192.168.1.0 255.255.255.0 any
access-list 102 permit ip 192.168.2.0 255.255.255.0 any
Apply this to the router that connects to your ISP. Make sure that your interface accurately reflects the actual bandwidth available as this is what QOS uses.
hi my friend,
well u apply the QOS and let it monitor ur network. coz QOS policies are not applied till the time there is congestion on the interface. if enough bandwidth available it will let all data go. bt when there is a congestion it will follow the policy.
all my seniors here,correct me if i am wrong.
We won't apply qos when backup is not actif.
We'll apply it on traffic to isp1 when isp2 is down or saturated and lan2 should be redirected to isp1.
and when isp1 is down or saturated , we'll apply bandwidth limitation on traffic to isp2 and lan1 should be redirected to isp2.
From this and from your initial description of the problem it looks like simply configuring routing once and forever won't give you exactly what you expect - while routing (BGP) will detect link failures it doesn't care about congestions; on the other hand QoS care about congestions but doesn't care about routing. Have you considered (more complex) Optimized Edge Routing? It's an add-on in IOS that makes routing and IP SLA monitor to work together and dynamically adjust routing depending on network performance (rather than only availability).
Especially this looks like your scenario:
"type echo protocol ipIcmpEcho" will be used to test the reachability of ISP, won't it?
What's the command to be used for testing "link load"? how can we use it with track?
Now, if you look at the IP SLA configuration
you can see "timeout" value can be set which
indicates the amount of time to wait for a
response from its request packet. If that
response is higher than the value specified
then reachability ICMP test should fail and
trigger the client object (in our case it is
a static route). Idea I had is that during
heavy load you will have your RTT times higher
so IP SLA can catch this condition.
I would recommend for you to measure RTT
times over the backup link during normal
load and during overload conditions and then
use these values to configure IP SLA tracking.
We'd like to know the response time during congestion before configuring timeout.
We've thougth of using path-jitter or icmp-jitter for this.We'd like to send the result of "ip sla statistics" to a syslog server.
We tried using "ip sla monitor reaction-configuration" with " ip sla monitor logging traps".
We got many log from router but none concerning "ip sla".
Is there any way to follow ip sla statistics?
To get response times during congestions
just load your link with different traffic valumes and measure RTT in each scenario,
then adjust your IP SLA accordingly.
As of logging make sure your logging on that
router is configured properly in the first