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FearlessRabbitt
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BGP route failover is too slow. Any way around this?

Thu Aug 09, 2012 12:57 pm

Hi all,

I have two BGP sessions connecting my RB1200 to two ISP providers. There are two default static routes with same metrics, pointing to two different ISP gateways.

Now, instantaneous route failover in case one ISP is down would be easy if I didnt have BGP enabled. Considering I do, BGP takes care of routing, assigning the attributes and failing from one peer to another. Sounds great in theory, but in real-life this failover is disturbingly slow due to BGP design. When one of the links goes down, I feel it takes ages until BGP understands the session is down, and switches routing to another peer. Last time is kept session as "established" even though there was no connectivity to that ISP at all!

Is there anything I could do to ensure instantaneous failover, without disabling BGP altogether?

Thank you all in advance!
 
vk7zms
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BGP route failover is too slow. Any way around this?

Thu Aug 09, 2012 1:44 pm

If you get really lucky your ISP's may support Bidirectional Forwarding Detection (which Mikrotik has recently added support for)
 
FearlessRabbitt
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Re: BGP route failover is too slow. Any way around this?

Thu Aug 09, 2012 3:01 pm

Thank you for your reply, highly appreciated. Any resource I can learn more about its practical values? I`d rather skip wiki-style general material.
 
vk7zms
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BGP route failover is too slow. Any way around this?

Thu Aug 09, 2012 3:25 pm

There are some reasonable Cisco resources available online that explain its operation - i suggest you ask your ISP's if the support it first though :)
 
changeip
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Re: BGP route failover is too slow. Any way around this?

Thu Aug 09, 2012 7:00 pm

Read about hold-time. If you lower it you will improve that. You should also ask the other side to match your setting.
 
vk7zms
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BGP route failover is too slow. Any way around this?

Fri Aug 10, 2012 2:15 am

Of you drop your BGP hold time down, be sure to set up some sort of prioritisation on BGP traffic. BGP sessions will often disconnect when link is saturated if hold times are set too low
 
FearlessRabbitt
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Re: BGP route failover is too slow. Any way around this?

Fri Aug 10, 2012 10:13 am

Thank you for your comments guys, I will look more into it asap!

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