How do routers route packets in the event a router goes down?

Question

On the network backbone I mean.

If a router goes down will the network reroute the packets around the router?

What have you done to try to answer this question yourself before asking it here? What about what you found do you need clarification on? — user, May 17 '17 at 18:07
I've tried mass tracerouting an up block to identify key routers, but I don't have the ddos capabilites to test what happens if a router goes down. Ive read lightly about routing protocols as well. — user1973385, May 17 '17 at 18:10
suggesting ddos is the preferred method of 'testing when a router goes down' is absurd. You've read lightly (at most) about all of this. — , May 17 '17 at 21:17

score 2 · Accepted Answer · answered May 17 '17 at 18:08

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In general, routers use protocols like RIP (slightly outdated) or OSPF and IS-IS (more modern) to determine the best current route to a specific network. "Best" obviously will include "is not down".

answered May 17 '17 at 18:08

PaterSiul

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score 0 · Answer 2 · answered May 17 '17 at 18:42

In addition to standard routing protocols like BGP, OSPF, IS-IS etc (as PaterSiul) mentions, there is also router-specific failover protocols like HSRP or CARP.

Using a failover protocol means that when a router fails, a different physical device assumes the failed devices address and keeps on routing.

How do routers route packets in the event a router goes down?

2 Answers2