routing

[carl_townshend]

Hi all

If I have routing set up that so that say if I have 3 routers A,B,C ,A being head office, B and C are remote, they are fully meshed, if I point a route from A to B, but then to get back to B it has to go via C, is this a loop, or will it still work ?

[gpulos]

in routing, loops are OK and one of the primary means of creating a redundant topology.

in switching/bridging, loops are NOT OK.

your fully meshed topology of routers A, B & C will work fine. your routes as stated will work fine. (taking the long way back to A may not be recommended, but it will work.)

see this link for more info on internetwork design:

http://www.cisco.com/en/US/products/ps6587/products_white_paper09186a00804f83c0.shtml

[chrihussey]

I think what your describing is asymmetrical routing, where traffic gets to a destination one way and returns another. It can happen and is not necessarily "wrong" although not always optimal.

A routing loop is more of a black hole for traffic. If you put a route in router A to go through B to get to a network at router C, and put a route in router B to go through A to get to C, this would be a loop. Traffic destined to router C from either A or B would bounce between the A & B routers.