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Can there be two active default gateways of same cost

Unanswered Question
Aug 30th, 2001
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I have two links at my setup, ISDN and lease. Presently ISDN is configured as a backup to lease link. There are two default gateways on my router, default gateway for lease link has a higher priority than ISDN link.


Will it be possible to make both the lines work simultaneously?



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pdinapoli Sat, 09/01/2001 - 19:54
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I believe there is a way to force traffic..but it's not pretty.

Assuming the links are quite different in speed (and therefore cost) and you're using a dynamic routing protocol (EIGRP, OSPF, etc..) the protocol will almost always put all traffic on the path with the better overall metric. You can get around this with static routes and force some traffic over the slower link, but of course you then run the risk of an administrative nightmare, and if that link fails your static route is no longer valid.

SAGAR52 Sun, 09/16/2001 - 14:14
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Yes, You can use both the links and there is no rocket science involved.

Just define 2 static routes to same destination using 2 links,the process switching will automatically send packets on 2 links in round robin fashion.BUt you dont have to use then fast switching.In case you are using fast switching then this load balancing won't work.The answer to that is yo have to use CEF(Cisco express forward) switching which is the best switching available in terms of load balacing and speed.

In case you are using dynamic routing protocols then u dont need to worry like EIGRP does equal cost and both unequal cost load balancing.

The condition is that both the links are active same time or you have to define load on ur leased link sayin that is traffic goes more than x% activate ISDN .

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