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OSPF load ballancing over differing carriers

Today we are using Dial plan-ISDN PRI as a backup through the same carrier and is not a viable backup any longer. Main links are 4 muxed t1 FR in a 7206VXR. We have Lucent VOIP trunks (Qos enabled) running through that circuit and I was looking for info on impact of diversion of Telco circuits(two t1 each) using OSPF and its possable impact on VOIP, (packet sequence mix up) and other issues/solutions I may not be aware of ...thanks!


Re: OSPF load ballancing over differing carriers

I have not come across any information that deals with your scenario. But, RTP takes care of sequencing and timing issues in VoIP environment which can solve these problems to some extent. Also Cisco devices have jitter buffers which playout voice after buffering. So I guess these mechanims will take care of out-of-sequence or delay related issues when these parameters are within the recommended limits.


Re: OSPF load ballancing over differing carriers

OSPF shouldn't impact packet ordering on the wire--the ordering of packets is going to depend on the way the router switches packets. For instance, CEF always uses a hash of the source and destination addresses to determine the right outbound interface, so even if you are load sharing traffic, it will always place the same streams on the same links, so you shouldn't get out of order packets. You could, of course, turn on per packet load sharing in cef, but this would possibly generate out of order packets.


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