What I don't know, is why is it that SS7, the telephone routing protocol, can do some of the things that are required, like load sharing across unequal paths, for example. Does anyone have any insight into this?
I *believe* one main difference is that telco sig is connection oriented whereas IP is pretty much collectionless (interesting comparison to netflow switching though); hence telephony switching protocols can afford to wait tenths of seconds finding a route whereas this would not be an acceptable per packet switching overhead. Another is that signalling between switches is carried out-of-band (i.e. is not itself affected by line congestion) which is the bane of many routing protocols. Also note that esp on intl circuits there is still manual preening activity. (prepares flame-suit for telco interconnect guru attack) Alex Bligh Xara Networks