You must use LACP (Link Aggregation Control Protocol) LACP is IEEE standard ,,,,,,,,,,,,,,,, And what the Nortel device model you have, I can help you to configure it
Path selection in BGP :1 weight2 local preference 3 local originator 4 as path 5 orgine 6 MED 7 EBGP or IBGP ,,,,,,,So in this question i think IBGP with higher weight will be installd in routing table Hope this help
