Nortel has released software 220.127.116.11 for the Ethernet Routing Switch 8600 that addresses a few issues that were identified since the previous release.
Repeated SSH sessions, with CLI command logging enabled, could potentially lock up and no longer allow any other connections to the node. JDM or console access could be still available initially and further lost as well once attempting to run any output command. This problem could lead to a complete Switch Fabric card software lockup. (Q02001015)
The 10GE ports on an 8683XLR card may flap for traffic rates at or very close to line rate. (Q01860167)
SMLT/Layer 2 switching
There can be a discrepancy in the ARP tables between IST peers where one peer has invalid or duplicate ARP entries, ARP entries with a negative TTL value or ARP entries which do not appear to be aging. (Q01999818)
After an IST MLT is flapped or the IST Peer is rebooted, invalid ARP entries can get repated on the IST Peer for a MAC that is present in multiple VLANs. (Q01992234). ARP entries are found to be persistently learned on the IST-MLT link while the FDB entries for the associated MAC addresses were properly learned on the SMLT links when multiple MLT/SMLTs returned to service at about the same time causing an overlap in IST synchronization for those MLTs/SMLTs.(Q01996928)
You can find the complete release notes here.