Dophiのブログ

    Nortel is going to release software version 25 for Alteon application switch soon. In this major release, it offers some new features and a new load balancing infrastructure with VMware. Some of them are not usually used in production infrastructure but I would like to note here. 

New Features:

1. GSLB client proximity metric: This is a new metric for GSLB calculating shortest response time between a client and each data center in layer 7. It supports only HTTP and HTTPS traffic.

2. Persistent timeout: Prior to version 24.0, Alteon supports session timeout control for virtual services and real servers only. Persistent timeout defines the aging of inactive persistent session. The timeout for aging of persistent sessions are prioritized. According to
the priority, persistent timeout is the highest followed by virtual service and real server timeout.

3. Backup preemption: By default, preempt is enabled. When the primary server becomes active it displaces the backup server and takes control.

4. Pool of PIP addresses to a port or VLAN:  More than one Proxy IP address (PIP) to a port or VLAN can be add to achieve high concurrent sessions in WAN Link Load Balancing setups.  These PIPs are selected in round robin for the incoming connections. Pooled PIP support is provided for all ports and VLAN ids from 1 to 60. A maximum of 32 proxy IP addresses can be added. This is the most useful new feature I expect. In one arm SLB, a PIP can theoretically serve maximum 65536 clients. With this feature, the limitation no longer exists.

5. Radius health checks: Radius health check can be used to non-standard RFC ports and support combined health check through raduis_aa health check type. The radius_aa type performs service port check in the beginning. If the service port is determined to be representing a RADIUS Authentication service, then a RADIUS Authentication health
check is performed. Accounting service query for health check is also performed. Finally, a TCP health check is performed if authentication and accounting service are not found.

6. FlexiRules for SIP over UDP traffic:  FlexiRules allow the administrators to customize the security policies and set rules. These rules monitor the SIP calls and dynamically filter the SIP traffic.

7. Automate session mirroring: Session mirroring can be automated to synchronize sessions from master to backup at the configured time and frequency. This provides stable fail-over session maintainance.

8. Flood of server connections prevention:  Alteon performs a slow start on the real server coming back after the health check fails and this prevents flood of connections. This situation usually occurs when real servers groups configured with least connection as metric. When the real server comes up, it doesn't contain connections and all the new connections are directed to it. This heavy connection flow might crush down the real server.

9. Virtual Control Service (VCS): VCS is a new Windows base software representing a connector between Nortel devices and VMware virtualization infrastructure. The VCS version 1.0 supports Alteon application switch and VMware version 3.5. It provides management, configuration, and monitor both on Alteon and VMware. VCS displays hosts and VM real servers of the virtualization infrastructure. During the server load balancing, VCS monitors system load based on the configured threshold value and dynamically adds or removes the VM from server group.This provides automatic management of load balancing on VMware.