Extreme Networks ExtremeWare XOS 11.3, Manual

Page: 461 / 698

ESRP Concepts
ExtremeWare XOS 11.3 Concepts Guide
461
ESRP Domain IDs
ESRP packets do not identify themselves to which domain they belong; you either configure a domain
ID or the ESRP domain uses the 802.1Q tag (VLANid) of the master VLAN. A domain ID in the packet
clearly classifies the packet, associates a received ESRP PDU to a specific ESRP domain, and tells the
receiving port where the packet came from.
Linking ESRP Switches
When considering system design using ESRP, Extreme Networks recommends using a direct link. Direct
links between ESRP switches are useful under the following conditions:
●
A direct link can provide a more direct routed path, if the ESRP switches are routing and supporting
multiple VLANs where the master/slave configuration is split such that one switch is master for
some VLANs and a second switch is master for other VLANs. The direct link can contain a unique
router-to-router VLAN/subnet, so that the most direct routed path between two VLANs with
different master switches uses a direct link, instead of forwarding traffic through another set of
connected routers.
●
A direct link can be used as a highly reliable method to exchange ESRP hello messages, so that the
possibility of having multiple masters for the same VLAN is lessened if all downstream Layer 2
switches fail.
●
A direct link is necessary for the ESRP host attach (HA) option. The direct link is used to provide
Layer 2 forwarding services through an ESRP slave switch.
Direct links may contain a router-to-router VLAN, along with other VLANs participating in an ESRP
domain. If multiple VLANs are used on the direct links, use 802.1Q tagging. The direct links may be
aggregated into a load-shared group, if desired. If multiple ESRP domains share a host port, each VLAN
must be in a different ESRP group.
ESRP and Hitless Failover—Modular Switches Only
When you install two Management Switch Fabric Module (MSM) modules in a BlackDiamond chassis,
one MSM assumes the role of primary and the other assumes the role of backup MSM. The primary
MSM executes the switch’s management functions, and the backup MSM acts in a standby role. Hitless
failover transfers switch management control from the primary MSM to the backup MSM and maintains
the state of ESRP. The ESRP extended version supports hitless failover.
For hitless failover support, ESRP switches and the primary and backup MSMs must run a version of
ExtremeWare XOS that supports hitless failover and operate in ESRP extended mode.
NOTE
Beginning with ExtremeWare XOS 11.0, the BlackDiamond 10K supports hitless failover for ESRP. If you are running
an earlier version of ExtremeWare XOS, the BlackDiamond 10K switch does not support ESRP hitless failover.
Beginning with ExtremeWare XOS 11.3, the BlackDiamond 8800 switch (formerly known as Aspen) supports hitless
failover for ESRP. If you are running an earlier version of ExtremeWare XOS, the BlackDiamond 8800 does not
support ESRP hitless failover.
The ESRP domain on the primary MSM is active and participates in the ESRP protocol. The ESRP
domain on the backup MSM is in the neutral state listening for configuration changes, tracking failures,