Huawei NetEngine80E Configuration Manual - Reliability page 378

HUAWEI NetEngine80E/40E Router
Configuration Guide - Reliability
Comparison Between the GR and the HSB
Table 6-1 Comparison between the GR and the HSB
Name
GR
HSB
Issue 02 (2011-09-10)
Advantage
l It is easy to implement and does not
need great modifications to the
existing software.
l It does not need to back up the
protocol status information.
l Few data needs to be backed up
from the AMB to the SMB. The
data includes configuration
modification, updated messages
and events, interface status change,
and topology information and
routing information from
neighbors after restart.
l During the switchover, there is
little probability of service
interruption.
l Normally, the network converges
rapidly.
l The AMB/SMB switchover on the
HSB router does not affect the
service forwarding and routing
process.
l The routing information and
topology information are not lost
and the protocol session is not
interrupted during the switchover.
l The switchover between the AMB
and SMB is self-contained.
l The neighbour routers do not need
to have the GR capability.
l There is no problem of
compatibility.
l The switchover does not affect the
neighbors.
l The network convergence is faster
than the network with GR routers.
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6 GR Configuration
Drawback
l Interoperability: Some of the GR
specifications are still drafts and the
implementation varies with
vendors.
l Concurrent collapse: If a GR router
and its neighbor(s) collapse
concurrently, GR cannot work
normally.
l Long convergence time: When a GR
router in the Down state cannot
recover again, its neighbors assume
that the GR Restarter will restart, so
the neighbors do not delete the
related routing and topology
information before the Recovery
timer times out. Compared with the
common network in which the
routers do not have the GR
capability, this network takes a
longer period to converge.
l Dependence of the recovery process
on neighbor routers: Neighboring
routers must support the GR
capability, because GR is not "self-
contained".
l More difficult to implement than
GR: More information, including
the protocol status, the session, the
route, the policy, and the update,
needs to be backed up.
l Usage of more communication
channel bandwidth: The HSB needs
to support the TCP backup between
the AMB and the SMB.
l Dependence on the hot backup of
the BGP/LDP session on the TCP
connection. If you do not expect the
neighbors to be aware of the
switchover, you must back up the
continuously changing TCP link
status from the AMB to the SMB.
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