Soft Iom Reset; Soft Reset - Alcatel-Lucent 7750 Configuration Manual

Interfaces

Soft IOM Reset

This section discusses basic procedures of the following service management tasks:
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Soft Reset

Soft reset is an advanced high availability feature that greatly reduces the impact of IOM/IMM
resets either during a software upgrade or during other maintenance or debug operations. The
combination of In Service Software Upgrade (ISSU) and Soft reset maximizes service availability
in an operational network.
A soft reset re-initializes the control plane while the data plane continues operation with only very
minimal impact to data forwarding. During the soft reset some processes that rely on the IOM
control plane will not run for a duration that is similar to the duration of an IOM Hard reset.
These processes include the updating of the IP forwarding table on the IOM (IP FIB downloads
from the CPM), Layer 2 learning of new MAC addresses on the IOM, updating of the MAC
forwarding table (for MAC addresses learned from other IOMs), ARP, Ethernet OAM 802.3ah,
LLDP and handling for certain ICMP functions such as Can't Fragment, Redirect, Host
Unreachable, Network Unreachable and TTL Expired. Note that protocols and processes on the
CPM continue to operate during a Soft Reset (BGP continues to learn new routes from peers, and
the new routes will be downloaded to the IOM once the Soft Reset has completed).
The combination of the very small data plane impact and special soft reset enhancements for
protocols ensures that most protocols do not go down and no visible impacts to most protocols are
detected externally to the SR/ESS platforms. BFD timers are temporarily increased for the
duration of a soft reset in order to keep BFD sessions up. Protocols such as BGP, OSPF, IS-IS,
PIM, etc with default timers remain up. A protocol using aggressive timers may go down
momentarily during a soft reset.
Note that although the majority of protocols stay up during a Soft Reset, there are some limitations
for a few protocols. Refer to the Known Limitations section of the Release Notes for the relevant
release for details.
The soft IOM reset procedure is applicable during the ISSU process and for a manual soft reset
procedure.
To manually perform a soft IOM reset, enter the clear card slot-number soft command.
Page 262
Soft Reset on page 262
Deferred MDA Reset on page 263
7750 SR Interface Configuration Guide