Application Support for Unified ISSU

When an application supports unified ISSU, you can configure the application on the router and proceed with the unified in-service software upgrade with no adverse impact to the upgrade.

Applications that do not support unified ISSU cannot maintain state and configuration with minimal traffic loss across the upgrade. When you attempt the unified in-service software upgrade on a router that is configured with an ISSU-challenged application, the unified in-service software upgrade is halted and cannot proceed unless you remove the configuration. An application that does not support high availability cannot support unified ISSU.

Table 20 indicates which applications support or do not support a unified in-service software upgrade, as well as limitations on their behavior.

Table 20: Application Support for Unified In-Service Software Upgrades

Application

Supported

Unsupported

Notes

Physical Layer Protocols

DS1
(E120 and E320)

DS1
(ERX1440)

DS3

HDLC

SONET/SDH

Unified ISSU support is provided only for non-channelized APS IOAs. Also, unified ISSU can proceed only if you have not configured APS on the OCx/STMx ATM or OCx/STMx POS line modules. If you have configured APS, a warning message is displayed and the router cannot proceed with the unified ISSU.

The unified ISSU process for channelized line modules remains unchanged.

E120 and E320 routers do not support APS.

SONET/SDH VT

Link-Layer Protocols

ARP

ARP entries in the ARP cache do not time out because no ARP aging occurs during unified ISSU. When the unified ISSU is completed, the ARP cache contains the same entries as it had before the unified ISSU began.

ATM

ATM 1483 bulk configuration of dynamic interfaces

ATM bulk configuration of static interfaces

Bridged Ethernet

Cisco HDLC

Ethernet (with and without VLANs)

Frame Relay

PPP

PPPoE

Transparent bridging

Unicast Routing

Access Routes

BGP

FTP

Although unified ISSU supports FTP in active state, no file transfer operation can be in progress while performing unified ISSU.

IP

IPv6

IPv6 is unified ISSU safe and compliant.

Unified ISSU is not supported for IPv6 configurations and IPv6-related applications that are not supported for the IPv6 high availability feature.

IPSec Transport
(E120 and E320)

E120 and E320 routers do not support IPSec.

IPSec Transport
(ERX1440)

IPSec Tunnels
(E120 and E320)

E120 and E320 routers do not support IPSec.

IPSec Tunnels
(ERX1440)

IS-IS

Support only when graceful restart is configured.

IS-ISv6

Support only when graceful restart is configured.

OSPF

Support only when graceful restart is configured.

RIP

Static Routes

Telnet

Authentication and command authorizations on Telnet sessions fail during the upgrade phase and Telnet sessions are dropped.

IPv4 Multicast Routing

Multicast Routing

ANCP (L2C)

Unified ISSU can proceed if ANCP is configured. However, ANCP has no graceful restart extensions and therefore it cannot maintain its dynamic state across the upgrade. Consequently, all ANCP sessions are brought down and then restored when the upgrade is completed.

DVMRP
(E120 and E320)

DVMRP
(ERX1440)

IGMP

PIM

IPv6 Multicast Routing

 

Multicast Routing

IPv6 routing protocols are unified ISSU safe, but do not support ISSU.

MLD

IPv6 routing protocols are unified ISSU safe, but do not support ISSU.

PIM

IPv6 routing protocols are unified ISSU safe, but do not support ISSU.

Multiprotocol Label Switching

MPLS

BGP signaling

Unified ISSU supports BGP IPv6 address families. For more information about unified ISSU support, see IPv6 BGP Behavior During Unified ISSU.

LDP signaling

RSVP-TE signaling

Local cross-connects between layer 2 interfaces using MPLS

Policies and QoS

 

Policies

QoS

Remote Access

AAA

The following configuration is not supported: The subscriber username and password are on an ATM circuit in Bridged Ethernet over ATM or IP over ATM configurations.

DHCP External Server and Packet Trigger

DHCP Packet Capture

Configuration of DHCP packet capture does not prevent unified ISSU from proceeding. However, the capturing of packets on the line modules is halted when the unified ISSU upgrade phase commences. Packet capture resumes automatically during the unified ISSU service restoration phase.

DHCP Proxy Client

DHCP Relay Proxy

DHCP relay proxy continues processing of DHCP release requests during the unified ISSU to maintain server-client synchronization. State is preserved across the upgrade; statistics are not preserved.

DHCP Relay Server

DHCPv4 Local Server

Forwarding outages that take place during a unified ISSU can affect DHCP lease renewal. Before you begin unified ISSU, we recommend that you configure the DHCP local server address pools with a minimum lease time of 120 minutes to ensure that leases do not expire during the upgrade.

DHCPv6 Local Server

IPv6 is ISSU safe and compliant. You can upgrade ISSU when DHCPv6 local server applications are configured. However, during the ISSU upgrade, new requests for IPv6 prefixes are blocked by the DHCPv6 local server.

L2TP

Unified ISSU forces an L2TP failover for all established tunnels. L2TP failover resynchronization is required for successful recovery of a tunnel and its sessions following the upgrade.

L2TP Dialout

IPv4 Local Address Pools

IPv6 Local Address Pools

IPv6 is ISSU safe and compliant. You can upgrade ISSU when IPv6 local address pool applications are configured on the server.

Local Authentication Server

RADIUS Client

RADIUS Dynamic-Request Server

RADIUS Initiated Disconnect

RADIUS Relay Server

RADIUS Route-Download Server

SRC Client

Service Manager

Subscriber Manager

TACACS+

Miscellaneous

Bulk statistics

Denial of Service (DoS) protection

HTTP server

IOA hot swap

J-Flow (IP flow statistics)

Line Module Redundancy

You can use the active spare line module for unified ISSU operations. You do not have to revert to the primary line module. The following sets of line modules and IOAs are supported:

  • ATM: OC3-4A, OC3/OC12/DS3-ATM
  • POS: OC3-4P
  • Line Modules
    • ES2 4G LM
    • ES2 10G Uplink LM
    • ES2 10G LM
    • ES2 10G ADV LM
  • IOAs
    • ES2-S1 GE-4 IOA
    • ES2-S1 GE-8 IOA
    • ES2-S3 GE-20 IOA
    • ES2-S1 10GE IOA
    • ES2-S2 10GE PR IOA
    • ES2-S1 OC3-8 STM1 ATM IOA
    • ES2-S1 OC12-2 STM4 ATM IOA
    • ES2-S1 OC12-2 STM4 POS IOA
    • ES2-S1 OC48 STM16 POS IOA

Mobile IP Home Agent

Network Address Translation (NAT)

You must remove the NAT license configuration as well as the NAT configuration from the router.

NTP

Resource Threshold Monitor

Response Time Reporter

Route Policy

SNMP

Subscriber Interfaces

Tunnels (GRE and DVMRP)

VRRP

Related Documentation