Specifications

71
Release Notes for Cisco 7000 Family for Cisco IOS Release 12.1 T
78-10811-05
New and Changed Information
HSRP Support for MPLS VPNs
Platforms: Cisco 7200 series and Cisco 7500 series routers
The HSRP support for Multiprotocol Label Switching (MPLS) VPNs feature enables ICMP redirection
on interfaces configured with the Hot Standby Router Protocol (HSRP).
The Internet Control Message Protocol (ICMP) is a network layer Internet protocol that provides
message packets to report errors and other information relevant to IP processing. ICMP provides many
diagnostic functions and can send and redirect error packets to hosts.
HSRP provides network redundancy in a way that ensures that user traffic immediately and
transparently recovers from first-hop failures in network edge devices and access circuits. By sharing
an IP address and a MAC (Layer 2) address, two or more routers can act as a single virtual router to the
hosts on a LAN. The members of the router group continually exchange status messages by detecting
when a router goes down. This HSRP group consists of an active router and a standby router to replace
the active router should it fail. The address of this HSRP group is referred to as the “virtual ip address.”
When running HSRP, it is important to prevent the host from discovering the primary MAC addresses
in its standby group. If a host is redirected by ICMP to a standby group that later fails, the packets are
lost. Previously, ICMP redirect messages were disabled on interfaces configured with HSRP. This was
done to avoid the host from being directed away from the virtual IP address (the HSRP group address
that provides redundancy) to the interface IP and MAC address of a single router. If this single router
failed, redundancy was lost.
The HSRP Support for the ICMP Redirect Messages feature now enables ICMP redirects on interfaces
configured with HSRP. This feature works by filtering outgoing ICMP redirect messages through HSRP,
where the next-hop IP address is changed to an HSRP virtual IP address.
Individual SNMP Trap Support
Platforms: Cisco 7200 series routers
The Individual SNMP Trap Support feature adds the ability to enable or disable SNMP system
management notifications (traps) individually. SNMP traps that can be specified are authentication,
linkup, linkdown, and coldstart. This feature expands the functionality of the
snmp-server enable traps snmp command.
MPLS Traffic Engineering and Enhancements
Platforms: Cisco 7200 series and Cisco 7500 series routers
Multiprotocol Label Switching (MPLS) traffic engineering software enables an MPLS backbone to
replicate and expand upon the traffic engineering capabilities of Layer 2 ATM and Frame Relay
networks. MPLS is an integration of Layer 2 and Layer 3 technologies. By making traditional Layer 2
features available to Layer 3, MPLS enables traffic engineering.
Traffic engineering is essential for service provider and Internet service provider (ISP) backbones. Such
backbones must support a high use of transmission capacity, and the networks must be very resilient so
that they can withstand link or node failures.
MPLS traffic engineering
• Enhances standard Interior Gateway Protocols (IGPs), such as IS-IS or OSPF, to automatically map
packets onto the appropriate traffic flows
• Transports traffic flows across a network using MPLS forwarding