Acl-Based Prefix Filtering; Rsvp Mib - Cisco CRS Configuration Manual

Implementing RSVP for MPLS-TE and MPLS O-UNI
contain the restart cap object, RSVP backs off sending hellos to that neighbor. If graceful restart is disabled,
no hello messages (Requests or ACKs) are sent. If a hello Request message is received from an unknown
neighbor, no hello ACK is sent back.

ACL-based Prefix Filtering

RSVP provides for the configuration of extended access lists (ACLs) to forward, drop, or perform normal
processing on RSVP router-alert (RA) packets. Prefix filtering is designed for use at core access routers in
order that RA packets (identified by a source/destination address) can be seamlessly forwarded across the
core from one access point to another (or, conversely to be dropped at this node). RSVP applies prefix filtering
rules only to RA packets because RA packets contain source and destination addresses of the RSVP flow.
RA packets forwarded due to prefix filtering must not be sent as RSVP bundle messages, because bundle
Note
messages are hop-by-hop and do not contain RA. Forwarding a Bundle message does not work, because
the node receiving the messages is expected to apply prefix filtering rules only to RA packets.
For each incoming RSVP RA packet, RSVP inspects the IP header and attempts to match the source/destination
IP addresses with a prefix configured in an extended ACL. The results are as follows:
• If an ACL does not exist, the packet is processed like a normal RSVP packet.
• If the ACL match yields an explicit permit (and if the packet is not locally destined), the packet is
• If the ACL match yields an explicit deny, the packet is dropped.
If there is no explicit permit or explicit deny, the ACL infrastructure returns an implicit (default) deny. RSVP
can be configured to drop the packet. By default, RSVP processes the packet if the ACL match yields an
implicit (default) deny.
Related Topics
Configuring ACLs for Prefix Filtering, on page 126
Configure ACL-based Prefix Filtering: Example, on page 149

RSVP MIB

RFC 2206, RSVP Management Information Base Using SMIv2 defines all the SNMP MIB objects that are
relevant to RSVP. By implementing the RSVP MIB, you can perform these functions:
• Specifies two traps (NetFlow and LostFlow) which are triggered when a new flow is created or deleted.
• Lets you use SNMP to access objects belonging to RSVP.
Related Topics
Enabling RSVP Traps, on page 132
Enable RSVP Traps: Example, on page 150
forwarded. The IP TTL is decremented on all forwarded packets.
Cisco IOS XR MPLS Configuration Guide for the Cisco CRS Router, Release 5.1.x
ACL-based Prefix Filtering
117