PIM Assert Mechanism
Table of Contents
10.1
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- Tap Interfaces
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- Layer 2 and Layer 3 Packets over a Virtual Wire
- Port Speeds of Virtual Wire Interfaces
- LLDP over a Virtual Wire
- Aggregated Interfaces for a Virtual Wire
- Virtual Wire Support of High Availability
- Zone Protection for a Virtual Wire Interface
- VLAN-Tagged Traffic
- Virtual Wire Subinterfaces
- Configure Virtual Wires
- Configure an Aggregate Interface Group
- Configure Bonjour Reflector for Network Segmentation
- Use Interface Management Profiles to Restrict Access
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- DNS Overview
- DNS Proxy Object
- DNS Server Profile
- Multi-Tenant DNS Deployments
- Configure a DNS Proxy Object
- Configure a DNS Server Profile
- Use Case 1: Firewall Requires DNS Resolution
- Use Case 2: ISP Tenant Uses DNS Proxy to Handle DNS Resolution for Security Policies, Reporting, and Services within its Virtual System
- Use Case 3: Firewall Acts as DNS Proxy Between Client and Server
- DNS Proxy Rule and FQDN Matching
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- NAT Rule Capacities
- Dynamic IP and Port NAT Oversubscription
- Dataplane NAT Memory Statistics
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- Translate Internal Client IP Addresses to Your Public IP Address (Source DIPP NAT)
- Enable Clients on the Internal Network to Access your Public Servers (Destination U-Turn NAT)
- Enable Bi-Directional Address Translation for Your Public-Facing Servers (Static Source NAT)
- Configure Destination NAT with DNS Rewrite
- Configure Destination NAT Using Dynamic IP Addresses
- Modify the Oversubscription Rate for DIPP NAT
- Reserve Dynamic IP NAT Addresses
- Disable NAT for a Specific Host or Interface
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- Network Packet Broker Overview
- How Network Packet Broker Works
- Prepare to Deploy Network Packet Broker
- Configure Transparent Bridge Security Chains
- Configure Routed Layer 3 Security Chains
- Network Packet Broker HA Support
- User Interface Changes for Network Packet Broker
- Limitations of Network Packet Broker
- Troubleshoot Network Packet Broker
PIM Assert Mechanism
PIM uses an Assert mechanism to elect a PIM Forwarder
of multicast packets on a multiaccess network, which prevents forwarding
of duplicate multicast packets.
To prevent routers on a multiaccess network from forwarding
the same multicast traffic to the same next hop (which would cause
redundant traffic and wasted bandwidth), PIM uses the Assert mechanism
to elect a single PIM Forwarder for the multiaccess network.
If the virtual router receives a multicast packet from a source
on an interface that the virtual router already associates as the
outgoing interface for the same (S,G) pair identified in the packet,
that means this is a duplicate packet. Consequently, the virtual
router sends an Assert message containing its metrics to the other
routers on the multiaccess network. The routers then elect a PIM
Forwarder in this manner:
- The PIM Forwarder is the router with the lowest administrative distance to the multicast source.
- In the event of a tie for lowest administrative distance, the PIM Forwarder is the router with the best unicast routing metric to the source.
- In the event of a tie for best metric, the PIM Forwarder is the router with the highest IP address.
Routers that are not elected as the PIM Forwarder will stop forwarding
traffic to the multicast group identified in the (S,G) pair.
When you Configure
IP Multicast, you can configure the interval at which the
virtual router sends PIM Assert messages out an interface (the Assert
interval). When you View
IP Multicast Information, the
PIM Interface
tab
displays the Assert interval for an interface.