Dvmrp Design Guidelines; Dvmrp Timer Tuning - Avaya 8800 Planning And Engineering, Network Design

Multicast network design
Important:
In some DVMRP scaled configurations with more than one thousand streams, to avoid multicast
traffic loss, you need to increase routing protocol timeouts (for example, the dead interval for
OSPF).
The scaling limits given in this section are not hard limits; they are a result of scalability testing with
switches under load with other protocols running in the network. Depending on your network design,
these numbers can vary.

DVMRP design guidelines

As a general rule, design your network with routed VLANs that do not span several switches. Such a
design is simpler and easier to troubleshoot and, in some cases, eliminates the need for protocols
such as the Spanning Tree Protocol (STP). In the case of DVMRP enabled networks, such a
configuration is particularly important. When DVMRP VLANs span more than two switches,
temporary multicast delayed record aging on the nondesignated forwarder may occur after receivers
leave.
DVMRP uses not only the hop count metric but also the IP address to choose the reverse path
forwarding (RPF) path. Thus, to ensure the utilization of the best path, assign IP addresses
carefully.
As with any other distance vector routing protocol, DVMRP suffers from count-to-infinity problems
when loops occur in the network. This makes the settling time for the routing table higher.
Avoid connecting senders and receivers to the subnets/VLANs that connect core switches. To
connect servers that generate multicast traffic or act as multicast receivers to the core, connect
them to VLANs different from the ones that connect the switches. As shown in
IP multicast access policies for DVMRP
and the IP multicast senders or receivers are placed on VLAN V4, which is routed to other VLANs
using DVMRP.
The Avaya Ethernet Routing Switch 8800/8600 does not support DVMRP in SMLT full-mesh
designs.

DVMRP timer tuning

You can configure several DVMRP timers. These timers control the neighbor state updates (nbr-
timeout and nbr-probe-interval timer), route updates (triggered-update-interval and update-interval),
route maintenance (route-expiration-timeout, route-discard-timeout, route-switch-timeout), and
stream forwarding states (leaf-timeout and fwd-cache-timeout).
For faster network convergence in the case of failures or route changes, you may need to change
the default values of these timers. If so, Avaya recommends that you follow these rules:
• Ensure that all timer values match on all switches in the same DVMRP network. Failure to do
so may result in unpredictable network behavior and troubleshooting difficulties.
June 2016
on page 187, V1, V2, and V3 connect the core switches,
Planning and Engineering — Network Design
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Figure 86: Applying
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