routing protocol bandwidth allocation

[jbluo]

Whether need remaining bandwidth for routing traffic on overload network?

[balajitvk]

hi,

yes some bandwidth is needed for routing protocol traffic. But i don't find any provision on routing protocols except eigrp to allocate any bandwidth for their operation.

Some routing protocols consume all of the available bandwidth on a low bandwidth link while they are converging (adapting to a change in the network). EIGRP avoids this congestion by pacing the speed at which packets are transmitted on a network, thereby using only a portion of the available bandwidth. The default configuration for EIGRP is to use up to 50 percent of the available bandwidth, but this can be changed with the following command:

router(config-if)# ip bandwidth-percent eigrp 2 ?

<1-999999> Maximum bandwidth percentage that EIGRP may use

[jbluo]

Some virus consume all of the available bandwitdh. So configure CBWFQ, allocate bandwidth for critical traffic. Need the routing protocol traffic allocate bandwidth for protecting routing update?

[balajitvk]

You can use cbwfq to limit your data traffic. But ensure there is enough bandwidth for control traffic while allocating bandwidth to your data classes.

By default, The sum of all bandwidth allocation on an interface cannot exceed 75 percent of the total available interface bandwidth. The remaining 25 percent is used for other overhead, including Layer 2 overhead, routing traffic, and best-effort traffic. Bandwidth for the CBWFQ class-default class, for instance, is taken from the remaining 25 percent.

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter09186a00800b75a9.html

[jbluo]

By default, Both of the routing protocol and virus traffic use the remaining 25 percent bandwidth. Shall the virus traffic affect the routing protocol traffic? How does the router guarantee the routing traffic privilege?

[spremkumar]

Hi

In the 8 different (TOS) class of service u will have routing protocols placed in precedence level 6.

Which is similar to CS-6 (class selector) when u think off DSCP.

By default virus traffic will affect everything and also end up in halting the whole system once it exceeds the limit or once it goes above the level which cant be handled by the router or devices.

So better to control/block the same so that other traffic patterns dont get backlogged which mite reflect in ur business..

regds