Administrator Guide

R5#
interface tengigbitethernet 1/1
Ip address 5.5.5.2/24
no shut
interface fortGigE 1/48
ip address 3.3.3.2/24
no shut
router bgp 2
maximum-paths ebgp 2
bgp dmzlink-bw
neighbor 5.5.5.1 remote-as 1
neighbor 5.5.5.1 dmzlink-bw
neighbor 5.5.5.1 no shutdown
neighbor 3.3.3.1 remote-as 1
neighbor 3.3.3.1 dmzlink-bw
Dynamic Re-calculation of Link Bankwidth
The Link cost associated with a port channel interface (LAG) changes whenever a member is added or deleted.
Continuous link flapping results in the re-calculation of the link costs. This behaviour also causes unnecessary processing overhead on the
device as it advertises these changed link costs to its peers and updates its RTM when ever there is a change in the member status.
To avoid the re-calculation of Link costs for continuous link flaps, the updated link cost is re-calculated using a timer. This timer is
activated every five minutes to check if there is any change in the link cost associated with the EBGP neighbors (directly connected).
Weighted ECMP for Static Routes
Dell Networking OS also supports Weighted ECMP for static routes.
You can configure weights corresponding to the paths for a static destination. If all configured paths have weights, traffic distribution is
performed using the Weighted ECMP method with the RTM these passing weights to the FIB.
If all configured paths do not have weights, regular ECMP is used to determine traffic paths. Also, paths that are configured with a weight
value of 0 are explicitly excluded from Weighted ECMP calculations. The RTM does not inform the FIB about these paths (next-hops).
NOTE:
Dell Networking OS also supports a global configuration parameter to enable or disable Weighted ECMP for
static routes on the system.
The following example shows weighted ECMP configuration for Static Routes:
Dell(conf)#ip route 1.1.1.0/24 4.4.4.2 weight 100
Dell(conf)#ip route 1.1.1.0/24 6.6.6.2 weight 200
Dell#show running-config | grep route
ip route 1.1.1.0/24 4.4.4.2 weight 100
ip route 1.1.1.0/24 6.6.6.2 weight 200
Dell(conf)#ip route vrf test 1.1.1.0/24 4.4.4.2 weight 100
Dell(conf)#ip route vrf test 1.1.1.0/24 6.6.6.2 weight 200
Dell(conf)#
Dell(conf)#
Dell#show running-config | grep route
ip route vrf test 1.1.1.0/24 4.4.4.2 weight 100
ip route vrf test 1.1.1.0/24 6.6.6.2 weight 200
ECMP Support in L3 Host and LPM Tables
The L3 host and Longest Prefix Match (LPM) tables provide ECMP next-hop forwarding for destination addresses. You can program
IPv6 /128 and IPv4 /32 route prefixes to be stored in the L3 host table and move IPv6 /128 and IPv4 /32 route prefixes between the host
table and the LPM route table.
By default, IPv4 route prefixes are installed only in the LPM table and IPv6/128 route prefixes are installed only in the L3 host table. In
previous releases, the IPv6 /128 entries in the host table were not supported by ECMP.
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Equal Cost Multi-Path (ECMP)