Broadcast traffic handling on Cisco 9500

 

Broadcast traffic handling on Cisco 9500

 

Faced interesting issue today - 

Traffic coming from remote site with destination IP of broadcast IP was not getting any replies. Performed packet capture on C9500 outgoing SVI and found that traffic was not going out.

Found this link of cisco blog to fix the issue.

Need to apply ip network-broadcast on incoming SVI and ip directed-broadcast on outgoing SVI to fix the issue!

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/17-3/configuration_guide/rtng/b_173_rtng_9500_cg/configuring_ip_unicast_routing.html#topic_jgn_gxx_kgb

 

Feature Information for IP Unicast Routing

Release	Feature	Feature Information
Cisco IOS XE Everest 16.5.1a	IP Unicast Routing	IP Unicast Routing is a routing process that forwards traffic to an unicast address. Routers and Layer 3 switches route packets either through preprogrammed static routes or through default routes.
Cisco IOS XE Amsterdam 17.3.1	New command ip network-broadcast	ip network-broadcast command was introduced to receive and accept network-prefix-directed broadcast packets.
Table 5. Feature Information for IP Unicast Routing