Wired Intelligent Edge

Hi Everyone,

   Imagine a scenario an incoming packet received by a layer 3 switch ,based on routing table the packet forwarding decision is done. I would like to know  that packet processing is done at CPU level or cache based forwarding or any algorithm .(considering routing table as well as policy based routing)

I appreciate your response in advance.

Cheers ,

Santhosh

Hi Santosh,

In general if ARP table for the next-hop IP is complete the forwarding will happen in ASIC and CPU won't be involved. I say 'in general' if we speak about normal unicast IPv4 traffic with no fancy options inside the IP header.

Hi Everyone,

   Imagine a scenario an incoming packet received by a layer 3 switch ,based on routing table the packet forwarding decision is done. I would like to know  that packet processing is done at CPU level or cache based forwarding or any algorithm .(considering routing table as well as policy based routing)

I appreciate your response in advance.

Cheers ,

Santhosh

Thanks Ivan_B for your response. Shall I conclude that ARP entries are based on memory provide by ASIC. What does no fancy options in IP header(Is it QOS parameter)?

Hi Santosh,

In general if ARP table for the next-hop IP is complete the forwarding will happen in ASIC and CPU won't be involved. I say 'in general' if we speak about normal unicast IPv4 traffic with no fancy options inside the IP header.

Hi Everyone,

   Imagine a scenario an incoming packet received by a layer 3 switch ,based on routing table the packet forwarding decision is done. I would like to know  that packet processing is done at CPU level or cache based forwarding or any algorithm .(considering routing table as well as policy based routing)

I appreciate your response in advance.

Cheers ,

Santhosh

Hi Santosh,

I have edited my initial response, please, check.

About IPv4 options - I mean these - https://www.iana.org/assignments/ip-parameters/ip-parameters.xhtml If a packet has IP option/-s in its header, such packet is punted to the CPU. But it is not relevant for your question, I believe what you want do find out is something like 'Does PBR work in software or hardware?' or 'Does PBR provide line-rate forwarding?' Correct me if I am wrong :) But if I got you right, then you need to specify the particular model of Aruba switch you are asking about, as implementation of PBR may differ between platforms.

------------------------------
Ivan Bondar

Original Message:
Sent: Mar 16, 2023 05:28 AM
From: sdhanapal
Subject: Policy Based Routing

Thanks Ivan_B for your response. Shall I conclude that ARP entries are based on memory provide by ASIC. What does no fancy options in IP header(Is it QOS parameter)?

Original Message:
Sent: Mar 16, 2023 05:11 AM
From: Ivan_B
Subject: Policy Based Routing

Hi Santosh,

In general if ARP table for the next-hop IP is complete the forwarding will happen in ASIC and CPU won't be involved. I say 'in general' if we speak about normal unicast IPv4 traffic with no fancy options inside the IP header.

------------------------------
Ivan Bondar

Original Message:
Sent: Mar 16, 2023 01:50 AM
From: sdhanapal
Subject: Policy Based Routing

Hi Everyone,

   Imagine a scenario an incoming packet received by a layer 3 switch ,based on routing table the packet forwarding decision is done. I would like to know  that packet processing is done at CPU level or cache based forwarding or any algorithm .(considering routing table as well as policy based routing)

I appreciate your response in advance.

Cheers ,

Santhosh

Hi Ivan_B,

    Yes . You are right. I would like to know how packet processing works in terms of PBR?

 If you need model no. I would prefer 6400 and 6300 series as they mentioned in Labs. And the IANA link informative one.

Hi Santosh,

I have edited my initial response, please, check.

About IPv4 options - I mean these - https://www.iana.org/assignments/ip-parameters/ip-parameters.xhtml If a packet has IP option/-s in its header, such packet is punted to the CPU. But it is not relevant for your question, I believe what you want do find out is something like 'Does PBR work in software or hardware?' or 'Does PBR provide line-rate forwarding?' Correct me if I am wrong :) But if I got you right, then you need to specify the particular model of Aruba switch you are asking about, as implementation of PBR may differ between platforms.

------------------------------
Ivan Bondar

Original Message:
Sent: Mar 16, 2023 05:28 AM
From: sdhanapal
Subject: Policy Based Routing

Thanks Ivan_B for your response. Shall I conclude that ARP entries are based on memory provide by ASIC. What does no fancy options in IP header(Is it QOS parameter)?

Original Message:
Sent: Mar 16, 2023 05:11 AM
From: Ivan_B
Subject: Policy Based Routing

Hi Santosh,

In general if ARP table for the next-hop IP is complete the forwarding will happen in ASIC and CPU won't be involved. I say 'in general' if we speak about normal unicast IPv4 traffic with no fancy options inside the IP header.

------------------------------
Ivan Bondar

Original Message:
Sent: Mar 16, 2023 01:50 AM
From: sdhanapal
Subject: Policy Based Routing

Hi Everyone,

   Imagine a scenario an incoming packet received by a layer 3 switch ,based on routing table the packet forwarding decision is done. I would like to know  that packet processing is done at CPU level or cache based forwarding or any algorithm .(considering routing table as well as policy based routing)

I appreciate your response in advance.

Cheers ,

Santhosh