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Can a 3640 router handle a peak payload of 24Mbps

simonreed
Level 1
Level 1

Can a 3640 router handle a Peak Payload of 24Mbps, consisting of 800 streams of video data at approximately 30kbps each.

Would I require any more than the standard memory spec, and could I use a NM-1FE-TX card?

All help appreciated

3 Accepted Solutions

Accepted Solutions

rais
Level 7
Level 7

I believe it should handle it. If that router can support multiple 10/100 ethernets, it should be able to support this rate. However, I am not sure.

You should try multicast. A single 30Kbps stream will serve 800 users.

Thanks.

View solution in original post

rlcarr
Level 1
Level 1

According to the Cisco documentation for the 3640 it can handle 4,000pps in process mode and 50-70,000pps in CEF mode. (testing states it used 64 byte packets).

Disclaimer, I didn't get straight A's in math.

But I *believe* it would look something like:

Packet = Ethernet MTU (1500) - header (64) = payload (1436)in Bytes. So each packet has 1,436 Bytes (the big B)

Now convert bits (the little b) into Bytes, then packets.

30Kbs = 3,750 Bytes = 3 packets (have to round up, can't have a partial packet).

So each stream is 3 packets * 800 streams = 2,400 packets per second (pps).

Should be no problem.

By the way,

If they are the same stream then you should be doing multicasting.

Are you sure on the the 30Kbs for a video stream? That is more around the size of an audio only stream. Typically video streams are like 300 to 600 Kbs.

~ron

CCNP, CCDA, CNE

View solution in original post

t.baranski
Level 4
Level 4

Your throughput will depend on what size packets are being sent within these streams. If the packets are large you should be in good shape: even a 2621 can do ~40Mbps with full-sized packets. At the other extreme, however, consider a 3640 with the smallest possible packets (64-bytes) at the rated speed of 50Kpps. With 46 bytes of data per packet (the Ethernet headers use 18 bytes), you're looking at around 17Mbps and this doesn't even include the overhead of the upper-layer headers (IP, UDP, etc).

Memory-wise you should be ok with whatever is standard. When you tend to need larger amounts of memory is when you have large routing tables, or are using various other protocols/features that don't fall into the "standard routing" category.

View solution in original post

4 Replies 4

rais
Level 7
Level 7

I believe it should handle it. If that router can support multiple 10/100 ethernets, it should be able to support this rate. However, I am not sure.

You should try multicast. A single 30Kbps stream will serve 800 users.

Thanks.

rlcarr
Level 1
Level 1

According to the Cisco documentation for the 3640 it can handle 4,000pps in process mode and 50-70,000pps in CEF mode. (testing states it used 64 byte packets).

Disclaimer, I didn't get straight A's in math.

But I *believe* it would look something like:

Packet = Ethernet MTU (1500) - header (64) = payload (1436)in Bytes. So each packet has 1,436 Bytes (the big B)

Now convert bits (the little b) into Bytes, then packets.

30Kbs = 3,750 Bytes = 3 packets (have to round up, can't have a partial packet).

So each stream is 3 packets * 800 streams = 2,400 packets per second (pps).

Should be no problem.

By the way,

If they are the same stream then you should be doing multicasting.

Are you sure on the the 30Kbs for a video stream? That is more around the size of an audio only stream. Typically video streams are like 300 to 600 Kbs.

~ron

CCNP, CCDA, CNE

t.baranski
Level 4
Level 4

Your throughput will depend on what size packets are being sent within these streams. If the packets are large you should be in good shape: even a 2621 can do ~40Mbps with full-sized packets. At the other extreme, however, consider a 3640 with the smallest possible packets (64-bytes) at the rated speed of 50Kpps. With 46 bytes of data per packet (the Ethernet headers use 18 bytes), you're looking at around 17Mbps and this doesn't even include the overhead of the upper-layer headers (IP, UDP, etc).

Memory-wise you should be ok with whatever is standard. When you tend to need larger amounts of memory is when you have large routing tables, or are using various other protocols/features that don't fall into the "standard routing" category.

Cisco told us that the 3640 would not handle a DS3, even though they had interface modules for it. Obviously the router can pump more than the 45mb a DS3 can produce. The issue was the interface module and its interface to the router.

Make sure you have enough memory and it might work better if the ethernets ( I assume you are using 2 Fast ethernets) are not on the same network module.

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