Is it better take 6724 with DFC3BXL then only S720-3BXL with 6516-GE-TX when having two peers sending the full bgp routing table ?

[edsge teenstra]

Hello

We want a router that can handle :

BGP to two peers with each sending the FULL BGP table

QinQ 802.1Q

BGP 4

IPv6

QoS with DSCP queuing

static routing and creation of vlan's

ACL's

We have 7 interfaces with rj45 connections.. all around 100Mbit per connection .. most likely in the future we will need a couple more interfaces.. i was thinking it would be better to take a WS-X6516-GE-TX card then a FE card as for example a WS-X6148-RJ-45 .

Now we want to implement a 7606 with a SUP720-3BXL with 1GB dram for the RP(MSFC3)...  so enough memory to support the 2x a FULL BGP table to two peers.

Q :  Does the SUP720-3BXL work well with two peers sending the FULL BGP table ?

Q : And does that also work with a WS-X6516-GE-TX connected to the two peers sending the FULL BGP table ?  .. or is it better to take a 6724 linecard with a DFC3-BXL so that the 6724 will lookup routes locally instead a 6516 will have the S720- perform the routing ? I know that adding the DFC's increases the bandwidth of the chassis significantly (40gbps per slot most 6700 linecards ,and  20gbps for the 6724 which is 1:2 oversubscribed )

Q: Or is it better to connect the two peers to the two SFP interfaces on the SUP720  , and connect the small routers and customer networks to the 6516 linecard? 

Thanks for al help and suggestions !

[Joseph W. Doherty]

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Posting

Q :  Does the SUP720-3BXL work well with two peers sending the FULL BGP table ?

I'm unsure. XL variant was designed for large route tables, but the Internet table has, of course, has grown and you want to work with 2 copies.

Q : And does that also work with a WS-X6516-GE-TX connected to the two peers sending the FULL BGP table ?  .. or is it better to take a 6724 linecard with a DFC3-BXL so that the 6724 will lookup routes locally instead a 6516 will have the S720- perform the routing ? I know that adding the DFC's increases the bandwidth of the chassis significantly (40gbps per slot most 6700 linecards ,and  20gbps for the 6724 which is 1:2 oversubscribed )

As the 6724 is a dCEF 720 card, I would prefer it only a 6516-GE which is dCEF 256 card.

The XL DFC corresponds to the XL sup, same possible issue for dealing with two full Internet BGP tables.

Unsure, but I doubt a dCEF 256 DFC can deal with a full BGP table.  If not, then you would have to use just the main sup for all forwarding.

BTW, DFCs don't increase bandwidth; they do add local card forwarding PPS.

You're correct, 6724 only has 20 Gbps, its oversubscription is also same as 6748, 1.2:1.  (If that's a concern, don't use all ports.)  (Also, 6516 oversubscription is 2:1, less RAM buffer per port, and inferior QoS support.)

Q: Or is it better to connect the two peers to the two SFP interfaces on the SUP720  , and connect the small routers and customer networks to the 6516 linecard? 

Also unsure, but suspect a 6700 line card would be a better choice.

[edsge teenstra]

Thanks for the advise ! , we will stick with the 6724 ..... we  initially thought to take the 6724 .. but since only around 2 Gbit/s of  data will be pushed we looked around for a less overkill solution. (in  regards to the forwarding capacity)

Sorry if i used the wrong words... but i thought  adding the DFC makes you go from the centralized forwarding (max 32Gbps -  classic bus)  to the Distributed forwarding that increases the  forwarding to 40Gbps per slot or 400Mpps/720Gbps for the whole system.

So if you would equip (for example) 5x 6704-10GE cards with DFC's  and all Xenpak's would forward packets to the max of want they can  forward in that 6704 ....would that not increase your forwarding capacity dramatically  ?  compared with CFC's installed ?

And in this case can we not speak of a increase of bandwidth ?

If not.... then i need to (re)study the term "bandwidth"

[Joseph W. Doherty]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

Sorry if i used the wrong words... but i thought  adding the DFC makes you go from the centralized forwarding (max 32Gbps -  classic bus)  to the Distributed forwarding that increases the  forwarding to 40Gbps per slot or 400Mpps/720Gbps for the whole system.
So if you would equip (for example) 5x 6704-10GE cards with DFC's  and all Xenpak's would forward packets to the max of want they can  forward in that 6704 ....would that not increase your forwarding capacity dramatically  ?  compared with CFC's installed ? 
And in this case can we not speak of a increase of bandwidth ? 

DFCs add PPS (to the line card) which may increase the forwarding performance, allowing higher amounts of bandwidths to be pushed through the chassis, but they don't change the underlying bandwidth capacity of the chassis and the line cards being used.  Basically, without DFCs, you may bottleneck on switching performance and be unable to utilize all the available bandwidth.

Some examples:

A sup2/sup720 provides up to 15 Mpps, shared by the whole chassis if you're not running in compact mode.

A sup2/sup720 provides up to 30 Mpps, shared by the whole chassis if you're running compact mode (no classic bus cards in the chassis).  This mode also supports the 30 Mpps for any packet size.

DFCs off load switching to the line card for ingress traffic on that card.  I.e. they no longer share the Mpps of the sup.  Different DFCs provide different Mpps.  I forget what the dCEF256 Mpps is, I believe the DFC3, for dCEF720, provides up to 48 Mpps.

(Note: wire-speed Ethernet, for minimum size packets, requires 1.488 Mpps per 1 Gbps).

You won't find DFCs on classic bus only cards, might not find it as an option on CEF256 cards.  I think it's an options on all CEF720 cards.

Classic bus cards only have a 16 Gbps (duplex) shared connection to the bus.

CEF256 cards either have one 8 Gbps fabric connection and one classic bus connection or dual 8 Gbps fabric connections.

CEF720 cards either have one or two 20 Gbps fabric connections.

Good read on details about this architecture may be found here: http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/prod_white_paper0900aecd80673385.html

[edsge teenstra]

Thanks for the explaination some things are new too me ... after working with Cisco gear for over 8 years , i have seen that link.. it is good reading thanks for showing that..

But there is a DFC option for the CEF256 cards so you can use dCEF256 .... it are the following daughter modules for the 6500 and 6800 series line cards , the WS-F6K-DFC is used with a s2/mfsc2 & SFM/SFM2

There are also DFC models which being used on a 6500/6800 series linecards with the s720(base model with PFC3A ) or the bit enhanced 720,s with the other PFC's 3B / 3BXL : WS-F6K-DFC3A & WS-F6K-DFC3B and even a WS-F6K-DFC3BXL for some of the WS-X65xx and WS-X68xx line cards ... But they are eos but still being sold by resellers.

Found this nice table on the link below..
http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/product_data_sheet0900aecd801459a7.html

These are the memory options for the DFC's that can be equipped on the eos 6500/6800 series linecards , so in theory the DFC 3BXL version for the 6500/6800 series linecards could be used for full bgp tables from two peers.. But i understand that the 6700 series linecards have more queues and higher buffer size on each port.

6700 :
• Tx-1p3q8T
• Rx-1q8T (2q8T when using dCEF)

6500/6800:
• Tx-1p2q2t
• Rx-1p1q4t


Table 5. Default Memory for CEF256 DFCs

Product ID
Default DRAM
Upgrade Options
WS-F6K-DFC3A*
256 MB


WS-F6K-DFC3B*. 256 MB Yes, MEM-XCEF720-512M=, or MEM-XCEF720-1GB=



WS-F6K-DFC3BXL*. 1GB Default .




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[Joseph W. Doherty · Accepted solution]

Disclaimer

The   Author of this posting offers the information contained within this   posting without consideration and with the reader's understanding that   there's no implied or expressed suitability or fitness for any purpose.   Information provided is for informational purposes only and should not   be construed as rendering professional advice of any kind. Usage of  this  posting's information is solely at reader's own risk.

Liability Disclaimer

In   no event shall Author be liable for any damages whatsoever (including,   without limitation, damages for loss of use, data or profit) arising  out  of the use or inability to use the posting's information even if  Author  has been advised of the possibility of such damage.

Posting

But there is a DFC option for the CEF256 cards so you can use dCEF256 .... it are the following daughter modules for the 6500 and 6800 series line cards , the WS-F6K-DFC is used with a s2/mfsc2 & SFM/SFM2

There are also DFC models which being used on a 6500/6800 series linecards with the s720(base model with PFC3A ) or the bit enhanced 720,s with the other PFC's 3B / 3BXL : WS-F6K-DFC3A & WS-F6K-DFC3B and even a WS-F6K-DFC3BXL for some of the WS-X65xx and WS-X68xx line cards ... But they are eos but still being sold by resellers.

Correct, but the reason I wrote ". . . might not find it as an option on CEF256 cards.", is:

• Distributed forwarding upgrade-This  feature is not supported. The WS-X6548-GE-TX, WS-X6548V-GE-TX,  and WS-X6548-GE-45AF do not support distributed forwarding (WS-F6KDFC  and WS-F6K-DFC3A).

I.e. it's not an option on all 65xx CEF256 cards.

Apologies if it appeared I was saying it wasn't an option on any CEF256 cards.