Unanswered Question
Jun 5th, 2007

Hi All,

I am reading about CEoP. I found mainly two different type of modules. One type can only connected to Cisco7600 and other one in small routers like cisco2600. But each type are using different encapsulation for xconnection. One is using mpls other one is using udp. If I want to integrate both in one network what will be the common encapsulation in both modules? Because i never see udp encapsulation used in Cisco7600.

I have this problem too.
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Rahul Kachalia Tue, 06/05/2007 - 15:17


CEoP, emulates circuit over AToM based pseudowires technology, 7600. Whereas CEoIP, emulates circuit over IP (UDP/RTP) based network . So its a 2 different technology with common goals. You may need to refer to url for additional details :







devang_etcom Tue, 06/05/2007 - 16:16


In some configuration i found xconnect command with encapsulation keyword and in some of the configuration there are some pseudowire classes are created and then those classess are associated with the xconnect command so what is difference between both.

and what will be the procedure if i want to go for the AToM in lower end routers like 2600 3600 3800.

will you please give us some details on difference between CEoP and CEoIP?



Rahul Kachalia Tue, 06/05/2007 - 19:18

Hi Devang,

You can directly use encapsulation mpls or pw-class cfg mode with xconnect cmd under the AC intf. pw-class can be used as template when sub-features are required to handle pw differently in PSN core along with transport type, ie sequence numbers, AToM Tunnel selection etc. You cannot do this using multiple statements, also can be seen as cfg scale problem. So if you want a very basic AToM cfgs you can use "xconnect encapsulation mpls" command, whereas if you need additional feature to handle pseudowire different within core you may have to use pw-class.

Regarding your 2600/3600/ISRs I m not sure if your qn is generic to AToM or CEoP. But AToM is not supported on 2600/3600s, it is supported on ISRs. Though I dont have complete matrix handy on what transports are supported.

Well, for a moment lets come out of acronym confusion. Circuit Emulation(CE) over Packet allows Mobile SPs to extend IP/MPLS PSN all the way down to Radio Access Network (RAN), where full/channelized T1/E1s can be transported either over MPLS using Pseudowire technology OR over IP core network. 7600 supports CE over Pseudowire OR CEoP, whereas low end platform supports CE over IP network. So each side should similar transport to deliver TDM transparency across SP IP/MPLS core...



senthil1976 Tue, 06/05/2007 - 21:07

In 7600, When you xconnect you use encapsulation mpls

xconnect 200 encapsulation mpls

In 2600, When you xconnect you use encapsulation udp

xconnect 200 encapsulation udp

if i want to xconnect a circuit from 7600 to 2600 how can i do that?



Rahul Kachalia Tue, 06/05/2007 - 21:51

Hi Sen,

As I mentioned earlier that scenario wont work, you cannot have 1 end TDMoMPLS and other end with TDMoIP.

You need to use AToM or TDMoMPLS between 7600 to 7600.

And use TDMoIP (UDP based) between 2600/3600/ISR that supports CE over IP core...



swaroop.potdar Wed, 06/06/2007 - 01:20

Technically when there is circuit emulation of any type, Layer2, TDM etc, it desires a PSN tunnel. This PSN tunnel can be provided by the under lying PSN which could be MPLS or IP.

A pseudowire needs a transport, could be IP or MPLS but not mandatory. Its upto the vendor what is desired to be implemented.

Here the tug between 2600/28xx/3xxx and 7600

and the support for IP encap and MPLS encap is purely a matter of device positioning perspective. And although technically nothing should prohibits doing IP and MPLS encap for the PSN tunnel in either router range as its only a transport.

Simply put 2xxx/3xxx range is never positioned and recommended as a MPLS edge device so they might have not wanted to include the MPLS encap. And lot is desired to be understood why the support for IP encap was not provided in 7600, since the 7600 is a carrier class device and a carrier by all means may want to emulate circuits across a IP core as well.

If anyone from the Cisco BU here comes a feature request :-).



devang_etcom Wed, 06/06/2007 - 06:47

Hello Swaroop,

so you mena to say 26xx or 3xxx sereis is not supporting the MPLS encapsulation for the L-2 tunnel where as 76xx is not supporting the IP encapsulation for L-2 tunnel. as they are design for specific goal... then differences between the CEoP and CEoIP are the normal differences between the IP and MPLS is that correct?


so we can say that PW-Class is like the virtual template which represent the same parameters. It looks like the same as multilink virtual tamplate interface right!!!



Rahul Kachalia Wed, 06/06/2007 - 07:28

Hi Devang,

That is correct. Today 2600/3600/ISRs do not support CE over pseudowires (AToM) & 7600s do not support TDMoIP (UDP/RTP).

And pw-class is more than a vtemplate. As I mentioned earlier, if you need special handling of pw in PSN network, ie imposing per pkt sequence number for real-time traffic that can be done by imposition PE router similarly you can ignore IGP path and set user defined egress path, Interworking type etc. So along with defining all types of characteristics it can also be used as a template to associate single pw-class to multiple AC intf...



devang_etcom Wed, 06/06/2007 - 12:03

so do you know any device which can support the multiple prot density with lowest cost?




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