[c-nsp] 7200 vs. 7600

Ryan O'Connell ryan at complicity.co.uk
Mon Oct 4 15:32:54 EDT 2004

On 04/10/2004 18:52, F. David Sinn wrote:

> What Supervisor are you looking to use in your 7600?  That will 
> determine some of the answers to your questions below.

Sup720-3BXL, specifically to start with:
WS-CAC-4000W-INT (Second PSU)
WS-X6548-GE-TX (For peering/transit connections and connections to 
access-layer switches)
OSM-4OC3-POS-SI+ (For aggregation/leased line termination)

> The only one that is consistent is the re-use of dot1q tags.  Since 
> the 7600 is a ethernet switch at heart, using the same tag on two 
> interfaces puts them on the same broadcast domain.  Also, I don't 
> believe that they have implement the physical sub-interface style of 
> configuration for dot1q as the regular routers do, so you would have 
> to migrate to VLAN interfaces to support dot1q (please correct me if 
> this has been fixed).

Not sure I follow in terms of "VLAN interfaces"? Do you mean you can 
only do:
interface GigabitEthernet1/1
  switchport mode trunk
  switchport trunk allowed vlan 111,222
interface VLAN111
  ip address
interface VLAN222
  ip address

But not:
interface GigabitEthernet1/1
  no ip address
interface GigabitEthernet1/1.111
  encapsulation dot1q 111
  ip address
interface GigabitEthernet1/1.222
  encapsulation dot1q 222
  ip address

I can cope with that, as long as features such as BPDU filter are still 
available on ports configured as switchports. (I.e. I don't want 
customers/peering partners seeing BPDUs, CDP etc etc. and I don't want 
them sending me similar and breaking things)

I've heard mention that the TCAM table on the 7600s can't handle a full 
routing table - however, I've been unable to verify this so I suspect it 
applies to Sup2s/MSFC2s and below only.

> On Oct 3, 2004, at 1:49 AM, Ryan O'Connell wrote:
>> Looking at the second hand cost of 6500/7600 parts vs. 7200s, they're 
>> very well priced so I'm considering 7600s instead of 
>> upgraded/additional 7200s with NPE-G1s for a forthcoming network 
>> upgrade.
>> However, I'm aware there are some things a 7600 can't do that a 7200 
>> with trunks to a lot of attached switches can. The ones I'm aware of 
>> are:
>> - It appears you can't (usefully) do anything ADSL/L2TP related on 
>> the 7600. (Which means you can't terminate an ATM circuit from a 
>> provider on it and use it as an L2TP Tunnel Switch, nor can you 
>> terminate L2TP circuits on it)
>> - You can't use the same dot1q encapsulation on two seperate 
>> interfaces, even if they're configured as Layer 3 interfaces.
>> - I presume the same restrictions on ACLs apply as when using 6500s 
>> with MFSCs in Hybrid mode. (I.e. src/dst port/ip can be 
>> hardware-switched, if you put anything more complex in there it's 
>> going to be process-switched and kill the CPU)
>> Is everything else possible? Features I'm using excluding ADSL at the 
>> moment are pretty basic ISP ones - BGP, OSPF, SPAN, ip verify unicast 
>> reverse-path, ACLs, BPDU filter, (Which I guess I won't need on 7600) 
>> Leased Line aggregation, (PA-MC-STM-1MM, but that could stay on a 
>> 7200) Netflow and some fairly basic rate-limiting on some 
>> (troublesome) customers ports. I'll probably also need Multicast soon 
>> and IPv6 "sometime".
>> -- 
>>         Ryan O'Connell - CCIE #8174
>> <ryan at complicity.co.uk> - http://www.complicity.co.uk
>> I'm not losing my mind, no I'm not changing my lines,
>> I'm just learning new things with the passage of time
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         Ryan O'Connell - CCIE #8174
<ryan at complicity.co.uk> - http://www.complicity.co.uk

I'm not losing my mind, no I'm not changing my lines,
I'm just learning new things with the passage of time

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