CSCuo20047 - 4451-X Gig interfaces support andgt; 8 MAC addr

[Ian Brennan]

Is this real life?  The 4451-X is a $20,000+ router and we can't have more than 8 MAC's per hardware interface??  Makes no sense, we are seeing this exact bug when trying to run port-channels with more than 8 sub interfaces.

[Philip D'Ath]

It's a bit hard to anything about this now, but perhaps you needed something more service provider focused, like an ASR 1k.  Do you have a layer 3 switch that might be usable to resolve the issue?

A cheaper option may be to get more physical routed ports.  A tough swallow, I think.

I don't think I have ever seem a customer even use sub-interfaces with a Port-Channel to that degree on the mid-range platforms.

[Ian Brennan]

I'll admit we are using port-channels in a unique way, but I really do think this should be supported.  Fair point about layer 3 switch.  The reason we are actually using the 4451 instead of the switch is because we are doing things like re-distribution & PBR on the 4451 for WAN failover with multiple providers, some are layer 3 and some are layer 2.  So we are actually terminating the WAN providers on the switch (4507/SUP7L-E) and maintain layer 2 access through the switch to a pair of 4451's via  VLAN over a port-channel.  That way we have some redundancy with the 2 4451's (even though it's a single handoff from WAN provider).  We could possibly do some of these things on the switch if we upgraded from IB base to enterprise services though... this is a hard thing to explain to the end customer.

Still, considering what the 4451-X is capable of performance wise, we should not be limited to 8 MACs per port, seems silly to me.

[Philip D'Ath]

I do like how you are using Port-Channel, and I understand that upgrading from IP Base to Enterprise on a 4507 would cost the same amount as a 4451 again.

Perhaps we could go sideways.  What about if you used a 4 port Gigabit module in the 4451 (such as NIM-ES2-4) which is comparatively cheap.

Connect two ports to your 4507.  On the 4507 use the "switchport backup interface ...." interface command, so the redundant link to the 4451 is held down unless the primary fails.  This means you don't have to worry about spanning tree.

Then just create VLANs on the 4451.  I like the Port-Channel method better, but this way will scale out on the 4451 much better and provide almost the same amount of functionality.

[Ian Brennan]

NIM-ES2-4 is cheaper than I was expecting actually, good point.  We are also doing things like EIGRP OTP (LISP), BGP, traffic shaping, and other stuff, not sure if it will all work on VLAN interfaces with etherswitch.

I wonder if NIM-2GE-CU-SFP (routed ports) would have the same MAC address limitation?

EDIT: I did just notice the bug report actually says it's fixed in some releases, the 4451 I'm on is running 15.4(2)S1.  Bug report says fixed in: 15.4(3)S0z,15.4(3)S1,15.5(1)S

I guess we will try upgrading first...

[Philip D'Ath]

I tend to put a NIM-ES2-4 in every router I sell, even if the client doesn't need it "right now".  They are such a cheap addition, and it has helped me out a lot of times having extra ports available.

[Ian Brennan]

I like that, I might have to steal that idea from you.  I can think of many times where that would of helped me too.  I have actually come across routers at new clients that have them installed for no reason, and I never knew why... maybe they were yours. :-)