[c-nsp] FW: Overruns

Thu May 6 07:38:24 EDT 2010

Dear Emanuel

does the document you sent apply for 7606 ?
because i didnt found the device 

thanks a lot for your assistance 

> Date: Thu, 6 May 2010 12:43:14 +0300
> Subject: Re: [c-nsp] FW: Overruns
> From: emanuel.popa at gmail.com
> To: eng_mssk at hotmail.com
> CC: cisco-nsp at puck.nether.net
> 
> One more thing that comes to mind: load-balancing algorithm for
> ether-channels with 5 links on Cisco 7600 is pretty tricky:
> http://www.cisco.com/en/US/tech/tk389/tk213/technologies_tech_note09186a0080094714.shtml
> 
> This means that on an ether-channel with 5 GE links, considering the
> hashing algorithm documented by Cisco and good entropy, you will have:
> - max. 1000Mbps on link #1
> - max. 1000Mbps on link #2
> - max. 1000Mbps on link #3
> - max. 500Mbps on link #4
> - max. 500Mbps on link #5
> - max. 4000Mbps (4Gbps) on the ether-channel
> 
> So why not using only 4 links in the ether-channel instead of 5?
> 
> Regards,
> Manu
> 
> 
> 2010/5/5 Mohammad Khalil <eng_mssk at hotmail.com>:
> > no , there is no congestion at all either in ingress or egress direction
> > and the overruns vary from one individual physical link to another
> >
> >> Date: Wed, 5 May 2010 13:05:42 +0300
> >> Subject: Re: [c-nsp] FW: Overruns
> >> From: emanuel.popa at gmail.com
> >> To: eng_mssk at hotmail.com
> >> CC: cisco-nsp at puck.nether.net
> >>
> >> Sorry. I'm not very familiar with that kind of linecards. Only using
> >> LAN cards 67xx with DFC modules.
> >>
> >> However, when we encountered overruns we had 2 options:
> >>
> >> 1. easy one: enable "fabric clear-block"; this will get rid of
> >> overruns but will drop packets in fabric which is gonna be harder to
> >> detect; the fabric is only going to internally prioritize CoS 5 with
> >> older IOS versions; with newer versions might be another story; never
> >> tested though
> >>
> >> 2. more difficult: "ingress queuing" is necessary to overrun only
> >> packets you afford to drop, but can be done only with CoS and 802.1q
> >> configured on your ether-channels
> >>
> >> Anyways, is there any congestion at the egress in your router that is
> >> causing the overruns in the first place? Or is this a different
> >> problem than what we experienced?
> >>
> >> Regards,
> >> Manu
> >>
> >>
> >> 2010/5/5 Mohammad Khalil <eng_mssk at hotmail.com>:
> >> > The cards are SFM-capable 48 port 10/100/1000mb
> >> > we connect 10 connections from each router to the ASN , each 5 are
> >> > grouped
> >> > together , 5 for VLAN that handle RAS to ASN communication and the other
> >> > 5
> >> > to handle ASN to Core communication
> >> >
> >> >> Date: Tue, 4 May 2010 23:50:31 +0300
> >> >> Subject: Re: [c-nsp] FW: Overruns
> >> >> From: emanuel.popa at gmail.com
> >> >> To: eng_mssk at hotmail.com
> >> >> CC: cisco-nsp at puck.nether.net
> >> >>
> >> >> hi mohammad,
> >> >>
> >> >> what kind of linecards are you using? what capacity? how many links
> >> >> per ether-channel?
> >> >>
> >> >> we had similar problems with overruns at ingress because of egress
> >> >> congestion. there are different workarounds for each setup. all
> >> >> problems are related to buffers and fabric connections though.
> >> >>
> >> >> regards,
> >> >> manu
> >> >>
> >> >>
> >> >> 2010/5/4 Mohammad Khalil <eng_mssk at hotmail.com>:
> >> >> >
> >> >> > hi all
> >> >> >
> >> >> > i posted this issue earlier but didnt get a solution
> >> >> > anyway the MTU settings from both side are the same 1500 bytes
> >> >> > i dont think that the MTU modification from Cisco side as its related
> >> >> > to
> >> >> > the number of packets sent from the ASN side and received by the
> >> >> > Cisco side
> >> >> > i was viewing the buffers on the Cisco side and found below
> >> >> > Public buffer pools:
> >> >> >
> >> >> > Huge buffers, 18024 bytes (total 2, permanent 2, peak 11 @ 5w5d):
> >> >> >     2 in free list (0 min, 4 max allowed)
> >> >> >     10062 hits, 182 misses, 364 trims, 364 created
> >> >> >     0 failures (0 no memory)
> >> >> >
> >> >> > do the misses number indicate anything ??
> >> >> > does the buffer tuning will solve the issue ?
> >> >> > even the IOS upgrade didn't solve the issue
> >> >> >
> >> >> > Thanks
> >> >> >
> >> >> > From: eng_mssk at hotmail.com
> >> >> > To: cisco-nsp at puck.nether.net
> >> >> > Subject: Overruns
> >> >> > Date: Tue, 6 Apr 2010 11:44:46 +0300
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> >
> >> >> > hi all
> >> >> >
> >> >> > i have 2 cisco 7606 routers connected to ASN GW for wimax traffic
> >> >> > we had a problem with overruns on the port channels
> >> >> > we connected 5 cables from the ASN to both routers and configured
> >> >> > port
> >> >> > channels for VLAN and the same setup for another vlan
> >> >> > one vlan is for communcations with RASs and one to transport the
> >> >> > traffic
> >> >> > for into the core cloud
> >> >> > anyway we upgraded the IOS version on the routers thinking thats
> >> >> > might
> >> >> > solve the issue but still
> >> >> > please find below
> >> >> >
> >> >> > CR1.KJ-Building#sh int po10 | inc over
> >> >> >     1 input errors, 1 CRC, 0 frame, 72395 overrun, 0 ignored
> >> >> > CR1.KJ-Building#sh int po20 | inc over
> >> >> >     6 input errors, 2 CRC, 0 frame, 734930 overrun, 0 ignored
> >> >> >
> >> >> > CR1.KJ-Building#sh run int po10
> >> >> > Building configuration...
> >> >> >
> >> >> > Current configuration : 259 bytes
> >> >> > !
> >> >> > interface Port-channel10
> >> >> >  description CORE_VLAN to ASN Gateway
> >> >> >  switchport
> >> >> >  switchport access vlan 10
> >> >> >  switchport trunk encapsulation dot1q
> >> >> >  switchport mode access
> >> >> >  load-interval 30
> >> >> >  speed 1000
> >> >> >  duplex full
> >> >> >  flowcontrol receive on
> >> >> >  flowcontrol send on
> >> >> > end
> >> >> >
> >> >> > CR1.KJ-Building#sh run int po20
> >> >> > Building configuration...
> >> >> >
> >> >> > Current configuration : 258 bytes
> >> >> > !
> >> >> > interface Port-channel20
> >> >> >  description RAS-VLAN to ASN Gateway
> >> >> >  switchport
> >> >> >  switchport access vlan 20
> >> >> >  switchport trunk encapsulation dot1q
> >> >> >  switchport mode access
> >> >> >  load-interval 30
> >> >> >  speed 1000
> >> >> >  duplex full
> >> >> >  flowcontrol receive on
> >> >> >  flowcontrol send on
> >> >> > end
> >> >> >
> >> >> > CR2.KJ-Building#sh int po10 | inc over
> >> >> >     0 input errors, 0 CRC, 0 frame, 17889 overrun, 0 ignored
> >> >> > CR2.KJ-Building#sh int po20 | inc over
> >> >> >     0 input errors, 0 CRC, 0 frame, 826604 overrun, 0 ignored
> >> >> >
> >> >> > CR2.KJ-Building#sh run int po10
> >> >> > Building configuration...
> >> >> >
> >> >> > Current configuration : 259 bytes
> >> >> > !
> >> >> > interface Port-channel10
> >> >> >  description CORE_VLAN to ASN Gateway
> >> >> >  switchport
> >> >> >  switchport access vlan 10
> >> >> >  switchport trunk encapsulation dot1q
> >> >> >  switchport mode access
> >> >> >  load-interval 30
> >> >> >  speed 1000
> >> >> >  duplex full
> >> >> >  flowcontrol receive on
> >> >> >  flowcontrol send on
> >> >> > end
> >> >> >
> >> >> > CR2.KJ-Building#sh run int po20
> >> >> > Building configuration...
> >> >> >
> >> >> > Current configuration : 258 bytes
> >> >> > !
> >> >> > interface Port-channel20
> >> >> >  description RAS-VLAN to ASN Gateway
> >> >> >  switchport
> >> >> >  switchport access vlan 20
> >> >> >  switchport trunk encapsulation dot1q
> >> >> >  switchport mode access
> >> >> >  load-interval 30
> >> >> >  speed 1000
> >> >> >  duplex full
> >> >> >  flowcontrol receive on
> >> >> >  flowcontrol send on
> >> >> > end
> >> >> >
> >> >> > any advice in regards
> >> >> > thanks
> >> >> >
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