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 <[email protected]>: > 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: [email protected] >> To: [email protected] >> CC: [email protected] >> >> 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 <[email protected]>: >> > 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: [email protected] >> >> To: [email protected] >> >> CC: [email protected] >> >> >> >> 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 <[email protected]>: >> >> > >> >> > 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: [email protected] >> >> > To: [email protected] >> >> > 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 >> >> > >> >> > Hotmail: Powerful Free email with security by Microsoft. 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